L -12758-T Thesis UC-714 Issued:April1994 Conceptual Design ofa Digital Control System for Nuclear Criticality Experiments St@zen Paul Rojas* “Graduate Research Assistantat Los AlamosGroupNE-6. Los Alamos, New Mexico 87545
L -12758-TThesis
UC-714Issued:April1994
Conceptual Design ofa Digital Control Systemfor Nuclear Criticality Experiments
St@zen PaulRojas*
“GraduateResearchAssistantat Los AlamosGroupNE-6.
Los Alamos, New Mexico 87545
ACKNOWLEDGMENTS
The authcr gratefullyacknowledgesall staffand personnelof the AdvancedNuclear
Technologygroup,NIS-5,at Los AlamosNationalLaboratoryfor their guidance,
support,and assistancein completingthis study.
v
TABLE OF CONTENTS
List of Tables...
00,.....0... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lull
List ofAppendix Tables..................................................................................xiv
List ofFigures ................................................................................................xv
List ofAbbreviations.......................................................................................xvii
Chapter
1. INTRODUCTION.....................................................................................1
l.l Background. .. . . . . . . . -.--.~---~--~.~~-~~-~~-~- ..-.....................1
l.l.l NuclearCriticality.......................................................................1
1.1.2MultiplicationFactor..-------ti--.--.-.-------- ....................1
1.1.3 FissileMaterial.. . . . . . ------------------------ ...............2
1.1.4PromptandDe1ayedNeutrons....................................................3
1.1.5 Cross Sections. . . . . . -...-----.--------..-.. ...................3
1.1.6Moderatorsand Poisons.............................................................3
1.1.70ver/UnderA40deratedSystems.................................................4
1.I.8PromptandDelayedCriticality ...................................................4
1.1.9ReactiviQ----------- ------------------------ ................5
l.l.lOAtom andNumberDensities......................................................5
l.l.ll ScramSystem............................................................................6
1.1.12HistoricalPerspective:LACEF.................................................6
1.20bjeetives ............................................................................................8
1.2.1MechanicalSystem......................................................................9
1.2.2HydraulicSystem.........................................................................10
1.2.2.1 Valves.................................................................................. 11
1.2.2.2Accumulator........................................................................ 11
1.2.2.3PressureSwitches................................................................ 11
vii
1.2.2.4Pump...................................................................................11
1.3Scope ofStudy ....................................................................................12
1.4ReportOutline ....................................................... .............................12
2.THE NUMERICALSTUDY.....................................................................13
2.1 Introduction.........................................................................................13
2.2 The Monte CM1OMethod....................................................................13
2.3 Los AiamosNationalLaboratoryand MonteCmlo........ . . . . . . .15
2.41nput File Overview..............................................................................16
2.5 UranylNitrateSolutionSystem...........................................................18
2.6 Results.................................................................................................21
2.7Summary .............................................................................................24
3. CONCEPTUALMECHANICALDESIGN..............................................25
3.1 Basic MechanicalRequirements..........................................................25
3.2 options for Performingthe SlabTanks Experimenton Honeycomb... . . . . . . . . . . . . . . . . . . . . . . . . . .26
3.3 MechanicalDesign Concepts. ...............................................................28
4. APPROACHESTO CRITICALEXPERIMENTCONTROL.............,....30
4.1 GeneraIModeofOperation .................................................................30
4~DigkalVs.An~ogHtitititio um.~.mm..~~..t~~ti~~~~ti~~. .................31
4.3 Custom Digita!Systems......................................................................31
4.4 PurchasedSystems..............................................................................32
5. CURRENTCONTROLSYSTEMHARDWARE....................................,33
5.i Introduction............................................................. ............................33
5.2Test Bench ControlSystem..................................................................35
5.3 Configuringthe System........................................................................37
5.4ComponentSumm~ ...........................................................................37
...Vlll
5.4.11785 PLC-5115Processor...................e.......................................37
5.4.21771-IBD DC inputModule... . . . . . . . . . . . . . . . . . . . . . . ........38
5.4.31771-OBD DC OutputModule. . . . . . . . . . . . . . . . . . . . . . . . . ..38
5.4.41771-IFEA AntdogInputModule.-.. -------- ........................38
j.4n5120VACPowerSupply ....~.......~~~..ti....... ..................38
5.4.6 CompumotorA.YLDrive..............................................................39
5.5 Control of DC Stepper Motors. . . . . . . . . . . . . . . . . . . . . . . ..............39
5.6 The StepperMotorDrive:Characteristicsand Selection......................41
6. CONTROLSYSTEMEXPANSION.........................................................43
6.1 PLCSystem ExpansionInto Kva I---------------- ....................43
6.1.11771-ASBRemotel/O Adapter. . . . . . . . . . . . . . . . . . . . . . . ......44
6.1.21771-MI StepperControlModule...............................................44
6.1.31771-OJPulse OutputExpander.. . . . . . . . . . ............................44
6.2 Control ofACSynchrcmous ConstantSpeed Motom..........................45
7. USING THE NUMERICALRESULTSTO SIZE HARDWARE...........48
7.1 Introduction. . . . . . . . . . ---.--ti.n...------~-.~- ...................-...48
7.2 HorizontalSolutionAssembly:the SlabTmks..... . . . . . . . . ..........48
7.2.1Requirements...............................................................................48
7.2.2A4aximumSpeedAllowable... . . . . . . . . . . . . . . . . . . . . . . . . ......50
7.2.3BasicFormulas. . . . . ----------------------- ...................51
7.2.4MaximumPulseRate... . . . . .. . . .. . .. . . . . . . . . .. . ...................52
7.2.5h4inimumSpeedPossible... . . . . . . . . . . . . . . . . . . . . . . . ...........52
7.2.6Resolution....................................................................................52
7.2.7RequiredOperating Torque........................................................53
7.2.8GearheadReduction....................................................................54
ix
7.3 Summary.................................................................,...........................55
8. CONTROL SYSTEM PROGRAMMING...............,................................57
8.1 Introduction.........................................................................................57
8.2 Basic ProgrammingConcepts. . . . . . . . . . . . . . . . . . . . . . . . . ............59
8.3 Programmingthe Ana!ogInput Module..............................................59
8.4 Programingthe StepperMotor Modules.............................................60
8.5 Programmingan IntegratedDrive........................................................60
8.6 StepperControlVia an IntegratedDrive..............................................61
8.7 SequentialFunctionChart: File 001.....................................................63
8.8 Ladder ‘Logic:Files 002-12..................................................................65
8.8.1 Rung2:0--ti --------- ------------------------- ............65
8.8.2 Rung2:1......................................................................................65
8.8.3 Rung2:2......................................................................................65
8.8.4 Rung2:3......................................................................................66
8.8.5 Rung3:0......................................................................................66
8.8.6 Rung4:0......................................................................................66
8.8.7 Rung4:1......................................................................................66
8.8.8Rungs4:2 ....................................................................................67
8.8.9 Rung4:3......................................................................................67
8.8.10 Rungs4:4-4:8.............................................................................67
8.8.11 Rungs4:9-4:10..........................................................................67
8.8.12 Rung6:0....................................................................................67
8.8.13Rungs 7:0..................................................................................67
8.8.14 Rung8:0....................................................................................68
8.8.15 Rung9:0....................................................................................68
3.8.16 Rung10:0..................................................................................68
x
8.8.17Rung10:1..................................................................................68
8.8.18Rung10:2..................................................................................68
8.8.19 Rung10:3...................................................................................69
8.8.20 Rung10:4...................................................................................69
8.8.21Rung10:5...................................................................................69
8.8.22Rung11:0....,.............................................................................69
8.8.23Rung11:1..................................................................................69
8.9 summary.............................................................................................70
9. USER INTERFACESOFI’WARE............................................................71
9.1 Ovexview..............................................................................................71
9.2 GeneralFeatures..................................................................................71
9.3 UranylNitrateExperimentinterface....................................................72
10.COST ESTIMATE...................................................................................75
!0.1 Labor Cos(s.......................................................................................75
10.2MaterialCosts....................................................................................75
10.2.1MechanicalHardware...............................................................75
10.2.2ControiS).slem Hardware .........................................................76
10.3cost summary ...................................................................................77
11. CONCLUSIONS ~ 78.....................................................................................
REFERENCES...............................................................................................80
APPENDICES...............................................................................................83
A. MCNP CARD SUMMARY....................................................................83
B. NUMBERDENSITY CALCULATIONS..............................................89
C. CONTROLPROGRAM LISTING....................................................... %
D. INPUT FILES........................................................................................ 117
xi
E. NUMBER DENSITYTABLES.............................................................. 125
xii
LIST OF TABLES
Table 2-1: AssumedValues for Number DensityCalculations.....................19
Table 2-2: Mdel Materials . . . . . . . . . . . . ....ti.............--....20
Table 3-l: MechanicalFunctionand SolutionFrom MosttoLeast Essential.............................................................................28
Table 6-1: Control ComponentsforKIVA IonHand .................................44
Table 6-2: NecessaryControl SystemComponentsfol KJVA.....................44
Table 7-1: MechanicalRequirements...........................................................49
Table 7-2: Load Requirements.....................................................................49
Table 7-3: SizingCalculationsSummary.....................................................56
Table 8-1: S]abTank ProgramFiles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...63
Table 10-1: ApproximateHardwareCosts ...................................................76
Table10-2: ApproximateControlHardwareCosts......................................’76
Table 10-3: TotalEstimatedCost .................................................................77
...Xlll
LIST OF APPENDIXTABLES
Table E-1: Number Densities.......................................................................127
Table E-2: .4tomFractions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .....128
xiv
LIST OF FIGURES
Figure l-l: CriticalityWindow...........,,, , .0,..,... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 1-2: PajaritoSite (TA.l8)..................................................................8
Figure l-3: SystemsOverview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..9
Figure l-4: HydraulicSystem...................................................... ...............10
Figure 2-1: ADart GameWith a HypotheticalFrequency13istribution.......l4
Figure 2-2: FissionCross Sections for SelectedIsotoPs ....-.-...-..-l7
Figure 2-3: Slab Geomet~........ ...................................................................19
Figure 24: &ff Vs. Air Gap ......................................................................2l
Figure 2-5: ReactivityVs.AirGap . . . . . . . .......--.-..............22
Figure 3-1: CurrentExperimentalConfiguration(“Honeycomb’’)..........,.....26
Figure3-2: AdjustmentsIdeallyAvailablefor SlabTank Alignment(S!abTank on MovableCart) 77......................................................A-
Figure 3-3: MicrometerAdjustmentwith aLead ScrewConcept..................28
Figure 3-4: An Option for the Mechmic~Configuration...........-...29
Figure4-1: Block DiagramoftheGeneral Control System. . . . . . . ............30
Figure5-1: TypicalCriticalAssemblyControlDeviceRequirements...........33
Figtire 5-2: CurrentControlRoomOne Configuration................................34
Figure 5-3: Programand HardwareTest Station.... ......-..........35
Figure5-4: Control HardwareatPajarito......................................................36
Figure 5-5: DC StepperControl Options.....................................................40
Figure 6-1: AnticipatedKIVAI ControlSystem..........................................43
Figure 6-2: AC Motor ControlCircuti. . . . . . . . . . . . . . . . . . . ....................46
Figure 7-1: StepperMotorVelocityProfile..........................50
Figure 8-1: Signal FlowThrough the System...............................................58
Figure 8-2: 13asicPLCProgramming Concepts......................59
xv
Figure 8-3: Analog InputProgramming.......................................................60
Figure 8-4: General Featuresof the SFC......................................................64
Figure 9-1: Screen Shot of ComputerGeneratedControlDisplay...............74
xvi
LK)TOFABM.EVIATIONS
PLC: ProgrammableLogicController
SCRAM:quickdecreaseinsystemreactivityduetotheengagementofmechanical
motiondevices
PROM: ProgrammableRead Only Memory
PID: ProportionalIntegralDerivative
IT”L:TransistorTransistorLogic
AIX: Analogto DigitalConvefier
MCNP: Monte Carlo NeutronPhoton Code
LACEF:Los AlamosCriticalExperimentsFacility
DOE: Departmentof Energy
NEMA:NationalElectricalManufacturersAssociation
SHEBA: SolutionHigh EnergyBurst Assembly
RAP: RemoteAutorangingPiccometer
SST: StainlessSteeI
BCD: BinaryCoded Decimal
xvii
CONCEPTUALDESIGNOFADIGITALCONTROLSYSTEMFOR
NUCLEAR CRITICALITY EXPERIMENTS
by
Stephen Paul Rojas
ABSTRACT
Nuclearcriticalityis a concernin manyareasof nuclearengineeringincludingwastemanagement,nuclearweaponstestinganddesign,basicnuclearresearch,and nuclearreactordesignand analysis. As in manyareasof scienceand engineering, experimentalworkconductedin this fieldhasprovideda wealthof data and insightessentialto the fommlationof theoryand the advancementin knowledgeof fissioningsystems.In light of themanydiverseapplicationsof nuclearcriticality,thereis a continuinginterestto learn and understandmore about the fundamentalphysicalprocessest’hroughcontinuedexperimentation.This thesisaddressesthe problemofsettingup and programminga microprocessor-baseddigitalcontrol system(PLC)for a proposedcriticalexperimentusing.amongotherdevices, asteppermotor,a joystickcontro!mechanism,and switches. Thisexperimentrepresentsa revisedconfigurationto testcylindricalnuclearwastepackages.
A MonteCarlo numericalstudy for the proposedcriticalassemblyhasbeen performedin order to illustratehow resultsfrom numericalcalculationsare used in the processof assemblingthe control systemand tocorrobor : previousexperimentaldata.This studyinvolvesmodelingasolutionsystemof uranylnitratein cylindricalgeometry(twocylindrical“slab”tanks approximately28 inchesin diameterand 4 inchesthick) withthe MonteCarloNeutronPhotoncode writtenat Los AlamosNationalLaboratory,New Mexico.The resultsof this studyyieldedthe sensitivityeffect of varyingthe distancebetweenthe tanks:informationused as designcriteriato size variouscontrolsystemcomponents.In addition,the softwarenecessaxyfor experimentcontrolwas developed.
In summary,a controlsystemutilizingsomecommondevicesnecessaryto performa criticalexperiment(steppermotor,push-buttons,etc.) has beenassembled. Controlcomponentswere sized usingthe resultsof aprobabilisticcomputercode (MCNP).Finally,a programwas writtenthatillustratesthe couplingbetweenthe hardwareand the devicesbeingcontrolledin the newtest fixture.
xix
Chapter 1.
INTRODUCTION
1.1 Background
1.1.1 NuclearCriticality
The term “criticality”gerlerallyrefers to the studyof fissioningsystems that
approacha state of equilibriumbetweenthe numberof neutronsbeing producedand
the number of neutrons “dying.”Neutrons are producedby the process of nuclear
fission. In a Los AlamosNationalLaboratoryreport [15], Hugh C. Paxton defines the
fissionprocess as:
The disintegrationof a nucleus (usually,Th, IJ, Pu, or heavier) into twomassesof similarorderof magnitude,accompaniedby a ‘argerelease of energyand the emissionof neutrons. Althoughsome fissionstake place spontaneously,neutron-inducedfissionsare of major interest in criticalitysafety....
Thus, the area of major interest in nuclearcriticality is in the generationand death of
neutrons. The same diffusiontheory that has successfullybeen applied to heat transfer
and fluid mechanicshas also been successfullyused to model the process of nuclear
fission. In addition,as will be seen in chapter thee of this document,probabilistic
approacheshave provenextremelyusefulin the designand analysisof f~sioning
systems.
1.1.2MultiplicationFactor
The multiplicationfactor is denotedwith the symbol “k”and is defined as
follows [9]:
k=numberoffissions in current generation
numberoffissions inpreceding generation
So if the multiplicationfactor is less than one, then the system is called “subcritical”
and the numberof fissionsoccurringin the system is decreasingwith time. On the
other hand, if the multiplicationfactor is greater than one, then the sys:cm is said to be
“supercritical”and the numberoffissionsincreaseswithtime. Ifthemi!hiplication
factor is equal to one, then the system is said to be exactly “critical”ar:dthe number of
fissionsoccurringis constantwith time. In a critical assembly, the raticlof the number
of neutronsproduced to the numberof neutronsdisappearingis commonlycontrolled
by the use of “poison”control rods (material that absorbsneutrons). Typically there
are two basic mannersin which neutronsmay vanish:
1. Absorptionduring a nuclear reaction
2. Leakage from the surface of the reactor
There are many methodsused to model the fissionprocess:
. diffusiontheory(Fick’slaw; differentialequations):a deterministicapproach
usingfinitedifferences
. MonteCarlo: a probabilisticapproachusing statistics
● transport theory (integralequations): a deterministicapproachusing discrete
ordinates
The simplest,most fundamentalapproachand the approachused early on in nuclear
system design is diffusiontheory.However, the MonteCarlo metho~ioffers improved
accuracyin modelingcomplexgeometriesand it has been the adapted method in the
current study.
1.1.3FissileMaterial
A materialis said to be fissile if it is capableof fissionat low energy levels (i.e.,
slow neutronswith low kineticenergy). 238U, which is abundanton the planet, is
used to “breed”fissileplutoniumby bombardingthe 238U with neutrons. Another
2
method used to create fissile material is the refinementprocess used to enrich the
percentageof235U innaturallyoccurringuranium.
1.1.4Prompt and Delayed Neutrons
More than 99 percentof the neutronsemitted in a fissioningsystem are emitted at
the instant fissionoccurs; these neutronsare called “prompt.”That fractionof a
percent of neutronsthat are emitted at a relativelylong time after the initial fission
event are called “delayed”neutrons.The averagenumber of prompt and delayed
neutronsreleasedper fissionevent is given the symbolV.
1.1.5 Cross Sections
A cross section is an experimentallydeterminedparameterwith units of cm2 which
indicatesthe probabilityof a certain event occurring.Differenttypes of cross section
data used in nuclearengineeringinclude scattercross sections,absorptioncross
sections,or fission cross sections.Cross sectionstake on the units of “barns”where
1barn = 1X10-24cm2. In essence, the nuclearcross section is the “effective”cross
section of the nucleus that a neutron sees when it is travelingnear the nucleus. The
total cross section is the combinationof the fission cross section, absorptioncross
section, scattercross section,etc., and is a measureof the probabilitythat any type of
interactionoccurs when a beam of neutrons impingeson a target composedof many
nuclei.
1.1.6Moderatorsand Poisons
A moderatoris a substancewhich tends to slow down (“thermalize”)neutrons.
TypicaJmoderatorsincludewater and polyethylene. A poison is a substancewhich
tends to absorb neutrons. Typical poisons includeboron and cadmium. Poisons may
be of the “burnable”type [14] which means their absorptioncross section decreasesas
time progresses(thus increasingthe reactivityof the system).
3
1.1.7 Over/Under Moderated Systems
A systemissaidtobe“overmoderated”if themultiplicationfactordecreases(i.e.,
criticalmass increases)with decreasingdensity (i.e., increasethe amount of
moderator).On the othel hand, if as the density is decreasedthe multiplicationfactor
increases(i.e., critical mass decreases),then the system is said to be
“undermoderated,”This informationis typicallyillustratedin a plot of muhiplication
factorvs. density (or equivalently,a plot of critical mass vs. hydrogento uranium
ratio).
1.1.8Promptand Delayed Criticality
Delayedcriticalityis used to describe the state of a fissilematerial ic which
the multiplicationfactor is unity from the contributionof both delayed and prompt
neutrons. Promptcriticality is a term used to describe the state of a fissile material in
which the multiplicationfactor is unity solely from the contributionof prompt
neutrons. Thus there is a “window”in betweendelayedcriticality (the steady-state
condition)and promptcriticality.’ This windowis given the symbol ~ and it follows
that the fractionof fission neutrons that are prompt is 1-$ This can be seen by
considering that a k of unity is due to both prompt and delayed neutrons; therefore,
+ ‘—)p<o (Do
k=l k = 1/(1-~)DelayedCritical PromptCriticalp=o P=P
Figure 1-1 : CrMcality Window
IIf notfor thjswindow,bombswouldberathereasytobuildwhile nuclearreactorswouldbemoredifficult; asit is, thereverseistrue.
4
to get rid of the delayed neutrons,we subtract the reactivityamount P. One may
question the validityof subtractingthese two values since at first sight they appear to
be different units; however,at closer inspectionit is apparentthat the units are dentical
since the reactivity~ is simplythe change in k whichhas been normalizedin ccordance
with value of unity at delayedcritical.Therefore,the multiplicationfactorconsidering
only prompt neutrons is ( l-~)k. When this value is unity, the system is said to be
prompt critical since a multiplicationfactorof unity is reachedwith only prompt
neutrons.
1.1.9Reactivity
Reactivityis definedas the percentagethe system is abovedelayedcritical:
k–1P~=
Thus, negativereactivityindicatesa systemthat is below delayedcritical while positive
reactivityindicatesa systemthat is abovedelayedcritical. Typically,the reactivityis
expressed in “dollars”(or fractionsof a dollar: “cents”)by using the conversionfactor:
~ reactivity= 1dollar. The value ~ is the differencein reactivitybetweendelayed
critil dity and prompt criticality. Thus, if a systemis promptcritical, then p=~
(remember,if the systemis delayedcritical, then the multiplicationfactor is one, and
the reactivity is zero).Typically,the texm“addingreactivity”is used when the system
is already at delayedcritical (i.e.,k=l, p=O).
1.1.10 Atomand NumberDensities
Typically,numberdensitiesare used for MonteCarlo input files to define the
materialcharacteristics. The numberand atomdensitiesare defined as follows:
5
N - ~NA= atom density = atoms I cm3M
atomsnumberdensity = (N )(1x10-24cm2/ barn)=
barn--cm
where:
NA = Avogadro’sNumber
M = molecularweight
1.1.11ScramSystem
A scram system refers to an electro-mechanicalsystem which produces a prompt
decreasein reactivitydue to physical movement. For example,a scram for the uranyl
nitrateexperimentwouldconsist of quickly moving the two fissileslab tanks apart
from one another to quicklydecrease the multiplicationfactor. TypicaI1yboth
automaticand manualscramsystems are designed into critic?l experimentapparatus
(the automaticmechanismsare coupled to particle detectors located around the
experiment). In addition, for the experimentproposed in this study, an additional
gravityassistedscram mechanismmay be incorporated. Althoughthis document
focusesonly on the primarymanualscrammechanism(a hydrauliccylinder),it should
be noted that two such redundantscram systems will also be incorporated:one
automatic,and one gravity assisted.
1.1.12HistoricalPerspective:LACEF
The urgency of World War 11that spurred the Manhattan Project also demanded
that a site be establishedat the Los Alamos National Laboratorywhich would serve as
an area for experimentalwork as well as isolate the populationfrom radiation in the
event of a criticalityaccident [12].The area chosen was in Los Alamos’Pajarito
Canyon and came to be known as “PajaritoSite.”Before 1947,critical experiments
were performedat the site by hand. This changed when, in 1946,Louis Slotin was
6
killed as a resultof a componentof an assemblyslipping into a more reactiveposition
producinga superprornpt-criticalpulseofradiation.As a result,thesiteestablished
much more exactingrules governingthe operationof criticalassemblies,one of which
was the policy of performingmost criticalexperimentsremotely.Suchexperimentsare
now performedin what are called “kiva..”:2buildingshousingcriticalexperimentsthat
are controlled from a remote location. The control systemoutlined in this document
will serve as the main control system for the original “kiva”which is now referred to as
KIVA I. Figure 1-2displaysa plan view of PajaritoSite. Today LACEF(Los Alamos
CriticalExperimentsFacility)housesthe mostsignificantcollectionof critical
assembliesin the westernhemisphem. The assembliesthat may be operatedat LACEF
can be divided into three categories:
. BenchmarkAssembliesare configurationscontainingpreciselyknown
componentsthat have interchangeableor adjustablefissilecores and reflectors.
. AssemblyMachinesare generalpurposeplatfoms into which fissile,
moderating,reflecting,and control componentsmay be loaded for short range
studiesof the neutronicpropertiesof the materials. The assemblymachine
describedin the followingsection falls into this category. IKis worth noting
that assembiymachinesdo not actuallycontain fissilematerial;they only
manipulateit.
● SolutionAssembliesallow criticaloperationswith fissilesolutions. The
experimentproposed in this study is a solutionexperimentmountedon an
assemblymachine.
2~c HoPi Indiannamefora roundceremonialchamber
7
1.2 Objectives
The main goal of this project is to create a numericaImodelof a fissioningsystem
(“criticalassembly”)using a well-establishedcomputercode and then bring togethera
systemfor controllingthe assemblybasedon the resultsof the numerical study.
Althoughthe numericaIresults will be specific to a certain criticalexperiment,the
control system will be inherentlygeneraland may readily be used to control other
experiments(specifically,an experimentinvolvinga steppermotorand hydraulic
system). In order to address the specificdetails that must be consideredwhen sizing
and selectingcontrolcomponents, a complete sizing analysis for the proposed system
is given in chapter seven. An introductionto the proposedexperiment follows.
T -“. ..’SJEbo..”’Kivo”i..
Bldg. PL-23 ● . ~ ‘ T
\
.‘, -. ., RYjcxito, / ‘, ”., .,.:: - ,;. ,,.. .“ . .‘- . Rood. . , . . . .. . . . . . /!? ‘, ~,““ .: : - ,,.. ..- . . ●‘.Fuprito-n “. “. .
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. , ....,. ... . . “----- y$yx..” -, ,, .
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. ......● .* -.. ,\~., “. . .,..’ . . .., . -.
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“-~ 1.., . ..-, ... . ,. .,. . ,. ... . ● Q,. . ... .... : .’
. - ..: . . .’”, , . ‘“ ““=?%*
,, “, : :: : ... . . ,. : . .: j /-
. ● ✎✎ ❞✎✎✛✌ ✞� ✌ ✎✌ ✌ ✚
8
Figure 1-2: Pajatio Site (TA-18)
1.2.1MechanicalSystem
‘I”hesystemchosen for study is a uranylnitratesolutionsystemin cylindrical
geometry. The experimentconsistsof two “slab”tanks filled with highlyenriched
uranyl nitrate,U02(N03)2, that must be pushed together remotely. The general
mechanicalsetup for achievingthis is shownbelow [11].Note that the detaileddesign
of mechanicalcomponents(e.g., supportbrackets or translationtables) has been
omitted in order to focus attentionon the two systems of primary interest from a
control system point of view: the stepper motorfleadscrew combinationand the
hydraulicsystem.PoisonMakrial (orGravityAssisted-
Movabkslabrank
sWr8mrorilrad~ oIlydradic cylidcr (Supplrrtfnma Orniaedfwchrily) (SupyrortfmrresomiucdfordAy)
,“” 3EE5L
SideView FrontView
Figure 1-3: Systems Overview
A hydrauliccylinder is used to push the movablecart toward the stationary tank.
Once the air gap betweenthe two tanks is decreased to a preset distance, the hydraulic
cylinder is shut down and the final approachto critical is made with a stepper motor
and lead screwthat drive a linear translationtable (upon which the moving tank sits).
The steppermotorlleadscrew combinationis used in favor of the hydraulic system for
finalclosure in order to increaseresolution(as will beeome evident in the following
chapters,such a systemis extremelysensitiveto small changes in the air gap). This
document focusesonly on the control of the stepper motorfleadscrew and hydraulic
systems. A completespecificationof all the syste~~ necessaryto perform the
experimentwould involvedesigning the frameworkfor the secondarygravity assisted
scram system (general concept illustratedin Figure 1-3)as well as all of the detail
design for componentssuch as mounting bracketsor mechanicalinterfaces(e.g., the
lead screwh.ranslationtable interface).
1.2.2HydraulicSystem
Figure 1-4below showsthe simplifiedhydraulicsystem circuit that is used to
control the hydrauliccylinderportion of the assembly [10]. Basically,the pressure
differentialm the cylinder is controlledby runningline pressurethrougha series of
three normallyopen or normallyclosed control valves.s
vI
No. ACC.
1
N.C.1
— IN
Figure 1-4: Hydraulic System
3Nom~]y open:whenpowerisofc,thewdveisopenNormatlyclosed:whenpowerisoff, thevalveisclosed
10
1.2.2.1Valve$
A total of three valves are used to regulate the pressure throughout the system.
When N.O. is open and N.C. 1and N.C. 2 are closed, the system is scrammed. When
N.O. is closed, either N.C. 1or N.C. 2 can be opened dependingon the speed desired
(speed is set by needle valves associatedwith N.C. 1and N.C. 2). When all of the
valves are off, the hydrauliccylinderis inactive.
1.2.2.2Accumulator
The accumulatorserves as a power source to the hydrauliccylinder in the case of
power loss. If power is lost, the normallyopen valve connectingthe accumulatorto
the scram line will open and N.C.1 and N.C.2will close,causingthe assemblyto
automaticallyscram.
1.2.2.3Pressure Switches
Two pressure switches, identifiedby PS1 and PS2, are used to check the
accumulatorpressure range and the scram line pressurerange. When a Iimit is
reached, the switch is activatedon.
1.2.2.4PumD
The pump provides the pressurenecessaryto move the hydrauliccylinder and
pressurize the accumulator. For the purposesof the control systemthat will be
discussed in the followingchapters, it is assumedthat controlof all hydraulicsystem
components requires 10-60volt DC power.Therefore,as will be made clear in the
followingchapters, the only type of control system output device needed is a DC
output “module”to send the appropriateDC voltage to the desired valve or pump.
11
1.3 scow of Study
This study completesthe preliminaryconceptualwork necessary for conductinga
criticalexperimentinvolvinguranylnitrate in cylindricalgeomet~ usinga horizontal
split table and, in essence,proves that such an experimentis feasibleby outliningthe
hardwareand softwarenecessaryfor conductingthe experiment.The scope of this
study includesthe conceptualdesignof the main mechanicalcomponentsas well as the
system needed to control these components. Detaileddesign of mechanical
components is outside the scope of this study and is taken as a “given.”
1.4 Report Outline
This report begins with a numericalstudy of the physical system to be controlled.
Next, the mechanicaldesign requirementsare outlinedand the conceptualmechanical
design that fulfills these requirementsis illustratedand brieflydiscussed. The
hardwareneeded to control this physical system is the next general topic addressed. In
these chapters ( chapters four, five, and six), the approach to control and the control
system componentsare discussed and introduced.In chapter seven, the results of the
numericalstudy are used to size hardwarecomponentsfor the experiment. In chapters
eight and nine, the softwareused in conjunctionwith the control hardware is
discussed. Finally, in chapter 10,a cost analysis for performingthe experiment is
presentedand discussed.
12
Chapter2.
THENUMERICALSTUDY
2.1 Introduction
Numericalstudies(as well as any availableexperimentalresults)will give an idea
of the characteristicsof the physicalsystembeingcontrolledand yield such design
informationas: how fast the systemcan be moved together, what kind of torque is
needed,and whatkind of control systemhardwarek needed to satisfy all of the
specifications. Used for this purpose,the Monte Carlo method (MCNP) is briefly
discussedhere and numericalresults for the experimentintroducedin chapter one are
generated.The data generatedhere is used to size a stepper motor and the peripheral
electrical&vices needed for the uranylnitrateexperiment. An admittedlysimple
modelof a uranylnitrate solutionsystemin cylindricalgeometryhas been created;
however,at this level of design, it is sufficientto corroborategeneral trends in data
froma previouslyconductedexperimentinvolvinguranylnitrateand similar
geometry.This numericalstudy is the fmt step in the followingprogressionof events:
● MCNP studies to determinevalues needed for the sizingof basic control
systemcomponents
● control system componentsizing: stepper motor, stepper motor drive
● componentinstallation
● programmingand debugging
2.2 The Monte Carlo Method
The methodof solving governingequationsby statisticalaccumulation(playinga
“game”)is used in many areasof scienceand engineeringincludingconductiveand
radiativeheat transfer, turbulence, and most pertinent to this paper, neutron physics.
The MonteCarlomethod involvesa physicalprocess that inherentlyexhibits some
form of randomness.The terms “randomwalk”or “Markovchain”often arise in the
discussionofsuchprocesses.Strictlydefined,a Markovchain is a seriesofsequential
events for which the probabilityof each succeedingevent is uninfluencedby prior
events [16].From this definitionarose the term “randomwalk”: an expression
describingthe randomnesswith which a dmnk man ambles down the street.This
random walk phenomenonis present nearlyeverywherein nature:
● the directiona bundle of photons is emitted during a radiativeheat transfer
process can be modeled as a random process
● the generationand death of vortices in turbulent fluid flow can be seen as a
random process
. the life and death of a neutron during the fissionprocess can be modeledas a
random process
Thus, any seeminglyrandomprocesscan be modeledas long as one critical piece of
experimentaldata is available: the frequencydistributionof the event or events. For
example, in a game of darts, the frequencyof a dart hitting at some radial positionon
the dart board may be graphicallydisplayedby plottingfrequency(i.e., numberof
times the dart hits) vs. radial position on the dart board.
14
Figure 2-1: A Dart Game Witha HypotheticalFrequency Distribution
Typically,thefrequencydistributionismathematicallymanipulatedintermsofmore
convenientfunctionssuch as the “probabilitydensity function”or the “cumulative
distributionfunction.”For instance,if the frequencydistributionis denoted by f(~)
then the probabilitydensity functionis foundby normalizingthe frequencydistribution
(i.e., dividingby the area under the j(<) curve):
p(g)= , f(~)Jf(E)4u
So if random numbersare chosen for& the resultingdistributionmust resemble that
defined by the equationshown above. In other words, we may create a probabilistic
model that repeatedlyplays the same “game”utilizingrandomnumbersand physics.
However,those random numbs must agree with the probabilitydensity function that
is observedin physicalrealityand definedby the generalequation shown.
2.3 Las Alamos National Laboratoryand Monte Carlo
The Monte Carlo methodemerged from work done at Los AlamosNational
Laboratoryduring World War II and the inventionof the method in general is
attributedto Fermi, Von Neumann,and Uhun. This initial work on the Monte Carlo
methodeventually led to what is now known as MCNP: the Monte Carlo Neutron
Photon computer code [6]. MCNP is a general purpose Monte Carlo code that can be
used for neutron,photon, or coupled neutron/photontransport and is generally
recognizedas one of the best codes in its class since it incorporatesstate-of-the-art
physics,data, and mathematicalmethods.
MCNP followsthe entire life of manyparticles from life to death; the “game”
15
(fissionprocess) is startedby a sourceof freedstrength specifiedby the user. When
run in neutron transportonly mode, there are four possibleevents a neutron can see
duringitslifetime:
1.Neutron scatter
2. Fission
3. Neutron capture
4. Neutron leakage
MCNP simply followsthe entire life of each particleby randomlyselectingone of the
possibleevents (and, if scatter is selected, a rdndomdirection)based on a set of rules
(physics)and probabilities(transportdata) governingthe processesand materials
involved.As the lifetimehistory of more and more neutronsis followed,the
distributionof neutrons is better known. Typical fission cross sectiondata for 235U
and other fissile materialsis shownon the followingpage [15]. In addition to fission
cross sections,other cross section data is used by MCNP includingscatter, absorption,
and capture data. As seen on the plot, 235U has a much higher probabilityof fission
occurring when the neutronsare in the “thermal”(i.e., ambient temperature)region
rather than the “fast”(i.e., greater than ambient temperature)region. In between the
thermal and fast regions, the probabilityfor fissionfluctuatesgreatly; becauseof this,
nuclear systemsare commonlyreferred to as being in one of two distinct states: “fast”
or “thermal”(the system is forced to be thermal or fast by design).
2.4 Input File Overview
A typical MCNP input file is composedof four major sections;each section being
composed of a number of input “cards”(horizontalrows of data). The four major
sections are:
. Geometryspecificationcards
. Surfacespecificationcards
‘F----”:”’
//.’
.’
17
● Importancecards
● Materialspecificationcards
● h4CNP“mode”cards
● Tally cards
Each of these sections is discussedin moredetail in Appendix A.
2.5 Uranyl Nitrate Solution System
A simple modelof a uranyl IIitratesolutionsystemin cylindricalgeometryhas been
created. The geometryused in the study is shown in Figure 2-3 and the [naterialsused
in the model are defined in Table 2-2. This geometrywas created by defining a total
of 13surfaces,nine of which were planes normal to the Y axis; three were cylinders
centered on the Y axis, and two were spheres centered about the origin. The cells
were created by defining the appropriateintersectionand union of surface senses as
explained in AppendixA. The two cylindricalslab tanks were sumoundeciby a
sphericalshell of six inch concrete;air was placed inside this sphere and around the
tanks. The importanceof the sphericalregion of interestwas assigneda value of one
v$ile everythingoutside that region was assignedan importanceof zero. The numtxr
densitiesused for the uranyl nitrate solution were calculated assumingthe data shown
in Table 2-1 (see AppendixB for the calculations)[4] while the numberdensities for
the remainingmaterialswere taken from publishedliterature [17] (in reality, atom
fractionswere entered; but as explainedin AppendixA, this is equivalentto number
densities). While not to be used in practice, the concrete shell was used in order to
crudely model any reflectioneffects from surroundingwalls.
18
28.5”DIA. I
27.ti”DIA.
Spherical shell made from two spheres
H w+4.48”Lh’i@ Nitmc .487”30%Bond Po]y
H
Figure 2-3: Slab Geometry
Table2-1 : Assumed Valizesfor Number Density Calcukztions?-
SolutionConcentration:405.2 gll
NominalOveidl Densityof UranylNitrate: 1.558g/cc
Solution Acid Content: .32 Molar (HNO~)
Enrichment:93.1 % 235U
5.9% 23%
1% 23%
8 for 2%J = .M7
2(I
Fission products such as 236U were not included in the model since the affect on
the fissionprocess has beenassumed negligible. In addition,other extraneous
elements that might be present in solution such as Fe, Na, or Al were not modeled.
The generalgoal of this study was to determinethe system sensitivityby varying the
air gap betweenthe two tanks, thereby revealing limitationsand characteristicsthat
must be consideredwhen assemblingthe control system.
Table2-2 : Model IUatcwiaic- —-.. - - . ------- ... . . . . —-
Material Composition NumberDensity(atoms/barn-cm)
UranylNitrate Solution 234 1.W33X1O-5 —235; 9.67I9x1O-4238u 6.0521X10-5
H .0544393850 .03600846N .00226872
StainlessSteel c .000317Cr .016471Mn .001732Fe .06036Ni .006483Si .001694
Concrete H 1.4868x10-2c 3.814x10-3o 4.15I9X1O-2Ca 1.1588x10-2Si 6.037x10-3
Mg 5.87x10-4Fe 1.968x10-4Al 7.35X1O-4Na 3.O4X1O-4
(table continues)
Air Ni .7840 .211Ar .005
30 wt% Berated Poly H 5.19X10-2c 2.O6X1O-2B 3.54x1O-2
2.6 Results
Figures 2-4 and 2-5 show the results of the air gap study. All values of I+ff shown
are at the 68% confidence level.The ~ff valuesshownhave been calculatedby
combiningthree separateestimationtechniquesthat MCNPemploys (collision,
absorption,and track lengthestimates).The followinggenera!characteristicsof the
model are noteworthywhen a comparisonwith experimentaldata is made:
● model does not include fissionproductsor other elements such as iron,
aluminuin,or sodium that could be present in solution
● modelgeometrymay differ slightlydue ambiguitiesin someexperimental
dimensions
Keff Vs. Alr Gap99
‘-0’0~MONPRooulm
flmsnt Rooults
0.0s0}’r
~9
-:----
7’-----.+...0.980
1.--%:+..-““l‘....>.>=
0.070
0900 L-m-T&A0.ss o.4a 0.6s o.ea o.7a o.8a o.sa t.oa I.w
AIR OAP (Inohoo)
Figure 2-4: Keg VS.Air Gap
21
I?eactlvlty Vs. Alr C3ap
0 MONP ROSU180- •lmll~f espcrtmon8 nDowlts
4.QOOO--—-—–——-—— ,4● % - 1.a4a - 2 /808 r-2 - 0 000
0.0000 - -.i -=-...,, .=
-1.0000
}
.. ,
““”-\-.,
f-2.0000 ‘=...---:--..>..
=E-
, L------ ‘--s.0000 -d I‘\ ““-..........
4
/?,‘\\ :;K-.
-4.0000 -= b’ ‘-”- ‘1-i y - -o. B2e - 2.890X r-2 - 0.6s4
-6.0000 ! II 1 I I , 1 r I 1
0.s3 0.43 0.63 0.03 0.7s O.ea 0.0s 1.0s 1.13AIR ~AP (Inuhoo)
Figure 2-5: Reactivity vs.Air Gap
The results shown are within two percentof similarexperimentalresults for uranyl
nitrate in slab geometry. Althoughthis error might ii~kkdly appear small, it is
enormous in terms of criticality. For example, a 1.426percentemor in ~ff translates
into approximatelytwo dollarsdifferencein re~ctivity:a differencebetweenthe system
being well subcriticalVS,the systcm beingdelayedcritical; refer to air gap= .45”on
Figures 24 and 2-5. While the experimentalreactivityat this separationdistance is
ze]’o,the reactivity from the MCNP study is calculatedas:
= -2.07 dollars
TJ
Duetotheextremeeffectsofsmallchangesin!+~,anymodelthatwillbeusedto
predict criticalitymust preciselyaccount for the effect of each material in the general
vicinityof the fissioningsystem. This was not the case for the exjxximentaldata
referencedhere; the model does not preciselyaccount for all materialspresent in the
actual experiment. So why model the system in the first place? Althoughthe
informationshown in the two figurescannot (and absolutelyshould not) be used for
criticalityprediction,it can be used for sizing the control system. This is because,
:d[hw]~k the MCNP resultr arc offset h:-I !heexperimentalresults. the slope oi the
MCNPdata is in approximateagreementwith the experll.i~,. . ..!ts.In fact, the
Monte Carlo results yield a 4.5 % conservativeestimate for the slope of the plot. This
means that the maximumrate at which the assemblywill be allowedto move (as
definedby the conservativeestimate)will be slowerthan the actual maximumspeed
allowable(as definedby the experimentalresults).In this case, we were lucky since
there were experimentalresults with which to compare the numericalresults. If an
experimentwere to be performedwithout such a luxury, we would need to
painstakinglyensure that the model resembledthe physicalsystem as accuratelyas
possibleby modelingeach materialpresent in the experimentexactly (e.g.:exact
dimensions,exact solutioncomposition).
Nominallyfour to five millioncollisionswembankedwith approximately 140,000
neut.mnsgeneratedper run. In assessingthe results of these Monte Carlo calculations,
a distinctionis made betweenprecisionand accuracy. Precisionis the uncertaintyin
the average valuecalculatedby the program itself. Accuracy,on theother hand, is a
measure of how close the calculated result is to truth. Jr other WO’-k, results may be
precise and not veg accltr: ‘f r .’onv .~!’iymi,- be:’ ‘( TaItZ’and ‘0[ very prcCi~. In
Ilnc]udingthe~ssiblc presenceof unventedradiolyticgws
-)3
thiscase,sinceweknowthatthetruthfulvalueisapproximately10.89centshm based
on previousexperimentswith the uranyl nitrate packages,we may conclude that the
model predictionof 11.38centshmn is very accurate(.49 cents/mmconservative)
despite the lack of highly detailed modeling. The precisionof the data shown is at the
68% confidence level; in other words, if 100runs are performed,then 68 of the values
(one standarddeviation)will fall within the precisionbars shown on the plot. While
the data shown is not extremelyprecise, the numberof cycles performed(50 cycles
with a nominal 3000 neutronsgeneratedper cycle) is considered large enough to result
in adequate accuracy. Therefore, the numerical results shown here corroborate the
slope measuredfrom experimentand suggest a moreconservativeestimate for sizing
the control components. This is the estimate that will be used in chapter eight.
2.7 Summary
The Monte Carlo studies performedindicate that approximately 11.38cents of
reactivityare added for each millimeterof closure betweenthe tanks.This value
conservativelycorroboratesthe experimentallymeasuredvalue of 10.89cents per
millimeterand, in general,providesan estimate for how muchexcess reactivityis
present in the system (i.e.,how sensitivethe system is to smaJldisplacements). As will
be shown in chapterseven, these valuesset the maximumallowablevelocity,the
stepper motor and drive type, the lead screw pitch, and the gear reduction ratio.
24
r
Chapter3.
COWEP’I’UALMECHANICAL DESIGN
3.1 Basic MechanicalRequirements
While it is not the goal of this study to provide the detailed drawings for
manufacturingexperimentalapparatus.the mechanicaldesign aspect of the project
must neverthelessbe addressedon a conceptuallevel. The fundamentalmechanical
requirementsfor the experimentincludethe following:
. Two frames must be de~ignedthat will hold eaeh of the two cylindrical tanks.
Reflectionfromthese framesmust be held to a minimum;therefore,a minimum
amountof materialtiwts!illprovidesthe greateststabilityand reliabilitymust
be used. Since the mean free path of aluminumis relativelylarge, this material
is somewhattransparentto neutrons and would serve well for the application.
. A translationdevice must be designedor purchasedthat will be driven by a
stepper motor upon which the movingslab tank will rest.
. Adjustmentdevices must be designedor purchased in order to adjust the
relativeslab tank positions.
The main requirementscan be summarizedby the need to secureboth slab tanks on
each cart with the maximumadjustmentcapability(positionalfine tuning) and the
minimumneutronreflection. Since these goals are contradictoryin nature, a number
of design iterationswill be necessary;a conceptualdesign to begin the process is
offered in this chapter.
As seen in Figure 3-1 on the followingpage, the “honeycomb”structure is a lattice
of extruded aluminumtubes that were placed together for a previousexperimenton
the horizontalsplit table referred to as “Honeycomb.”
25
26x 243.in. quxm Al Idah
Figure 3-I : Current Expen”mentalConfiguration(“Honeycomb”)
This is the cumentconfigurationof the experimentalassembly;as shown,the extruded
aluminum tubes are held in place by four clamp %x. The next section discusses the
options availablein fit~.ingthis split table for the slab tanksexperiment.
3.2 Options for Performing the Slab Tanks Experiment on Honeycomb
There are two options that may be considered when approachingthe conceptual
mechanicaldesign. The first is to mount the tankson the existing split table with the
honeycombstructures in place. The second option (Figure 1-3)is to take the
honeycombstructureoff of both tables and design space frames for each tank from
scratch (as opposed to retro-fittinga design to the existing honeycombstructure). The
latter of these two options is preferablesince positioningof the slab tanks maybe
accomplishedin a much more precisemanner using this approach. As the numerical
studyclearly indicated,the system is exfremelysensitiveto small changes in tank
position; therefore,relativelysmall toleranceson the order of .001 inch must be
imposedon the mechanicaldesign. Ahhough this avenue is more costly, it provides
for greater experimentalaccuracysince positionaladjustmentsmay readily be designed
into the structure from the outset. The advantageof removing the Honeycomb
material is particularlyevidentwhenconsideringthat locatingany singlepoint within
the lattice is achieved at best with large uncertaintiesdue to the structure’s
26
constructionand the originalexperimentalintent: to mockuprelativelylargecritical
systemswith inherentlyloose tolerances. As seen in Figure 3-2 below, the tank would
ideallyhaveadjustmentcapabilitiesintheX,Y,Z,THETAX,and THETAZ
directions in order to ensure proper tank alignmentand increaseexperimental
flexibility.Whilethis goal is ideal,cost and fabricationconstraintspracticallylimit the
adjustmentfeatunx to a minimum:the X and Y directions.z
THETA Z
-x-x
t
z
I
Figure 3-2: Adjustments Ideally Avaikble for Sikb TankAlignment (Sikb Tank onMovable Cart)
Adjustmentin the Y directionallows for final closure via a steppermotorfleadscrew
attachedto a translationtable while adjustmentin the X directionoffers fine
adjustmentto ensure the tanks are not offset with one another. The remaining
adjustmentaxes shown must be fixed accuratelyby the mechanicaldesign itselfor
adjustedwith shims.
27
3.3“MechanicalDesign Concepts
Table 3-1 displays the generaldesign philosophyfrom the mostessential,basic
functionsat the top, down to the less essential but no less desirabledetailed functions
at the bottom. Included in this table are likely hardware solutionsto the desired
functions.
Table3-I: Mechanical Function an
FUNCTION
Tank securityand stability
Roughtank movementover a relatively
Ionz distance
Fine tank movementover a relatively
short distance
Tank alignmentadjustmentin the X
direction
Tank alignmentadjustmentin the Z
direction
Rotationaladjustments
Solution From Most to Least Essential
SOLUTION
Rigidaluminumspace frame
Hydrauliccylinder
Stepper motor/lead screw
Micrometerhead/leadscrew device
(figure 3-3)
Micrometerhead/Ieadscrew device
(figure 3-3)
Rotationaltable/micrometerhead device
Micrometer x
Figure 3-3: MicrometerA~”ustmentwith a Lead Screw Concept
28
Figure3-4 belowillustratesone possibIemechanicalconfigurationfor achievingthe
minimumrequirements. In this option, two translationtablesare essentiallystackedon
top of one another in order to provide for the X and Y translation. A micrometerhead
is used as the means for adjustmentin the X directionwhile a stepper motor is used to
achievefinal closure intheYdirection.Figure3-4 presentsone feasibleoption for the
mechanicalhardwareconfigurationand is not intendedto be exclusiveof other
configurationsthat may be equally viablesuch as differentspaceframedesignsor slab
mountingmethods. The followingchaptersdiscusshow such a system will be
controlledremotelyand assumea given mechanicalconfiguration.
XTr+ioII Table
),
, I( I
Imuknl [email protected]
\
r 7 ———
lid
pJ I 0 1[ MOVABLE CART 1 I~... 1
FrontView SideView
Figure 3-4: An @ion for the Mechanical Con#igumtion
29
Chapter4.
APPROACHES TO EXPERIMENT CONTROL
4.1 General Mode of Operation
After determiningthe basic systemparameters(namely,the system’smechanical
design and change in reactivitywith linearposition),we are in a positionto consider
the control system. Typically, the control system used for critical experimentswill not
operate using PID type automaticcontrol and will not require the extremely fast
response found inhighperformanceservo-typecontrol systems [8,19].Instead, the
system will incorporatesimple feedback to verify the state and positionof output
devices;this is the simplestsystemthat achievesconsistentand reliablemechanical
control. Although feedbackis present in such systems (opticalencoder,
thermocouples,etc.), it will generally not be used for proportional type control of an
experiment(as indicatedby the dashed line in Figure 4-1 below).This restriction is
dictatedby current DOE enforced technicalspecifications.
t I
I I I
I
!L — ——— —— ——.--Eiizl-----
————IIIII
I————
Figure 4-1: Blbck Diagram of the General Control System
30
4.2Digital Vs. Analog
In the past, control of criticalexperimentremoteassemblymachineshasbeen
achievedthroughthe use of hard wired control systems.Althoughsuch systems have
proven reliable, the advent of the powerful,dependable,low cost, microprocessorhas
madedigital systemsa very lucrativeoption. Uniikehardwiredsystems,a digital
control systemoffers the flexibilityof quicklyand easilychangingthe controller
characteristicsby simply re-writingthe control program.For example, if the estimate
for the slope calculated in the previous chapter is later found to be too conservative,
the closurevelocitymay be easily changedsimplyby re-writinga few linesof code.
This flexibility,combinedwith increasedpowerand reliability,has propelledthe digital
control system past its hardwiredcounterpartfor critical experimentcontrol
applications.There are two avenues that might be pursued when controllinga system
digitally:a custom designedsystem,or an off-the shelf purchasedsystem.
4.3 Custom Digital Systems
The first option involvesdesigning the entire control systemaround a single
microcontrollerchip. Typically,such chips contain on-boardmemo~, timers,ports,
and other support functions that would normally require separate IC chips.
Customizedmicrocontroller-basedsystemsoffer the followingadvantagesto the
potential user:
. control of the system and softwareat the machine languagelevel
. increasedflexibilityto meet exoticdemands
On the other hand,customizedsystems involvethe followingdrawbacks:
. the system is harder to maintaindue to its increasedcomplexity
● to construct such a system requires a PROM burner and other additional
peripheralhardwareinvestments
31
● debugging,maintenanceand constructionrequiresspecializedknowledgeand
experience
Thus, for specializedapplicationsdemandinga largedegree of flexibilityin control, a
customizedsystem may be appropriate.
4.4 PurchasedSystems
The other alternativeis to purchase a pre-manufacturedmicroprocessorbased
system, typically referred to as a ProgrammableLogic Controller (PLC) [13], from a
vendor. This alternativeis preferredin the nuclearcriticalityarena because in-depth
documentationand verificationof control systemreliabilityis greatlysimplified.
Unlikemost customizedsystems,pre-purchaseddigital systemsoffer relativelysimple
programmingsoftwareand allow for more efficient andthorough maintenance.For
these reasons, it was decided to purchasea PLC system from the Allen-Bradley
corporationrather th creating a customizedcontrol system. This control system is
introducedin the followingchapter.
32
ChapterS.
CURRENTCONTROLSYSTEMHARDWARE
5.1 Introduction
Currently,Control Room One at LACEF is fittedwith a digital control system
that was originally installedto control the SHEBA(SolutionHigh Energy Burst
Assembly)experiment(see Figure 1-2). Specifically,the systemis manufacturedby
the Allen-Bradleycorpmtion and incorporatesconvenientsystem modularitywith a
simplegraphicalprogramnu“nglanguage. An overviewof the typicalphysicalsystem
to be controlled is seen below in Figure 5-1.
MICROPROCESSORCONTROLPROGRAM
HYDRAULICSYSTEMS SCRAMSYSTEMS MECHANICALSYSTEMSValvesMotorLimit switchesPressureswitchesControl switches
PneumaticcylindersValves
Stepper motorEncoder/ResolverTableMountingbrackets
Figure 5-1: T~ical Cri&al Assembly ControlDevice Requirements
The main goal of this sectionof the study is to assemblea functionalcontrol systemon
a test bench that will allow for programdevelopmentand hardwaretesting without
intrusionon the current system in Control Room One at LACEF.With such a system,
the followingtypes of devices maybe tested:
. DC stepper motors (with two different approachesto their control as discussed
later)
. digitallycontrolledday contactdevices
. AC synchronousccnstant speed motors
The devices shown in Figure 5-1 are basic to controllingmany types of critical
assemblies.An assemblythatrequiresrotationalortranslationalmotionwillemploy
one or all of these devices in addition to the peripheralcomponentsthat form the
backboneof the control system; these peripheralcomponents makeup the test bench
control system that is described in the followingpages. In chapter seven,expansionof
law controlPlonselectcx Module rack
/
CloseddrcuitTV and inct&tmGghts Additic)nd1 . Ma (X@smOn
34
I-4 I I ! t ! I/ I I
I
v L I I RAPunit-1 JoysWk \ \Con?ldlel
v.-
I Nw
Ci%%2.s‘am \Cmlputergenefoted
stat-up controlcS@oy
pink%
L
\
Figure 5-2: Current Control Room One Configuration
the control system thatisalreadyin use in Control Room One to includeexperiments
in IUVA I is discussed.This chapter, as well as the next, form the groundworkfor the
eventualexpansion into KIVA I (note in Figure 1-2that the SHEBA building is
separatefrom IUVA I; the SHEBAbuildingcurrentlyemploysan Allen-Bradley
systemwhileKIVA1doesnot).Figure 5-2 onthepreviouspageshowsthecurrent
configurationof Control Room One.
5.2Test Bench ControlSystem
Shown in Figure 5-3 is a schematicof the control system test station that has been
setup at Pajaritosite. This system has been created from spare parts available from the
SHEBA system; when it is required to expand the current Control Room One system,
parts from this system may be used.The pwpose of the setup that currentlyexists is to
provide a platform for on-line programrningand testing that can be used to write and
debug “ladderlogic”programswhich will eventuallybe uploadedto the processor
UJCALW3CNA!LW 8 SUJTS.4GROWS(1~1.A2B) REMOTE W2CNASW% 12SWTS.4GROUPS(IT31-A3BIA)
o 1 2 3 4 5 6 7 8 9 10 I J2
O- 1771ASBREMOTElK3ADAPTER!-l ! =>WY IKJMODULESWTSJ2->120VACKJWERSUPPLY
0-178I=> 177LJBDIX JNPUlMODULE(I030V)2* 1771OBDm~~ MODULE(I06W)
o6!&swmsmFMm0R
3-> t731-lFEAANALIXJ JNPUTMODULE
46=> EMPTY 10MmuLEsm7* 120VACRXVSRSUPPLY
=“ REMOTEmCHAssJsJSNOTwlREDTOLKALCNASSISSINCE NOLX OU13Wl MODULES ARECURRWLY AVAILABLE FORTNLSPURPOSE
Figure 5-3: Program and Hardware Test Station
currently used in Control Room One. In addition, such a test platform serves asa
center for the test and evaluationof hardwarethat might eventuallybe used for the
KIVA I system.This separatesystem allows for on-line programmingand hardware
.,!,
familiarizationwithoutintrudkgon thesystemcurrmtlyinoperationinControlRoom
One.AsseeninFigure5-3,theassemblyusesadriverwhichcontrolsa steppermotor
attachedto a turntable;thisisoneof twooptionsfordrivinga steppermotor.
5.3ConfiguringtheSystem
Systemconfigurationinvolvedsettingdipswitchesonthetopandbottomofthe
PLC-5/15processormoduleand theI/Ochassisbackplane[1.2,3].Theseswitch
settingsdeftnedparameterslike:Aeracknumber,theI/Ogroup(usedwhen
programmingthePLCsystem),thetransmissionrate,andthepowersuppliespresent.
TheCompumotorAXdrivewasconfiguredby settinga singledipswitchassembly
nearthebottomof thecase[7]. Thisswitchassemblydefinedwhatkindof motor
(i.e.,currentrequirement)wasto bedrivenandtheaddressof theAXdrive(tobe
usedwhenwritinga programtobe storedin thedrive).
5.4 ComponentSumrn8ry
5.4.11785PLC-5/15Processor
Thisis theheartof thecontrolsystem.Thecontrolprogram(writtenin “ladder
logic”usingthe PLCsoftware)is uploadedto thePLC-5PROMfromthepersonal
computervia the 1784Kl”/Bcommunicationboard.A shorttestprogramutilizingtwo
switchesandLEDindicatorsavailableon theDCoutputmodulewaswrittento
validatethateachcomponentseeninFigure5-3isoperable[1].ThePLC-5module
seinesas themaincontrolmodule;thesolepurpw a; thePCis as a programming
terminalanddatamonitorstation(usingControlViewsoftware).ThePCdoesnot
directlycontrolanything.
37
38
h
5.4.21771 IBDDC InputModule
TheDCinputmoduleacceptsinputfromcommonDCdevicessuchasswitchesor
pushbuttonsandcommunicateswiththeprocessorvia the“backplane”(printedcircuit
board)locatedonreartheI/Ochassis.DCinputandoutputmodulesrequirea
separateDCpowersourceas seeninFigures5-3and5-4.Forthe KIVAI expansion
discussedinchzptersix,a DCinputmodulehasbeenplacedin the remoteI/Orackin
orderto providefor theoptionof a scrammechanismlocatedinsidetheKIVAitself.
5.4.3177] OBDDC OutputModule
The DCoutputmoduleis the logicalcounterpartto theDCinputmoduleand,like
allothermodulesin thechassis,communicateswiththeprocessorviathebticlcplane.
Theoutputmoduleis wiredto devicesrequiring10-60VDCpowersuchas lights,
seven-segmentdisplays,horns,or valves.
5.4.41771IFEA AnalogInputModule
As itsnameimplies,theanalogmoduleacceptsanalogsignalsfromrealworld
devices.Forcontrolof a criticaiassembly,thismodulewillacceptanalogsignak from
thepotentiometersthatmakeupthejoystickcontroldevice(a typicaljoystickis made
usingoneor morepotentiometers).Theladderlogicprogramwilldictatethedetails
of the interfacebetweenthejoystickandtheoutputdevice.Thismoduleis simplyan
analogto digitalconverter.
5.4.5120 VACPower Supply
Thisprovidespower(convertingvoltagefromACto DC)via thebackplaneto the
moduleslocatedin therack.A powersupplyof this typeis requiredforeachJ/O
chassis.
5.4.6 CompumotorAXLDrive
ThecompumotorAXLdrivecombinestwofunctionsinonepackage.First,it acts
asa pulsesource. Thisisbasicallya sourceof squarepulsewavesthatis usedto tell
thesteppermotorhowfarandfastit shouldrotate. Thesecondfunc!ionof the
Compumotorpackageis asa driveor “translator.”A translatortakesthepulsetrain
generatedbytheprogrammingcommandsandtranslatesi: intothevoltagenecessq
forenergizingthemotorwindings.Themotordrivemaybeprogramn,sdviaan RS-
232 port froma regularPC. Theprogramiswrittenina simplelanguagedeveloped
ky compumotorand is stored in the AXL’Sresident PROM (up to seven such
programs may be stored). A storedprogrammaybeexecutedviatheRS-232
connection,or, it maybeexecutedvia thePLCcontrolsystem.To runtheprogram
viathePLCsystem,onesendsa pseudoBCDnumber(3 bitsinsteadof four)to the
SEQI, SEQ2,andSEQ3linesof theAXLdrive. Dependingon thecombinationof
thethreesequences,oneof thesevenprogramswillbe run. Althcughthismethodof
steppermotorcontroloffersa greatdealofpowerandflexibility,thereis another
optionto steppercontrolthat ispreferred.Thisoption(a separatepulsesource)is
di.scusscdinthe nextsection.Theprogrammingthataccompaniestheintegrateddrive
isdiscussedinchaptereightas well. In thefuture,detaileddevelopmentsinclude
addingfollowingcomponentsto thesystem:
. encoderfeedbackmodule
. powercontactrelaymodule
● stepperpositioningmodules,translator,andnewsteppermotor
5.5Controlof DCStepperMotors
Often,anexperimentalapplicationrequiressmall,precisechangesin motion;thisis
typicallyachievedwitha DCsteppingmotor.A DCmotorusesdirectcurrentpower
‘#
inorderto inducea currentontherotorof themotorthatcausestheoutputshaftto
rotate [5]. This is accomplishedby theuseof a commutatorandbrush. The
:ommutatorisacylindricalobjectuponwhichthebrushesridetochangethedirection
of current in thewindingsin orderto keepthe rotorrotating.A “brush”is a pieceof
conductivematerialridingonthecommutatorwhichconductscurrentfromthepower
supplyto therotorwindings(stator). A “permanentmagnet”DCmotorusesa
permanentmagnetas thestatorinsteadof windings;windingsareusedforthe rotor.
Therearetwomainoptionsavailablefor thecontrolof a standardpermanent
magnethybridsteppermotor.The firstoptioninvolvespurchasingan integratedunit
froma manufacturer(liketheCompumotorAXLdrivediscussedin theprevious
chapter).Thesecondoptioninvolvespurchasinga standalonepulsesourcefromthe
ElPLCChassis
LPulse/kmslator StepperMotorsource
OptionI: CombinedPulseSource/I’ranslatofProgrammingLoadSplitBetweenthePLCandPulse/hanslator
PukeSource TranslatorStepperMotorPLC
Chassis
Option2:SeperatePulseSource,TranslatorProgrammingLoadConsolidatedtothePLC
Figure5-5: DCSte~er ControlOptions
40
PLCvendorandsendingthatpulsetrainthroughaseparatetranslator(i.e.,splitup
thetranslationandpulsegenerationfunctions).DCsteppermotorsarecontrolledby
varyingthepulseratesentto themotortranslator(or“drive”).Thetranslatorand
motoraresizedaccordingto thespecifictaskandthepulserateis controlledthrough
software.Asdescribedbefore, a translatorbasicailytakesthepulserate(generated
extemailythistime)and“translates”thepulserateintotheappropriatevoltage
necessaryto movethemotor.Thefirstof thesetwooptionswasrealizedon thetest
bench;however,it is preferableto consolidateallof theprogrammingandcontrolto
onlytheremotePLCchassis(insteadof programrningbothan integrateddriveandthe
PLCsystem).Forthisreason,a stepperpositioningassemblythatsplitstranslationand
pulsegenerationfunctionshasbeenusedin theControlRoomOneexpansionlayout
discussedinchaptersix.
5.6The StepperMotorDrive:Characteristicsandselection
Thesteppermotortranslatorcontainsthe logicnecessaryto “translate”thepulses
generatedby steppermotorcontrolassembly(indexer)intothecorrectvoltageneeded
by the steppermotorforshaftrotation.Thesteppermotorwillrotateonestepfor
eachpulsereceivedfromthecontrolleranditsperformance isve~ closelycoupledto
thetranslatorsperformance.If a lowperformancetranslatoris usedin conjunction
witha highperformancesteppermotor,theoverallperformanceisdefinedby the
lowestperformingdeviceanda costlymismatchexists. Translatorsmaybe purchased
tooperatein a numberof “ferentmodes;typically,full, half,or micro-stepping
mode. In thefullstepmode,the translatorwillstepthemotoronefullstepforeach
pulsereceivedwhileinthehaifstepmodethemotorwillbesteppedone-halfofitsfull
step(0.9degreesif themotorusedhas1.8degredstep). Microsteppingreferstoa
featurtfoundonmoreexpensivetranslatordeviceswhicharecapableofsteppingthe
motorby as littleas 1/125of thefullstepperpulsereceived.Thetranslatoralso
containstheciruitrynecessarytoopticallyisolatethehighervoltageareafromthe
controlsystem.
42
Chapter6,
CONTROL SYSTEM EXPANSION
6.1PLCSystemExpansionIntoKIVAI
Figure6-1showsa controlsystemdesignthatmaybe usedfor thecurrentPLC
controlsystemexpansionintoKIVA1.In particular,theconfigurationshownmaybe
usedto controlup to threesteppermotorsandwouldbe idealfora varietyof
experimentalsetupsincludingtheuranylnitrateexperimenton thehorizontalsplittable
“honeycomb.”
LOCAL
REMOTE\
\REMOTEIK3CHASSIS:12SKY2S.6GROUPS(1771.A3BI)
kpm’‘qf’’’-”’k” ACPowerin
Iwiw&1‘k!? \\
LOCALUOCNA.SSIS:6 SLOTS,4GROUPS(1771-A2B~o I 2 3 4 5 6 ‘7 8 9 10 1} )2
b 4
‘tI,
ACPawt
o=> 1771-ASBREM(YI’ELIOADAPTER
AL.
G!!9
I => 1771-IBDDC INPUT MODULE (IW30V)
2=> 1771-0BDCCOLIlT~MODU3X (10.6OV)
3=> 1771-MISTEPPERCONTROLLERMODULE4 -6=> 1771-OJPULSEOU1’PLtrEXPANDER
7-II m EM37Y LfOMODULESIXJIS12=> 120VACPOWER SUPPLY
C!i!!9I
ih’a!!\
\
\
I \>‘lo SsEm BUILDINGREMOIERACKS
0=> 1785flc-~is PROCFAW’OR \
1e IT?l-IBD DC INP~MODULE(10.30V)\
2=> 1771OBDDCOWPW MODULE IKMOV)3 = > 1711-lFEA ANALOGINPUl MODULE \
4.60 EMPTY UOM.C;JULESLOTS
7=> 120VAC POWERSUPPLY\
Figure6-1: AnticipatedKWA I ControlSystem
This layoutcontainsthe followingadditionalmodulesthat havenot beenused in the
43
testbenchsetupshowninchapterfive.
6.1.1 1771-ASBRemoteI/OAdapter
The remoteI/O adapterservesas a communicationlinkwith the localPLC-5
processor and communicateswith all of the other modules in its rack via the
backplane.
6.i.2 1771-A41Stepper ControlModule
Thismodulecontrolsthe pulseoutputthat is sentout to thesteppermotor.
6,1.31771-OJPulseOutputExpander
Onepulseoutputexpanderis requiredforeachsteppermotorto becontrolled.One
steppercontrolmodulemayaccm.modatea maximumof threesuchmodulesand
thereforethreesteppermotors. Thepulseoutputexpanderis responsiblefor
communicatingthepulseinformationfromthecontrolmoduleto thesteppermotor
itself. In orderto fabricatethesystemshowninFigure7-1, thefollowingpartsmust
be usedfromtheteststationthat iscurrentlysetupinbuilding30:
Table6-1: ControlComponentsfor KWA Ion HandITEM FUNCTION
1771-IBDDCinputmodule providefor localDCinput177I-OBDDCoutputmodule providefor localDCoutput1771-A3B112slotI/Ochassis houseremotel/O modules1771-ASBremoteI/Oadapter providecommunicationforremoterack1771-A2B8 slotI/Ochassis houselocalI/Omodules
4
?naddition,thefollowingcomponentswhicharenotinstockareneeded:
Table6-2: NecessaryControlSystemComponentsfor KIVAIITEM FUNCTION
1771-OBDDC outputmodule ProvideforremoteDCoutputPLC-5/15to 1771ASBtwinaxial Enableconnectionbetweenlocalandcable(either1770-CDor custom remoterack
made) (maximumdistanceis 10,000feet)(tablecontinues)
44
11771-QAstepperpositioning “assembly
Slo-Synsteppermotor
S1o-Syntramlatorlpowersupply(steppermotordrive)
Generatepulsesourcefor steppermotorcontrol
Convertelectricalenergyintousefulmechanicalenergy
Translatedigital informationfrom pulsesource to motor shaft rotation; providepowerandisolation
The remainingitemsnecessaryto realizethe systemshownin Figure6-1 are in stock
on site(i.e.,PC,powersupplies,andconnectors).
6.2 Controlof ACSynchronousConstant SpeedMotors
Whenanapplicationrequireslessdemandingprecisioninsmallmovements,anAC
constantspeedmotorisoftenusedas anonloffdeviceto fulfilltherequirements.For
example,whilea steppermotormightbe usedto preciselypushtwotankstogether
througha leadscrewinoneexperiment,anACconstantspeedmotormightbeusedto
rotatesafetydrums(containingpoison)in andoutby 180°inanotherexperiment.An
ACmotorisdifferentiatedfroma DCmotorby the factthat,for ACmotors,rotor
currentsarenot inducedbya commutatorandbrushes. Instead,currentis inducedin
therotorconductorsby thestator’schangingmagneticfield(sometimesreferredto as
“inductionaction”);thus,thistypeof motoroperatesby settingupa rotatingmagnetic
fieldona rotor.Typically,therotorisof the “squirrelcage”typeandthe rotating
magneticfieldis setupbysendingsinglephasesof muhiphaseACpowerintospecific
“polewindings”(woundupconductivewire).Wheneachphaseof thepolyphaseAC
poweris correctlydirectedto itspolewinding,a magneticfieldis setupwhichtendsto
rotatethesquimelcage. Bycontinuallykeepinga rotatingmagneticfieldappliedin
thisway,thecage(rotor)is keptcontimmllyrotating.Typically,one,two,or three
phaseACpoweris usedto rotatethecage. Thedifferencebetweenthespeedof the
rotatingmagneticfieldandthecageitselfis termedthe“slip.”Whenthedesignof the
45
motorallowsthecageto “lock”intothespeedof therotatingmagneticfield,the “slip”
is zeroandthemotoris saidto be operatingat “synchronousspeed.”Whenthismode
of operationis reached,themotoroperatesat a constantspeedthat isdirectly
proportionalto thefrequencyof thepowersupply.
ACsynchronousconstantspeedmotors,specificallySlo-SynSS seriesmotors,may
becontrolledwithaPLC systemby utilizingtheRCcircuitshowninFigure6-2 [1$].
Figure6-2: AC MotorControlCircuit
Theconstantspeedmotoris turnedon andoffandchangesdirectionby selectingthe
appropriateswitchshowninFigure6-2. Thepurposeof theresistorandcapacitoris
tochangethesinglephaselinevoltageintothetwophasevoltagethat is appropriate
forenergizingthemotorcoils.Althoughan actualthreewayswitchcouldbeusedto
controlthemotorstatus,criticalexperimentsmustbeoperatedremotely;therefore,a
powercontactoutputmodulethatcanopenandcloserelaysmaybe usedto select
fromamongthethreeswitchpositions.Basically,thisty-pcof moduleallowsremote
relaysto be turnedonandoff via thecontrolprogramstwed in themicroprocessor
46
memory(locatedin a localI/Ochassis).Oncethemotorhasreachedits finalposition,
a limitswitchcanbe usedto turnthemotorto itsoff position. In thisway,useof
opticalencoderf=dback iseliminatedwithoutlosingfinalpositionalinformation.
47
Chapter7.
USINGTHE NUMERICALRESULTSTO SIZE HARDWARE
7.1 Introduction
Nowthatthegeneralcontrolsystemcomponentshavebeenestablished,thenext
stepis to sizea motorandtranslatordriveto thespecificjob of runningtheuranyl
nitrateexperiment.Typically,thisinvolvesperfoting thefollowingtasks:
. determinewhattypeof motionisdesired:typicallyeitherlinearor rotational
● approximatethemaximumandminimumallowablevelocitiesbasedon
criticalitycalculationsor measurements
● determinewhattypeof translatorwillbeused
. determinethemotortorquerequired
Thisgeneralprocesshasbeenperformedfortheuranylnitrateslabtankexperiment.
Thegenera!approachis to defineallof therequirementsbasedon thesystem
informationandthenmatchthemanufacturedhardwareto thosespecifications.
7.2HorizontalsolutionAssembly:theSlabTanks
Recallthegeometryandphysicalsetupdiscussedin thepreviouschapters.The
mechanicalgoalis to pushtwocylindricaltankstogetherwithoutaddingmorethan
fivecentsof reactivitypersecond.Thiswillbe achieved,inpart,throughtheuscofa
steppermotorandleadscrewthatwillpushthetablesupportingoneof thetanks
!owardtheotherstationarytank.
7.2.1Requirements
Inorderto preciselychoosethecorrectsteppermotor,it is firstnecessaryto deeide
whatgeneralperformancecharacteristicsmustbesatisfied.Theblocksof information
on thefollowingpageserveas a datasummaryareafora steppermotorthatwillbe
drivinga 61kg massthrougha leadscrew.Notethatcertaincharacteristicsare listed
48
as “tobecalculated.”Thesevalueswillbe determinedlater. Figure7-1showsa
graphicalrepresentationofthedesiredvelocityprofile.
MECHANICALREQUIREMENTS
ApplicationWeight
MountingResolutionAccuracy
Environmental
Damper(to reducesettlingtimeforeachstep)bads orTerminals
Gearing/LeadScrews
Table7-1: MechanicalRequirementsVALUE
TranslationalTableWeight=61 kg
NEMAtypeflange200stepsper revolution(1,80/step)
.0540/step(3%of resolution)Becauseof lowpoweroperation,thereareno special
environmentalconsiderations —
None
8 leadsThompsonleadscrew
Table7-2: LoadRequirementsLOADREQUIREMENTS VALUE
Torqueat speed to be calculatedInertia to becalculated
MaximumSpeed to becalculated
49
(seefigure1)Acceleration/DecelerationRequired .5secto maxvelocity
.5sectostandstillSinglesteptimenxponsedesired 2.5ms
PulseRate Max,Velocity/PulseRate
.5sec Position
Figure7-I: StepperMotorVekbcityI+ofle
7.2.2MaximumSpeedAllowable
Inchapterthree,theabsolutevalueof theslopeof thereactivityvs.airgapplot
wasfoundto beapproximately11.38centshm, whichequals2.89$/inch. The
maximumreactivityinsertionratefora Class11reactor(reactorthatgoesdelayed
critical)asspecifiedbythetechnicalspecificationis fivecentshec.Withthis
information,wemaycalculatethemaximumpermissiblelinearspeedof thesystemas
follows.Thisvaluewillbe usedwhenwritingthecontrolprograminchaptereight.
(maxah~wablereactivity)(constant)maxlinearspeed = —slope
(5=)( 1$ )00 cents=2.89~
inch
= 1.038=
50
Dueto thisextremelyslowspeed,a gearheadreductionwillbe neededinorderto
increasethenominaloperatingspeedofthemom andavoidlowpowerresonance
eff=ts.
7.2.3Basic Formulas
Therearethreebasicformulasthatareoftenusedinchoosingcontrolsystem
componentsfora translationaltypesystemusinga leadscrew. In thecasepresented
here,equation(/) maybeusedtosolveforthegearheadoutputspeed,equation(2)
yieldsthemotorshaftspeed,andequation(3)maybeusedto calculatethepulserate.
G/f = (P)(h”nearSpeetf)[=]qvm (1)
where:
GH=gearheadoutputshaftspeedinrpm
P = leadscrewpitchinthreaddkch
LinearSpeed= speedin incheshinute
Next,thespeedatwhichthemotoris rotatingis foundwith:
AUS= (x)( GH)[=]rpm (2)
where:
MS= motorshaftspeedinrpm
x = theplanetarygearratiox:1
Finally,themaximumpulserateallowablecanbefoundusingtheequation:
PSEC= ~sp:;s)[=$r’::: (3)
51
where:PSEC= pulseskc output by the stepperpositioningassembly
SP= steps/pulse
DS=degreeshtep
7.2,4MaximumPulseRate
Usingthevaluedeterminedforthemaximumspeedallowable,themaximumpulse
rateof thesteppercontrolassemblymaybe calculated
maximumgearheadoutputshaftspeedis foundto be:
GH= IOrpm
Usingequation(1),the
Usingequation(2), themaximummotorspeedis foundto be:
MS= 520rpm
Finally,usingequation(3), themaximumpulseratethatthestepperpositioning
assemblymaysendoutwithoutexceedingthereactivityinsertionlimitis:
PSEC=~60 pUk/H
7.2.5MinimumSpeedPossible
Theabsoluteminimumspeedat whichtheunitcanbe runcanbedeterminedby
consideringthesmallestpulseratethecontroldeviceiscapableofgenerating.
Assumingtheminimumis 1pukkc, useofequations(1) throttgh(3)yielda
minimumspeedof .0025irhin. Sincethispulserateisextremelylowandmight
resultin motorvibrations,a minimumpulsemteof 500pulseskc is assumed.With
thisvalue,theminimumlinearspeedis foundI.Obe .15inhnin.
7.2.6Resolution
Theresolutionmaybe calculatedbyconsideringtheminimumnumberof single
pulsesthestepperassemblycansendout in a onesecondperiod. Thustheresolution
isjust theminimumvelocity(inkc) multipliedbythetotaltimetogeneratethefinite
52
numberof pulses.Fora minimumpulserateof 1pulsehec,theresolution is .00004in.
Fora minimm pulserateof 500pulseshec,theresolutionis .0025in.
7.2.7RequiredOperatingTorque
Thelaststepis tocalculatetheamountof torquerequiredto movethe61kg mass
at thedesiredvelocitybyappiyingthebasicequation:
(4)EM oments= Ia
where:
1= totalsystemmassmomentof inertia
a = angularacceleration
Thetotalsystemmassmomentof inertiais foundbyaddingeachseparateinertia
component:
Itotal = Ieq + IsCrew+ I rotor (5)
Where Ieq istheequivalentinertiaofthemassbeingmoved.TherotorinertiaiSfound
frommanufacture’spublishedMeratursfora selectedsteppermotorto be2.5lb-in2
whilethescrewandequivalentinertiasarefoundwiththe followingequations[18]:
It~(lb- in2) =weightx.025screwpitch
where:
weightis inpounds
screwpitchis in threadsper inch
IK,W(lb- in2)= diameter’x lengthx.028
(6)
(7)
when:
screwdiameterandlengtharebothin inches
.028isthenominaldensityofsteellb/in3
Next,thetotaltorquerequiredis foundusingthefollowingequation:
~O,u,(oz- in)= ~Cc,p,+ T,,iC,iO~
= I,da,x ‘e’*ciV Xconversionfactortime
force+
screwpitchx q x conversionfactors
(8)
where:
velocity[=]rad/sec
time[=]sec
force[=]in/lb
q = screwefficiency
Notethevelocityusedhereis thevelocityin radkx of thegearheadoutputshaft. An
additional10oz-inof torquehasbeenaddedtoaccountformiscellaneoustorques
fromgearheadinertkoroffset loads. AssumingtheconstantsshowninTable7-3,
equations(4) through(8) yielda requiredtorqueof 8.05in-lb.
7.2.8GearheadReduction
Thefinalstepis tochoosethe translator-motor-gearheadcombinationthatwill
satisfj allof therequirementssummarizedabove.Thetotaltorquerequiredto
accelerate!heloadwithouta gearhcadattachedwascalculatedas 8.05in-lb.!Vhenthe
gearheadisadded,it willhavetheeffectof multiplyingthenominalmotortorqueto
increasetheoutputtorque:
O~tputTorque= Motor Torquex Eficiency x Ratio (9)
54
I
Sofora motorwitha ratedtorqueof 1.87in-lbat750rpm,theactualoutputtorque
(k to thegearheadis approximately79.475in-lb(assuminga gearheadefficiencyof
.&f); thisobviouslyexceedstherequiredamountandwouldsufficeforaccelerating
ittt loadto themaximumvelocityin.5 seconds.“Pull-in”torqueis themaximum
to;que thatcan acceleratea loadwithoutlosingsynchronismwiththepulserate. The
‘~.otorchosen musthavea pull-intorquethatis greaterthanthecalculatedvalueof
38.97Oz-in.in additionto providinga torque multiplication,the gearhcadreduction
was used in orderto reducethespeedof thesteppermotorandavoidpossible
vibrationproblemsthat may be present at timlow or high endof thetorquevs.speed
(steps/see)curve. Thetranslatorchosenforthis applicationis theSlo-Syn430-PT
packagedtranslatordrive. Thisdriveoperatesin halfstepmode(0.9 degktep)and
utilizesa bipolarchopper,2 phasesteppermotordrive.
7.3Summary
Allof thecalculationsdiscussedhavebeenplacedin a spreadsheettoexpeditethe
processofparametricvariation.TheresultsareshowninTable7-3on thefollowing
page.Thecalculationsperformedin thissectionhavedefinedthebasicvelocityprofile
andmotortorquetobe usedforthe steppermotorin the uranylnitratesolution
experiment.In.5 seconds,the 17.85inllb(minimum)steppermotorwillacceleratethe
massto a maximumlvelocityof 1.038irthnin.Thiscorrespondsto an accelerationof
17.3rev/sec2to a pulserateof 3461pulsedsec. Withknowledgeof thenumbers
summarizedinTable7-3,alongwiththegeneralprofileshowninFigure7-1,weare
nowin thepositionto programa systemutilizingeitheran integrateddriveor a
separatepuke source.
55
Table7-3: SizingCalcuk#ionsSummary]INPUT PAJ?AMTERS I I 1
12345678
1?31112131415161718
OUTPUT123456789101112131415-161718 TcXdtmuera red(hlb) : 17.85CD7{
Slcpec#rea3ivity@cjt($fin) ~\~ 2.89
Mm. lnsdkn 17’de(omtshw),.Lea3Sc.mwPitch(th/ln) 15 10.Mcx Pdse Rde(pha&x) ~ ~ mm.Plmetay Gea Reckticn f?cilo~ 50.Trcmldx St@ngh&&(st~@se) ~ 0.5.st~ng Ma Resd@cn (ct@t@ : 1.8
.DesircdR~dutkn @n) . O.ml
.Tdd W@@t (M) ! : 4347,Tknetor~vdodty(s ec) ; ~ 0,5.Saavdawta (h) , : ~ 1.5.SmV1.=@h On ).. . ~ . 48.Scxmvf3tch(thjn) . . 5,Screweffidw 0,9.~dg rdcf Inertla(lbin%?) : 2.5:Frldicn facatosli&w@@t(@ ~ 6.Mdrwn PUse Rate,@ sesAmcj . ~.MSC Taw(cx-ln) . . 5FfWAJvE”TE RS,fvb. LimaSpedkwed(ln~n) 11,038062jhkx. G@ i+edOu@t Shcft Spged(rp)! 10.38062~hkx.,Ivk3tcxSpe@(r~) ! I 519.OJ1lNIx Ma Speed(cb@sec) . ] 3114,187.MCX.Pdse Rc#e@ses~@ . . 3~”2~~.Mn. tvkia Speeg(r~),Mn. Ivlda Sp3ed(d3gk) ~ : m,Mn. G&x Hea50ut@ Shd Sp=d(rm). ;.5,Mn. Lima Spf3edQnmn) . .0.15.Mn. Linea Spe@(in&c) ~ o.Qq?5,Eqjvcht hhs InErtia(lblnW): ; 4.-&l7!s~~ IMO fl~jnq) 6:804;Accd=cikm&M~@m (rw,$&2) j i7.3olo4:Totd Inertiaflbjw). I j 30.952g4.Taqmto-qerqfijdt~(~_-in) ~0,21-~. —-...Ta~tocqx@@O syst~ (gzfln) ~280.3891.T@d tgcper-~red(a-in) 285.6011,—. .,
56
Chupter8.
CONTROLSYSTEMPROGRAMMING
8.1Introduction
In thischapter,theinformationgeneratedin theprevioussectionswillbe usedto
writea controlprogramforthetwomainsystems:thehydrauliccircuitandthestepper
motorpackage.The numericalresultsandsizingcalculationsof chapterstwo and
sevenwillbeusedto setthemotorspeedin theprogramandthecontrolsystem
hardwareoutlinedintheotherchapterswillbe“wiredwithsoftware.”Thisisthemain
advantageof a digitalcontrols~tstem:tk systemcharacteristicsmaybequickly
modifiedwithouta greatdealof hardwaxoreffoflinvested;if thecalcu!a!ionsprove
tobeoverlyconservative,thespeedof closuremaybe changedsimplybyre-writinga
fewlinesof code.
Programmingof thePLCcontrolsystemis achievedthroughtheuseof whatis
‘knownas “hidderlogic”prograrnming[2]. Theterm“ladder”refersto the ladderlike
structureof thisgraphicprogramminglanguage(seeprogramlistii~gin AppendixC).
Theprogranum“ngis doneon an IBMcompatiblecomputer,can x savedto thehard
chive,andthenuploadedto theprogrammable logiccontrollerlocatedin the localI/O
chassis;or, theprogrammingcanbedone“on-line”whileconnecteddirectl:~~~the
procewor.Thebasicsignalflowthroughthesystemis shownon thefollowingpagein
Figure8-1[1].
57
InputModuleI I
OutputModuleI I
IntmtDevices:
RocessorMemoryA
Input)
“)
outputData OutputDc~:ices:
switches Data) Table Table > Motors
Joystick LightsSensors Valvesetc.
1+ ~) etc.
Programming(LadderDiagram)
Figure8-1:SignalFlow17voughthe System
Someofthemorebasicladderlogicinstructionsinclude:
● “Examine-on”:if theexaminedbit is “l” the instructionis true
● “Examine-off’:if theexaminedbit is “O”theinstructionis true
● “Blocktransferread/write”:transferblocksof datato or fromartintelligent
module
● “Timeron(TON)flimeroff (TOF)”:timeevents
● “File/Arithmetic/Logical(FAL)”:convert,manipulate,andmovedata
Eachof theseinstructionshasassociatedwithit a mnemonicanda graphicalsymbol
thatis displayedon thescreenwhenusedandwillbediscussedin thischapter.
Theconceptof a examiningandmanipulatingbitsis essentialto understandinghow
a PLCis programmed.Thefactthat inputsandoutputscanhaveonlya valueof “on”
or “off’cangreatlysimplifytheoftendauntingtaskof prograrnrninga seemingly
complexsystem.The “on”(or “high”)settingisdefinedbya pre-determinedvoltage.
If thevoltageonthe lineis greaterthanthatpm-definedvalue,thenthelineis saidto
be “high”;likewise,if thevoltageon thelineis lessthanthepredeterminedvalue,the
statusof the lire is saidto be “low”(orzeroor “off”).Withsuchsimplebinarylogicin
place,onemaythenapplyBooleanalgebrato thestatusof differentlinesby utilizing
simpleintegratedcircuitchipssuchas “nand”gates,“nor”gates,or “exclusiveor”
58
gates(’ITLlogic). Basically,themicroprocessorbasedcontrolsystemoperatesby
assigninga labelto eachbit thatis usedwithinthemicroprocessor.Inthisway,the
status ofeachbitmaybeexamined,managed.andmanipulatedas desiredthroughthe
use of a program.
8.2 Basic ProgrammingConcepts
Figure8-2showsthefundamentalideabehindprogramminga FLC.Basically,the
entireprogramconsistsof a numberof “rungs”inside“steps.”The steps define the
overallprogramflowwhiletherungsdefinethedetailsof theprogram(i.e.,the logic
dictatingwhatwillbe turnedoffandonforexample).Therungshownin Figure8-2
LADDERLOGIC SEQUENTIALFUNCTIONCHART(SFC)(“steps”)
InsideEach“Step”Are“Rungs”2:Q
~ :~’’’’;’’N’’’’’cK)
Figure8-2:BasicPLCfiogrammingConcepts
willexaminethectateot a bit (either“l” or “O”)andthensetan outputbit to “l” if
the examinedbit wasfoundtobe” 1“(i.e.,a truepathresultsinanenergizedoutput).
Thisis the“examineon”iv-truction.
8.3ProgrammingtheAnalogInputModule
Programming theana!oginputmoduleconsistsof initializingthemodulewitha
“blocktransferwrite”(usuallypreconditionedwitha switch).Next,a “blocktransfer
read”mustbedonein ordertocontinuallyreadtheinputfromthemodule(i.e.,the
valueof theanalogsignalcominginas wellas otherstatusbits). Oncethevalueof the
59
analogsignalcomingin isknownandscaiedbytheuserasdesired,theprogrammer
maymanipulate,display,orstorethedatainanywayneeded.Forexample,input
froma potentiometerhooked into a constant voltage DC source couldbe readintothe
inputmodtiie,readbythePLC,andthendisplayedinasevensegmentdisplay.
ADC Rocessor Memory
(AnalogInputModule)AnalogSensor: DataTable
Temperature,Pressure,HowRate,Ctc.
ISteppingMotor, AnalogorDCDeviceValve, metc.
DACor DCoutput
Figure8-3: AnalogInputProgramming
8.4Programmingthe StepperMotorModules
Pmgrammingthesteppermotorassemblyinvolvesinitializingtheassemblywi:ha
blocktransferreadandwrite,andthenprogrammingthedesiredmotionusingthe
ladderlogiclanguage.Thenumlxrandrateof pulsessentbythesteppermotor
assemblydeterminestherateat whichthemotorturns. Pulsesareoutputto themotor
throughtheuseof “moves”in theladderlogicprogramminglanguage.Althoughthis
modulewasnotusedintheprogramwritten,it isplannedtousethis(aswellasan
opticalencodermodule)in thefuture.
8.5Programmingan IntegratedDn”ve
Asdiscussedin chaptersix, theotheralternativeto steppermotorcontrolis an
60
integrateddriveunit. Typicallywithsucha unit,programrningis achievedviaanRS-
232 interfaceas describedinchapterfive. Shownbelowis theprogramthatwas
writtenandstoredinthememoryofthecompumotorAXLdrive.Thisprogramwas
then executed from the ladder logic program stored in the processormodule memory .
LD3MNA17.3V5D2500G
where:
LD3:disablesthe limit switchesMN:setsthe modeto “normal”(i.e.,cansetdistance,acceleration,andvelocity)A17.3: sets the accelerationto 17.3rev/sec2V5:setsthevelocityto 5 rps(max:8.65rpsascalculatedearlier)D2500:setsthedistanceto 2500stepsG:executesthemove
Thisprogramminglanguageis completelyseparatefromthatofthc PLC. As
mentionedbefore,thisisoneincentiveforusinga stepperpositioningassemblyrather
thanan integrateddrive:centralizedprogrammingreducesdocumentationand
complexity.
8.6StepperControlViaan Integratedlk”ve
A programhasbeenwrittenthatsetsthe frameworkforcontrolof theslabtanks
experimentthroughladderlogiccode. Thetwomainsystemscontrolledby the
programarethe hydraulicandsteppermotorsystems(referto Figures1-3and 1-4).
AnintegratedcompumotorAXLdrivewasusedto drivethesteppermotorwhile
lightson the 1O-6OVDCoutputpanelwereusedto symbolizetheon/offactionof
hydrauliccomponents.Byno meansis theprogramshowncomplete.Writingand
puttingtogetherthecontrolsystemfortheentireexperimentwouldi“~wolveadditional
hardwarecomponents,linesof code,andsystems(e.g.,automaticandsecondag
scramsystems).Theprogramdiscussedin thissectionis intendedtoprovidea clear
61
——
exampleof the programmingprocess and methodsand serves as the first version of the
softwarethatwilleventuallycontroltheslabtanksexperiment.
A listingof the AIlen-Bradleyprogram is shown in AppendixC and the following
section gives a rungbyrunginterpretationofthisprogram.Theprogramisdivided
intofiles.Typically,thefilemaybe a ladderlogicfileora sequentialfunctionchart
file.A sequentialfunctionchartis the“overall”pictureof the programand contains
steps, shownasrectangleson the listing. Withineachstepis a ladderlogicprogram.
Thisisdirectlyanalogousto theconceptof modularprogrammingin FORTRANwith
subroutines.TheflowwithintheSFCiscontrolledby “transition”ladderlogicfiles
whichdictatewhetheror notcontinuitywillbegrantedso thattheparticularstepmay
be run.Transitionsoperatelikeon/offvalvesregulatingwhichiadderlogicprograms
willbe scannedby theprocessor.Theseconceptsareclarifiedgreatlybywalking
througheachsectionof theprogramshownin AppendixC (thenextsection).
Asprogrammed,thebasicoperationof thecriticalassemblyis as follows(referto
theSFCin AppendixC). Afterthe initializationandclearstepsareautomatically
completed,theuserhastwomodesto selectfromviatoggleswitches:eitherrunor
test. In runmode,theuseris forcedto firstclosetheair gapwiththehydraulic
cylinder.Onceclosureviathecylinderhasreacheda pre-&finedlimit,theusermay
thenclosetheairgapvia thesteppermotor. Throughouttheapproachto critical,the
userhastheoptionof scrammingthemachineusingthescrambutton. Oncethe
minimumpossibleairgapisreached,boththehydrauliccylinderandthesteppermotor
arede-activated(to preventa runawaychainreaction,an automaticscramsystemis
usuallybuiltintothesystemas well). Intestmode,thesteppermotorandhydraulic
ram arebothde-energizedinorderto providefor testingof thevalves. ThevaJves
maybe forcedon andoffby forcingbitson or off fromthecontrolprogram.
62
8.7 SequentialFunctionChart:File001
Theactualsequentialfunctionchart(SFC)isshowninAppendixCandit is
illustratedfor clarity in Figure 8-4. A total of 12files were created (Table 8-1).
FileNumber
001
002
003
004
007
008
009
10
11
12
Table8-1: !
Name
MAIN
30YSTICK
INIT_DONE
INIT
CLE.4R
RUN
TESTS
DONE
CONTROLS
MAINTAIN
NOPS
h TankProgramFiles
Function—.-
Scquentialfunctionchartfile— ---
Coni”dtheDCoutputsviaswitchesand
thepotentiometer.Thisis fundamentally
thesameas ajoystickcontroldevice.
Controlthe transitionfromfile004
(INIT)to file006(CLEAR)
Initializehardware
Ensurethatall outputsareoff before
continuing
Selectthemn branchto runthemachine
Selectthetestbranchto testthemachine
Controlthetransitionfromtestingor
nmningto thefinish
Controlthesteppermotorandhydraulic
system
Testthehydraulicvalveswiththemotor
andpumpoff
Emptytransition
63
Files5, 13,and14shownontheprogramlistingremainedemptyandwereneverused.
64
startvINIT
~ANS ITION:INIT.00NE
CLEAR
TRANSITIOhTESTSANSITION:RUN
COPJ’IROLSJOYSTICK
TRANSITIONDONEu + TRANSITION: DONE
I
9CLEAR
TRANSITION:NOPS
End
Figure8-4: GeneralFeaturesof the SFC
Programflowforthesequentialfunctionchartis fromtop to bottom. Whentwo files
(“steps”)areplacedin parallellikefiles002and 10(CONTROUANDJOYSTICK),
theyarescanned(i.e.,run)simultaneouslyby theprocessor.Whena transitionlike
INIT-DONE(file003)goestrue,it allowstheprocessorto dropdownandbranchto
eitherof twooptionmodes:runor test. Whentherunmodeis selected,JOYSTICK
(002)andCONTROLS(10)arebothsimultaneouslyscanned by theprocessor
allowingtheusertooperatetheassemblyforanexperiment.Whenthe testmodeis
selected,theassemblyisdeactivatedto allowfortestingof thehydraulicvalves. Once
eithertestor runhasbeencompletedandthemachineis scramme~theprocessorruns
throughtheCLEARstepthatensurestheassemblyisoff andthenreturnsprogram
controlto fileINITat thetopof thesequentialfbnctionchatt.
8.8 Ludder LQgic:Files 002-12
Arungisspecifiedbythefilethatit is in,andtherungnumber.So,forexample,in
AppendixCat thebeginningof theladderlisting,“Rung2:0”indicatesthatwithinfile
002(denotedby the“2”), thisis the firstrung(denotedby “O”).Whenthepathon a
rungis true,it proceedsto theinstructionfurthestrightandexecutesit. The
instructionsfoundon therightarereferredto as outputinstructionsandareusedto “
turnonmotors,lights,or anyotherdevicethatmustbecontrolled.Theprocessor
scanstherungsfromleft to rightandtopto bottom.
8.8.1Rung2:0
Thisis the firstnmgin file2 “JOYSTICK.”Thefirsttwoinstructionson thisrung
examinetwodifferentbits fortheirstatus. If thebitsarefoundto be “O”in thedata
table,thenthepathis tree;othenvise,ifbet!!bitsare”l,” thenthepathis false(this is
the“examineoff’ instructiondiscussedearlier).Thebitsexaminedare“enable”bits
thattelltheprogramwhetheror nottheanaloginputmodulecanbe read. Whenthe
pathis true,the “BTR”(BlockTransferRead)instructionis executed.This
instmctionreadsthepowerstatusof theanaloginputmodule.
8.8.2Rung2:1
This rungbasicallysays:“iftheBTW(BlockTransferWrite)is notalreadydone,
thendo it”by examiningtheBTWdonebit. WhentheBTWwriteinstructionis
executed,it writesa configurationfileto theanaloginputmodule.Thisconfiguration
filedeterminesthingslikewhatkindof analoginputwillbe used,howtheanaloginput
willbe scaled,orwhethertheinputwillbedigitallyfiltered.
8.8.3Rung2:2
Thisrungcheckstheanaloginputvaluefromthevariablevoltagesourceandsets
bitslocatedin a binarydatatabledependingon thevalue. A literalinterpretationof
65
this rungisas follows:if thejoystickvalueisgreaterthan5(KNand less than9619 and
if the steppermotoris offand ifswitch1isonand ifpushbutton1ispushed,thenset
the “pump”bit to 1.This bit is examinedin theCONTROLSsteptodetermine
whetherthepumpshouldbe energizedor not.
8.8.4Rung2:3
Thisis the same logic used in rung 2:2 with the exception that the “stepmotor”bit
isbeingsetinsteadofthe“pump”bit. ThisbitisexaminedintheCONTROLSstepto
determinewhetherthesteppermotorshouldbeenergized.
8.8.5Rung3:0
Thisis thetransitionfileMT-DONE usedto verifythatproperinitializationhas
occurredin the INITstep.Thetransitionbecomestrueonce the INI’’I-DONEbit is
set true in the initializationroutine.
8.8.6 Rungs4:0
This is the initializationstep,the firstblockexecutedby theprocessor.Typically,a
numberof I/Odevicesrequiresomeformof initializationbeforebeingused. Although
nosuchdeviceswereusedas prutof thisexample,thisstepwasincludedsincesuch
blocksaresocommonwhenwritinga lengthycontrolprogram.Theexternallights
locatedon theDCoutputmodulewerereservedto representinitializationoutputs.
Whenswitchoneis turnedon,rung4:0 startsa ten secondtimer. Whenthe timer
reachesone,two,three,and foursecondsrespectively,lights10,11,12,and 13are
‘“latched”on. A latch commandretentivelysetstheoutputstatehigh;thatis, when
power is lost,theoutputwillremainin a highstate.
8.8.7Rung4:i’
Thisrungturnsoff (“unlatches”)lights10-13if switch1is turnedoff. An
“unlatch”commandretentivelysetstheoutputdevice’sstatusto “O.”
66
8.8.8 Rung4:2
Thisrungchecksthevalueof thetimer. Whenthevaluereaches5 seconds,lights
10-13are turnedoff.
8.8.9Rung4:3
Thisrungturnsallof theinitializationligh!sbackonwhenthetimerreaches6 seconds.
8.R1ORungs4:4 - 4:8
Rung4:4performsanFALinstruction(“FileArithmetic/Logical”)whenthetimer
value reaches7 seconds. The FALinstructionallowstheuserto sendanyword(16
bits)to anoutputlocation. In thisexample,a random16bit sequenceis sentto the
DCoutputmoduleto flashthelightsina randomsequenceto furtheisimulate
initializinga module. Thisinstructionmaybeusedtoarithmeticallymanipulate,
convert,move,andperformBooleanlogicto individualbits orcodednumericaldata.
Rungs4:54:8 utilizetheFALinstructionina similarmannerto flashandblankthe
initializationlights.
8.8.11Rungs4:9 -4:10
Thisrungresetstimersthatareusedin theCONTROLSstepandlatchesthe
INIT-DONEbit inorderto recordin thedatatablethat initializationhcsbeen
completed.
8.8.12Rung6:0
ThisrungensuresthatthePUMPandSTEPMOTORbits in thedatatableare
unlatchedandalsounlatchestheNT-DONE bit incasetheusergoesthroughthe
SFCmorethanonce.
8.8.13Rung 7:0
if therunselectionswitchis onand if thetestselectionswitchisoff, thenthis
transitionrungbecomestrueandrunmodehasbeenselected.
67
I
8.8.14Rung8:0
If the tsst selectionswitchis onmd if therunselectionswitchis off, thenthis
transitionrungbecomestrueandtestmodehasbeenselected.
8.8.15 Rung9:0
Ift!!epumpand stepperand N.O. valve and N.C.l valve and N.C.2 valve am off
and if thescrambuttonis on, thenthistransitionis true,andcontrolis returnedto file
004(INIT).
8.8.16Rung 10:0
If the pumpbit is true,thenstarta 5 secondretentivetimer,energizethepump,and
opentheN.C.I valve.Alongwithrung 10:1,thispressurizesthecylinderandbegins
movingthetankstogetherviathehydraulicram. Theretentivetimerretainsthe
accumulatedtimethepumphasbeenrun(eventhoughtherungmaygo false)as a
meansof ~eterminingwhenthepumpshouldbeabandonedin favorof the increased
resolutionofferedby thesteppermotor.
8.8.17Rung 10:1
If PB2 is off,and if thescramlatchbit isoffand if the run selectionswitchis on,
thenenergizetheN.O.valve(thusclosingit andpreventinga scram)andde-energize
theN.C.2 valve(thusselectingtheclosurespeedsetby theN.C. 1valve).
8.8.18Rung 10:2
If thesteppermotoris on, thenstarta tensecondretentivetimerandenergizethe
steppermotorforoperation.Thetimeris usedinconjunctionwithlimitswitchesto
determinewhenallclosureshouldbeterminated.Knowingthelinearvelocityof the
table(calculatedinchaptereightas 1.03inhnin)andgiventhemaximumdistancethe
tankmaybe movedviathestepper,thenthemaximumamountof timethesteppermay
beoperatedis knownandmaybe set in thetimer.Thisinformationmaybe usedas a
68
redundancytothelimitswitcheswhichphysicallysensewhenacettainpositionhm
been reached.The same idea applies to the hydraulictimer mentionedearlier.
8.8.19 Rung10:3
If thepumptimeris done(i.e.,fivesecondshavebeenreached)or if thelimit
switchforthehydraulicramhasbeenactivated,thenturnoff thepump,unlatchthe
pumpbit,andclosetheN.C.1valve(thushaltingmovementof theslabtankvia the
hydraulicram).
8.8.20Rung10:4
If the steppertimeris done(i.e., ten seconds has been reached) or if the stepper
limit switchhasbeenactivatm thenunlatchthesteppermotorbit andturnoff the
steppermotor(thushaltingallmovementviaboththehydraulicramandthestepper
motor).
8.8.21Rung10:5
If the scrambuttonis pressed,thenopentheN.O.valve,closetheN.C.1andN.C.
2 valves,latchthescramlatchbit, andturnoff thesteppermotor.Thispressurizesthe
cylindercaus!ngit to quicklymovethetanksapartandensuringnoclosureviathe
steppermotor.
8.8.22Rung11:0
If the testseltztionswitchis on, thenturnoff thepumpandsteppermotor.Thisis
themaintenancemodethatallowsfortestingof thevalveswithoutthepumpor
steppermotoron.
8.8.23Rung11:1
Thisrungisexactlythesameas rung 10:5interpretedabovewiththeexception
thatit isplacedin theMAINTAINstep.
69
8.9 Summary
Thisprogramwaswrittenwiththemajorgoalof illustratingthebasicsof
prograrnrm“nga typicalPLC.Theanaloginputsimulatesajoystickand theDCI/O
areusedto controlvalves,motors,or anyotherdevicerequiring1O-6OVDCvoltage.
Whenwritingtheprogramto controlanysystemusingthistypeof PLC,the
commandsandstructuresshownwillbe usedrepeatedly;therefore,theprogram
discussedis a representativesampleofmuchlarger,butnomoreconceptuallydifficult,
controlprogram.Theprogramshownin AppendixC isversiononeof theuranyl
nitrateslabtankexperimentcontrolprogram.
70
Chupter9.
USERINTERFACESOFTWARE
9.1 Overview
Oncethemicroprocessorcontrolprogramhasbeenwrittenanddebuggedandthe
hardwareestablished,theuserinterfacemustbedefinedandcreated. Ideally,theuser
wouldinterfacewitha graphicalrepresentationof thephysicalsystembeingcontrolled
aswellas a controlpanelconsistingof switches,buttons,ajoystick,andanyother
similarinputdevicesthatmightbenecessary.Asin theselectionof thecontrolsystem
hardware,therearetwooptionsthatmaybe pursuedwhenconsideringhowtheuser
willinteractwiththecontrolsystem. If thecustomapproachis beingfollowed,one
mustwritetheinterfacesoftware“fromscratch”usingprogramminglanguagessuchas
C or BASIC. Ontheotherhand,if a systemhasbeenpurchased,a softwarepackage
is typicailyavailableto augmentthehardwareandserveas a linkbetweentheuser,the
controlprogram,and the actualhardware.In thecaseof thesystemthatwas
purchasedandoutlinedin thepreviouschapters,a softwarepackagecalled
ControlViewwasavailable.
9.2GeneralFeatures
ControlViewoffersa widevarietyof capabilitiesthatinvolvea relativelysmall
amountof labor. Thesoftwareallowstheuserto “tag”memorylocationsin thePLC
anddisplaythevalueson thescreenin a graphicalor numericalmanner;it “talks”to
thePLCviathe 1784KT/Bcommunicationscardshownin Figure5-3. Oncethe
memorylocationsof interesthavebeentagged,a databaseof thecurrentvaluesis
createdandcontinuallyupdatedas thesoftwarescanstheprocessorfor thevalues
locatedineachof thetaggedmemorypositions.Afterthisdatabaseis created,the
usermayproceedto thegraphicseditor;here,a graphicairepresentationof the
-7!
physicalprocessbeingcontrolledmayheciGakd.I’heusermaydisplaythenumerical
valueof taggedmemory,drawgeometricshapes,andevenanimateor fillsuchshapes
at a rateproportionalto a value in memory. For example, if the positionof the
hydraulicramis fedbackas an analogvalueviaanopticalencoder,thena rectangular
figurecanbedrawnon theinterfacescreenthatwillfillwitha color proportionalto
thepositionof the ram. Whentheramisat its“out”position,therectanglewillbe
empty of color; when the ram is at its full “in”position, the rectangle will be
completelyfilledwkhthecolorchosen.Suchaninterfacewascreatedfor theuranyl
nitrateexperimentandisdiscussedin the followingsection. In additionto such
features, the softwareprovidesothercapabilitiessuchaseventdetection,alarming,
mathematicalmanipulationof data,menucreation,andsecurityadministration.
9.3UranylNitrateExperimentInterfxce
Aninterfacefor theprogramandhardwarsdevelopedfortheuranylnitrate
experimentwascreatedusingtheControlViewsoftware.Basically,Figures 1-3and 1-
4 were taken, reproduced into one display using the graphicseditor available,and then
linked to memorylocationsdefinedin the ladderprogramlistedinAppendixC. The
steppermotorandhydraulicramaredrawnas rectanglesof differentsizesthat fill
greenwhenfullyextended.Thenormallyopenandnormallyclosedvalvesas wellas
thepumpin the programareshownas redwhenclosed(oroff)andgreenwhenopen
(oron). Theswitchesandpushbuttonscontrollingtheseactionsarewiredas shown
inFigure 5-3 and placed inside a small aluminumbox servingas thecontrolpanel.
Theseswitchesaredisplayedon thecontrolscreenas rectangularbuttonsthatturn
greenwhenon andredwhenoff.Whenthehydraulicramis actuated,theentirecart is
animatedandmovesforwardtowardsthe fixedslabtankwhiletherectangle
representingtheramis filledgreen. Oncethemaximumdisplacementviatheramis
72
realized, it is deactivatedand the stepper motor is selected. When the stepper motor is
activated, therectanglerepresentingthe stepper motor begins to fill with green and the
movableslab tank continues its approach towardthe fixed tank. When the system is
scrammed,thecart is returnedto itsoriginalpositionandtheairgapbetweenthe
tanksis increasedto its maximumvalue. Figure9-2 on the followingpage shows a
screenshotof theinterfacethatwascreated.
Thecreationof theuserinterfacecompletestheprogrammingexamplethatwas
begunin thepreviouschapter. It is worthnotingthattheinterfaceisjust that:an
interface.Althoughit readsvaluesfromthePLC,it innowaycontrolsthephysical
system.Theonlysoftwarecapableof energizingoutputbits is theladderlogic
programdiscussedin thepreviouschapter. Again,althoughthe interface,ladder
program,and hardwarethat have been discusseddo not fully satisfyeach and every
requirementnecessaryforperformingtheuranylnitrateexperiment,theirdevelopment
asoutlinedherelaysthepreliminarygroundworkthatiscrucialtocreatingthemuch
larger,butnomoreconceptuallydifficultfinalsystem.
73
II--mm
OFF
I
Ii!l RUNu I
1
EEKl
74
Figure9-1: ScreenShotof ComputerGeneratedInt@&e
chapter10.
COSTESTIMATE10.1LaborCosts
It isestimatedthattwofull-timeengineerswillbeneededinordertoimplementthe
experimentoutlinedinthisdocument.Oneengineerwillberesponsiblefor
implementationof thecontrolsystemandhardwaremanufacturingwhjletheother
enginee:.willbe responsibleforthenuclearengineeringconcerns;it is assumedthat
bothWNworkonexperimentdocumentation.Assumingappro~.imatelythreemonths
of worktime,theengineeringcostis calculatedas:
(50$#w)x (8hr/&y)x (90hys)x (2)= $72,000 (10)
It is anticipatedthattwotechnicians(onemechanical,oneelectrical)willbe needed
tocompletetheexperiment.Inaddition,onedraftsmanwillbe needed The
mechanicaltechnicianwillbe responsibleforfabricatingpartsin theshopwhilethe
electricaltechnicianwillberesponsibleforwiringthecontrolsystem;theddtsman
willbe responsiblefordocumentingelectricalandmechanicalconstmc!ion.Assuming
threemonthsof work,techniciancostjs calculatedas:
(30$/hr)x (8hrAiay)x (90dizys)x (3)= $64,800
10.2Material Costs
Thehardwareneededfor theexperimentmaybe brokenup intotwoareas:the
mechanicalhardwareandthecontrolsystemhardware.
10.2.1MechanicalHardware
Themechanicalhardwarecostsareestimatedwiththeassumptionthathardware
willbemanufacturedanddesigned“h house.”Table10-1summarizesthegeneral
anticipatedhardwarecosts.
(11)
75
a Wu, v a w-a ● np~ w W* W,SWSG ● aut W WWJ S Vuoms
ITEM APPROXIMATE
COST
Materialfor twotranslationstages(SST) $100
Micrometerhead $100
Stepper Motor $120
AluminumMaterial $100
Miscellaneoushardware(fasteners,welding $]00
materials,etc.)
APPROXIMATETOTAL HARDWARE $520
COST
10.2.2ControlSystemHardware
Table10-2: ApproximateControlHardwareCosts
ITEM APPROXIMATECOST
2 DCOutputModules $600
ElectricalCabling $100
Stepper Positioning.Modules $2,080
Translator $800
APPROXIMATETOTALCONTROL $3,580
[ HARDWARECOST I 1
76
10.3 CostSummary
Summingtogetherthelaborandmaterialcostsandadding10%forunfweseen
contingencies,thetotalestimatedcostfor the experiment is shownbelow in
Table10-3.
T~lble10-3: To&lEstimatedCost
ITEM VALUE
Materials $4,100
14a~ I $136,800
TOTAL DIRECTCOST $140,900
10%Contingencies $14,090
TOTAL ESTIMATEDCOST $154,990
77
78
Chapter11.
CONCLUSIONS
This thesis has addressed the problemof setting up and programminga
microprocessorbaseddigitalcontrolsystem(PLC)forcontrollingacriticalexperiment
involvinghighlyenricheduranylnitrateincylindricalgeometry. Asa resuhof this
study,wemaydrawthe followingconclusions:
● AnAllen-Bradleymicroprocessor-baseddigitalcontrolsystemis theidealchoice
forcriticalexperimentcontrolbecauseof its tlexibility,relativesimplicity,and
proventrackrecord. Implementingthistypeof controlsystemforcritical
experimentcontrolis highlydesirablesinceit providesa commonplatfoxmfrom
whichtocontrola varietyof criticalexperiments.Thisisgenerallynotthecasefor
systemscustomizedtospecificexperimentssincetheresultis a patchworkof
differentcontrolsystems,eachwithitsownuniqueapproachtocontrol. An
Allen-BradleyPLCunifiestheapproachtocontrolwhilemaintainingtheflexibility
to performmanydifferentexperiments.
. Themechanicaldesignrequirementsforperforminga criticalexperimentwith
cylindricalgeometryon a horizontaltableareachievable.Theserequirements
includethedesignof spaceframesto holdtheslabtanks,aswellas a translation
tableforpositioningthemovabletank. Inaddition,therearedistinctsafety
advantagesinperformingsuchanexperimenthorizontallyratherthanvertically
includingthepossibilityof a gravityassistedscrammechanismandeliminationof
theworstcasescenarioinwhichonetankdropsverticallyontotheother.
. A probabilisticcomputercodesuchas MCNPmaybe usedforsensitivitystudies
to providea roughestimateof systemsensitivity;however,dueto thestatistical
natureof sucha code,it is notideallysuitedto sensitivitystudiesrequiringa high
degreeof accuracy.Wemayconcludethatthecylindricaluranylnitratesystem
discussedisvetysensitivetochangesintheairgap:approximately9centshnmto
14centshm.
. Theresolutionrequiredfortheuranylnitrateexperimentis achievableusinga
steppermotor,leadscrew,andgearheadreductionforfineadjustment.
In general.thisstudyhasproventhata PLC system manufacturedby the Allen- ‘
Bradleycorporationoffers the flexibilityneededto performnot only the uranyl nitrate
experiment,but a widevarietyofcriticalexperimentsinvolvingfissilematerial.A
unifiedapproachtocriticalexperimentcontrolhasbeenpresentedthat,when
implemented,willgreatlyenhancethecapabilityofthc LosA1arnosCritical
ExperimentsFacilitytosafelyandexpeditiouslygathervaluablecriticalitydataviaa
commoncontrolsystem.
79
REFERENCES
[1] AllenBradleyCompany. 1992.Introductionto Programminga 1785-PLC-5ProgrammableController,Student’sManual. Wisconsin:AllenBradleyCompany.
[2] AlienBradleyCompany. 1992 PLC-5ProgrammingSo@are Manuals.Wisconsin:AllenBradleyCompny.
[3] Allen-BradleyCompany.1991.PLC-5and ModuleinstallationManuals.Wisconsin:AllenBradleyCompany.
[4] Anderson,R. 1986. PersonalNotesfora SolutionArrayExperiment. LosAlamosNationalLaboratory:GroupN-2.
[5] Bociine,Clay. 1978. till Motor&Geannoto& Cent o! HandbookrFourthUULQL
. . IllinoixRodineElectricCompany.
[6] Briesmeister,J. et al. 1986.A4CNP-AGeneralMonte CarloCodejorNeutronand PhotonTransport. Los AlamosNationalLaboratory:ManuaiLA-7396-MRev. 2.
[7] CompumotorDivision,PnikerHannifinCorporation.1989.AXDrive Users’Guide. California:CompumotorDivision.
[8] Houpis,C.; Lament,G. 1992.Q@”talControlSvs!ems7%off. Hae r~w~. .
$oilware. SecondE$ulon%New York:McGraw-Hill.
[9] Lamarsh,John. 1983. lhtroduan to Nuc&QrEw?mee n~. . .ri
Massachusetts:Addison-WesleyI%b!ishingComp’any.
[10] Osbom,L.et al. 1970. HydraulicSystemfor HoneycombCart. Los AlamosNationalLaboratory:Drawing19Y-29431C38.
[11] Patemostcr,R.R.et al. 1992. SafetyAnalysisReport~orPajarito Site(TA-J8)and the LosAlamos CriticalExperimentsFacility (LACEF). Los AkimosNationalLaboratory:ReportLA-CP-92-235.
[12] Paxton.HughC. 1983.A Histoq~ofCritical Experimentsat Pajarito Site.Los AlamosNationalLaboratory:ReportLA-9685-H.
80
[13]
[14]
115]
[16]
[17]
[18]
[19]
petm’~l!a. Frank D. 1989, ~~ ~ontrol~”r.~ New York:McGraw-Hill.
Sanchez, Rene. 1993. PersonalNotes ONNuclearEngineeringFundamentok Los AlamosNationalLa*oratory:GroupN-2
Schlesser,JohnA.et id. 1992.Nuclear CriticalitySafety:3-Day TrainingCourse,SfudenrsManual. Los AlamoiNationall,abora!ory:ManualLA-12387-M.
Siege!,Robert;Howell,John. 1992.~. on ~~“ ii ~~h WtihiflgtoriD.C.:HernisphcrePt~blishi~gCorporation.
Spriggs,GreggD.et al. 1986. Cri~icalityof Uranyl-NitrateSolutionin SlubGeonletry. Los AlamosNationalLaboratory:ReportLA-UR-06-2245.
SuperiorElectricCompany. 1975.DesignEngineersGuide to IICSteppingMotorsandAC SynchrmousMotors. Connecticut:SuperiorElectricCompany.
Vande Vegte,John. 1990.~~v~~ Ew~NewJersey:PrenticeHail.
81
AppendtiA
MCNPCardSummary
Surface Cards
The surfacecards define generic surfacessuch as cylinders,spheres,planes, or
ellipsoids. Surfacecards are referencedby a surfacecard number. For example, in
order to define an infinitecylinderalongthe y axis,one wouldenter the followingline
in !he input file:
1 Cy 36.195
This card says “surface 1is definedby an infinitecylinderalongthe y axis with a radius
of 36.195cm.” Similarsurfacecard mnemonicsmaybe used to define spheres, infinite
planes,and other standardgeometricalshapes whoseequationsare well defined by
analyticgeometry.
Cell Cards
The geometryof the system is specifiedby applyingBooleanoperators to the
surfacecards. For example,surfacecard 1 may specifya cylinder(infinitein length)
alongthe Y axis and surfacecards 2 and 3 may specify two infiniteplanes
perpendicu~arto that cylinder (planes 1 and 2 ). In order to define a systemconsisting
of a cylinder with finiteends (referredto as a “cell”),one may insert the following
geometrycard in the input file:
1 10 -7.9 2 -3-1
Thiscardsays“cell1isdefinedbyeverythingto thepositivesense(totheright)of
surface2 intersectedwith everything to the negativesense (to the left) of surface 3
intersectedwith everythingto the negativesense (inside)surface 1“(italicnumbers).
The numbersthat aren’tin italic type representthe material type (10, in reference to
materialcard 10)and the materialdensity (7.9) in grardcc.
85
VarianceRedl . ‘on:ImportanceCards
Importancecards are the most common form of variance reductionavailable to the
MCNP user. With this card, the “importance”of each cell maybe assigneda value of
one (important)or zero (not important). If a cell is assigned an importanceof zero,
particlesenteringthat cell wili not be followedor banked as part of the “game.” Cells
that ~re “voids”(contain no material ) and that are predicted to have little or no
influenceon the system understudy are typicallyassignedan importanceof zero in
order to reduce computer time.
MateriulCards
Materialspecificationcards do just what their name implies: ICllthe ccmputer what
kind of mat.rial the cell is composedof. This informationis typicallytransmittedin
the form of numberdensities (atoms/bam-cm)and cross section table references.
Materialspecificationcards fix the relativeproportionof each element or nuclide
withineach cell and dictate whichcross section tables will be used (the probability
portion of the “game”being played). MCNP really cares only about the relative
proportionof each element or nuclide within the material;therefore,either number
densitiesor atom fractionscan be entered in the materialcard since atom fractionsare
foundsimplyby multiplyingthe numberdensitiesby a constant. Also as a resultof
this, the numberdensitiesof a certain materialcan be summedand the resultingvalue
may be entered as the densityon thecell card. Thisis indicatedbyenteringthevalue
withouta negativesignprecedingit (seeinputfiles,AppendixD).
86
Mode and Tally Cards
Lastly,MCNP mode and tally cards are used to determine the operation mode of
MCNP and the data that is to be tabulated as the simulationis being run. When doing
criticalitycalculations,the “kcode”card is alwaysused. This card allows for the
definitionof the position, and size of neutronsources that are present as well as a few
other parametersrelated to programexecution. The tally cams determine what data
will be generatedby the program.Options(amongmany others) includeneutron flux,
current, and fluence. For this study, the main parameterof interestwas keff:a
parameterthat is automaticallycalculatedfor the user when doing kcode calculations.
ComputerCharacteristics
A total of six input files werecreated.These files were accessedby MCNP version3A
on a Sun Spare 10workstationwith 32 megabytesof memory and a 40 MHZclock
speed. The operating system used was Solaris 1.0.1.
87
Appendix B
Number Density Calcuhztions
A
[ ~
b y
Rcc ~ P]= ~
x
=
()* X I
=
( .)~ X ) X )
()~.
= +
=
0 ) =
[
3
= : 0 )
=
s u t
=
+ =
= +
=
X X )
=
= =
=
T
= - -
= 1 .
=
= — X ) X )
=
= =
=
=
= =
=
=
= = +
=
=
C
..
! O !1
9 S 1D L R Q (
S++ +* Ook ●
+ *
I+.I 006 i+
I+ .I I
I I+ Ii 011 j ~+ I I
+- +1 010 II 002 I
I + +I I
II 1
!
: !. . . . . . . . . . . . . . . .
I+I 006 t+
.
I+-
N O $ 9 S Lm O R - O P D R
P D P S - -[ O 1I v S I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I
iIIII
iIIIIIIIIII
iII
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778
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1 :1 :0I ;1111NNNNN
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T
I
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9 S 1P O A B
C
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I- - I
+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -....+ B T +I 15 is I I
i 1 jI I
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N II
IN
I II I II +. . . . . . . . . . . . . . . . . . . . . . . + 1
I E III N + - i+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T V +
I/ I 1 ;I I II I B N II I NI I !I I II . . . . . . . . . . . . . . . . . . . . . . . . . I
I C C II J JI S S I i
I Ii S S II S FI + . .+ ~1 1+ + ; [ [I I I II I > I I II + -+. . . . . . . . . . . . . . . . . .+ i
I C CJ J
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SS S P T
I FLmF SV2I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 >+ + [ - [ [I I I I I 01 >} I I l?lll:~ <20680 \
- - -+ .
100
—
N Om L R
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IF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I
101
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102
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . ..+.
!:;I
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+ T O N- - - - -- - - - - - - -. . +:- D *
I TI l 1I\+ - - .. . . . . . . . . . . . . . . +
IT
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l A TII Il B
I i. . . . . . . .I
ii
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i. . . . . . . . . . . . . . . + 0 I+ +
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l B
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ISOU?CO A T
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103
104
S O ? 9 S 5m L R . O 1
1I . II W II II
0 !: - -“ - ”“ -II I 0:000 [ II 4 I
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I I 111 i. . . . . . . . . . . . . . . . . . + I 0:000 I j
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105
! Om L R -
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II
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[ 1 !I I 0 I I
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.
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[ - -- - --I
I+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [ S NI I
.
106
N O 9 S 8P L R P O
I CJ i
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S/ + . . . . . . . . . . . . . . . . .+ I●. + - - A (I I l RI I > ; I L ~I + -l
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.
107
N O 9 S 9m L R . O
I NI S :
Ii PUW II I : B3 j+ [ - -- - - -.
1 I/ l ]1 II 53I 1 II I 96 ] jI II I S ; ~I I
+ . . . . . I/ 1
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108
—— -
S O 9 Sm L R - O
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1 I+- - -”!/[ ------------ - ------------------- -------------------- ...I 116 I
\ I I II S I II S /I
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+ - . - - ][ . . . . . . . .] / [ . . . . . -. . ] / [I
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I I
109
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114 I
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113
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115
D
I $ 12 $ 13 $ s a 1
4 $ 15 $6 $ 27 $ 28 $ s a 29 $ 2
I $ 2$
$
i $2 i3 $ 14 $ 15 $ 16 $7 $ 2 +8 $ 2 +9 $ 2 +
$ 2 +2
$SO $
1 1 1 1 1 1 1 1 1 1
$1
$
$$
=
1 $ 12 $ 13 $ 14 $ 1~ ] 2 $6 $ 27 $ 28 $ 29 $ 2
$ 2$
$
1 $2 $ 13 $ 14 $ 15 $ 16 $7 $ 2 +8 $ 2 +9 $ 2 +
$ 2 +2
$$
1 1 1 1 1 1 1 1 1 I O 1 1$ 1
$1
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1 $$
= 50 c
120
123456789
$ceJ1 first slab cover 1$ 1$ 1
$ I$
$ 2$ 2$ 2
$ 2$ 2
0 $ cell 11:outer void - -$
1 $2 $ 13 $ 14 $ 15 $ 16 $7 $ 2 +8 $ 2 +9 $ 2 +
$ 2 +2
$$
1 1 1 1 1 1 1 1 1 1
$1
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$
1 $$
=
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$ 1$ 1$ cell steel 1$ 1
$$ 2
2$ 2$ 2
$ 2
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$$
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$ 1$ 1$ 1$$ 2 +$ 2 +$ 2 +$ 2 +
2$$
1 1 1 1 1 1 I 1 1 1
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$$
=
122
1 1 - $ 12 $ 13 $ 14 $ 15 $6 $ 27 $ 28 $ 29 $ 2
$ 2$
$
1 $2 $ 13 $ 14 $ 15 $ 16 $7 $ 2 +8 $ 2 +9 $ 2 +
$ 2 +! 1 2
$$
1 1 1 1 1 1 1 I 1 i O 1 1
Z8000.sfk $1
$
$$
=
123
1 $ 12 $ 13 $ 14 15 $6 $ 27 $ 22 $ 29 $ 2
$ 2$
$n
1 $2 $ 13 $ 14 $ 15 $ ]6 $7 $ 2 +8 $ 2 +9 $ 2 +
$ 2 +2
$$
1 1 1 i 1 1 1 1 1 1
$1
$ W
$$
1 $ Jt $ n c !~ fnl ~~•iy
$ wurce JIZ., i: = I, S
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127
I
lmtm@* ----- IN (dcms@mm) : V( m % J. ?I W Y Fj A t c f nFr = ! g...s t . @t t i s- I~
1
—- —— — -— - -—j .0.000317 84.62294~”2.68E+22: O@ i 4 1 , : - ’. - ” ; .
Q - - - -- JOL016471— ‘--—--y- .!-
-~{ 1.39~’ ~~i 0.389198 -
J O . 0 0 1 7 3 2 i‘ - -
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1 . 4 7 ~ + 2 3 10 . 0 1 9 8 9 5F = - -~ ;
- - — v- — ——.— —j o -
Ni ‘ 4 5.11E+241 0.6933~0--’ -- --, o.og64831 5.49Ez3~.074448~i... ... .. -: -- ————. —.-...: —.—.
0 (X31694!—— —-. —— —
4. —— 1.43E+23i 0.~9-tj9——— .. ...———-+—— —.-..... — ,.;<m AD= 871 E+22 — km
—— —..——— ..= — .. .—-———’ —.-,- — 1 -
.m-(dcfmltYw3) :-8,71E+22: ~ 7:37E=+24[ ‘- - ‘“-—”- :— .-— -— -—- —+. _!--—- .——. —- *— - —- — -. J- .-.--.j__ . . :..-. -. -..”,,Uq mr(je I
U234 “—-” ----” ‘“m&j- “ —.... ——-.
—— _—. .—— 2395 59! 2.08E+22~3.’@j&-’-’ “u235
— —.—._ . —Qp~~ I
——_. ——.. ——
u 236+... ----- — - .-JmxEv2~o. m%7—–“ ‘“————— - -
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I I
4.65E+23‘N/ANi & Ur O
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128