AD-A257 470 0 Defense Nuclear Agency Alexandria, VA 22310-3398 DNA-TR-92-34 DELFIC Fallout Prediction Code Radiation Physics Package Upgrade DTIC ELECTE James A. Roberts, st al. 0 NOV4 1992D Science Applications International Corporation 10260 Campus Point Drive S San Diego, CA 92121 C October 1992 Technical Report CONTRACT No. DNA 001-88-C-0197 Approved for public releas; distribution Is unlimited. 92-28816 lM2 A
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
James A. Roberts, st al. 0 NOV4 1992DScience Applications International Corporation10260 Campus Point Drive SSan Diego, CA 92121 C
October 1992
Technical Report
CONTRACT No. DNA 001-88-C-0197
Approved for public releas;distribution Is unlimited.
92-28816
lM2 A
Destroy this report when it is no longer neoded. Do notreturn to sender.
PLEASE NOTIFY THE DEFENSE NUCLEAR AGENCY,ATTN: CSTI, 6801 TELEGRAPH ROAD, ALEXANDRIA, VA22310-3398, IF YOUR ADDRESS IS INCORRECT, IF YOUWISH IT DELETED FROM THE DISTRIBUTION LIST, ORIF THE ADDRESSEE IS NO LONGER EMPLOYED BY YOURORGANIZATION.
".4
O•4.
REPORT DOCUMENTATION PAGE ' Fo7rmApovedI Omit NO O704-O088
fothVW an ffi6{q1,I•411A,A, the date nede A~lr eO•qdrol- 0n4~me SM €reivli• Wa 940 0 40msitof Send ceowteqt reestlkns thm bwff 90ý141 or~ 0.4 ofte, 61SWI of Ih..
- 11 no Wolmelon. •WKIIWOW4 to,• ns em t t edweet Cho bwor . to Washowe Weaevle"O'te4 W-t owectoert e nfoef"0 k! w elS•O ,tet Wt Ret~to 121S J~fOrtw.•04sWfeo',e Sm~v l e, Sd 12;04 Anwqton. VA 22202 4X)2. a~ndtthe olfce of kmonet noffelnd 6~4,. P~orwo, ei-lk 01o nonhopm1•?04-01I8& Weshe*10". OC WW0 3
6. AUHS TA - R
1. AGENCY USE ONLY Deave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED
an921001 TechnicJl 880726 - 9203134. TITLE AND SUBTITLE .B FUNODING NUMBERSG A
DELFIC Fallout Prediction Code Radiation Physics C - DNA 001-88-C-0197Package Upgrade PF - 62715HPR - RM
6.AUTHOR(S) TA - RHJames A. Roberts , Dean C. Kaul , Farhad Dolatshahi NU - DH049560
and Joseph T. McGahan7. PERFORMING ORGANIZATION NAME(S) AND ADDRESSMES)' B. PERFORMING ORGANIZATION
Science Applications International CorporationREOTNMR
10260 Campus Point Drive SAIC-92/1045San Diego, CA 92121
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS4ES) 10. SPONSOR!NG/MONITORING
Defense Nuclear Agency AGENCY REPORT NUMBER
6801 Telegraph Road DNA-TR-92-34Alexandria, VA 22310-3398RARP/Kehl et
11. SUPPLEMENTARY NOTES
This work was sponsored by the Defense Nuclear Agency under RDT&E RMC CodeB4662D RM RH 00070 RARP 3500A 25904D.
12s. DISTRIBUTION/AVAILABIUITY STATEMENT 12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
13. ABSTRACT (Maximum 200 wordaJ
The DEfense Land Fallout Interpretive Code (DELFIC) is the DefenseNuclear Agency standard phenomenology code for computing falloutenvironments from nuclear weapons detonations. This report describesthe results of a program to update the DELFIC radiation physicspackage, that portion of the code which calculates the radioactivedecay of initial fission product inventories and their contributionto radiation exposure rate. Updates include corrections to errorsin following multi-path decay chains, the inclusion of ENDF/B-6decay constant data and the expansion of the number of radionuclideswhich contribute to direct exposure to irradiation from surfacecontamination.
14 SUBJECT TERMS 1I. NUMBER OF PAGES64Fallout Radiation 16. PRICE CODE
Computer Codes Fission Products17. SECURITm CLASSIFICATION IS SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF
OF REPOR' OF THIS PAGE OF ABSTRACT ABSTRACT
UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED SAR
NSN 7540.01 .2•1.55•0 j Standard Form 298 (Rev 2-89)PNu dW O, ANiSuI So 1)2 1112t8-10|
UNCLASSIFIEDMEURRlY ClASS PIA~lO or. THis WAGE
CLASSIFIED BY:
N/A since Unclassified
DECLASSIFY ON.N/A since Unclassified
SECUNrrV CLASSIF ONOF THIS P
UNCLASSIFIED
CONVERSION TABLE
Conversion Factors for U.S. Customary to Metric (SI) Units of MeasurementMULTIPLY BY v TO GET
TO GET • BY 4 DIVIDE
angstrom 1.000 000 X E-10 meters (m)atmosphere (normal) 1.013 25 X E +2 kilo pascal (kPa)bar 1.000 000 X E +2 kilo pascal (kPa)barn 1.000 000 X E -28 meter 2 (m2 )British thermal unit (thermochemical) 1.054 350 X E +3 joule (J)calorie (thermochemical) 4.184 000 joule (J)cal (themiochemical)/cm 2 4.184 000 X E -2 mega joule/m2 (MJ/m2 )curie 3.700 000 X E +1 giga becquerel (GBq)"degree (angle) 1.745 329 X E -2 radian (red)degree Fahrenheit Ik - (t0f+459.67)/1.8 degree kelvin (K)electron voft 1.602 19 X E -19 joule (J)erg 1.0o0 000 X E -7 joule (J)erg/second 1.000 000 X E -7 watt 'W)foot 3.048 000 X E -1 meter (m)foot-pound-force 1.355 8818 joule (,)gallon (U.S. liquid) 3.785 412 X E -3 meter (mi3 )inch 2.540 000 X E -2 meter (m)jerk 1.000 000 X E +9 joule (J)joule/ldlogram (Jtkg) (radiation dose absorbed) 1.000 000 Gray (Gy)kilotons 4.183 terajouleskip (1000 ibf) 4.448 222 X E +3 newton (N)kip/lnch2 (ksi) 6.894 757 X E +3 kilo pascal (kPa)ktap 1.000 000 X E +2 newton-second'm 2 (N-s/m 2 )micron 1.000 000 X E -6 meter (m)mil 2.540 000 X E -S meter (m)mile (Inteonational) 1.609 344 X E +3 meter (m)ounce 2.834 952 X E -2 kilogram (kg)pound-force (ibs avoirdupois) 4.448 222 newton (N)pound-force inch 1.129 848 X E -1 newton-meter (N - m)pound-force/Inch 1.751 268 X E +2 newton/meter (N/m)pound-force/loot 2 4.788 026 X E -2 kilo pascal (kPa)pound-force/inch 2 (psi) 6.894 757 kilo pascal (kPa)pound-mass (Ibm avoirdupois) 4.535 924 X E -1 kilogram (kg)pound-mass-foot 2 (moment of inertia) 4.214 011 X E -2 kilogram-meter 2 (kg - in2 )pound-mass-foot 3 1.601 846 X E +1 kilogranvmeter 3 (kg/r 3 )rad (radiation dose absorbed) 1.000 000 X E -2 Gray (Gy)'"roentgen 2.579 760 X E -4 coulomb/kilogram (C/kg)shake 1.000 000 X E -8 second(s)slug 1.459 390 X E +1 kilogram (kg)torr (mmHg, DOC) 1.333 22 X E -1 kilo pascal (kPa)
• The becquerel (Bq) is the SI unit of radioactivity; 1 Bq - I event/s."The Gray (Gy) is the SI unit of absorbed radiation.
ii iii
TABLE OF CONTETS
Section Page
OONFlRa ON T. IN . . . . . . . . . . . . . . . . . . iiiIIGU.38..............................*..***... v
A-4 DELFIC original and upgrade decay constants andexposure rate multipliers, 88 : Atomic Wt. 4 92 ........ 31
A-5 DELFIC original and upgrade decay constants andexposure rate multipliers, 93 < Atomic Wt. C 97. . . . . 32
A-6 DELFIC original and upgrade decay constants andexposure rate multipliers, 98 1 Atomic Wt. : 102 .... 33
A-7 DELFIC original and upgrade decay constants andexposure rate multiplierc, 103 1 Atomic Wt. 1 106. . . . 34
A-8 DELFIC original and upgrade decay constants andexposure rate multipliers, 107 1 Atomic Wt. < 110. . . . 35
A-9 DELFIC original and upgrade decay constants andexposure rate multipliers, 111 S Atomic Wt. : 115. . . 36
A-10 DELFIC original and upgrade decay constants andexposure rate multipliers, 116 1 Atomic Wt. < 120. . . . 37
A-11 DELFIC original and upgrade decay constants andexposure rate multipliers, 121 1 Atomic Wt. -< 125. . . . 38
A-12 DELFIC original and upgrade decay constants andexposure rate multipliers, 126 : Atomic Wt. : 130. . . . 39
A-13 DELFIC original and upgrade decay constants andexposure rate multipliers, 131 1 Atomic Wt. i 135. . . . 40
A-14 DELFIC original and upgrade decay constants andexposure rate multipliers, 136 < Atomic Wt. S 141. . . . 41
vii
TABLhE (Continued)
Table Page
A-15 DELFIC original and upgrade decay constants andexposure rate multipliers, 142 : Atomic Wt. 5 146. . . . 42
A-16 DELFIC original and upgrade decay constants andexposure rate multipliers, 147 : Atomic Wt. - 151 .... 43
A-17 DELFIC original and upgrade decay constants andexposure rate multipliers, 152 : Atomic Wt. S 156. . . . 44
A-18 DELFIC original and upgrade decay constants andexposure rate multipliers, 157 - Atomic Wt. - 161 .... 45
B-1 Fission products not in DELFIC for which decayconstants and exposure rate multipliers areavailable, 31 : Atomic No. < 44. . . . . . . . . . . . . 48
B-2 Fission products not in DELFIC for which decayconstants and exposure rate multipliers areavailable, 45 5 Atomic No. 5 49. . . . . . . . . . . . . 49
B-3 Fission products not in DELFIC for which decayconstants and exposure rate multipliers areavailable, 50 : Atomic No. : 58. . . . . . . . . . . . . 50
B-4 Fission products not in DELFIC for which decayconstants and exposure rate multipliers areavailable, 59 S Atomic No. : 68. ........... . . . 51
viii
SECTION 1INTRODUCTION
The Pfense Land fallout Interpretive Qode (DELFIC) (Ref. 1)is the Defense Nuclear Agency standard phenomenology code forcomputing fallout environments from nuclear weapons detonations.Such environments include spatial and temporal distributions ofradioactive fission products, activation products, unreacted bombdebris and their associated radiation exposure rates. A largenumber of available fallout and special applications codes arecalibrated to DELFIC data or actually include portions of DELFIC intheir construction. These codes include NewFALL (Ref. 2), DNAF1(Ref. 3), SEER (Ref. 4), CIVIC (Ref. 5), FAS (Ref. 6). Analternative fallout code, WSEG-10 (Ref. 7), was developed beforeDELFIC, based on empirical data. Thus, neither it or its progenyshare a specific development heritage with DELFIC. However, bothhave been influenced by the same limited amount of testobservations.
DELFIC describes the rise of the fireball in the time frame ofseconds and later, the formation of the cloud stem and, ultimatelythe formation of the stabilized radioactive cloud. It computes thefractionation of the fission products, i.e., their association withvarious particle sizes, depending on their volatility, and finally,it calculates the deposition of radioactivity on the ground, basedon the same particle size considerations.
Basic to the DELFIC model is the radiation physics package,which calculates the isotopic inventory of radioactive nuclides asa function of time after burst. This inventory is important tofractionation analysis and determines the exposure to radiationemissions. In this report DELFIC is either referred to as"Original" DELFIC, meaning the current code before modification, or"Upgrade" DELFIC, meaning the code as modified by work performedduring this study. Original DELFIC follows the decay of a largeinventory of isotopes, but has gamma ray emission data for only asmall fraction. Thus, its calculation of exposure to gammaemissions from fallout is incomplete. In addition the decay andbranching constants and initial fission product inventories havenot been revised in over 20 years. Finally, it has been observedthat the code does not treat properly the decay of some portions ofthat inventory.
This report describes an effort to rectify as many of theseproblems as possible within the constraints of available resources.Thus, it contains explanations of problems associated with thelogic of radioactive decay as treated in DELFIC and the steps takento solve these problems. It also describes efforts to upgradenuclear data in the code, particularly decay constants and theexposure rate multipliers associated with gamma ray emission rates.
1
SECTION 2DECAY CRAIN LOGIC UPGRADE
DELFIC treatment of radioactive decay is limited to betadecay, beta-neutron decay and isomeric transition (IT). DELFIChandles radioactive decay by arranging its inventory in chains ofincreasing atomic number, which follow the decay process from theparent isotope through a number of daughter products and until astable daughter is produced. Chains in which the decay process islimited to beta emission and IT are characterized by a singleatomic mass number. Chains which include beta-neutron decayinclude isotopes having more than one atomic mass number. The codecontains 118 such chains, including 692 isotopes, of which 118 arestable. A listing of the isotopes in the DELFIC library, arrangedby chain, may be found in Appendix A of this report.
2.1 CONSERVATION OF INVENTORY IN A SINGLE, BRANCHING CRAIN
As originally written, the DELFIC decay scheme has problemsconserving inventory. One instance of this problem occurs whenDELFIC encounters a branch in a decay chain. An example of such abranching chain is shown in Figure 2-1. The compartments representisotopes. The balloons represent the rate of transfer byradioactive decay from one compartment to the next, which iscontrolled by the "dcon," i.e., the decay constant. In the middleof the chain AsB3 may decay to either Se83m (Probability - 0.44) orSe83 and Se83m may undergo isomeric transition to Se83 (Prob. =0.1) or it can undergo beta decay to reach Br83. The probabilitiesgoverning the decay path are referred to as branching ratios.
DELFIC handles the problem of branching by computing the decayfor this chain separately for monolithic subsets of the chain, eachaccounting for a single branch, and adding the results. In orderto avoid miscounting the contribution of initial inventory nuclides(nuclides which exist at zero time) in this process, DELFICmultiplies the abundance of each by the product of all subsequentbranching ratios in the subset. In this way DELFIC partitions aportion of initial inventory for use in each subset of the chainand so conserves that inventory. Further, according to DELFIClogic, all isotopes which occur subsequent to a branch are notaffected by it and therefore contribute 100% of their inventory tothe subset.
In the case of the chain depicted in Figure 2-1, the resultingthree monolithic subset chains and the associated initial inventorypartitions are given in Table 2-1. The first subset includes thepath through Se83m and Se83, the second through Se83 alone, and thethird through Se83m alone. It can be seen from Table 2-1 that theDELFIC logic works well until after the first branch occurs. Up tothat poin': the sum of the inventory partitions for each isotopeover all subsets is unity, as shown in the last column of thetable. After the first branch occurs, however, the logic goes
2
m
E0
V
.1A0
0
Cl) 0
9):0
124
cc4
Va
NC
Table 2-1. Original DELFIC inventory partitions for subsets of
&wry, in that each subset includes 100% of the initial inventory ofall isotopes subsequent to the branch. In the case of the chaindepicted in Figure 2-1, this results in the initial inventory ofSe83 being counted twice and those of Br83 and Kr83m being countedthree times.
The existence of the initial inventory conservation problem inbranchirng chains arises because the code treats each subset of thechain serially, never assembling the probability array given inTable 2-1. The upgrade of DELFIC solves the problem by proceedingthrough the creation of branching chain subsets twice, once toassemble the partitioning array and re-normalize its values, asshown in Table 2-2, and a second time to actually calculate thedecay and total isotopic abundance. Note that the decay of initialinventory below the branch is the same for every subset of thechain. Therefore, the initial distribution of that inventorybetween the subsets is not important, so long as the total isconserved.
4
Table 2-3. Comparison of original and update DELFIC activitycalculation for chain of mass number 83.
ITRA-9n8.02 I 0E~O. 0.0009+00 9.1011-01 1.86101 1.22S5.01 1.3631+01 8.9071-01 3.267t-04
Siff ent m No Change no Change No Chlange No C•ange No Change -18.71% -34.121 -47.28X
a. Differzne: (Upgracb-Orwlgneat/Origlnst * 1002
Using the chain shown in Figure 2-1 as an example, the impactof the upgrade correction is illustrated in Table 2-3 for the chainapplicable to mass number 83. In this case the difference betweenactivity of an individual isotope located below the branch, ascalculated by original and update DELFIC, is significant, with theupgrade providing activities which are 20% to 50% less than thosecalculated with the original code.
2.2 CONBV RVATION OF INVENTORY IN MULTIPLZ, fMUCOKING C111N3
A beta-neutron decay results in a daughter isotope which hasa different atomic number than the parent and is therefore alsolikely to have a beta decay parent. Thus, a branch of a decaychain may be held in common by two chains. In DELFIC thissituation can become quite complicated, as shown in Figure 2-2,which is a simplified depiction of the relationship between twochains, initially of mass numbers 89 and 90, which couple at KrS9.
The coupled chains depicted in Figure 2-2 produced an initialinventory conservation problem similar to that described in 2.1 forbranching chains. DELFIC assembles a set of monolithic chains
5
00
0)0C0
I *10)0.0 A
SdI aAUA
I 0U
0 0 if0 0
if
0 I d's
hI
S I6
which represent the branching chain. In doing so the code includesnuclides which have been included in another decay calculation. Asoriginally configured, DELFIC also includes the initial inventoryof all members of each monolithic chain in the new decaycalculation. Thus, the initial inventories of isotopes are addedto the calculation as many times as the isotopes are found withina chain.
The problem of inventory conservation in multiple, branchingchains is solved in upgrade DELFIC by the simple expediency ofsetting the initial inventory value to zero after it has been usedonce. Thus, inclusion of an isotope subsequent to its initialappearance in a decay chain adds only the inventory attributable todecay. This solution is illustrated in Table 2-4, which depictsmass number chain 89 and that portion of the same chain proceedingfrom the chain of mass number 90, decayed to 8.02 sec. In thelines of data which represent the original DELFIC treatment ofthese two chains, it can be seen that the initial inventory isbeing counted twice, once in the 89 chain and again in the 90chain. Upgrade DELFIC zeros out the inventories of the isotopescommon to both chains in the second pass through them. The effect
Table 2-4. Comparison of original and update DELFIC activitycalculation for coupled chains, mass number 89and 90.
Initial Inventory Conservation In Decay Chains with Common Branch"
Isata": ASO9 so89 Ir89 Kr89 *b99 1r89 Y89
Originml DILFICTotal Iny-ntory (AtgM/lO fissigm):
T a 0 1.5281.00 4.824.Efnl 1.233E102 4.060E#01 6.300E+00 9.500E-03 O.001E*00fIat One In'" w otv (Atm/ls.omisLT a 0 1.SW1.00 4.829E*0 1.233E+02 4.060E#01 6.3001*00 9.500E-03 0.000E+00T a 8.02 sec O.O000÷Uu J.'aEgO00 5..77E+01 1.394E*02 9.066E+00 5.4271E-02 3.M3-06$&ueet Two inventory (At12.ALj9isins):T a 0 4.060M#01 6.300E+00 9.500E-03 0.0001.00T a 8.02 sec 6.034E*01 7.870%#00 5.186E-02 3.808-10
Original DELFICTotal Inventory (AtoujlO4fissions):I a 8.02 sec O.000E,00 3.0641*00 5.4771,01 1.991[#02 1.6941.01 1.062E-01 7.6911-08
Upgrsde DELFIC 4I etl g I o (Atom/lO flnlons):T a 0 1.9951R00 4.8241ý01 1.233E#U2 4.0601E01 6.300E100 9.500E-03 O.001E*00ILM t Two Inventory (Atom/10 fissions);TI 0 0.0001.00 O.O00100 0O.000100 0.0001.00
Dlfferencess No Change No Change No Change -19.73% -43.791 -47.83% -48.99%
a. Oifference: (Upgrade-OriginsL)/OHginst * 1001
7
of this change on the chains portrayed in Table 2-4 is to reduce
the decayed inventory of some isotopes by as much as 50*.
2.3 KLI'RM•RTIV DECAY MODES
At this time nothing has been done to include additional decaymodes, such as positton emission or electron capture, in the DELFICdecay scheme. Sut-A, inclusion is necessary in order to increase thenumber of nuclides treated by the code. Ultimately, this must bedone in order for DELFIC correctly calculate early time activity.
8
SECTION 3DATA BASE UPGRADE
DELFIC contains data for 692 nuclides, having atomic numbersbetween 27 and 66. These nuclides are accounted for in decaychains, as described previously in Section 2, in which the decay isfollowed from an initial radioactive isotope, which is the productof fission or activation, to the final, stable element in thechain.
The data required by DELFIC to calculate the population ofradioactive isotopes and their associated contribution to exposurerates from surface contamination, i.e., fallout, include thefollowing:
Initial AbundanceRadioactive Decay Constants
Branching RatiosExposure Rate Multipliers
This program of DELFIC data base review and upgrade occurredas the Evaluated Nuclear Data File (ENDF) (Ref. 8) was beingupdated from version 5 to version 6. Initial availability ofENDF/B-6 was limited to decay constants and gamma ray emissionspectra. Therefore, this report describes the revision of DELFICto include new decay constant data and new exposure ratemultipliers, calculated using ENDF/B-6 gamma ray emission data.
3.1 RADIOACTIVE DECAY CONSTANTS
DELFIC contains a library of 692 fission products of which 118are the stable ends of decay chains. Therefore, 574 decayconstants were replaced with new values taken from ENDF/B-6. Inaddition to the data required to update the existing DELFIClibrary, ENDF/B-6 offers decay constants for an additional 171radionuclides. New decay chains would have to be added to DELFICin order to accommodate the remaining data.
The mean difference between new and old decay constants is +72± 593%. Thus, it can be seen that, while there is little netchange in the decay constants overall, there is tremendous variancein the value of individual differences. The original and upgradedecay constants are listed in Appendix A.
Tables 3-1 through 3-8 give the most important 32 isotopesfrom the standpoint of surface exposure (R/hr/KT/m2 ) one hour afterU235, U238 and Pu239 fast fission and U238 thermonuclear fission.Part of the reason for the difference between the original andupgrade lists for each fissile isotope is the decay constantrevision. The total activity listed at the bottom of the isotopeinventory column represents 100% of the activity and is not simplya sum of column values. The difference in total activity is
9
partially due to decay constant changes. However, it is also dueto changes in the handling of initial inventory, as described inSection 2. The separate impact of each change can be inferred fromthe following values for total activity one hour after U238thermonuclear fission:
Original DELFIC: 4.391*108 Ci/KT
Upgrade DELFIC (Partial): 4.264*108 Ci/KTRevised Initial Inventory Conservation Only
The effect of revising the treatment of initial inventoryconservation is to reduce the total activity by a few percent. Thenet effect of the decay constant changes is to increase theactivity, which is consistent with the longer mean value for therevised decay constants.
3.2 ZIPOSURI RAT3 MULTIPLIERS
DELFIC translates ground surface-deposited activity intoexposure rate by means of Exposure Rate Multipliers (ERM). Thedimensions of the ERM library used in DELFIC are
(R/Hr)/(Disintegrations/Sec-cm2)
The original DELFIC contains ERM values for 181 isotopes. Inupgrade DELFIC the number has been expanded to 574, i.e., all theradioactive elements in the DELFIC library.
Expansion of the DELFIC ERM data base required that new ERM'sbe calculated. This was accomplished using gamma ray source ratesand one-dimensional radiation transport methodology to obtain theexposure rate one meter above a flat plane due to gamma emissionson the surface of that plane. The gamma ray source rates wereobtained from the emission spectra (per disintegration) forindividual fission product isotopes contained in ENDF/B-6. Theone-dimensional transport code used in the calculation was ANISN(Ref. 9), which solves the boltzmann equation in one dimension withanisotropic scattering.
The ANISN calculation was performed in the adjoint mode todetermine the importance of isotropic gamma ray emissions of allenergies and all locations in producing gamma ray tissue kerma(rad(tis)) one meter above the ground surface. The calculationswere performed using cross sections from the PVC 36 energy grouplibrary (Ref. 10) using an S., quadrature and a P5 legendrescattering order. The ground and air constituents used in the
10
calculations are given in Table 3-9. Tissue kerma was converted toroentgens (R) by dividing tissue kerma by 0.957.
The results of the ANISN calculations for a source location onthe surface of the ground (actually 0.25 cm above the surface) aregiven in Table 3-10 and depicted graphically in Figure 3-1. Theenergy boundary format of the data shown is changed somewhat fromthat originally calculated to make it consistent with the format ofthe available source spectra data. These data were multiplied bythe gamma rays per energy group per disintegration from ENDF/B-6for each DELFIC radioactive isotope to obtain the new ERM library.
Note that the URM values in DELFIC do not include the effectof attenuation due to ground roughness. Ground is not smooth onthe scale of fallout particles, which range in size from microns tohundreds of microns. Rather it is made up of granules havinginterstitial crevices, having sizes of the same order as thefallout particles. The tendency for fallout particles to depositin these crevices results in the attenuation of emitted radiation.The effect of ground surface roughness typical of a smooth dirtfield is to reduce gamma ray exposure rates by approximately 30%(Ref. 11).
Appendix A contains a listing of ERN values for the originaland upgrade DELFIC libraries. Appendix B provides ERM values foran additional 171 radionuclides included in ENDF/B-6 but nottreated by DELFIC. Comparing upgrade ERM values with those of the181 elements in original DELFIC, the difference between the new andold is +29 ± 131%, i.e., the new values are slightly larger, whilethe variation for individual isotopes is substantial. Tables 3-1through 3-8 give the most important 32 isotopes from the standpointof surface exposure (R/hr/KT/m2) one hour after U235, U238 andPu239 fast fission and U238 thermonuclear fission. The tables alsoprovide values for original and upgrade EP?!'s for the listedisotopes.
11
Table 3-1. Original DEIFIC, U235 fast fission at 1 hr, 32most important isotopes for surface exposure.
Energy (MOV)Figure 3-1. Exposure rate multiplier (ZERM) data base.
21
SECTION 4TIM IXPACT OF DBLVIC UPGRAD3
Calculations have been performed with the old and upgradedDELFIC radiation physics packages to assess the aggregate effect ofchanges in coding and data. Tables 4-1 through 4-4 give theactivity (Curies per kiloton) and exposure rate [(Roentgens perhour) per (kiloton per square meter)] calculated by DELFIC with andwithout upgrades for thermonuclear fission of U238 and fast fissionof U235, U238 and Pu239.
4.1 ACTIVITY
It can be seen from the data in Tables 4-1 through 4-4 thatthe impact of the upgrade on activity inventory are small, with thechanges generally resulting in small reductions in activity,particularly at late times. The amount of activity reductioncaused by the upgrades is consistent with that observed for codingchanges to the decay package, being of the order of a few percent.Updates in radionuclide half-lives do not appear to have had asignificant net effect on activity levels. However, some effect isnoticeable at early times, i.e., between one and fifteen minutes.
4.2 ZXPOIURB RRTZ
The upgrade of Exposure Rate Multipliers (ERM), replacing thevalues for the 181 radionuclides in DELFIC which had ERN's andincluding ERM's for anl additional 393 radionuclides, affects thenet exposure rate as a function of time similarly for all nuclidesand fission types included in Tables 4-1 through 4-4. The increasedue to the upgrade in exposure rates at one minute is mostdramatic, on the order of a factor of four or mo:7e. Of coursefallout at one minute is not particularly important, however thechange in surface exposure rate must be mirrored in that due toexposure to the rising cloud and its stem. Such early timeexposure rates are potentially important to aircraft attempting topenetrate an array of clouds in the first few minutes afterdetonation.
Eventually, DELFIC must be reconciled at early times with suchinitial. radiation codes as the Air Transport of Radiation (ATR)code, which calculates exposure rates from the rising cloud out to60 seconds. ATR uses the aggregate gamma ray emission rate perfission as its source. Using this source in place of thatcalculated using the DELFIC inventory yields a surface exposurerate which is approximately 50% greater than that calculated by theupgraded DELFIC. Therefore, it must be assumed that the success ofDELFIC-ATR reconciliation will depend not only on the upgrade ofexposure rates associated with the current DELFIC inventory butalso on the addition of more short-lived nuclides to thatinventory. Additional fission products for which decay rates andgamma emission data are available are given in Appendix B.
22
At one hour, a time generally used as a standard for falloutassessment, the exposure rates of the upgraded DELFIC are generallybetween ten and twenty percent greater than the old values. At oneday the upgraded values have dipped below the old values byapproximately twenty percent. However, by one week the upgradedvalues have risen to within a few percent of the old values.
IE+10
I1E+10
1E+10
OE+09
~'4E+00e
+00 . ,,. ........ I . ......
1E-M tE-1 IE+00 IE+01 IE+02 1E+03
HoumFigure 4-1. DELFIC original and updated exposure rates for U238
thermonuclear fission.
Figure 4-1 illustrates the progression of exposure rate valuesfor U238 thermonuclear fission from one minute to one week.Exposure rate values in the figure are multiplied by time to reducethe number of decades which must be portrayed. Also, in a semi-logplot of the product of time and exposure rate versus time, the areaunder the curve is proportional to the time-integral exposure forany given time begment.
Figure 4-1 shows the stark contrast between early time doseaccumulation as portrayed using the old and upgraded versions ofDELFIC. It also illustrates the decrease in dose accumulation ofthe upgrade relative to the old DELFIC in the vicinity of one day.
23
table 4-1. Fallout activity and exposure rates, U238
4. P.W. Wong and H. Lee, UtilLsation of the 533R Fallout Model ina Damage Asessmaent Computer Program, DNA3608F, StanfordResearch Institute, February 197S.
5. E.J. Swick, et al, CIVIC, Installation Damage and Casualtyassessment Program, SAIC-91/1028, Science ApplicationsInternational Corporation, 1991.
6. E.J. Swick, et al, Fallout Assessment System (PAS), User'sGuide and Maintenanoe Manual, SAIC-91/1029, ScienceApplications International Corporation, 1991.
7. G.E. Pugh and P.J. Galiano, An Analytical Model for Close-InOperational-Type Studies, WSEG RM No. 10, Weapon SystemEvaluation Group, October 1959.
3. P.F. Rose and C.L. Dunford, Eds., 3XDF-102 Data Formats andProcedures for the Nvaluated Nuclear Data File, ZIDW-6, BNL-NCS 44945, Rev. 10/91, Brookhaven National Laboratory, 1990.
9. W.W. Engle, Jr., A User's Manual for ANION - A One-DimsensionalDiscrete Ordinates Transport Code With Isotropic scattering,K-1693, Oak Ridge Gaseous Diffusion Plant, 1967.
10. R.W. Roussin, PVC-34 Group, P , Photon Interaction Crosssections for 35 Materials in AbNIM Format, DLC--48, Oak Ridge
National Laboratory, 1977.
11. S.D. Egbert, D.C. Kaul, J. Klemm and J.C. Phillips, FIIDOS-ACamputer Code for the Computation of Fallout Inhalation andIngestion Dose to Organs, Computer User's Guide, DNA-TR-84-375, Science Applications International Corporation, 1985.
26
APPENDIX ADBCRT CONUTh•NSlD UK 11'a
This appendix contains a listing of all the decay constalesand exposure rate multipliers (E]M's) in the original DELFIC and inthe upgraded version of the code.
27
Table A-1. DELFIC original and upgrade decay constants andexposure rate multipliers, 72 : Mass No. _S 77.
This appendix contains a list of fission products for whichdecay rates and gamma ray emission rats are available but whichare not included in the DELFIC inventory.
47
Table 9-1. Fission products not in DELFIC for which decayconstants and exposure rate multipliers areavailable, 31 _ Atomic No. _S 44.
DEPARTMENT OF DEFENSE INTERSERVICE NUCLEAR WEAPONS SCHOOLATTN: lTrV
ARMED FORCES RADIOB'OLOGY RSCI INST 2 CYS ATTN: TTV 341VTH TTSOATTN: AFFRI RADIATION BIOCHEMISTRYATTN: BHS JOINT DATA SYSTEM SUPPORT CTRATTN: DIRECTOR ATTN: C-332ATIN: EXH ATTN: JNSVATTN: MRAATTN: PHY NATIONAL DEFENSE UNIVERSITYATTN: RSD ATTN: ICAF TECH LIBATIN: SCIENTIFIC DIRECTOR ATTN: NWCLB-CRATTN: TECHNICAL LIBRARY ATTN: LIBRARY
ATTN: STRAT CONCEPTS DIV CTRASSISTANT SECRETARY OF DEFENSEINTERNATIONAL SECURITY POLICY NET ASSESSMENT
ATIN: NUC FORCES & ARMS CONTROL PLCY ATTN: DOCUMENT CONTROL
ASSISTANT TO THE SECRETARY OF DEFENSE OFC OF MILITARY PERFORMANCE ASSESSMENTATTN: EXECUTIVE ASSISTANT TECHNOLOGYATTN: MIL APPL C FIELD ATTN: F HEGGE
DEFENSE INTEWGENCE AGENCY PROGRAM ANALYSIS & EVALUATIONATTN: DB ATTN: NAVAL FORCES
5 CYS ATTN: DB-4 RSCH RESOURCES DIV ATTN: STRATEGIC PROGRAMS & TNFATTN: DB-5CATTN: DS-B STRATEGIC AND THEATER NUCLEAR FORCES
ATTN. DB4E ATTN: DR E SEVINATTN: DIAIVPA-2 ATTN: DR SCHNEITERATTN: DIW.4 THE JOINT STAFFATTN: DN ATTN: JKACATTN: DT ATTN: JLTATTN: OFFICE OF SECURITY ATTN: JPEPATTN: OS
THE JOINT STAFF
DEFENSE INTELLIGENCE COLLEGE ATE rNT ES30
ATTN: DIC/RTS-2 ATTN: J-3 SPECIAL OPERATIONSAT'AN: DIC/2C AT-N: 4-8
DEFENSE LOGISTICS AGENCY ATTN: JAD/SFD
ATTN: COMMAND SECURITY OFC ATTN: JSOA
DEFENSE NUCLEAR AGENCY U S EUROPEAN COMMAND/ECJ-6-DT
AITN: CID ATTN: ECJ4
ATTN: DFRA JOAN MA PIERRE U S EUROPEAN COMMAND/ECJ2-TATTN: NANF ATTN: ECJ2-TATTN: NASFATTN: OPNA U S EUROPEAN COMMAND/ECJ3-CCDATTN: OPNS ATTN: ECJ.3ATTN: RAEE
20 CYS ATTN: RARP U S EUROPEAN COMMAND/ECJ4-LW2 CYS ATTN: TITL ATTN: ECJ4-LW
DEFENSE TECHNICAL INFORMATION CENTER U S EUROPEAN COMMAND/ECJ5-N2 CYS ATTN: DTIC/FDAB AM.*:. ECJS-N NUC BRANCH
FIELD COMMAND DEFENSE NUCLEAR AGENCY U S EUROPEAN COMMAND/ECJ7/LWATTN: FCPR ATTN: ECJ-7LWATTN: FCPRTATTN: NUC SECURITY UNDER SEC OF DEFENSE FOR POLICY
DEPARTMENT OF TNE ARMY U S ARMY MATERIAL COMMANDATrN: DRCOE-D
COMBAT MATERIAL EVAL ELEMENTATTN: SECURITY ANALYST U S ARMY NUCLEAR & CHEMICAL AGENCY
ATTN: MONA-NUDEP CH OF STAFF FOR OPS & PLANS 4 CYS ATTN: MONA.NU DR 0 BASH
ATTN: DAMO.SWMATTN: DAMO-ZXA U S ARMY TEST & EVALUATION COMMAND
ATTN: STECS-NEHARRY DIAMOND LABORATORIES
AiTN: SLCH-NW-RS JOSIP SOLN U S ARMY WAR COLLEGEATTN: SLCISIM-TL ATTN: LIBRARY
ATTN: STRATEGIC STUDIES INSTITUTEJOINT SPECIAL OPERATIONS COMMAND
ATTN: J-2 U S MILITARY ACADEMYATI•N: J-5 ATTN: BEHAVORIAL SCI & LEADERSHIP
ATTN: PHYSICS COL J G CAMPBELLNUCLEAR EFFECTS DIVISION ATTN: SCIENCE RESEARCH LAB
ATTN: STEWS-NE-TUS ARMY MATERIEL SYS ANALYSIS ACTVY
U S ARMY AIR DEFENSE ARTILLERY SCHOOL ATTN: DRXSY-DSATTN: COMMANDANT
USA SURVIVABILITY MANAGMENT OFFICEU S ARMY ARMAMENT RSCH DEV & ENGR CTR ATTN: SLCSM-SE J BRAND
ATTN: DRDAR-LCN-FUSACACDA
U S ARMY ARMOR SCHOOL ATTN: ATZLCAD-NATTN: ATSB-CTDATTN: TECH LIBRARY DEPARTMENT OF THE NAVY
U S ARMY BALLISTIC RESEARCH LAB DEPARTMENT OF THE NAVYATTN: SLCBR-D ATTN: PMS-423ATTN: SLCBR-DD-T ATTN: SEA-0eGNATTN: SLCBR-TBATTN: SLCSR-VL-I DR KLOPCIC MARINE CORPSATrN: SLCBR.VL-V ATTN: CODE PPO
ATTN: PSI G/RASPU S ARMY COMBAT SYSTEMS TEST ACTIVITY
ATTN: JOHN GERDES NAVAL OCEAN SYSTEMS CENTERATTN: MIKE STANKA ATTN: CODE 9642-B
U S ARMY COMO & GENERAL STAFF COLLEGE NAVAL PERSONNEL RES & DEV CENTERATrN: ATZL-SWJ-CA ATTN: CODE P302ATTN: ATZL-SWT-A NAVAL POSTGRADUATE SCHOOL
U S ARMY CONCEPTS ANALYSIS AGENCY ATTN: CODE 1424 LIBRARYATTN: TECHNICAL LIBRARY NAVAL RESEARCH LABORATORY
U S ARMY FIELD ARTILLERY SCHOOL ATrN: CODE 1240ATTN: ATSF-CD ATTN: CODE 2627
U S ARMY FORCES COMMAND NAVAL SURFACE WARFARE CENTERATTN: AF-OPTS ATTN: CODE F-31
ATIN: G RIELU S ARMY FOREIGN SCIENCE & TECH CTR
ATTN: C WARD NAVAL TECHNICAL INTELLIGENCE CTRATTN: NTIC-DA30
U S ARMY INFANTRY CENTERATTN: ATSH-CD-CSO NAVAL WAR COLLEGE
ATTN: CODE E 11U S ARMY ITAC ATTN: CTR FOR NAV WARFARE STUDIES
ATrN: IAX.Z ATFN: DOCUMENT CONTROLATTN: LIBRARY
U S ARMY LABORATORY COMMAND ATTN: STRATEGY DEPTATTN: DIRECTORATTN: DR D HODGE NAVAL WEAPONS EVALUATION FACILITY
ATTN: CLASSIFIED LIBRARY
Dist-2
DNA-TR42-34 (DL CONTINUED)
NUCLEAR WEAPONS TNG GROUP ATLANTIC LAWRENCE LIVERMORE NATIONAL LABATTN: CODE 222 ATTN: Z DIVISION LIBRARYATrN: DOCUMENT CONTROL
LOS ALAMOS NATIONAL LABORATORYNUCLEAR WEAPONS TNG GROUP PACIFIC ATTN: D STROTrMAN
ATTN: CODE 32 ATTN: REPORT LIBRARY
OFFICE OF CHIEF OF NAVAL OPERATIONS MARTIN MARIETTA ENERGY SYSTEMS INCATTN: NIS-22 ATFN: B SANTOROATI•N: NOP 06D ATTN: G KERRATTN: NOP 403 ATTN: J WHITEATTN: NOP 50 ATTN: W RHOADESATTN: NOP 60ATTN: NOP 60D SANDIA NATIONAL LABORATORIESAMTN: NOP 603 ATrN: TECH LIB 3141ATTN: NOP 91AMiN: OP 654 OTHER GOVERNMENTAITN: PMS/PMA-423 CENTRAL INTELLIGENCE AGENCY
OPERATIONAL TEST & EVALUATION FORCE ATTN: COUNTER-TERRORIST GROUPATTN: COMMANDER ATTN: DIRECTOR OF SECURITY
ATTN: MEDICAL SERVICESPLANS, POLICY & OPERATIONS ATTN: NIO-T