02.-KTA-3201.4.pdf

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Safety Standardsof theNuclear Safety Standards Commission (KTA)

KTA 3201.4 (06/99)

Components of the Reactor Coolant Pressure Boundaryof Light Water ReactorsPart 4: In-service Inspections and Operational Monitoring

(Komponenten des Primärkreises von Leichtwasserreaktoren;Teil 4: Wiederkehrende Prüfungen und Betriebsüberwachung)

Previous versions of this SafetyStandard were issued 6/82 and 6/90

If there is any doubt regarding the information contained in this translation, the German wording shall apply.

Editor:

KTA-Geschaeftsstelle c/o Bundesamt fuer Strahlenschutz (BfS)Willy-Brandt-Strasse 5 • D-38226 Salzgitter • GermanyTelephone +49-5341/885-(0) 901 • Telefax +49-5341/885-905

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KTA SAFETY STANDARDJune 1999

Components of the Reactor Coolant Pressure Boundaryof Light Water Reactors;

Part 4: In-service Inspections and Operational MonitoringKTA 3201.4

CONTENTS

Fundamentals ............................................................5

1 Scope ..................................................................5

2 Definitions ...........................................................6

3 General principles ...............................................7

4 Test procedures ..................................................94.1 General requirements..........................................94.2 Examination of surfaces ......................................94.3 Volumetric examination .....................................114.4 Integral visual examination................................114.5 Pressure test .....................................................114.6 Functional tests on safeguards against

excessive pressure............................................12

5 Extent of testing and test intervals.....................125.1 General requirements........................................125.2 Extent of testing.................................................125.3 Test intervals .....................................................13

6 Test and inspection schedule............................136.1 Preparation........................................................136.2 Review and updating.........................................13

7 Preparation of tests, test instructions ................197.1 Preparation of tests ...........................................197.2 Test instructions ................................................19

8 Evaluation of the test results .............................198.1 Volumetric examinations as well as examina-

tions of surfaces and near-surface regions .......19

8.2 Visual examination............................................ 208.3 Pressure test .................................................... 208.4 Functional tests of safeguards against

excessive pressure ........................................... 20

9 Operational monitoring ..................................... 219.1 General requirements ....................................... 219.2 Monitoring of loadings....................................... 219.3 Monitoring of the chemical water quality........... 219.4 Monitoring of changes of metal properties........ 219.5 Leak monitoring ................................................ 219.6 Monitoring the primary circuit for loose

parts.................................................................. 22

10 Participation in in-service inspections andoperational monitoring ...................................... 22

11 Documentation.................................................. 2311.1 General............................................................. 2311.2 Documents required for in-service

inspections........................................................ 2311.3 Period of document filing for in-service

inspections........................................................ 2311.4 Documents required for the monitoring of

mechanical and thermal loadings ..................... 23

Annex A: Regulations referred to in this SafetyStandard ................................................... 24

Annex B: Changes with respect to the edition 6/90and explanations (informative).................. 25

PLEASE NOTE: Only the original German version of this safety standard represents the joint resolution of the50-member Nuclear Safety Standards Commission (Kerntechnischer Ausschuss, KTA). The German version wasmade public in Bundesanzeiger No. 200a on October 22, 1999. Copies may be ordered through the Carl HeymannsVerlag KG, Luxemburger Str. 449, D-50939 Koeln (Telefax +49-221-94373-603).All questions regarding this English translation should please be directed to:

KTA-Geschaeftsstelle c/o BfS, Willy-Brandt-Strasse 5, D-38226 Salzgitter, Germany

KTA 3201.4

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Comments by the editor:

Taking into account the meaning and usage of auxiliary verbs in the German language, in this translation thefollowing agreements are effective:

shall indicates a mandatory requirement,

shall basically is used in the case of mandatory requirements to which specific exceptions (and onlythose!) are permitted. It is a requirement of the KTA that these exceptions - other thanthose in the case of shall normally - are specified in the text of the safety standard,

shall normally indicates a requirement to which exceptions are allowed. However, the exceptions used,shall be substantiated during the licensing procedure,

should indicates a recommendation or an example of good practice,

may indicates an acceptable or permissible method within the scope of this safety standard.

KTA 3201.4

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Fundamentals

(1) The safety standards of the Nuclear Safety StandardsCommission (KTA) have the task of specifying those safetyrelated requirements which shall be met with regard toprecautions to be taken in accordance with the state ofscience and technology against the damage arising from theconstruction and operation of the facility (Sec. 7 para 2subpara 3 Atomic Energy Act) in order to attain the protectiongoals specified in the Atomic Energy Act and the RadiologicalProtection Ordinance (StrlSchV) and which are further detailedin the “Safety Criteria for Nuclear Power Plants” and in the“Guidelines for the Assessment of the Design of PWR NuclearPower Plants against Incidents pursuant to Sec. 28 para 3 ofthe Radiological Protection Ordinance (StrlSchV) - IncidentGuidelines”.

(2) With respect to the subject matter of this safety standard,Criterion 1.1, Basic Requirements for Safety Precautions, ofthe “Safety Criteria for Nuclear Power Plants” specifies thata) a reliable monitoring of operating conditions,b) an adequate extent of in-service inspections andc) a documentation, evaluation and safety-oriented applica-

tion of operating experience

shall be realized. To this end, the causes and consequencesof possible operational damage mechanisms shall bemonitored on the basis of the current knowledge. In-serviceinspections are also called for in the RSK-Guidelines forPressurized Water Reactors. These requirements are detailedin this safety standard.

(3) The pressure boundary of the primary circuit has the taskof safely retaining the reactor coolant. To ensure that this taskis fulfilled during the service life of the reactor, in-serviceinspections (operational monitoring) are performed atspecified time intervals to demonstrate the integrity of thepressure boundary and the functional capability of thesafeguards against excessive pressure.

(4) The task of this safety standard with respect tooperational monitoring is to determine relevant measures aslisted in a) to e) in order to exclude effects that may impair thecomponent integrity, as follows:

Monitoring of causes of operational damage mechanisms:a) monitoring of the parameters and data relevant to primary

circuit integrity by standard instrumentationb) monitoring of the chemical water quality in the primary and

secondary circuit

Monitoring of consequences of operational damagemechanisms:a) leakage monitoring of the primary circuit for the detection

of leakage to the outside as well as from the primary to thesecondary circuit

b) loose parts monitoringc) monitoring of the vibration behaviour of the primary circuit

components for the early detection of changes.

(5) The task of this safety standard with respect to in-serviceinspections is to determine the relevant measures as listed ina) to d) hereinafter in order to ascertain the componentintegrity by:a) non-destructive examinations of the external and internal

surfaces and, as far as required by this safety standard, ofthe volume of the pressure retaining wall,

b) integral visual examinations that serve to evaluate thegeneral condition during regular plant inspection andselective visual examinations to evaluate the condition ofindividual components,

c) pressure tests as integral loading test,

d) functional tests addressing the safeguards againstexcessive pressure.

All above tests and examinations shall be documented in a so-called “test and inspection schedule” which takes intoconsideration the requirements for the individual component ofthe primary circuit and contains the entire extent of in-serviceinspections.

(6) During in-service inspections test and examinationprocedures are used to detect defects in the reactor coolantpressure boundary in due time prior to reaching theacceptability limit. When determining the extent of tests andexaminations, the design, material properties, fabricationprocesses and loading of the respective component as well asexperience gained with already performed inspections shall betaken into consideration.

(7) KTA 3201 safety standard series “Components of theReactor Coolant Pressure Boundary of Light Water Reactors“comprises the following additional standards:KTA 3201.1 “Materials and Product Forms“,KTA 3201.2 “Design and Analysis“,KTA 3201.3 “Manufacture“.

1 Scope

(1) This safety standard shall apply after first criticality to thein-service inspections and operational monitoring of pressureretaining components of the primary circuit of light-waterreactors.

(2) In the case of pressurised water reactors, the reactorcoolant pressure boundary comprises the followingcomponents without internals:a) the reactor pressure vessel,b) the primary side of the steam generators, the secondary

shell of the steam generators including the feedwater inletand main steam exit nozzles up to the pipe connectingwelds, but not the minor nozzles and nipples, shall also betreated in accordance with this safety standard,

c) the pressurizer,d) the reactor cooling pump casing,e) the connecting pipes between the above components and

the valve casings of any type contained in the pipingsystem,

f) the pipes branching off from the above components andtheir connecting pipes including the valve bodies installedin the piping system up to and including the first shut-offvalve,

g) the pressure retaining walls of the control rod drives andthe in-core instrumentation,

h) the integral parts of the component support structures inaccordance with Fig. 8.5-1 of KTA 3201.2 and the weldedattachments.

(3) In the case of boiling water reactors, the reactor coolantpressure boundary comprises the following componentswithout internals:a) the reactor pressure vessel,b) the pipework belonging to the same pressure space as the

reactor pressure vessel including the installed valve bodiesup to and including the first shut-off valve, pipeworkpenetrating the containment shell and belonging to thesame pressure space as the reactor pressure vessel up toand including the last shut-off valve located outside thecontainment shell,

c) the pressure retaining walls of the control rod drive and in-core instrumentation,

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d) the integral parts of the component support structures inaccordance with Fig. 8.5-1 of KTA 3201.2 and the weldedattachments.

(4) This safety standard shall apply to components wherethe design and manufacture have been based on theprinciples of basic safety.

Note:The requirements of the safety standards KTA 3201.1 to KTA3201.3 were established taking into account these principles.

(5) This safety standard may also apply to components ofthe primary circuit of light water reactors or to regions of thesecomponents where a re-evaluation shows that they meet theprinciples of basic safety.

(6) In the case of components that do not meet theprerequisites under subpara. (4) or (5), it may becomenecessary to specify stricter requirements regarding in-serviceinspections and operational monitoring on the basis of thespecific situation. The previously specified requirements andguidelines for the in-service inspections and operationalmonitoring remain applicable.

2 Definitions

(1) Pipe attachment weldThe pipe attachment weld is a weld seam that connects thenozzle with the corresponding pipe section.

(2) Indications and types of flawsThe correlation between indications and flaws are shown inFigure 2-1.

Indications Flaws

noise level

minimum detection level of examination procedure

recording limit for F.E. and I.I.

evaluation limit for I.I.

acceptability limit

critical flaw size

unac

cept

able

flaw

s

criti

cal f

law

s

dete

ctab

le fl

aws

F.E.: examination during fabrication I.I.: In-service inspection

reco

rdab

le in

dica

tions

rele

vant

indi

catio

ns

Figure 2-1: Indications and types of flaws

(3) Operational flawsOperational flaws are flaws due to operational damagemechanisms.

(4) Higher stress locations of the primary circuitHigher stress locations of the primary circuit are suchlocations of a component or component part thata) compared to the general level of stress intensity are more

highly stressed taking the frequency additionally intoaccount

orb) are more susceptible to corrosive action.

(5) Calibration blockA calibration block is a standardized or non-standardizedblock of a known material with a specific surface quality andgeometry for the adjustment of the ultrasonic testing systemand for checking the adjustments.

Note:Standardized calibration blocks are e.g. calibration blocks inaccordance with DIN 54 120 (K1) and calibration blocks inaccordance with DIN EN 27 963 (K2).

(6) Measured valuesMeasured values are documented and stored values (e.g.pressure, temperature, amplitude, time base ranges, position)

(7) Types of tests, test procedures and techniquesThe terms, their acronyms and correlation of the types oftests, test procedures and techniques are shown in Table 2-1.

(8) Examination of surfacesA surface examination is a non-destructive examination of thesurface and near-surface regions in which case the depthexamined depends on the method and wall thickness.

(9) Representative locations, components or componentparts

Such locations, components or component parts areconsidered to be representative where the in-serviceinspection will lead to sufficiently comparable safety relatedresults for other locations, components or component parts,taking into consideration the material composition, design andmanufacturing quality as well as the stress type, level andfrequency.

(10) Operational damage mechanismsOperational damage mechanisms are such mechanismswhich are of importance for the component integrity under thegiven operating conditions (e.g. fatigue, corrosion).

(11) Standard instrumentationThe standard instrumentation serves to monitor theparameters and data relevant to primary circuit integrity andcomprises measuring equipment to monitor global loadingsand – if required – measuring equipment to monitor localloadings (e.g. due to thermal stratification)

(12) Nozzle attachment and insertion weldA nozzle attachment and insertion weld is a weld seam thatconnects the nozzle with the vessel wall or the pipe wall.

(13) Pipe joint weldA pipe joint weld is a weld seam that joins pipe sections ofequal diameters.

(14) Reference blockA reference block is a block adapted to the test object withrespect to geometry and physical characteristics and thatcontains reference flaws adapted to the individual testing task.

(15) Volumetric examinationA volumetric examination is a non-destructive examinationwhere the body of the wall is examined and evaluated over itsentire cross section with the exception of the examined near-surface regions.

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SerialNumber Type of Test Test Procedure Test Technique

Magnetic particle flaw detection Magnetic particle examination (MT),magnaflux examination

Liquid penetrant examination (LT) e.g. dye penetrant examination

1Ultrasonic examination procedure (US) e.g. surface waves, mode conversion, dual

search units with longitudinal waves,electromagnetic ultrasonic waves

Eddy-current examination procedure (ET) Single frequency, multiple frequencyRadiographic examination procedure (RT) X-ray

Radioisotope

Examination withregard to cracks in thesurface or innear-surface regions

Selective visual examination (SV) With or without optical meansUltrasonic examination procedure (US) e.g. single probe technique with straight

(ES) or angle beam scanning, tandem(angled pitch-catch) technique, modeconversion

Radiographic examination procedure (RT) X-rayRadioisotope

2 Volumetricexamination

Eddy-current examination procedurefor thin walls

(ET) Single frequencyMultiple frequency

Integral visual examination

Pressure test 3 Integral examinationFunctional test

Table 2-1: Type of tests, test procedures and techniques

3 General principles

(1) To ensure the component integrity during operation theprinciples outlined hereinafter shall be met with respect tooperational monitoring and in-service inspections.

(2) Based on the quality standard of a component obtaineddue to the design and manufacture for safeguarding againstdamage mechanisms that may arise from accidents andincidents, the causes of operational damage mechanismsshall be monitored by the standard instrumentation (e.g.monitoring of loadings) to ensure the required componentquality. The monitoring of the causes of operational damagemechanisms shall ensure that the selection of measuringlocations, parameters, extent of measurement and measuringequipment takes into account the operational parameters andthe mode of operation as well as the function of individualstructural components (e.g. supports, valves) and possibleswitching operations.

(3) To monitor the presumed consequences of operationaldamage mechanisms, in-service inspections and operationalmonitoring measures (e.g. leakage control, vibration control)shall be performed in representative areas.

Note:Additional measures to enlarge the knowledge on prevailingoperational damage mechanisms may be supplementary exami-

nations, e.g. non-destructive examinations, destructive examina-tions on representative locations of parts exchanged for thepurpose of replacement measures.

(4) The re-evaluation for proof of the component integritymay be made as follows in accordance with Figure 3-1:

a) At first the design and manufacture shall be evaluated indue consideration of previous operating experience madewith the component quality.

b) The results obtained from the evaluation of the loadingsspecified for the design compared with the actual opera-tional loadings shall be used, if necessary, to establishsupplementary operational monitoring measures (monito-ring of causes of operational damage mechanisms).

c) The in-service inspections to be performed in representa-tive areas, which shall be fixed to monitor the consequen-ces of operational damage mechanisms result from theabove mentioned integrity evaluation of the operationalloadings occurred. The selection of examination proce-dures shall be related to the component in dependence ofthe component quality with respect to the operationaldamage mechanisms expected in which case the fracture-mechanic assessment of critical crack sizes and assumedcrack growth values shall be taken into account.

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Evaluation of loadings

Establishment of measures to monitor consequences

Supplementary measures(e.g. refined analyses,additional monitoring)

Evaluation of the quality obtained

Determinationof

relevant loadings

Evaluationof

the structure

Havethe principles of

basic safety beensatisfied ?

Havespecified load cases

been satisfied ?

Documentation of variables ofpotential operational damage

Monitoring of consequencesof presumed operational damage mechanisms

examinationmethods

relevant areas

mechanical andthermal loadings

water chemistry

examinationintervals

Consistentconcept

EvaluationTotal concept

positive

Furthermeasures

Changein state ofknowledge

no no

yes yes

(e.g. stress analysis, fatigue analysis,fracture-mechanic analysis)

Determinationof operational

damagemechanisms

(e.g. non-destructive examinations, loose parts monitoring, destructive examinations)

Figure 3-1: Safeguarding of component integrity during operation

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4 Test procedures4.1 General requirements4.1.1 Type and location of flaws

(1) The test procedures and techniques shall be chosensuch that service-induced flaws with their possible orientationswill be detected. Such orientations are:a) planes perpendicular to the directions of principal stress,b) planes parallel to the fusion faces of weld seams

(longitudinal flaws),c) planes perpendicular to the direction of weld seams

(transverse flaws).

(2) The test procedures and techniques for testing steamgenerator tubes shall be chosen such thata) flaws on the inside and outside surfaces,b) any local wall thinningwill be detected.

4.1.2 Detection capability of test procedures

(1) The detection capability of the test procedures withrespect to the type and orientation of flaws shall be such thatcompliance with the recording limits specified in Sections 4.2and 4.3 can be ensured. This shall be demonstrated prior tothe initial application of a test technique (e.g., by usingreference blocks).

(2) Where the required detection capability is not achieved inlimited areas by the test procedures selected, special proofsshall be furnished regarding the effectiveness of the test or ananalytical proof (e.g. fracture mechanic analysis) shall beperformed or the inspection intervals shall be shortened.

4.1.3 Comparability of the results of consecutive tests

(1) The results of consecutive tests must be comparable toeach other. If the test procedure or technique is changed, aproof of the comparability of results shall be furnished.

(2) If, for the purpose of accessibility or comparability, in-service inspections are to be performed in a mechanized way,a reference test is initially required using the same testingequipment as will later be used for the in-service inspectionsprovided that the results of the mechanized tests are notcomparable to the tests performed during fabrication.

(3) If in-service inspections are performed manually, theresults of the first in-service inspection shall be compared withthat fabrication test which qualifies the final fabricationcondition of the component.

4.1.4 Recording of test results

(1) In the case of mechanically performed tests, allmeasured values and the corresponding coordinates shall bedocumented by automatic recording equipment.

(2) In the case of manually performed tests all recordableconditions shall be documented in the same way as requiredfor the fabrication test in accordance with Sec. 13.13 ofKTA 3201.3.

(3) Fluctuations of the ultrasonic signals due to coupling,absorption and scattering shall be checked for the chosenbeam angles. The results shall be recorded and considered inthe sensitivity adjustment and in the evaluation.

4.1.5 Permissible examination procedures

(1) The examination procedures as per Table 2-1 as well asper Sections 4.2 and 4.3 may be applied. Other test

procedures are permitted provided their suitability forachieving the test objective has been proven.

(2) The surfaces of components made of ferritic materialsshall preferably be examined with the leakage flux procedure,those of components made of austenitic materials with theliquid penetrant procedure.

(3) If the test results from one procedure alone giveinsufficient information then an additional procedure shall beapplied that is based on a physical interaction different fromthe first. Where the results obtained from the additional testprocedure are not sufficient, further steps shall be agreed withthe authorized inspector.

4.2 Examination of surfaces

4.2.1 Leakage flux procedure

When applying the leakage flux procedure, the magneticparticle examination shall preferably be employed.

4.2.2 Liquid penetrant procedure

When applying the liquid penetrant procedure, penetrantsshall be used the characteristics of which have been tested inaccordance with DIN 54 152 Part 2.

4.2.3 Ultrasonic examination procedures

4.2.3.1 Surfaces and their near-surface regions close to thesearch unit

(1) Suitable ultrasonic examination techniques shall beemployed when examining surfaces and their near-surfaceregions close to the search unit.

(2) Ultrasonic examination techniques considered to besuitable are, e.g., techniques employing surface and creepingwaves, the dual search unit with longitudinal waves, ortechniques exploiting the corner effect after reflection of thesound beam. The examination for flaws in the transition regionbetween cladding and base material shall be performed withexamination techniques especially designed for this depth.

4.2.3.2 Surfaces and their near-surface regions away fromthe search unit

(1) When examining the surface away from the search unitwith its near-surface regions for planar discontinuities, atechnique utilizing the corner effect shall preferably beemployed. In this case vertically polarized transverse waveswith the incident angle of the sound beam in the rangebetween 35 and 55 degrees shall be employed. Examinationtechniques with an incident angle of the sound beam in therange between 65 and 70 degrees may also be employed.

(2) Furthermore, the following techniques may be applied:a) the mode conversion technique, where the transverse

waves striking the examined surface with an incidenceangle of 33 degrees are converted to longitudinal wavesthat run almost parallel to the surface and encounter theexpected flaw in perpendicular direction,

b) the mode conversion technique where the longitudinalwaves reflected from the flaw of the surface away from thesearch unit are converted to transverse waves and in thismode reach the search unit.

(3) If, for reasons of test object geometry or of microstruc-ture (e.g. in the case of clad surfaces, austenitic weld seamsand dissimilar material weld seams), the above mentionedtechniques do not achieve the necessary sensitivity then,provided a prior verification of suitability was performed, theexaminations may be carried out employing horizontally or

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vertically polarized transverse or longitudinal waves with otherthan the specified beam and incidence angles. An angledpitch-catch examination may also be performed on thevolumetric region adjacent to the cladding.

4.2.3.3 Sensitivity adjustment

(1) The sensitivity adjustment shall basically be performedon grooves where the reflecting surface is orientedperpendicular to the surface. Rectangular grooves, wedge-shaped grooves and spark-eroded slots may be used.

(2) Rectangular grooves or slots shall not be wider than1.5 mm; their length, not counting the runout, shall be 20 mm.Where a sonic beam is used with a diameter (see Sec. 5.3.3.5of DIN 25 450) larger than 20 mm at the location of thegroove, then the groove must be created such that itsacoustically effective length is restricted to 20 mm.

(3) Table 4-1 specifies the depth of the grooves (slots) as afunction of wall thickness.

Wall thickness s, mm 8 < s ≤ 20 20 < s ≤ 40 s > 40

Groove depth, mm 1.5 2 3

Table 4-1: Groove (slot) depth for adjusting the testingsensitivity

(4) Calibration blocks shall be designed such that areproducible adjustment of the sensitivity is ensured.Calibration blocks shall always be unclad and fabricated frommaterials that have the same acoustic characteristic as thematerials of the test objects.

(5) In the case of materials or complex geometries that areacoustically difficult to examine, measurements shall beperformed on reference blocks and the resulting transfercorrections shall be considered in the sensitivity adjustment.

(6) Reference blocks shall be representative of the geometryand acoustic characteristics of the component to be tested.Where the opposing surface influences the examinationmethod applied, then the wall thickness should deviate lessthan 10 % from that of the component to be tested.

(7) The reflectors machined into the reference blocks shallbe sufficient with respect to number and varying dimensions tomake definite statements regarding the sensitivity of theexamination technique possible.

(8) Where a dual search unit is used and a depth regionfurther down than 10 mm must be examined, the sensitivityadjustment shall be performed on transverse or flat-bottombore holes extending down to the required depth.

(9) The search unit shall be adapted accordingly if the radiusof curvature of the component surface would lead to a gapbetween search unit and component larger than or equal to0.5 mm. The sensitivity calibration of adapted search unitsshall be performed with a curved reference block or calibrationblock where the radius of curvature shall not deviate from thatof the component by more than 10 %.

Should deviations from this requirement be necessary, thenproof is required that the specified sensitivity will be achieved.

4.2.4 Eddy-current examination procedure

(1) When applying the eddy-current procedure for theexamination of surfaces it is required that coils adapted to theindividual testing task coils are used. For the adjustment of thesensitivity, calibration reference blocks of materials withmagnetic characteristics similar to those of the test object shallbe used.

(2) The grooves for adjusting the sensitivity shall not bewider than 0.3 mm.

4.2.5 Radiographic examination procedure

(1) When performing radiographic examinations it shall beensured that S does not exceed 0.3, where S is the fogdensity of the film caused by the radioactivity of thecomponent and by scattered radiation.

(2) The radiation source shall be directed such that thedirection of the flaws assumed as originating from the surfaceis parallel to the direction of radiation.

(3) The application of the radiographic examinationprocedures should be limited to a wall thickness s of less thanor equal to 25 mm (in the case of double-wall radiography, thethickness of the radiographed wall shall be less than or equalto 50 mm).

4.2.6 Selective visual examination

(1) The selective visual examination is performed to assesscertain examination regions and aims at the unambiguousdetection of specific characteristics of the examined region(e.g. erosion, corrosion, formation of cracks).

(2) It is performed as a direct visual examination by thehuman eye and, if necessary, with the help of opticalinstruments (e.g. magnifying glass, mirror, endoscope) or asan indirect visual examination by the human eye and with thehelp of a system of equipment receiving, transferring anddisplaying or recording the image.

4.2.7 Recording limits

(1) In case of the magnetic particle and liquid penetrantexaminations all indications with linear dimensionsexceeding 6 mm shall be recorded. Linear or planaraccumulations of indications whose length or width exceedone half of the wall thickness shall also be recorded even ifthe length of the individual indication is less than 6 mm.

(2) In the case of ultrasonic examinations both in closevicinity of the search unit down to a depth of less than or equal10 mm and of the corresponding opposing surface, allindications shall be registered where the echo amplitude isequal to or exceeds the value of the echo amplitude of thegrooves in accordance with Table 4-1 minus 6 dB.A signal-to-noise ratio of at least 6 dB with respect to therecording limit shall be observed.The influence of cladding or, possibly, of the microstructure orof the shape of the weld seam on the ultrasonic signals shallbe monitored on the test object itself or on the reference blockand shall be taken into consideration when evaluating the testresults.In the case of ultrasonic examinations in close vicinity of thesearch unit down to a depth larger than 10 mm as well as atthe respective depth away from the search unit, all indicationsshall be recorded where the echo amplitude corresponds to orexceeds that of a circular disc reflector with a diameter of3 mm if the examined wall thickness region is larger than40 mm and of 2 mm if it is equal to or smaller than 40 mm.In the case of wall thicknesses s smaller than or equal to8 mm (e.g. steam generator tubes) the recording limits shallbe specified in each individual case.

(3) The recording limits of the eddy-current examinationshall be specified on the basis of reference blockexaminations taking para 4.2.4 (2) into consideration.

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In the case of eddy-current examination of steam generatortubes, any indications suggesting cracks or a reduction in wallthickness exceeding 20 % shall be recorded.

4.3 Volumetric examination

4.3.1 Ultrasonic examination procedures

(1) The volume of the wall shall be examined with the singlesearch unit technique and, in the case of a nominal wallthickness equal to or exceeding 100 mm, additionally withtechniques for detecting planar flaws perpendicular to thesurface. To this end, the angled pitch-catch technique –preferably with transverse waves – or mode conversiontechniques on the basis of longitudinal wave dual crystalsearch units or LLT search units shall be used for plane-parallel and concentric surfaces.

(2) When determining the nominal wall thickness, thethickness of the cladding shall not be taken into account. Inwell founded individual cases and depending on the results ofprevious in-service inspections and on the actual loadingsdeviations from the specified nominal wall thickness arepermitted.

(3) If, in special cases with a nominal wall thicknessexceeding 100 mm, a dual search unit examination or modeconversion examination for flaws oriented perpendicular to thesurface is impossible or not meaningful on account of thegeometry, then an incident angle shall be chosen where theangular deviation between the sound beam axis and thesurface normal to the flaw does not exceed 20°.

4.3.2 Radiographic examination

(1) When performing radiographic examinations it shall beensured that S is not larger than 0.3, where S is the fogdensity of the film caused by the radioactivity of thecomponent and by scattered radiation.

(2) The radiation source shall be adjusted such that thedirection of the flaws assumed to originate from the surface isparallel to the direction of radiation.

(3) The application of the radiographic examinationprocedures should be limited to a wall thickness s of less thanor equal to 25 mm (in the case of double-wall radiography, thethickness of the radiographed wall shall be less than or equalto 50 mm).

4.3.3 Eddy-current examination procedures

In the case of thin-walled components made from non-ferromagnetic materials (e.g. steam generator tubes) theeddy-current examination procedure may be applied toexamine the body of the wall.

4.3.4 Recording limits

(1) In the case of an examination procedure based on thefact that the angle of incidence of the sound beam is 90° to thecrack surface of the expected flaw orientation, or in case of anangled pitch-catch or mode conversion examination, all echosignals shall be recorded where the amplitude is equal to orexceeds the echo amplitude of a circular disc reflector with adiameter of 10 mm. The dependency of the planar angle of thereflector may be generally considered by lowering therecording limit by 6 dB.

(2) If, in the case of a single search unit technique, only thediffusely scattered radiation is used for the indication of flawsurfaces, then those echo amplitudes shall be recorded thatcorrespond to perpendicularly encountered circular discreflectors as specified in Table 4-2.

These recording limits shall be observed over the entireexamination region. If ultrasonic techniques are employed thatare not treated in this safety standard, the recording limit validfor the individual technique shall be specified on the basis ofcomparative examinations.

Wall thickness s, mm 8 < s ≤ 20 20 < s ≤ 40 s > 40

Circular disc reflector, mm 1.5 2 3

Table 4-2: Diameter of circular disc reflectors for sensitivityadjustment

(3) The sensitivity adjustment may be performed oncalibration blocks with transverse bore holes. The resultingexamination sensitivity shall be corrected such that itcorresponds to the recording limit specified in para. 2.

(4) The recording limits of the eddy-current examinationshall be specified on the basis of reference block examina-tions taking para 4.2.4 (2) into consideration.

In the case of eddy-current examination of steam generatortubes any indications suggesting cracks or a reduction in wallthickness > 20 % shall be recorded.

4.4 Integral visual examination

(1) Integral visual examinations serve to assess the generalcondition of systems and components. These examinationsare usually performed in the course of plant revisions withoutremoving any insulation material.

(2) During integral visual examinations the following shallespecially be taken into consideration:a) mechanical damage (points of friction, bends and tears),b) indications of leakage,c) faults with respect to

ca) bolt connections (loosening, condition of the boltlocking devices),

cb) connections of measuring points and instrument lines,cc) insulation,

d) Displacement of components (free end displacement ofpipes, damage to foundations and anchor points).

4.5 Pressure test

4.5.1 Test conditions

(1) Pressure tests shall basically be performed at 1.3 timesthe design pressure. If in periodic pressure tests a deviationfrom from this value is made, care shall be taken that safety-relevant information is obtained that is comparable to the initialpressure test.

(2) The test temperature should be at least 33 K, howevernot more than 55 K, above the NDT temperature calculated forthe point of time of the test.

(3) To ensure relevant results from the pressure test thefollowing conditions shall be met:a) The rate of change of pressure and temperature shall be

selected in accordance with the startup and shutdowndiagram specified in the operating manual until therespective test temperature of the components is reached.

b) After reaching the respective test temperature, the changerate of the test pressure shall not exceed 10 bar perminute up to the allowable working gauge pressure, andthen, not more than 1 to 2 bar per minute up to the testpressure.

KTA 3201.4

Page 12

c) The holding time at test pressure shall be at least 30minutes.

(4) Before starting the leakage check in accordance withpara. 7.2 (7) the pressure shall be reduced to the operatingpressure.

4.5.2 Non-destructive examinations following the pressuretest

(1) Subsequent to the periodic pressure tests non-destruc-tive examinations shall be performed in selected areas oncomponents of the pressure boundary

(2) If non-destructive examinations are performed in partialsections, it shall be ensured that the partial section coincidingwith the pressure test contains tests of locations that arerepresentative of higher stress locations.

4.6 Functional tests on safeguards against excessivepressure

All safeguards against excessive pressure shall be subjectedto functional testing at regular intervals. In these tests thefollowing shall be checked:a) the response pressure,b) the opening and closing behaviour.Parameters relevant to function (e.g. dead times, actuatingforce reserves) shall be evaluated with respect to the specificplant and design.

5 Extent of testing and test intervals

5.1 General requirements

(1) In-service inspections shall basically be performed to theextent as specified in Section 5.2. When planning a plant thisextent of in-service inspections shall be taken into account.

(2) Where new findings are made from the monitoring ofconsequences and causes of operational damage mecha-nisms as well as from the observation of the state ofknowledge of the plant condition as per Figure 3-1, thestipulations of Sections 5.2 and 5.3 shall be re-evaluated withrespect to the specific plant. To this end, the examinationprocedures, areas and intervals for the component groupsmentionend in Section 1 under (4), (5) and (6) shall beadapted accordingly.

(3) If the design, construction, fabrication or other aspectssignificantly limit the extent of testing, additional measuresshall be taken (e.g. fracture mechanic analyses) that lead tothe required information on safety. Any limitations with regardto the specifications of this safety standard shall be noted inthe test instructions.

(4) If operational loading is one of the criteria in Section 5.2for selecting the component areas to be tested, thenrepresentative higher stress locations shall be included withinthe intended extent of testing. Besides the usage factoroperational experience shall also be taken into account.

(5) The distribution of extent of testing within the test inter-vals for components installed in multiple number as specifiedin Tables 5-1 to 5-4, 5-6 and 5-7 is based on the 4-loop or4-circuit power plant concept. In the case of two or threeprimary coolant loops or circuits, the distribution shall bespecified by agreement with the authorized inspector.

5.2 Extent of testing5.2.1 Non-destructive examinations5.2.1.1 General

(1) When testing butt weld seams, the examination shallinclude the weld metal and the base metal zone on a width ofat least 10 mm on both sides of the weld seam for a wallthickness ≤ 30 mm and on a width of at least 20 mm on bothsides for a wall thickness > 30 mm.

(2) When testing insertion and attachment weld seams ofnozzles, the width of the adjacent base material to be includedin the examination is defined by the wall thickness of theconnecting wall thickness.

(3) Locations of former auxiliary welds shall be included inthe test and inspection schedule if it cannot be ensured thatthe strain-hardened area of the heat affected zone has beencompletely removed by dressing.

5.2.1.2 Reactor pressure vessel

(1) The extent of examinations to be performed on thereactor pressure vessel is specified in Table 5-1. All ligaments(shortest distance between two openings) in nozzle fields ofthe reactor pressure vessel cover or head shall be subjectedto an ultrasonic examination where the examination techniqueshall primarily be used for the detection of cracks extending tothe centre of the ligaments and being loacted in the near-surface region. The volume areas covered by the examinationas well as the areas between the ligaments shall be includedin the evaluation of the test results. In the case of inaccessibleligaments, para. 5.1 (3) shall apply.

(2) If a reference test in accordance with Section 4.1.3 isrequired for the reactor pressure vessel, the reference testshall be performed on all items to be examined in accordancewith Table 5-1 prior to commissioning the plant but after thepressure test. However, it shall be ensured that all the basemetal zones are accessible for testing.

5.2.1.3 Pressure thickness of control rod drives

The extent of testing to be performed on the pressureretaining wall of control rod drives is specified in Table 5-2.

5.2.1.4 Steam generator

The extent of testing to be performed on the steam generatoris specified in Tables 5-3 and 5-4. The external and internalsurfaces with their near-surface regions shall be examined.

5.2.1.5 Pressurizer

(1) The extent of testing to be performed on the pressurizeris specified in Table 5-5. The external and internal surfaceswith their near-surface regions shall be examined.

(2) Special measures shall be taken for the ligaments in thenozzle field of the pressurizer head (e.g. fracture mechanicanalysis, leakage detection).

5.2.1.6 Pipework

The extent of testing to be performed on the pipework isspecified in Tables 5-6 and 5-7. The external and internalsurfaces with their near-surface regions shall be examined.

Note:In-service inspection on pipes with a nominal diameter smallerthan or equal to DN 50 shall be fixed by agreement with theauthorized inspector for each individual plant.

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5.2.1.7 Main coolant pump casing

At least once within 15 years a selective visual examination ofthe internal surfaces of the main coolant pump casing shall beperformed. The extent of the examination shall be fixed withrespect to the specific plant.

5.2.1.8 Valve bodies

On valve bodies with a nominal diameter equal to or greaterthan DN 150 a selective visual examination shall be performedto a representative extent in conjunction with an inspection(opening of the valve body).

5.2.1.9 Bolted joints

The extent of testing to be performed on bolted joints onpressure-retaining walls of reactor pressure vessels, steamgenerators, pressurisers, main coolant pump casings as wellas valve bodies and control rod drives is specified in Tables5-1 and 5-8.

5.2.2 Integral visual inspection

(1) The extent of the integral visual inspections shall dependon the inspection objectives stated in Section 4.4.

(2) The extent and date of the integral visual inspectionsshall be specified plant-specifically (e.g. in test instructions).

5.2.3 Pressure tests

All components within the scope of this safety standard shallbe subjected to periodic pressure tests.

5.2.4 Functional testing of safeguards against excessivepressure

All safeguards against excessive pressure shall be subjectedto functional tests. If the safety device consists of a pilot and amain valve the test shall be performed such that in addition tothe function of the pilot and main valve the functionalcapability of the control lines can also be assessed. Theperformance of the test shall be specified with respect to thespecific plant design and construction.

5.3 Test intervals

(1) All test intervals start at the time of first criticality of thereactor. The time intervals within which the specified testshave to be performed are specified in Section 5.2. The in-service inspections in accordance with Section 5.2 shall beperformed during plant shutdown (e.g. during refueling).

(2) The non-destructive examinations in accordance with5.2.1 shall be performed in test intervals of 5 years, unlessspecified otherwise in clause 5.2.1. In justified cases the non-destructive examinations specified for the test interval may beperformed, by agreement with the authorized inspector, duringthe next plant shutdown intended for refueling and followingthe test interval. If similar components are installed in multiplenumber and if the operating conditions are the same, then theextent of testing may be distributed over 2 succeeding testintervals where the extent of testing shall be combined suchthat at each test interval an entire loop or circuit is tested.

(3) Integral visual examinations in accordance with 5.2.2shall be performed during regular plant inspections after plantshutdown for refueling.

(4) The pressure test in accordance with 5.2.3 shall beperformed every 10 years. In justified cases deviationsherefrom may be agreed with the authorized inspector.

(5) Functional tests of the safeguards against excessivepressure in accordance with 5.2.4 shall be performed duringregular plant shutdowns for refueling.

(6) Since the time interval between two refuelings can be upto 18 months, the individual tests shall be performed duringthat refueling that is closest to the due date of the tests. If thisleads to longer time intervals than specified in this Section, thedue dates for the next in-service inspections shall beadvanced accordingly such that in the long run the timeintervals remain as specified. In the case of plant shutdownsof more than 6 months special arrangements may be agreed.

(7) The test intervals specified in (2) and (4) as well as in5.1.7 shall apply if the monitoring of the causes andconsequences of operational damage mechanisms as well asthe observation of the actual state of knowledge on the plantcondition is made to a consistent concept as per Figure 3-1.Should this not be the case, the tests and examinations as per(2) shall be performed at an interval of 4 years, the test as per(4) at an interval of 8 years and the inspections as per 5.2.1.7at an interval of 12 years.

6 Test and inspection schedule6.1 PreparationThe test and inspection schedule shall be prepared inaccordance with Section 5.1 and shall be available andagreed upon by the authorized inspector at the latest at thetime of first criticality (see also KTA 1202).

6.2 Review and updatingPrior to each, even partial, in-service inspection the type,extent and date of testing shall be reviewed for each individualcomponent and shall be updated, if necessary. Here, thefollowing shall be taken into consideration:

a) Previous in-service inspectionsThe results of previous in-service inspections shall betaken into account. This may lead to an updating of thetype, extent and date of testing for the previously specifiedin-service inspections as well as to a change in thespecified test location within the realm of items to betested.

b) Repair or replacementAfter performance of repair or replacement it shall bedecided upon whether or not in-service inspections shouldbe introduced at these locations or whether or not the type,extent and date of already specified in-service inspectionsshould be changed. This also applies to the sealing ofsteam generator tubes by means of plugging.

c) Irradiation influencesThe evaluation of tests on accelerated irradiationspecimens shall be considered when performing periodicpressure tests and non-destructive in-service inspections.

d) Operational monitoringThe results of operational monitoring in accordance withSection 9 shall be considered in the reviewing andupdating procedure.

e) Operational experienceThe operational experience from the own plant as well asfrom other plants shall be considered in the reviewing andupdating procedure.

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Item to be inspected Test procedure /Test technique

Flaw orientation Extent of testing Test intervals

Longitudinal andcircumferential welds

US

Nozzle-to-shell welds≥ DN 250 1) US

l, q

all weld seams, entire length,entire volume as well as thesurface areas with their near-surface regions

Nozzle inside edge≥ DN 250 1) US

surface areas with their near-surface regions of the entireinside edge of all nozzles

Ligaments in nozzlefields US

rall ligaments, surface areas andcentres of ligaments

Cladding SV anyrepresentative locations, the testextent shall be specified for theindividual plant

5 years

Screw bolts

USor MTor ET,SV

q, relative tothe bolt axis

surface areas with their near-surface regions of all bolts, entiretensioned length including thethreaded regions

Threaded blind holes US or ET,SV

q, relative tothe threadaxis

surface areas with their near-surface regions of all blind holes,entire thread length

NutsSVor ETor US

q, relative tothe threadaxis

threaded region and loaded endface (contact surface) of all nuts

Washers SV any both contact surfaces as well asthe surface of the washer hole

Within 5 years 2) at least25 % of the bolts with thecorresponding threadedblind holes, nuts andwashers, however, atthree successive testintervals of 5 years 100 %shall be tested.Alternatively, the test maybe performed at intervalsof 10 years 2) where100 % each shall betested

Attachment welds Agreements shall be made because of the differing design details. The type and extent of the testsshall be incorporated in the test instructions.

Auxiliary welds MT or US The requirements shall be specified in accordance with 5.2.1.1 (3).

Abbreviations for the test procedures and techniques are explained in Table 2-1.l : longitudinal flaw q : transverse flaw r : radial flaw (e.g. for nozzle inside edges or ligaments in nozzle fields)

1) In the case of nominal diameters of the connecting pipe < DN 250 the requirement for in-service inspections shall be reviewed from case tocase.

2) Selective visual inspection of stud bolts (where accessible), nuts and washers after each unbolting of bolted joints

Table 5-1: Non-destructive in-service inspections on the reactor pressure vessel



Circumferential weldsPWR 1)

ET orRT orUS

lInner surface of representativewelds on 10 % of pipes in dueconsideration of accessibility

Circumferential weldsBWR

LT orET orUS

lInner surface of circumferentialwelds of 4 rod drive housingpipes

10 years

Abbreviations for the test procedures and test techniques are explained in Table 2-1. l : longitudinal flaw

1) These welds also include in-core instrumentation and control rod nozzle welds

Tabelle 5-2: Non-destructive in-service inspections on pressure-retaining walls of control rod drives

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Page 15



Regions of base metal US circumferentialdirection

entire extent of the fillets in thetransition between tube sheet andcrown, the inside surface with itsnear-surface regions

Circumferential weldseams US or MT

connecting seam between tubesheet and crown, the outside andinside surfaces with their near-surface regions over the entireseam length

Nozzle-to-shell welds≥ DN 250 US or MT

l, qone reactor coolant nozzle,preferably the inlet nozzle, theinside and outside surfaces withtheir near-surface regions overthe entire seam length

Nozzle inside edge≥ DN 250 US r

one reactor coolant nozzle,preferably the inlet nozzle, theinside and outside surfaces withtheir near-surface regions overthe entire inside edge

Cladding SV anyrepresentative locations, the testextent shall be specified for eachindividual plant

Every 5 years one half ofthe steam generators;however, at 2 successivetest intervals of 5 yearseach, all steam generatorsshall be covered.

Steam generator tubes ET

flaws on theoutside andinside surface,wall thickness

In each steam generator 10 % ofall tubes 1) in the regions wettedby the secondary medium up tothe first rolled-in joint

Every 5 years; however,within 2 years one half ofthe steam generators shallbe covered.

Support bracketattachment welds MT or LT any All tension loaded regions of

outside surfaces

Every 5 years one steamgenerator; however, at 4successive test intervals of5 years each, all steamgenerators shall becovered.

Other attachment welds Special agreements shall be made because of the differing design details.The type and extent of the tests shall be incorporated in the test instruction.


Abbreviations for the test procedures and test techniques are explained in Table 2-1.l : longitudinal flaw q : transverse flaw r : radial flaw (e.g. for nozzle inside edges)

1) During each in-service inspection those tube regions shall be examined which are known from design and operational experience to bemore susceptible to corrosive attacks.

Table 5-3: Non-destructive in-service inspections on the steam generators, primary side

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Page 16



Regions of basemetal US circumferential

direction

- fillets in the transition tubesheet / secondaryshroud, inside surface with its near-surfaceregion over the entire circumference,

- knuckle of the dished head, inside surface withits near-surface region over the entirecircumference

Circumferentialand longitudinalweld seams

l, q

- connecting seam of the tubesheet,- one further representative circumferential seam,- 25 % of the number of all longitudinal seams,the inside and outside surfaces with their near-surface regions over the entire seam length

Pipe connectingnozzles

US or MT

depending onthe examina-tion task

- entire circumference of one feedwater nozzle- entire circumference of one further

representative nozzle ≥ DN 250in each case the surface with its near-surfaceregion of the inner nozzle edge or of theconnection region of the thermal sleeve

Every 5 yearsone half of thesteam gene-rators; however,at 2 successivetest intervals of 5years each, allsteam gene-rators shall becovered

Steam generatortube supports inthe bent tuberegion

SV any representative supports

Every 5 yearsone steam gene-rator; however, at4 successive testintervals of 5years each, allsteam generatorsshall be covered.

Attachment welds

Special agreements shall be made because of the differing design details.The type and extent of the tests shall be incorporated in the test instruction.The requirements that apply to steam generator tube supports also apply to the attachment welds of anyinternals.


Abbreviations for the test procedures and test techniques are explained in Table 2-1.l : longitudinal flaw q : transverse flaw

Table 5-4: Non-destructive in-service inspections on the steam generators, secondary side



Circumferentialand longitudinalweld seams US or MT l, q

- entire circumference of one crown connectionseam, outside and inside surface with theirnear-surface regions

- entire seam length of 25 % of all longitudinalwelds, in each case the outside and insidesurface with their near-surface regions

5 years

Nozzles USdepending onthe examina-tion task

- entire circumference of the of the surge linenozzle

- entire circumference of one representativenozzle ≥ DN 250

in each case the surface with its near-surfaceregion of the inner nozzle edge or of theconnection region of the thermal sleeve

5 years

Cladding SV any representative locations, the test extent shall bespecified for each individual plant 10 years 1)

Attachment welds Special agreements shall be made because of the differing design details.The type and extent of the tests shall be incorporated in the test instruction


Abbreviations for the test procedures and test techniques are explained in Table 2-1.l : longitudinal flaw q : transverse flaw

1) At a test interval of 5 years an integral visual inspection shall be performed

Table 5-5: Non-destructive in-service inspections on the pressurizer

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Page 17

Item to beinspected

Test procedure/Test technique

Flaworienta-

tionExtent of testing for PWR Extent of testing for BWR Test intervals

Weld seamson straighttubes andelbows≥ DN 250

MT or US l, q

- all connection welds to thereactor pressure vessel 4)

- connection welds and (ifany) longitudinal welds ofthe highest loaded elbowin each loop

- one further seam in eachloop, changing seams fromone test interval to the next

In each case the outside andinside surface with their near-surface regions of the entireseam length shall beexamined.

30 % of all pipe weld seams consisting of thefollowing partial entities:a)all connections to the RPV 3)

b) further attachment and connection welds tobe selected in accordance with the followingcriteria:- attachment welds on vessels, valves,

pumps,- connection welds of T-joints and elbows,- operational loading also taking corrosion

into account,- composite materials (only ferrites),- fabrication quality with regard to seam

surface.c) 4 % of all other attachment and connection

welds even of pipes with stagnating steam;these shall vary from test interval to testinterval by agreement with the authorizedinspector.

In each case the outside and inside surfacewith their near-surface regions of the entireseam length shall be examined.

Weld claddedelbows≥ DN 250

MT or USl, q(relativeto theaxis)

highest loaded base materialregion of one representativeelbow in each loop, outsideand inside surface with theirnear-surface regions

MT or US l

connection weld of onenozzle 2) in each loop. In eachcase the outside and insidesurface with the near-surfaceregion of the entire weldlength shall be examined.

connection weld of one nozzle 2) in eachcircuit. In each case the outside and insidesurface with their near-surface regions of theentire weld length shall be examined.

Nozzles forconnectingpipes≥ DN 250

Internal integral visualinspection or anothertechnique to check thecondition of the thermalsleeve

one representative thermal sleeve for each design type

Cladding Visualinspection 5)

anyrepresentative locations,the test extent shall bespecified for each individualplant

Within5 years onehalf of thenumber ofloops (PWR)or circuits(BWR),however, theentirenumber ofloops orcircuits shallbe coveredat twosuccessivetestintervals.

Bends andelbows≥ DN 250 notweld cladded

MT or US l, q highest loaded base material region of onerepresentative elbow, outside and insidesurface with their near-surface regions

Bends andelbowsDN ≥ 250 notweld claddedwith steamflow-through 1)

US(wall thickness)

p one elbow with a bend angle ≥ 90°, wallthickness determination in a point grid

5 years

Locations offormer auxi-liary welds

MT or USonly if it is not ensured that the strain-hardened regions have been completely removed(cf. para.5.2.1.1 (3)).

Abbreviations for the test procedures and test techniques are explained in Table 2-1.l : longitudinal flaw q : transverse flaw p : flaw parallel to the surface1) Those bends and elbows are meant through which steam flows continuously during normal operation. Bends and elbows sporadically loaded by

static steam are not considered to be in this category.2) The selection of nozzles shall be based on the following criteria:

- the loading is restricted to normal operation or to incidents, loading collective- fabrication quality.

3) Connection welds of the feedwater line: all connection welds within 5 years.4) All connection welds within 5 years.5) Selective or integral visual inspection shall be specified for each individual plant.

Table 5-6: Non-destructive in-service inspections on ferritic pipes

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Page 18

Item to be inspected Testproce-

dure / Testtechnique

Flaworien-tation

Extent of testing for PWR Extent of testing for BWR Test intervals

Surge lineone connection weld and thehighest loaded bend or elbow,in each case the outside andinside surface with their near-surface regions

5 years

hot (≥ 200 °C) cold (< 200 °C)

40 % 20 %20 %

of all connection or attachmentwelds of pipes of the nuclearresidual heat removal system;selection in accordance withloading criteria

of all connection or attachment weldsof pipes of the nuclear residual heatremoval system; selection inaccordance with loading criteria

≥ DN 150

In each case the outside and inside surface with their near-surfaceregions of the entire seam length shall be examined.By agreement with the authorized inspector the pipes subjected totesting should vary from test cycle to test cycle.

hot (≥ 200 °C) cold (< 200 °C)

20 % 10 %10 %

of all connection or attachmentwelds of pipes of othersystems; selection inaccordance with loadingcriteria

of all connection or attachment weldsof pipes of other systems; selection inaccordance with loading criteria

Weldseamsonstraightpipes, onbendsandelbowsor higherstresslocations

< DN 150> DN 50

In each case the outside and inside surface with their near-surfaceregions of the entire seam length shall be examined.By agreement with the authorized inspector the pipes subjected totesting should vary from test cycle to test cycle.four attachment welds;selection in accordance withloading criteria

all attachment weldsAttach-mentwelds offerriticnozzles(dissimilarmetalwelds)

≥ DN 200

LTor USor RT

l

In each case the outside and inside surface with their near-surfaceregions of the entire seam length shall be examined.

The extent oftesting maybe distributedover two suc-cessive testintervals of 5years each(cf. para.5.3 (2))

Abbreviations for the test procedures and test techniques are explained in Table 2-1. l : longitudinal flaw

Table 5-7: Non-destructive in-service inspections on austenitic pipes


Extent of testing Test intervals

Threaded bolts Surface of the visible region of allthreaded bolts

Nuts SV Region of threads and the loadedend face (contact surface)

Upon each unbolting of the boltedjoint for operational reasons

Washers Both contact surfaces includingthe inside surface of the bore hole

Abbreviations for the test procedures and test techniques are explained in Table 2-1.

Table 5-8: In-service inspections of bolted joints in the pressure retaining wall of steam generators, pressurizers, primarycoolant pump casings as well as valve bodies and control rod drives

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7 Preparation of tests, test instructions

7.1 Preparation of tests

(1) The tests shall be adequately prepared with respect togeneral organization and required equipment. The preparationshall especially include the planning of the employment of testpersonnel taking the general organization of work, theRadiological Protection Ordinance and Guideline “RadiologicalProtection“ into consideration.

(2) The areas of the components that will be subjected totesting shall be put in a condition suitable to testing (e.g. byremoval of insulation material, cleaning of surfaces).

(3) Details of the tests shall be specified in test instructions(cf. KTA 1202). These include specifications of the locations tobe tested, the test procedures to be applied and references tothe corresponding standard test instructions or testspecifications.

7.2 Test instructions

(1) Magnetic particle examinations and liquid penetrantexaminations shall be performed in accordance withDIN 25 435 Part 2.

(2) Eddy-current examinations as well as special ultrasonictechniques shall be performed by agreement with theauthorized inspector. The in-service inspection of steamgenerator tubes shall be performed in accordance withDIN 25 435 Part 6.

(3) Radiographic examinations shall be performed inaccordance with Test Class B to DIN EN 1435. The generalaim shall be to meet Test Class B to DIN EN 1435 withoututilizing the replacement procedures cited therein. The imagequality classes in aacordance with image quality class B toDIN EN 462 Part 3 shall be adhered to.

(4) Automated ultrasonic examinations shall be performed inaccordance with DIN 25 435 Part 1.

(5) Manual ultrasonic examinations shall be performed inaccordance with Annex B of KTA 3201.3.

(6) Visual examinations shall be performed in accordancewith DIN 25 435 Part 4.

(7) Pressure tests shall be performed in accordance withDIN 25 435 Part 3. However, the visual inspection requiredtherein is limited to a leakage check.

(8) Functional tests of the safeguards against excessivepressure shall be performed in accordance with the test andinspection manual.

8 Evaluation of the test results

8.1 Volumetric examinations as well as examinations ofsurfaces and near-surface regions

Note:The steps specified in 8.1.1 and 8.1.2 refer to Figure 8-1.

8.1.1 Decision-making procedure

(1) At the end of an operational period (Step 1), the n-th in-service inspection IIn (Step 2) is performed.

(2) If indications are found, the further procedure shall followthe decision-making procedure (Figure 8-1) structured as flowchart.

(3) When evaluating the results (Step 3) it shall be decidedwhether or not the indications have exceeded the acceptability

limit. If this is not the case, the component may be operatedfurther (Step 12).

(4) If indications exceed the acceptability limit they shall betermed relevant indication. At first, a comparison with theresults of the previous in-service inspection IIn-1 shall beperformed (Step 4). If findings have changed, the results of in-service inspections lying further back shall also be taken intoaccount to possibly detect the time history of the change. Onthe basis of the comparison of the measured values it shall bedecided whether it is a first occurrence of the indication orwhether an existing indication has grown larger (Step 5). If thisis not the case, the component may be operated further (Step12).

(5) In the case of ultrasonic examination techniques,evaluation methods may be used that are based on an imagepresentation of the test results. However, the recording limitsin accordance with 4.2.7 or 4.3.4 shall remain discernible. Theprocedure shall be agreed with the authorized inspector foreach individual case.

(6) In the case of a first occurrence of an indication or ofgrowth of an existing indication an analysis is required thatleads to information on its type, location and size. Whererequired, further examinations employing more refined testingtechniques (Step 6) shall be performed.

Figure 8-1: Schematic decision-making plan to evaluate theresults of non-destructive examinations

Comparisonwith II

no

Endof operational

period

Growthof existing indicationor first occurrence?

no

yes

control

Leaveflaw

as it is?

Performanceof n in-service

inspection II

yes Analysis:

Does theindication exceedthe acceptability

limit?

yesno

no

Releaseor

measuresof causereplacementoperation

remove cause

use of variousanalysis techniques

for

Take measures,

Determinationof cause

andsafety analysis?

removal

controlmeasures

yes

Decison 5confirmed?

repair+

+

+

2

4

8

12

6

11

1

7

10

5

3

9

th

n

(n-1)

KTA 3201.4

Page 20

(7) If it is found out that it is a first occurrence of anindication or an existing indication has grown (Step 7) then thecause shall be determined and subsequently a safety analysisshall be performed (Step 8). This shall be based, among otherthings, on the operational records.

(8) The safety analysis may, for instance, comprise:- a stress analysis- a fracture mechanic analysis (see also Sec. 7.9.3.4 of

KTA 3201.2),- laboratory experiments,- checks on similar components in the case of indication of

systematic defects- an evaluation of experience gained with other plants.

(9) The results of the cause determination and the safetyanalysis are decisive regarding the specification of theacceptability limit, i.e., the decision whether or not a flaw maybe left as it is (Step 9). If it follows that the flaw may be left inthe component as it is then the causes, if possible, shall beremoved e.g. by the following measures:a) change of the operational mode of the plant,b) installation of additional structures (e.g. pipe support struc-

tures).

(10) The success of the measures taken shall be checked,e.g. by:a) instrumentation for a continuous monitoring of the flaw

location,b) shorter intervals of in-service inspections.

(11) Taking the measures specified above into account, thecomponent may be operated further (Step 12).

(12) If it is established that the flaw may not be left in thecomponent as it is, the causes shall, as far as possible, beremoved and a repair or replacement of the componentinitiated (Step 11). The success of the measures shall bechecked, e.g., bya) instrumentation,b) shorter intervals of in-service inspections.

Prior to the release for operation, a fabrication test or, ifrequired in accordance with Section 4.1.3, a reference testshall be performed on the repaired component.

8.1.2 Acceptabilty limits

(1) To avoid that measured values which are scattered dueto the test technique used are to be evaluated as relevantindications, the following acceptability limits are specified forin-service inspections.

(2) All indications reaching or exceeding the recording limitshall be documented in an examination record (except forindications clearly subject to component shape) and thoseabove the acceptability limit (Step 3) shall be treated asrelevant indications. The individual acceptability limits aredefined by the values specified in a) and b) as follows:a) Examination of the surface near-surface regions

aa) In the magnetic particle and liquid penetrantexaminations the acceptability limit shall beconsidered to be exceeded if the indication shows alinear dimension of more than 10 mm. Areas withaccumulated smaller indications shall be evaluated ifthe size of the area is larger than 1000 mm2.

ab) Indications in the ultrasonic examination shall beconsidered to be relevant indications- if their echo amplitudes exceed the recording limit

in accordance with Section 4.2.7 by 6 dB or more,

or- if their echo amplitudes reach or exceed the

recording limit and show a linear dimensionexceeding half the nominal wall thickness (at least10 mm) or 50 mm; the method for determining thelinear dimension shall be agreed with theauthorized inspector,

or- the echo amplitude of an indication not yet

documented reaches or exceeds the recording limitand this indication cannot be explained bytolerances due to the examination techniqueemployed.

ac) The acceptability limit for the radiographic examinationshall be specified for each individual case. Indicationswhich suggest the presence of crack-like defects orincomplete fusions shall be treated as relevantindications.

ad) In the case of an eddy-current examination theacceptability limit shall be specified for each individualcase.

b) Volumetric examinationsba) In the ultrasonic examination the acceptability limit

shall be considered to be exceeded- if their echo amplitudes exceed the recording limit

in accordance with Section 4.3.4 by 6 dB or- if their echo amplitudes reach or exceed the

recording limit in accordance with Section 4.3.4 anddemonstrate a linear dimension exceeding half thenominal wall thickness or 50 mm. The lineardimension shall be determined in accordance withSec. B 5.2.4 of KTA 3201.3.

bb) The evaluation limit for the radiographic examinationshall be individually specified. Indications whichsuggest the presence of crack-like defects orincomplete fusions shall be treated as relevantindications.

bc) In case of an eddy-current examination of steam-generator tubes the acceptability limit shall beconsidered to have been reached if the results indicatea wall thickness reduction by 30 %.

The linear dimension mentioned in ab) and ba) shall applyonly to locations remote from discontinuities. In the case ofother regions, e.g. the inner edge of nozzles and holepatterns, the length dimension shall be individually specified.

8.2 Visual examination

If anything unusual is noticed in the course of visualexamination, then in each individual case it shall be decidedwhether or not further examinations and, if so, what kind ofexaminations are required.

8.3 Pressure test

The pressure test shall be considered to have been passedsuccessfully if the components have withstood the requiredpressure level over the entire holding period (cf. Section 4.5).

8.4 Functional tests of safeguards against excessivepressure

The functional tests shall be considered to have been passedsuccessfully if the values specified in the test instructions havebeen achieved.

KTA 3201.4

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9 Operational monitoring

9.1 General requirements

(1) Operational data that are important regarding theintegrity of the components of the reactor coolant pressureboundary shall be monitored.

(2) Only measuring equipment suitable for the respectivedefined task (e.g. with respect to sensitivity, resolution ofmeasured values for data recording and representation, setpoint of alarms) shall be used.

(3) If operating conditions occur that are not covered by thespecified load regime, these operating conditions shall beevaluated with special regard to their safety-relevant effects.

9.2 Monitoring of loadings

9.2.1 Monitoring of mechanical and thermal loadings

(1) It shall be ensured that temporal and local temperaturechanges relevant to fatigue are monitored by a sufficientlydense net of measuring points. When selecting the measuringpoints the effects of the mode of operation (little mass flows,indifferent pressure conditions, switching operations,temperature differentials) and the construction (pipelineinstallation, isolating function of valves) shall be taken intoaccount

(2) Where thermal stratification is expected to occur, thetemperature measuring points shall be located such that allrelevant loading variables across the pipe cross-section andaxially to the pipe run can be measured.(3) The results of measurement shall be assigned to therelvevant operating conditions and be evaluated with respectto their effects on component fatigue in accordance with KTA3201.2.

(4) Where the operating conditions as per para. 9.1 (3) affectcomponent fatigue, it is necessary to recalculate the predictedcumulative usage factor determined in accordance with thedesign as per equation (7.8-1) of KTA 3201.2. Contrary to thespecification of KTA 3201.2, equation (7.8-1), a cumulativeusage factor D larger than 1 may be applied, provided it isensured that the advance of fatigue is kept within safepermissible limits by appropriate measures taken with respectto operation, operational monitoring or in-service inspections,or by a combination of these measures.In particular, plant operation may be continued in the case ofD larger than 1, as long as no crack formation has beendetected and fracture mechanic analyses of postulatedincipient cracks prove that there will only be a limited crackpropagation in the time period until the next, maybepremature, in-service inspection. It shall, however, be ensuredthat no critical flaw size will develop even for the mostunfavourable load case.The time of the next in-service inspection shall be determinedon the basis of the fracture mechanic analysis and on therequirement that the new predicted cumulative usage factorwill not increase by more than ∆D = 0.1.Any changes in this respect will have no effect on the intervalsof in-service inspections as specified in this safety standard.(5) Where new knowledge is gained with respect to thermalloadings, the measuring system shall be modified accordingly(6) Where the mode of operation, the pipe routing orcomponents are changed, the thermal loadings shall beevaluated close to the time where the change took place.(7) The measuring results shall generally be evaluated onceper refueling cycle and be documented in a report.

9.2.2 Vibration monitoring

(1) The vibration behaviour of the components of the primarycoolant system shall be measured during the firstcommissioning of the plant. This shall also take representativesmall lines into consideration. The results shall be evaluatedwith regard to the analysis of cyclic strength and shall be usedas comparative basis for operational vibration monitoring. Inthe case of a follow-up plant, a smaller measurement programis allowed than for a first plant of this type (see also Sec. 9.4.2of KTA 3204).

(2) DIN 25 475-2 specifies the requirements for the system,the extent of monotoring of the reactor plant and the in-serviceinspections of the system.

(3) The instrumentation for measuring the vibrations duringcommissioning should be chosen such that these measure-ments can also be performed during operation of the nuclearpower plant.

(4) The decision whether or not vibration monitoring isrequired during plant operation shall be made, taking intoconsideration the results of the vibration measurements duringcommissioning in conjunction with a substantiation by way ofcalculation as well as operational experience gained withcomparable plants.

(5) If vibration monitoring is performed during operation thenthe following boundary conditions shall be observed:a) The monitoring shall aim at the detection of changes in the

vibration behaviour at representative locations of theprimary coolant system.

b) Vibration monitoring shall be possible at all times. It maybe performed discontinuously.

c) At least two measurements shall be performed for eachrefueling cycle. One of these measurements is requireddirectly after refueling and one before the next refueling,with the plant being in steady-state operation.

d) If vibration monitoring fails due to partial or completefailure of the measuring equipment, the latter`s returning toservice may be postponed at the latest to the nextregularly scheduled plant shutdown.

9.3 Monitoring of the chemical water quality

The chemical and physical limit values to be obeserved whenmonitoring the chemical water quality of the primary andsecondary circuits as well as the frequency of measurementsshall be specified by the plant manufacturer; these valuesshall be documented in the operating manual.

9.4 Monitoring of changes of metal properties

(1) The irradiation behaviour of the belt-line materials of thepressure-retaining wall of the reactor pressure vessel shall bemonitored in accordance with KTA 3203.

(2) From components repaced for retrofitting purposes,representative samples shall be taken which shall beexamined for possible changes of material properties anddamage due to operational influences. To this end, non-destructive and destructive examinations (determination ofmechanical properties and examination of metallographicstructure) shall be performed. The examination programmshall be fixed individually for each plant.

9.5 Leak monitoring

9.5.1 Requirements

The leakage monitoring system shall be designed such that itis capable of detecting and localizing leakages with sufficient

KTA 3201.4

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accuracy in the reactor coolant pressure boundary duringplant operation. This system shall be sensitive enough todetect those leakages which would not yet lead to anautomatic activation of safety measures due to pressure build-up in the surrounding building or due to the measurement ofother system parameters (e.g. drop in pressure or coolantlevel). The detection sensitivity of the leakage monitoringsystem shall be demonstrated.

9.5.2 Measurement procedures

(1) The following measured values, alone or in combinationwith other values, are suited for leakage monitoring:a) air humidity or dew point temperature,b) air temperature,c) radioactivity of compartment exhaust air,d) condensate or water level increase in the recirculating air

coolers,e) water level in building sumps.

(2) The corresponding measuring instruments shall bedesigned for the following ambient conditions:a) temperature 100 °C,b) relative humidity 100 %,c) loadings by the leakage rate test of the containment (cf.

Sec. 5.4 of KTA 3405).

(3) For the localization of leakages it is advisable to grouptogether individual compartment areas.

(4) The leakage monitoring system should be designed asself-contained system for the individual compartment areasunder para. (3). Available operational measuring equipmentmay be used for the evaluation provided its use is permittedfor the changed ambient conditions upon the occurrence ofleakages.

(5) The measurement points for air humidity or dew pointand air temperature shall be located in the directed flow of theair recirculation system such that the localization of leakagesis possible.

(6) If the air recirculation system is made up of partialsystems that are correlated to different compartment areas,the condensate level increase in the recirculating air coolersshall be measured individually for each area.

(7) The radioactivity monitoring of the compartment exhaustair shall be used to determine whether or not the leakage isfrom a system that carries a radioactive medium.

(8) The water levels in the sumps of the building drainsystem shall be monitored individually.

(9) The measured values of the leakage monitoring systemshall be recorded in an adequate way. Selected measuredvalues shall be displayed in the control room or in an adjacentor computer room such that the course of leakagedevelopment can be pursued over the time.

(10) Adequate threshold values shall be specified for selectedmeasured values which, when being exceeded, would trip analarm annunciation to the control room during power operationof the plant.

9.5.3 Leakage monitoring of the control rod drives

The pressure retaining wall of the control rod drives shall beintegrally monitored for leakages during operation.

9.5.4 Monitoring of the leakage between primary andsecondary circuit

In plants with pressurized water reactors the main steam shallbe monitored for radioactivity. If a leakage is detected, themeasured values shall be evaluated with respect to the size ofthe leakage in the steam generator tubes.

9.6 Monitoring the primary circuit for loose parts

(1) For an early detection of damage and the localization ofloose parts, the primary circuit shall be monitored by a looseparts monitoring system.

(2) The requirements for this system, the extent of reactorplant monitoring and the in-service inspections of this systemare specified in DIN 25 475-1.

(3) If the structure-bound sound monitoring system fails dueto partial or complete failure of the measuring equipment, itsreactivation may be postponed at the latest to the next regularscheduled pant shutdown.

10 Participation in in-service inspections andoperational monitoring

(1) The nuclear power plant user shall take the necessarysteps to ensure that the tests and examinations listed in thetest and inspection schedule are performed at the dates fixedand by the institutions specified in Table 10-1.

(2) Where, for the purpose of inspection, the authorizedinspector himself has to perform manual examinations, thenthe corresponding examinations need not be performed by theplant user.

(3) The authorized inspector shall participate in operationalmonitoring measures. Details shall be fixed individually foreach plant.

Performed by Surveilled by Recorded by Certification,countersignatureType of examination

B S S B S SExamination of the surface with its near-surface regions X X X X

Volumetric examination X X X XVisual Examination X X 1) X X X 1)

Pressure test X X X XFunctional test X X X XB : Plant user (licensee) S : Authorized inspector1) Random examination of bolted connections in accordance with Table 5-1 and 5-8

Table 10-1: Participation of plant user and authorized inspector in in-service inspections

KTA 3201.4

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11 Documentation

11.1 General

The performance of in-service inspections, tests andoperational monitoring as well as the results obtained shall bedocumented. The requirements specified in KTA 1404 apply.

11.2 Documents required for in-service inspections

(1) The documents required for documenting the automatedultrasonic examinations are specified in Figure 11-1. Similardocuments shall be established for other test and examinationprocedures.

(2) In accordance with KTA 1202, the test and inspectionschedule 1 shall contain the basic specifications regardingareas, procedure, extent and interval of the tests andexaminations. The details regarding the performance of thetests or examinations shall be specified in test instructions 2relating to the specific test object or general standardinstructions/specifications 3 for each test or examinationprocedure.

(3) In order to be able to smoothly perform the examinationsat the test/examination locations, documents 4 specific to thetest/examination areas shall be established. In the case ofautomated ultrasonic examinations, these shall contain, e.g.,the manipulator drive sequence, channel identification,sensitivity adjustment requirements.

(4) To be able to reproduce the results of an examination,the essential data of the examination equipment shall bedocumented in a technical manual 5.

(5) The examination shall be started on the basis ofdocuments 1 to 5. Should the conditions at the examinationlocation require that changes be made to the examinationarea documents or to the equipment data, these shall bedocumented in revision sheets 4a.

(6) At first, all measured values (base data 6) shall berecorded on data storage media. Upon evaluation of the testresults 7 all indication liable to recording shall be entered inthe list of relevant indications 8.

(7) All relevant indications shall be recorded in the relevantindication record 9. The indication lists and the relevantindication records shall be contained in the test report (finaltest report 10).

11.3 Period of document filing for in-service inspections

(1) The documents 1 to 5 and 10 shall be stored at thenuclear power plant for the operating life of the component.

(2) The base data storage medium 6 shall be filed at leastuntil the completion of the next in-service inspection of theparticular examination area of the component. Should theevaluation of indications show up changes with respect to theprevious examination (cf. Step 7 of Figure 8-1), the base datastorage medium shall be filed for the operating life of thecomponent.

(3) Since there are justified fears that over the period ofstorage and despite appropriate storage conditions documentsor data storage media will show distorting data loss, the datashall be copied to new data storage media in time.

11.4 Documents required for the monitoring of mechanicaland thermal loadings

For the purpose of documentation, the documents shallcontain the following data on the:a) measuring and evaluation system (systems and compo-

nents to be monitored, their function and operational

mode, requirements to be met by the measuring andevaluation system)

b) measuring system (temperature measuring range,response times, recording frequency, measuring accuracy)

c) location and site of measuring points, type of measuringpoints, recording frequency

d) measuring results and component-specific fatigue analysis

Figure 11-1: Documents for the documentation of automatedultrasonic in-service examinations

4

5

3

1

2

10

4a

6

7

9

8

Documents specificto examination/test areas

Technical description/manualof test equipment

Commencementof test/examination

Test report(Final report)

Base datastorage medium

Test results

List of relevant indications

Test instructions

Standard testinstructions/specifications

Relevant indication record

Updated documents specificto test/examination areas

Test and inspectionschedule

KTA 3201.4

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Annex A

Regulations referred to in this Safety Standard

(The references exclusively refer to the version given in this annex. Quotations of regulations referred to therein refer to theversion available when the individual reference below was established or issued.)

StrlSchV Ordinance on the Protection against Damage and Injuries Caused by IonizingRadiation (Radiological Protection Ordinance – StrlSchV) October 13, 1976 (BGBl IPage 2905, 1977 Page 184, 269), as promulgated on June 30, 1989 (BGBl. I, 1989,Page 1321) corrected on October 16, 1989 (BGBL.I, 1989), at last amended by theOrdinance of August 18, 1997 (BGBl. I Page 2113)

RSK Guidelines RSK Guidelines for pressurized water reactors, 3rd Edition, October 14, 1981(Bundesanzeiger No. 69 of April 4, 1982)

Guideline Guideline Relating for the Protection against Radiation of Personnel During the“Radiological Protection“ Execution of Maintenance Work in Nuclear Power Plants with Light Water Reactors;

Part 2: The Radiological Protection Measures During Commissioning and Operation ofthe Plant, made public on August 4, 1981 (GMBl. 1981, Page 363)

KTA 1202 (06/84) Requirements for the testing manual

KTA 1404 (06/89) Documentation during the construction and operation of nuclear power plants

KTA 3201.1 (06/98) Components of the reactor coolant pressure boundary of light water reactors;Part 1: Materials and product forms

KTA 3201.2 (06/96) Components of the reactor coolant pressure boundary of light water reactors;Part 2: Design and analysis

KTA 3201.3 (06/98) Components of the reactor coolant pressure boundary of light water reactors;Part 3: Manufacture

KTA 3203 (03/84) Monitoring Radiation Embrittlement of Materials of the Reactor Pressure Vessel ofLight Water Reactors

KTA 3204 (06/98) Reactor pressure vessel internals

KTA 3405 (02/79) Integral leakage rate testing of the containment vessel with the absolute pressuremethod

DIN 25 435 -1 (11/87) In-service inspections for primary circuit components of light water reactors;Remote-controlled ultrasonic inspection

DIN 25 435 -2 (Draft 04/96) In-service inspections for primary circuit components of light water reactors;Magnetic particle and liquid penetrant method

DIN 25 435 -3 (11/87) In-service inspections for primary circuit components of light water reactors;Hydrotest

DIN 25 435 -4 (Draft 04/96) In-service inspections for primary circuit components of light water reactors;Visual examination

DIN 25 435 -6 (Draft 04/96) In-service inspections for primary circuit components of light water reactors; eddy-current examination of steam generator tubes

DIN 25 450 (09/90) Ultrasonic Equipment for Manual Testing

DIN 25 475 -1 (10/83) Nuclear facilities; Surveillance systems;Monitoring of structure bound sound for loose parts detection

DIN 25 475 -2 (Draft 03/94) Nuclear facilities; Operational monitoring; Vibration monitoring for early detection ofchanges in the vibration behaviour of the primary circuit

DIN 54 152 -2 (07/89) Non-destructive testing; Penetrant inspection;Verification of penetrant inspection materials

DIN EN 462-3 (11/96) Non-destructive testing; Image quality of radiographs; Part 3: Image quality classes forferrous metals; German version of EN 462-3:1996

DIN EN 1435 (10/97) Non-destructive examination of welds; Radiographic examination of welded joints;German version of EN 1435:1997

KTA 3201.4

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Annex B (informative)

Changes with respect to the edition 6/90 and explanations

(1) This safety standard was adapted in several sections,especially with regard to terms and requirements for testprocedures and techniques in consideration of applicable DINstandards and in conjunction with KTA Safety Standard3211.4 (6/96), to the state of science and technology toensure the use of equal terms and uniform rules for periodicinspections.

(2) The term “calibration block“ was specified to indicate thatcorresponding to the current examination practice not onlystandard, but also non-standard calibration blocks are used.The calibration blocks are unclad to ensure a sufficientreproducibility of in-service inspections.

(3) For a better understanding of the safety standard text,some new definitions were included.

(4) The stipulations for the test and examination proceduresand techniques in Table 2-1 were specified in correspondencewith KTA 3211.4 to adapt to the current examination practice.Here, the examination techniques developed further since theadoption of KTA Safety Standard 3201.4 (06/90) were takenover. Today the examination techniques described as “specialtechniques“ in the edition 6/90 are used as standardtechniques, use of radiography for surface examination) andeditorial changes were included.

(5) A new section 3 “General Principles“ was included tocover the stipulations for ensuring the component integrity byin-service inspections and operational monitoring. By thismeans the principles mentioned in the section “Fundamentals“which have been used in practice up to now are comprised toform a systematic procedure.

(6) In clause 4.1.1 it was made clear that the test proceduresand techniques are to be selected for the detection ofoperational flaws.

(7) In correspondence to KTA 3211.4 a new clause 4.1.5“Permissible examination procedures“ was included in thissafety Standard.

(8) Section 4.2 “Examination of surfaces“ was completelyrevised and adapted to the state-of-the-art as laid down inKTA 3211.4. The inclusion of ultrasonic examination for smallwall thicknesses (up to ≥ 8 mm) takes the current state-of-the-art in ultrasonic examination techniques into account. This,however, does not mean that ultrasonic examinations arepreferable to radiography. The establishment of a wallthickness range with s ≤ 25 mm for the use of radiaographywas based on the idea that also double-wall radiography ispermitted (wall thickness radiographed by double walltechnique ≤ 50 mm). The selective visual inspection wasadditionally included as surface examination procedure sincethis examination is used additionally or alone for specific tasksto correspond to the state-of-the-art.

(9) The use of longitudinal wave dual crystal search units asmentioned in section 4.2 is described in a DGZGP guideline(in preparation) where the search unit parameters, thedetermination of the focal zone, the influence of the radius ofcurvature as well as the dependence of the sensitivity from thedepth by using groves, transverse bores or flat bottom holesare dealt with

(10) The stipulations of the volumetric examination (Section4.3) were– revised to correspond to the ultrasonic examination

requirements as per DIN 25435 Part 1

– adapted to meet the state-of-the-art by including newultrasonic examination techniques and precise require-ments for radiography

– editorially revised with respect to the recording limits andadapted to the reduced wall thickness range with s > 8 mmfor ultrasonic examination

(11) Section 4.4. “Integral visual examination“ was revised tocorrespond to KTA 3211.4.

(12) Since the closing behaviour and not the reseatingpressure of safety devices is decisive for the test and it shallnot be the intention of functional testing to always reduce thesystem pressure to reach the reseating pressure, subpara c)in section 3.6 was deleted without replacement text.

(13) Section 5 “Extent of testing and test intervals“ wascompletely revised to include the following main items:– new text was included to say that where new findings are

made from the monitoring of causes and consequences ofoperational damage mechanisms as well as from theobservation of the state of knowledge of the plantcondition, the stipulations of sections 5.2 and 5.3 regardingexamination procedures, areas and intervals shall be re-evaluated.

– all tables were adapted to the current examination practicein which case the examination procedures and techniqueswere revised to the current state of technology and inmany cases the selective visual inspection of claddingswas included

– the examinations on the reactor pressure vessel wereadopted to the current examination practice with regard toligament areas

– on account of operating experience gained the text intervalfor the bolted joint on RPV (Table 5-1) was changed suchthat, alternatively to the current rule, the examination maybe performed as one single examination (100 %) at aninterval of 8 years. In addition, a visual examination ofbolts, nuts and washers was laid down to correspond tothe current examination practice after each unbolting of thebolted joint.

– the nozzles of the control rod drives and in-coreinstrumentation as well as the control rod drive housingspipes, which up to now had been considered by a footnoteto Table 5-1, now are included in a separate Table 5-2 dueto damage occurred in foreign nuclear power plants. Thistest was included as precautionary measure althoughGerman plants cannot be compared to those plants wheredamage occurred on the above mentioned components.For the next revision, the necessity of including Table 5-2further will be checked on the basis of experience gaineduntil the next revision.

– footnote 2 in Table 5-3 was deleted. However, it isassumed that the application of this footnote may becomenecessary which then shall be agreed for each individualcase.

– in Table 5-6, footnote 3 was revised to the current state ofexamination practice and footnote 5 was supplementedsince in the case of visual examination of pipe claddings itshall be fixed in each individual case whether an integral orselective visual examination has to be performed. Here it isagreed that the performance of visual examinations mustbe performed by means of specific devices (underwaterinspection instruments).

KTA 3201.4

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– the extent of in-service inspection on austenitic pipework(Table 5-7) was enlarged to take into account the currentstate of knowledge on hot reactor-water containing pipingsystems of German BWR plants. The systematicevaluation of these crack formations clearly shows theinfluences of the specific conditions (e.g. O2-content)prevailing in BWR plants. In-service and specialinspections in BWR plants confirmed this; no operationaldefects were detected during the extensive non-destructiveexaminations. In correspondence with KTA 3201.1 (6/98)and KTA 3201.3 (6/98) hot piping systems are those withan operating temperature ≥ 200 °C. It was consideredreasonable in this connection to fix the limits for nominaldiameters anew and to include the examination of theinternal surfaces in the case of pipework with < DN 200which up to now only had to be subjected to liquidpenetrant and visual examinations of the external surfaces,and to have austenitic pipework DN 50 covered by theextent of testing. The extent of testing shown in Table 5-7was fixed on the basis of the current state of knowledgeand corresponds to twice the extent of testing provided forexternal systems in KTA 3211.4. It is planned during thenext review of this safety standard, to check whetherchanges are necessary with respect to the increasedextent of testing for BWR plants.

– the limitation of nominal diameters for valve bodies (clause5.2.1.8) was reduced to ≥ DN 150, thus corresponding tothe limitations of Table 5-7. The exception of valves havingsmaller nominal diameters is not considered necessarysince they are subject to only little loadings (oversizing)

– the test intervals for main coolant pump casings have beenconcretized. For valve bodies a further concretization wasnot necessary due to the higher number of valves and therelated large number of tests and examinations as well asin due consideration of the operational monitoring. Whenfixing the extent of testing and test intervals for maincoolant pump casings it was considered that a selectivevisual examination of the main coolant pump may e.g. beperformed by means of underwater inspection equipmentto take the specific design of KSB Pumps into account.

– the stipulations for the functional testing of safety valves inclause 5.2.4 were specified in consideration of theexamination practice usual for the various valve designsfeatures

– section 5.3 (Test intervals) was adapted to the currentstate of knowledge in due consideration of the operatingexperience gained, the international practice, the currenttechnical rules and standards (especially Pressure VesselOrdinance as reworded on 21st April 1989) and theposition of the reactor safety commission on in-servicenon-destructive examinations and operational monitoring(Annex 1 to the records of the 321st meeting). In addition,stipulations were added with respect to the procedure inthe case of deviating test intervals. Here, by agreement

with the authorized inspector, the procedure shall be fixedin the case of unplanned deviations from the test intervaland a differentiated optimization of in-service inspectionsbe made possible.

(14) Section 8 “Evaluation of Test Results“ was revised tocorrespond to KTA 3211.4. In clause 8.1.1, subpara 8, thestress analysis was added as additional safety analysisprocedure since the assumption of crack growth is notreasonable in each case. In the same subpara therequirement was fixed again to perform control checks onsimilar components in the case of systematic defects. Therequirement of clause 8.1.2 (2) a), third dash, to treat not yetdocumented indications which exceed the recording limit likefindings has been laid down to prevent the growth of newdefects, if any, in due time. This is only required if suchindications give rise to the suspicion that important defectsmay be the cause of indication.

(15) Section 9 “Operational monitoring“ was revised andsupplemented with the following main items– the requirements for monitoring the mechanical and

thermal loadings and for monitoring changes in materialproperties were extended

– stipulations were included regarding the procedure tofollow if a cumulative usage factor D > 1 is attained.The next time of inspection depends on the intervals laiddown in this safety standard.Where the calculation proves that the predicted cumulativeusage factor is exceeded, a safe statement on the detec-tion of new crack formation can only be made inconsideration of the difference between number of loadcycles for crack initiation and the number of load cycles tofailure of

NA > (0.2 to 0.8) NB,

if the loadings during the operating period until the nextdate of inspection do not lead to an increase of thepredicted usage factor by more than ∆D = 0.1.Further explanations can be found in Annex 1 to AD-Merkblatt S2 (3/90). Here, specific reference shall be madeto the literature mentioned in the Annex which was used toestablish the load cycle curves for crack initiation. A furthercriteria for the determination of the next date of inspectionis the fracture mechanic analysis especially on the crackpropagation behaviour in the case of a postulated incipientcrack to ensure that until the next date of inspection nocritical flaw size will develop from an undetected incipientcrack.

(16) Sections 10 and 11 which up to now only containedrequirements for in-service non-destructive examinations,were supplemented to include operational monitoringrequirements.

02.-KTA-3201.4.pdf

Documents

operational monitoring

pressure test

monitoring of changes

monitoring of loadings

kta safety standardjune

monitoring of mechanical

leak monitoring

test intervals