ML20082L936

Responds to Request for Addl Info Re ISI Plan for Third 10-yr Interval

ML20082L936
Person / Time
Site:	Point Beach
Issue date:	08/29/1991
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	Samworth R NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
CON-NRC-91-089, CON-NRC-91-89 TAC-79795, VPNPD-91-295, NUDOCS 9109040479
Download: ML20082L936 (32)

Text

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o-Wisconsin Electnc POWER COMPANY 231 w wnon po room Maaee wn320$ Inw 23e VPNPD-91-295 NRC 089 August 29, 1991 Document Control Desk U. S. NUCLEAR REGULATORY COMMISSION Mail Station P1-137 Washington, DC 20555 Attention: Mr. Robert Samworth, Senior Project Manager Project Directorate III-3 Gentleman:

DOCKETS 50-266 RESPONSE TO REOUEST FOR ADDITIONAL INFORMATION INSERVICE INSPECTION PLAN FOR THIRD INTERVAL (TAC 79795)

POINT BEACH NUCLEAR PLANT UNIT 1 In a letter dated July 12, 1991, the NRC staff requested additional information in order to complete the review of our inservice inspection (ISI) plan for the third 10-year interval'for the Point Beach Nuclear Plant Unit 1. A summary of our inspection plan and our requests for relief from certain inspection requirements were provided to the staff with our letter dated December 20, 1990.

Enclosed with your July 12 letter was a listing of the additional information items which you have requested. The following is.a summary of how we are responding to each element of theLinformation request. The responses are identified with the same paragraph designation as the enclosure to your July 12. letter:

2A. Under separate cover we are providing a copy of the_"ISI Long Term Plan Third Interval Basis Document", Revision O. Appendix A.to.that document includes the ISI Classification Boundary Drawings requested by this item.

2B. Under separate cover we are providing a copy of the "ISI Long Term Plan Third Interval". This document contains the listing of the welds'and components subject to examination during the inspection-interval.

2C. A listing of the ISI isometric drawings is provided in Section VII of the long term plan provided in item 2B, A copy of these drawings is included with the package i containing item-2B.

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. s Document Control Desk August 29, 1991 Page 2 2D. A list of the ultrasonic calibration blocks is provided in Section VIII of the ISI Long Term Plan. The sizes and material specifications are shown on these drawings. The drawings are in the Point Beach drawing system. For your convenience a copy of these drawings has been enclosed with the package containing item 2B.

2E. A discussion of compliance with BTP ASB 3-1 is enclosed.

2F. A discussion of compliance with Regulatory Guide 1.150 is enclosed.

2G. A discussion of our intended inspection method for the reactor coolant pump flywheel is enclosed. This response is augmented by a drawing and photographs of the flywheel configuration which have been provided with item 2B.

2H. A discussion of the ISI ultrasonic examination techniques used by Wisconsin Electric for cast Stainless Steel is enclosed.

2I. After further review of this requirement, we have decided to withdraw Relief Request RR-1-01. We will conduct the code required examination.

J. A discussion of the conditions you have imposed on Relief Request RR-1-02 is enclosed.

2K. Our response to this item is enclosed.

2L. After consideration of your comments concerning relief request RR-1-10, we are withdrawing the request.

2M. Enclosed are copies of the pages you reported missing from relief requests RR-1-11 and RR-1-12, 2N. We agree to perform the-exams in accordance with code Case-N-481 and also verify that a surface' examination will be performed on all three welds of one pump if a pump is not disassembled for maintenance. A revised request is provide in Appendix A of the long term plan-provided_under item 2B.

20. A revised relief request has been provided with Appendix A of-the long term plan.

Document Control Desk August 29, 1991 Page 3 2P. We have submitted with our long term plan document all the relief requests of which we are aware. Should we discover that additional relief requests are required, we shall notify you promptly and amend our submittal accordingly.

As requested in your letter, we are providing a copy of this response and the additional material submitted under separate cover directly to Mr. Boyd Brown at EG&G Idaho, Inc. The NRC copy of the additional material is being sent directly to Mr. Samworth.

Please contact us if you have any questions concerning these responses to your information request or concerning our inservice inspection program.

Very truly yours,

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C. W. Fay Vice President Nuclear Power Enclosures Copy to: NRC Regional Administrator Region III ,

NRC Resident Inspector Mr. Boyd Brown, EG&C Idaho, Inc.

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ATTACHMENT t

l Response to Request for AdditionalInformation inservice Inspection (ISI) Plan

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l Third interval 4

! Point Beach Nuclear Plant Unit 1 I

Items 2E, 2F 2G, 2H, 2J, 2K, 2M t

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RESPONSE TO ITEM 2E As required by Paragraph B.2.d of Branch Technical Position AS8 3 1,

• Protection Against Postulated Piping Failures in Fluid Systems Outside Containment,' the ISI classification for tio Main Steam and Foodwater systems was rnanntained as ISI Class 2 to the outboard restraint.

Since the constructkm permit for Point Beach Nuclear Plant, Unit I was issued in July 1967, Wisconsin Electric has fulfilled the requirements stated in Paragraph B.4.d of the Branch Technical Position, No additional requirements or examinations are required by this Branch Yechnical Position.

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Response to item 2F:

Wisconsin Electric Power Company agrees that Regulatory Guide 1.150 is applicable to examination of all reactor pressure vessel welds, including nozzles. It is not the intent of Wisconsin Electric to limit the use of this Regulatory Guide to only the reactor pressure vessel beltline welds.

Components within the following ASME Section XIitem numbers are part of the Point Beach Nuclear Plant Unit 1 reactor pressure vessel. Examination of these item numbers are augmented by implementation of Regulatory Guide 1.150.

Item No. Parts Examined f;.Klen1 B1.11 Shell Welds, Circumferential One Beltline Region Weld 81.12 Shell Welds, Longitudinal One Beltline Region Weld B1.21 Head Welds, Circumferential Accessible length of one weld 81.30 Shell-to-Flange Weld 100% of weld length B1.40 Head to-Flange Weld 100% of weld length B3.90 Nozzle-to-Vessel Welds All Nozzles with full penetration welds B3.100 Nozzle inside Radius Section All Nozzles with full penetration welds B5.10 Reactor Vessel, NPS4 or Larger, Nozzle to Safe End Bolt Welds All Welds 88.10 Reactor Vessel, Integral Welded Attachments Weld (Lugs)

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Attached is a transcript of Regulatory Guide 1.150, Revision 1, annotated with comment. These comments identify the method of implementation. Comments are relative to the Regulatory Position portion of the Regulatory Guide only.

SOUTHWEST RESEARCH INSTITUTE IMPLEMENTATION OF REGULATORY GUIDE 1.150 REOUIREMENTS The following is a transcript of Appendix A to Regula-tory Guide 1.150, Revision 1, annotated with SwRI comments. These comments identify SwRI's technical methods of implementing the Regulatory Guide.

Comments are made relative to the Regulatory Posi-tion portion of the Regulatory Guide only, as this is the portion to which the Nuclear Regulatoiy Commission (NRC) will audit for compliance.

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APPENDIX A Ultrasonic examination of reactor vessel welds should be performed according t'o the requirements of Section XI of the ASME B&PV Code, as referenced m the Safety Analysis Report (SAR) and its amendments, supplemented by the following:

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1. INSPECTION SYSEM PERFORMANCE CIIECKS The conduct of a quality examination requires that the performance characteristics of the inspection system used be well defined and documented. This is particularly true for situations which require comparisons of examination results generated during successive examinations on the same components.

A system comprises:

a. a transducer;

b. a single-channel instrument or each channel of a multichannel instrument; and

c. a given cable type and length.

The checks described in paragraphs 1.1 and 1.2 should be made for any UT system used for inspection of reactor pressure vessel (RPV) welds.

The field performance checks described in 1.2 (with the possible exception of 1.2.c) should be conducted on a basic calibration block that represents the thickness range to be examined.

SwRI agrees with the need to depne and docwnent the ruja:~ wnce chamcteristics of UT

. systems, and we have been doing so for manyyears. Afost of the checks identiped herein have been standant opemtingpmetice for SwRI. SwRI applies these requirements to all recsctor vessel weld examinations, whether the e .uninations are manual, automatedfrom the inside surface, or awomatedfmm the outside surface. Since the results of the field performance checks described in 1.2 are independent of calibmtion block design, SwRI procedures allow the use of any calibmtion block that willpmvide the signal responses neededfor the performance check.

1.1 Preexam Performance Checks

a. Frecuency of Checks These checks should be verified within 6 months before reactor pressure vessel examinations performed during one outage. Pulse shape and noise suppression controls should remain at the same settings during calibration and examination.

b. RF Wavefann A record of the RF (radiofrequency) pulse waveform from a reference reflector should be obtained for each search unit used in the examination in a manner which will provide frequency amplitude information. At the highest amplitude portion of the beam, the RF return signal should be recorded before it has been rectified or conditioned for display. The reflector used in generating the RF F1

return signal as well as the electronic system (i.e., the basic ultrasonic instru-ment, gating, and form of gated signal) should be documented. These records should be used for comparison with previous and future records.

SwRIperforms a complete laboratory anabsh of every search unit in inventory at least every 12 months. Thu anabsh includes not only recording the RF puhe waveform identified above, but also determmation of the frequeuy spectrum and dhtance amplitude ciuvefor each search unit. Search units that do not meet strictperformance tolerances are discarded or labeled as not acceptable forfield use. Documentation of thu analysis &

provided to swr 1 clients prior to the job and is aho included in the final examination report.

In addition to the labomtory search unit anahsh, SwRIphotogmphs the RF waveform in thefield during initialandfinal calibratioru. Thu provides a record of the RF waveform obtained using the specific system components (tmruducer, instrument, and cable) that are used for calibmtion and examination.

1.2 Field Performace Checks

a. Frequency of Checks As a minimum, these checks should be verified on site before and after examining all the welds that need to be examined in a reactor pressure vessel during one outage. Pulse shape and noise suppression controls should remain _

at the same settings during examination and calibration.

b. Instrument Sensitivity Durine Linearity Checks The initial instrument sensitivity during trie performance of 1.2.c should be such that it falls at the calibration sensitivity or at some point octween the calibration sensitivity and the scanning sensitivity.

c. RF Waveform A record of the RF (radiofrequency) pulse waveform from a rderence reflector should be obtained and recorded m, a manner that will permit extraction of frequency amplitude information. At the highest amplitude portion of the beam, the RF return signal should be recorded before it has been rectified or conditioned for display. This should be determined on the same reflector as that used in 1.1.b above. 'Ihis record should be retained for future reference.

d. Screen Heicht Linearity Screen height linearity of the ultrasonic instrument should be determined according to the mandatory Appendix I to Article 4,Section V of the ASME ,

Code or Appendix I to Section XI of the ASME Code.

e. Amnlitude Control Linearity Amplitude controllinearity should be determined according to theinandatory Appendix II of Article 4,Section V, of the ASME Code or Appendix I of Section XI of the ASME Code.

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f. Ancle Beam ProGe Characterization The vertical beam profile should be determined for each search unit used during the examination by a procedure similar to that outlined in nonmandatory Appendix B-60, Article 4,Section V, of the ASME Code or Appendix I to Section XI of the ASME Code. Beam profile cutves should be determined at different depths to cover the thicknesses of materials to be examined. Interpola-tion may be used to obtain beam orofile correction for assessing flaws at intermediate depths for which bean. . rofile has not been determined.

Beam proGe measurements should be made at the sensitivity required for sizing. For example, sizing to 20-percent DAC criteria requires that the beam profile be determined at 20-percent DAC.

The field performance checks desenbed above are performed by Sm"I as follows:

I (1) RF Waveform SwRIphotogmphs the RF waveform bs thefield dring each initial andfinal calibmtion. Thh pmvides a record of the RF uweform obtained using the specific system components (tmnsducer, insmunent, and cable) that are used for calibration and examinanon.

(2) Screen Height Linearity - Screen height imeanty checks are performed for each instmment in accordance with the Reg Guide requirements. These checks are performed immediately before and after completion of the czammations.

(3) Amplitude Conavl Linearity - Amplitude contmllinearity checks establish a linear relatiomhip between an adjastment of the gain, or sensitivity, controls (knobs or switches) and the corresponding signal amplitude change observed on the CRT.

In the case of manual erammations, the gain controh are used to determine the amplitude as a percentage of the Dhtance Amplitude Correction (DAC) curve by adjusting the controls until the signal meets the DAC curve and en!<-"Indng the mdication amplitude based upon the amount of gain adjustment. Since the gain controk are used to indirectfy calculate irvlimrion amplitude, it is importantfor the relationship between contml adjustments and corresponding signal changes to be linear reganifess of how large or small the indication is prior to the contml adjust.

ment. In the case of manual examinatiom in accordance with Reg. Guide 1.150, amplitude controllineari,y h determinedfor each instmment in acconiance with the Reg Guide requirements. These checks areperformedin conjunction with the screen height lineanty checks immediately before and after completion of the examinas.'om.

Pamgmph 1.2.b above requires that the instrument semitirity dunng theperformance of amplitude contml imeanty checks should be at the calibmtion seminvity or between the ca'ibmtion semidvity andscanning sensitivity. However, the calibmtion sermnvnty leveh (and scanning senntivity levels) vary with the different techniques used during vessel examinations. Therefore, SwRIperforms these linearity checks at the extreme upper and lower ends of the senntivity range, This emures that the instrument h linear across a wide mnge of calibration and scanning sensitivity leveh.

In the case ofautomated examinations, SwRI's Time Conavl Gain (TCG) cimuitrj clectronically compensates for the normal signal attenuation that causes a sloping DAC curve and pmvides a vanable gain adjustment across the CRT screen such H-3

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that a constant, horkontal DA C curve is attained *%erefore, with TCG, indication amplitudes as a pexentage of DAC are not ded~nined 17 adjusting the gain controls, but intead, can be determined directly by monitoring the digithed signal voltage, or vuually by using the horkontal screen grids. The performance of the TCG cimuiny is ascenained at SwRI's calibmtion labomtory at least every 12 months and also omite during examinatioru lypenodically venfying that the TCG b, in fact, maintaining a stmight horkontal DAC. In essence, whenever the amplitude controls are usedfor indication amplitude measurement, SwRIperforms amplitude controllinearity checks; however, in mast cases the checks are unneces-sary when using the TCG system.

(4) Angle. Beam Prople Chamcterka: ion A beam pmple for each single element pulse-echo angle beam search unit is determined on site in accordance with the Reg Guide requirements. These proples are genemted using the 1/4,1/2, and 3/4T side. drilled holes in a calibmtior: block that U as thick or thicker than the compo-nent to which the search unit will be applied. Since Appendit A of the Reg Guide permits sking at either 20% or 50% of DA C, SwRI takes both 20% and 50% beam proples.

With the use of tandem dual-refmeted longitudmal unve search units for near surface examination, typicalshing methodologies are not applicable because of the unique search unit performance. Therefore, when near surface indications are observed with these techniques, special supplemental shing techniqua may be required depending upon the observed chamcteristics of the paw. These special supplemental shing techniques have been substantiated and quahfied using mockups, peld experience, and research project data over many years. ,

2. CAT mRATION System calibration should be performed to establish the DAC curve and the sweep range calibration in accordance with Article 4,Section V, of the ASME Code or Appendix I to Section XI. Calibration should be confirmed before and after each RPV examination, or each week in which the system is in use, whichever is less. Where possible, the same :alibration block should be used for successive inservice examinations of the RPV.

System calibration is performed on site by SwRIin accordance with Reg Guide require-ments on the applicable basic calibmtion block.

l Calibmtion conprmatwn during manual examinations is performedprior to the examina-tion; at least everyfour houn during the erammations; with any sub& don ofseamh unit, cable, orpower source; and upon completion of the examinattom.

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For mechanked aaminations, SwRIperforms calibmtion confumanon prior to the start of a series of aaminations (a series U comidered to be smular examinatiom performed tuing the same examination techniques and the same equipment conpgumtion); with any sub& don of search unit, cable, orpower souxe; whenever t'.e device is rernovedfmm the eramination area; at least every week during the examinations; and at the completion of a series of aaminatiom. Msile this calibmtion conprmatwn frequency is consktent with the Reg. Guide, it sometimes does not comply with the 12-hourfrequent.y require-ments ofPamgmph T-432.1.2 ofSection V. Because oftheinherentstabilityarulreliability of the SwRIelectronic equipment, however, SwRIhas never experiencedproblems meeting calibmtion confumation criteria when going beyond the 12-hour time period. The H-4

acceptability of exceeding the Section V 12-hour calibmtion check can be demonttmted as allowed in Pamgmph IWA 2240 of Section X7.

2.1 Calibration for Manual Sennnine For manual sizing of flaws, static calibration may be used if sizing is performed using a static transducer. When signals are maximized during cabbration, they should also be maximized during sizing. For manual scanning for the detection of flaws, reference hole detection should be shown at scanning speed and detection levei set accordingly.

As required above, SwRI uses static calibmtion and static sising techniques for manual examinattom, maximi:ing both calibmtion andflaw signals. Reference hole detection is verified by scanning over the calibmtion block at the manmum scanning ned and verifying that the signal meets or acceds the recording level.

2.2 Calibration for Mechanhed Scanning When flaw detection is to be done by mechanized equipment, the calibration should be performed using the following guidelines:

a. The DAC curve should be established using either a moving transducer mounted on the mechanism that will be used for examination of the component or a mechanism that duplicates the critical factors (e.g., transducer mounting, weight, pivot points, couplant) present in the scanning mechanism.

b. Calibration speed should be at or higher than the scanning speed, except when correction factors established in 2.2.d are used.

c. The direction of transducer movement (forward or backward) during cahtration

to establish the DAC cutve should be the same direction during scanning unless it can be shown that a change in scanning direction does not reduce flaw detection capability.

I d. One of the following alternative guidelines should be followed to establish correction factors if static calibration is used:

l (1) Correction factors between dynamic and static response should be l established using the basic calibration block or, (2) Correction factors should be established using models and taking scaling factors into consideration (assumed scaling relationship should be verified) or, (3) Correction factors should be established using ful! scale mockups.

, SwRI complies with these requirements for calibmtion for mechanized scanning in accordance with 22d(1) in that we lutve repeatedly demonstrated equivalency between the scanning with the SwRI par devices or track-mounted scanners.and our static calibmtion techniques. SwRI routinely pmvides a report to its customers documenting l this equivalency using the equipment perrinent to each customer's application.

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2.3 CalDrnth Connimation Calibration cortfirmation performed u midshift or interim confirmation between onsite calibrations should comply with s: ability requacments in T 433, Article 4,Section V, cf the ASME Code.

Wheu an electronic .imulator is used for onsite calibration confirmation after a Code.

required block calibration performed off site, the following should also apply:

a. Complete system performance should be maintained stable priot to offsite calibtations and onsite calibration confirmation by use of target reflectors. The target reflectors should be mounted with identical physical displacement in both the offsite calibration facilities and the onsite mechanized equipment. Each onsite periodic calibration <hould be preceded by complete system performance verification using a minimum of two (2) target reflectors separated by a distance representing 75 percent of mulmum uickness to be examined.

b. Written records of calibration shotdd be established for both target reflector tesponses and Code calibration block DAC curves for each transducer. These written records may be used to monitor drift since the original recorded calibration.

c. Measures should be taken to ensure that the different variables such as te.nperature, vibration, and shock ilmits are minimized by controlling packaging, handling, and storage.

SwRI calibmtiors confumations are performed at the frequency specified in pamgmph 2 above and are in compliance with the stability requirements of the Reg Guide. SwRJ calibntrion confirmations are performed on site using the basic calibmtion block, not an electwnic block sirnulator. As such, the additional requiremenss identified in this pam-gmph for the use of an electwnic block simulator do not apply.

In addition to periodic calibmtion confumations, functional checks of the UTinstnanents and the TCG system are typically performed at shift changeover. These checks utilise electronic signal genemtors to moniscrfor changes in sweep and amplitude displays. The stabilit %eria of Pamgmph T433 of Article 4 are used for acceptability of

funcil nichecks.

For PWR ftal vessel examinations using SwRI's Fast par n1 tem, en Atta Acquisition Systemt are utilised in pamilel K7sile one system is used for scanning and data acquisi.

tion, the other system is being a'ibmtedfor the next series ofexaminations, in effect, two sepamte cable systems are used, onefor calibmtion aru. anotherfor examination. SwRI's Remote Cable Calibmsorsystem allom comparbon of the difference in cableperformance and also provides electronic signal genemtion forperiodic venfication that the performance '

of the two cable systents has not changed. These cableperformance checks are performed at the same time, and using the same criteria, as the electmnicfunctional checkt described above.

2.4 Calibration Blocks Cah'bration blocks should comply with Appendix I to Section XI or Article 4, i Section V, of the ASME Code. When an alternative calibration block or a new conventional block 11 - 6 L

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' is used, a ratio between the DAC cutves obtained from the original block and from the new block l should be noted (for reference) to provide for a meaningful comparison of previous and current {

data. 1

'!he cali$ ration side drilled holes in the basic calibration block and the block surface i should be protected so that their characteristics do not change during storage. These side drilled holes or the block surface should not be modined in any way (e.g.' by polishing) between successive exarninations. If the block surface or H calibration reDector holes have been polished by any chemical or mechanical means, this fac. ,aould be recorded.

SwRIpmcedures require the use of cal 3mtion blocks that are fabricated h accontance with the Reg Guide requirementsforstandaru Code techniques. When specialtechniques are utilised, such as dual tandem beam examination of the near surface vohune orspecial nozzle inner mdius examination, SwRI recommends modiftcation of conventional blocks in onier to accommodate the requirements of the special technique. Wheneverpossible, exhting Code requirements are used as guidance for ths SwRI recommendations.

It is SwRI's recommeruiation that the same calibmtion block be used for repetitive examinations. However, whennercalibmtion blocks are changed, SwRIahorecommends t that a correlation beperfonned ifpossible to aid in comparison ofin dications if necessary, \

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3. EXAMINATION The scope and extent of the ultrasonic naminations should comply with IWA 2000,Section XI, of the ASME Code.

If electronic gating is used to define the examination volume within which indications are recorded, the start and stos control points should include the entire required thickness including the material near each sur' ace.

If a single gate is used, it should be capable of recording multiple indications appearing in the gate. Alternative means of recording may be used providing they do not reduce flaw detection and recording capability.

Examination should be done with a minimum 25-percent scan overlap based on the trans.

ducer element size.

The scope and exsent of manual examinatioru are addressed in the examination plan and examination procedures in accordance with (WA 2000, in onter to ensure that the scope and ertent of automated examinations comply with IWA 2000 of Section XI, SwRIprepares a detailed Scan Plan for each automated-examination activity in addaion to typical eramination procedures. ThLt plan addresser device configumtions, scanning pammeters, calibmtion pammeters, gate settings, anu otherspecific information needed to perform the work. Impicmentation of the SwRI scan plan, as preparedfor a specific application, will ensure that the full volume of the ASbfE examination area is examined to the extent allowed by that vessel con)igumtion. Covemge is accomplished using a combination ofseveral beam angles and examination techniques as specified in the scan pla u.

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The electronic gating system unlued by SwRIdoes not limit the aamination wiume within which indicatiom are recorded When the SwRI standard data acquisition ostem is used 1

a video reconting is made of the actual UT imtmments ' CR*t'persentations with the search  :

unit positional infonnation su;xnmposed in real time. \

swr 1's ' state of the. art'enhanceddata acquisition system has overlapping electronicgating for each UT channel such that a full volume aaminatkn is digithed, reconied, and duplayed. The SwRI enhanced data acquisition system gating is cajuble of reconting multiple simultaneous indicadons.

All camination performed in accontance with this Reg. Guide are performed using a 25 percent overlap, unless a greater overlap k requhed.

3.1 Internal Surface

'Ihe capability to effecttvely detect defects at the internal clad / base metal interface shall be considered acceptable if the examinction procedure (s) or technique (s) meet the require-ments of Section 6.0 of this document and demonstrate the following:

a. Procedures for examination from the outer surface, or when usin ; full vec from the inside surface, should include the use of the 2 percent notes which pcne-trates the internal (clad) surface of the calibration blocks, defined by Section XI.

Appendix 1. Figure I 3131, or Section V, Article 4, Figure T 434-1. Procedures for examination from the internal surface when not using the full vee should conform to paragraph 3.1.b below,

b. An alternate reflector, other than the 2 percent notch descrit>ed above, may be used provided: (1) that it is located at the clad / base metal interface or at an eciulvalent distance from the surface, (2) that it does not exceed the maximum alowable defect size, and (3) that equivalent or superior results can be demon-i strated,

c. 'Ihe examination procedure (s) should provide for volumetric examination of at least 1 inch of metal as measured perpendicular to the nominal location of the base metal cladding interface.

SwRIprocedures for aamination from the outside surface of the ve.ssel wall use the 2-percentnotchforreferenceasspecifiedinPamgmph 3.1(a). Theseproceduresalsoinclude a half vee calibmnon with the notch usedfor enluation of allindications which appear at the inride surface of the aamination area.

swr 1procedruer for tandem bearn aamination from the inside surface utilke 1/8-inch diameter side drilled holes at the cladpase metalinterface as described in Pamgmph 3.1(b). In both casa, SwRIprocedurespmvidefor vokunetric aamination ofgreater than 1 inch depth below the cladding interface as required by Pamgmph 3.1(c). SwRI has demonstmted that the reference sensit! 'ty established on the 1/16 inch diameter side.

dn'lled holes meets or accedt that specified in Section XI of the ASME Code. This technique has also been demonstmted to lutve the capab lity of detecting flaws with good signal to-nohe discrimination at depths of at least 2 3/4 inches ,dow the clad to-base metal interface, thus overlapping the through wal! zone of calibmted sensithity of the 45 degree and 60-degree beams. Using the tandem beam tmnsducers, SwRI has detected H-8

k flaws of minute she in the area between the clad.to base metal interface and the first 45-degree and 60 degree DACpoint.

SwRI has also used 70 degree dual (side by side mounted picoelectric elements) search units for underciad examinations; however, the meful mnge & limited to appmtimatey 1 inch ofdepth below the claddmg with no discemible impmvement over the tandem beam search unit at the clad to base metalinterface.

3.2 Scant h Weld-Met 11 Interface The be m angles used to scan welds should be based on the peometry of the weld /

patent metal interf.U Where feasible for welds such as those identified m Section T-441.4.2 of Article 4,Section V, of the ASME Code, at least one angle should be such that the beam is 3erpendicular (tl5 degrees to the perpendicular) to the weld / parent metal interface, or it shout ye demonstrated that unfavorably oriented planar flaws can be detected by the UT technique bein used. If this is not feasible, use of alternative volumetric NDE techniques, as permitted by the ASME Code, should be considered.

3 For RPV shell seam welds, SwRI uses the nominal Code specified 0-degree, 45 degree, and 60 degree, beams to examine thefull volume of the wallsection exceptfor the volume of material near the beam entrypoint, for which we use thepreviously mentioned tandem scarch units.

Section T-441.4.2 (or T-441.3.2.2 of the 1986 Edition) ofArticle 4,Section V, states that beam angles other than 0-degree, 45 degrees, and 60-degrees should be used for the examination of(a) flange welds when the examination is conductedfmm theflangeface, (b) noules and no=le welds when the examination is conductedfrom the noule bore, (c) attachment and support welds, and (d) aamination of double taperfunctions. SwRI has employed this appmach for manyyears.

SwRIprocedures, however, oftenpmvide more than Code specified covemge wherefeasible.

Each of the unique weld configumtions noted above b evaluated to determine the best asui most comprehensive covemge attainable. Where necessary, other angle and stmight beam examinations areperformed to assure complete covemge ofnocle to shell, vessel to flange, '

and attachment welds. Previously mentioned tandem beam techniques are aho utilhed to pmvide the required near surface covemge when nocle bore staminatiora art per.

formed.

4. BEAM PROIM31 Delete entire para Profile Characterization. graph. This section included in Recommended Change 1.2.f Angle Bea

5. SCANNING WEin METAL INTERFACE Delete entire paragraph. This section included in Recommended Change 3.2, Scanning Weld Metal Interface.

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6. RECORDING AND Sf71NG The capability to detect, tecotd, and size the flaws delineated by Section XI, IWB 3500, should be demonstrated. The measurement tolerance established should be applied when sizing Daws detected and tecorded during scanning (see paragr5ph 7.a).

The requirement to demonstmte the capabuity to detect, record, and she paws can be interpreted many ways. A libemiinterpretation might be thatyears ofindustry operience has demonstmted that Code techniques are capable of detecting, recording, and sking paws. A consenutive interpretation might be that a mockup of every concehuble wcld configumtion should be fabricated containing implantedflaws and aamined in order to demonstmte and document the capability. SwRIfeels that the real need is somewhere in between.

It'e have considemble operience and documentation to show that the 45 degree and 60<legree Code aaminatiom and those using the tandem pmbes are effectivefor detecting and recordingpaws in seam welds when scanningfrom either the imide or outside surface of the vessel. Our experience also shows that beam angles that are designed to be essen-nally normal to the weld are effective in detecting and recordingjlaws in the no=le to sheu weldt fmm the no=le bore. By vinue of actualflaw detection using current techniques, SwRI's UTpmcedures are weu qualified Although the capabuities of SwRIprocedures to detect and recordpaws has been demon-stmted on a significant variety of test specimens and in reactor vessels during actual inservice and presenice aaminations, it cannot be pmctically demonstmted that the techniques and equipment have the capability to sheflaws with anypredictable tolemnce.

Afany researth studies thmughout the history of the nuclear industry have attempted to quantify the sking abuity of various NDE applications, none have estabushed universauy acceptedresults. ThedifJerentjointconfigumtions,platethicknesses,flawlocationswithin the weld, flaw orientations, and acoustic chamcteristics of the component material all contribute to the inherent vanability of shing techniques.

As alway , 3wRI will continue to recommend to our customers the thomugh enluation of anyflaws that are detected and recorded dunng our examinations. These recommenda.

tions have included, and will continue to include, Code and non Code si:ing techniques, the use of supplemental NDE techniques if pmctical, construcn'on of mockups of the particular cor.figumtion in question, researth of data fmm simliar examinatioru and studies, and caning in consultants with panicular apertise in the type of problem @:m outside SwRIif appropriate) to fully emluate the eramination and the results. 11'e will aho a.tnst our clients in every waypossible with NRC enluations of reponable indications and in the use of Fmeture Afechanics techniques.

6.1 Geometric Inhtions Indications determined to be from geometric sources need not be sized. Recording of these indications should be at 50-percent DAC, When indications are evaluated as geometric in origin, the basis for that determination should be described. After recordinj sufficient informa.

tion to identify the origin of the geometric indication, further recording anc evaluation are not required.

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I Indication anabsis and shing are performed as an independent onsits activity ly SwRI.

All of the aamination data h rntewed ly Level 11 or Level fit aaminers to the atent necessary to determine the origin of ary reconied trutications.

Indications that are geometric in origin are recorded at 50-percent DAC and the nature of each such indication is documented 6.2 Indications with r%nein, Metal Path

a. Indications that change metal path distances (indicating tnrough. wall dimen.

ston), when scanned in accordance with the requirements of ASME Section XI for a distance greater than that recorded from the calibration reDector, should be recorded.

b. Reflectors which are at metal peths representing 25 percent and greater of the through wall thickness of the vessel wall measured from the inner surface should be recorded in accordance with the requirements of ASME Section XI and characterized at 50 percent DAC.

c. Reflectors which are within the inner 25 percent of the through wall thickness should be recorded at 20 percent DAC. Characterization should be in accor-dance with the demonstrated methods under paragraph 6.0, When the indica-tion is sized at 20-percent DAC, this size may be corrected by subtracting the beam width in the through thickness direction obtained from the calibration hole (between 20 percent DAC points) which is at a depth similar to the flaw depth. If the indication exceeds 50 percent DAC, the length should be recorded by measuring the distance between 50 percent DAC levels. The determined size should be the larger of the two.

SwRI believes that the intent of this pamgmph is to require that the aaminer attempt a determine and document the mast accumte she of a reflector having thmugh unil dimension. To the extent pmcticable, SwRI data anahsis of tmveling indications is performed in acconiance with thue requirements.

SwRI nplcallyperforms both 20-percent and 50-percent bewn spread measurement at the time of calibmtion in case the information is nreded during data analysis. However, shing with beam sperad conection at 20-percent DAC.should not be genemlh' applied without caution as this appmach pmd.sces wideh* varied shing data, including negathw flaw skes in certain cases.

For tandem beam search units, the use of beam spread correctionfor shing is not nonnally applicable becasue of the unique beam pmfile chamcteristics. When near surface indications are obsenal during a vessel aamination that are nuluated to be flaws, SwRI routinely applies one or r ar sking techniques in onier to obtain the best estimate of the flaw she before comparing the ske to the acceptance criteria of Section XI.

In genemi, SwRI concurs with the specified appmach, but also recommends application ofselectedalternate shing techniques when necessary based upon a case by case enluation to detr ~ ine whids technique h considered most appmpriatefor the anticipatedflaw type and orwstation.

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t 63 InWe=tions Without Chneine Metal Path

a. Indications which do not change metal path distance when scanned in accor-dance with the requirements of ASME Section XI and are within the outer 75 percent of the through wall dimension should be recorded when any continu-ous dimension exceeds 1 inch,

b. If the indication falls within the Inner 25 percent of the through wall dimensions, it should be recorded at 20 percent DAC and evalcated at 50 percent DAC.

c. Precautionary note: Indications lying parallel to welds may appear as nontravel-ing (without changing metal path) w 1en scanned by parallel moving tr ansducers whose beams are aimed normal to the weld, i.e., at 90 degrees. Multiple scans, however, may reveal that these indications are traveling indications. Ifso, recording and . sizing are to be done in accordance with paragrLph 6.2.

To the extent pmcticable, SwRI data analysis of nontmveling indications is perfonned in accontance with these regtdrements, along with the use of additional shing techniques where appmpriate.

The precautionary note of Pamgmph 62.c is oppwpriate. To alleviate this concern, SwRI perfonns scanning in the di:ection of the beam component whereverpossible. In thme instances when this preferred mode of scanning cannot be utilhed, swr 1 pmcedures address this concem by requiring adda'lonal scans (alcng with sound beam direction) of any nongeometric angle-beam indkation observed during scaru made pamilel to the weld.

These additional scans are perfonned using small scan increments (or large emnsducer overlap) in onier to develop a very accumte data set. This data set allows a detennination of whether the indication is a smveling or nontmveling indication and also provides accumte data for sking purposes if necessary.

6.4 Additional Recordine Critsda ne following information should also be recorded for indications that are reportable according to this regulatory position:

! a. Indications should be recorded at scan intervals no greater than 1/4 inch.

b. He recorded information should include the indication travel (metal path

, distance) and the transducer position for 20-percent (where applicable),50-t percent, and 100 percent DAC and the maximum amplitude of tbe signal.

c. When multichannel equipment is used in the examination system such that all examination displays are not available for simultaneous viewing, an electronic pting system should be used which will provide on line, reproducible, recorded mformation regarding metal path, amplitude, and position of all indications exceeding ,a preset level ne preset level should be the minimum recording level requtred. To ensure that all recordable indications are recorded, a preferred methet would incorporate multigates in each channel or a single gate for each channel with multi iadication recording capability.

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in reference to Pamgmph 64.a. SwRI typically performs initial scanning using a 23% l overlap at specified in Pamgmph 3 However, data to be utakedfor specific shing or 1 imestigation ofindicasicru that exceed the allosuble limits of Section XI is acquired at 1/4 inch, or less, scan intenuls.

The information required in Pamgmph 64.b is typicalho reconied 71 SwRIfor all vessel 1 examinatioru, whether the examination b performed manually or ustry automated equipment.

In reference to Pamgmph 64.c which addre,ues the use of multi. channel equipment, the SwRI standani data acquisition system satisfles this requirement by virtue of the video recording of the instrument screcru. Since the entire screen presentation is recorded, j simultaneous multiple signals are reconied if encountered. The data anabsis process also includes review of all of the video tape data thenby eruuring thu rach recorded signalit 4

uviewed and anahud.

SwRl's ' state of the art

• enhanced data acquhition system has the capability to individually reconi simultaneous multiple indications by digitking and storing the entire naveform, thus signifwantly streamlining and accelemting the data acquhition and anat>1h pnwess.

7. FEPOR*ITNG OF RFSULTS Records obtained while following the recommendations of regulatory positions 1.2,3, and 6, along with discussions and explanations, if any, should be kept avad' able at the site. If the size of an indhation, as determined in regulatory positions 6.2 or 6.3, exceeds the a110wable limits of Section XI of the ASME Code, the indications should be reported as abnormal degradation of reactor pressure boundary in accordance with the recommendation of regulatory position 2.a(3) of Reg. Guide 1.16.

Along with the report of ultrasonic examination test results, the following information should also be included:

a. De best estimate of the tolerances in sizing the flaws at the r,ensitivity required in Section 6 and the basis for this estimate.

nis estimate may be determined in part by the use of additional reflectors in the basic calibration block.

b. A description of the technique used to qualify the effectiveness of the examination procedure, including, as a minimum, material, section thickness, and reflectors,

c. He best estimates of the portion of the volume required to be examined by the ASME Code that has not been effectively examined such as volumes of material near each surface because of near. field or other effects, volumes near Interfaces between cladding and parent metal, volumes shadowed by laminar material defects, volumes shadowed by part geometry, volumes inaccessible to the transduosr, volumes,affected by electroruc gating, and volumes near the surface opposite the transducer.

• lt should be noted that the licensee is required to apply for relief from impractical ASME Code requirements according to 50.55a of 10CFR. If the licensee is committed to examine a weld as per the inspection plan in the plant SAR, the licensee is required to file an amendment when the commitments mace in the SAR cannot be met.

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Sketches and/or descriptions of the tools, fixtures, and component geometty which contribute to incomplete coverage should be included.

d. Provide sketches of equipment (Le., scanning mecFanism and transducer holders) with '

reference points and necessary dimensions to ADuw a reviewer to follow the equip.

ment's indication location scheme. l

e. When other volumetric techniques are used, a descripilon of the techniques used j should be included in the report.

In reference to Paragmph 7.a, SwRI feels that the shes obtained using Code sking techniques should be used cornistently for comparkon to Code acceptance standards whenever possible. Based on SwRI e.xperience, Code shing techniques appear to be somewhat conservative; however, there & little evidence to support the feasibility of developing specific tolemnces or correction factors for Code skm' g sechnigs.es. Nor is there significant evidence ofimproved accumcy and covistency resultingfrom the use of any one alternate shing technique. Alternate shing methods must be used carefully and, in effect, should be used only when it can be determined that the Code shing techniques are, for some reason, inappropriate for the specipc type offlaw encountered.

These statements do point out thatpaw skes based on UT are estimates. We, of course, have wrying degrees of conpdence in flaw size estimates depending on pertinent aamina-tion wnables. Since the mmifIcattoru of ourpaw she estimations are very great, SwRI will typically recommend certain actioru to our customer which can increase our conf.

dence in paw ske estimation. These recommendations may include actioru such as: ,

(a) placing additional holes in the calibmtion block (b) corutructing mockups of the examination area (c) using other NDR equipment (d) applying alternate NDE methods (e) performing certain labomtory tests (f) calling in specialists with panicular experience in similarpmblerru.

1 In reference to Pamgmph 7.b, the bash for all SwRIpmcedure qualipcations is docu.

mented and amilable for audit by client or regulatory' personnel at any time, in reference w Pamgmph 7.c, SwRIprovides a detailed limitations reportfor all reactor vessel ~+% 7he limitations report h a combination of tables and sketches that depict and quantify the wrious limitations to the Code requimi covemge. These reports

, compile all of the wrious peninent data into a conche, understandable format and can be used as the basis for Relief Requests if neces.cary.

')he infonnation identiped in Pamgmph 7.d is routinelypmvided in the SwRI Scan Plan prior to performance ofexaminations. In adduion, a copy of the 'as executed

• Scan Plan h reproduced and included in the SwRI Final Report.

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In reference to Paragmph 7.e, when alternate techniques are utill:ed, eitherfor e.zamination ,

or si:ing purposes, a complete description of the application and results is included in the <

swr 1 Final Report. t i

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RCJDonse to item 2G:

The reactor coolant pump (RCP) flywhccis for Point Beach Nuclear Plant Unit 1 are constructed from plate. Each flywheel consists of two (2) plates held together with eight (8) bolts (1 1/4 inch diameter). Additionally there are other holes machined into each plate. These are used for attaching lif ting eyes 1.nti rotation devices and balancing weights. A drawing and photographs of the flywheel configuration have been provided under separate cover.

The ultrasonic method is the most appropriate method for volumetric examination for the flywheel high stress concentration areas (bore and keyway). When the flywheelis in place, no access is available to the lower plate. The flywheelis secured to the shaf t of the reactor coolant pump motor with a nut. This nut covers the area around the bore and keyways. This prevents examination of the area of interest in the top plate. Examination of the bore and keyway area from the edge of the flywheel does not produce meaningful results. The area of interest is greater than 30 inches from the edge. The holes through the plates prohibit continuous sound transition to the bore from the edge of the plates.

Wisconsin Electric proposes to examine the bore and keyway area only when the flywheel is removed (five year frequency). The methods of examination will be a dye penetrant and visual (VT 1). There are no limitations to the exam with the flywheel removed. Additionally a volumetric (ultrasonic) examination will be conducted of both plates on a 10-year frequency. The only limitation to a complete volume examination are in the area of the machined recesses for the bolts and anti rotation pawls.

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, b%QDse to item 2H:

Wisconsin Electric Power Company is aware of the difficulties in ultrasonic examination of cast stainless steel. Our Point Beach Nuclear Plant was constructed with several cast stainless steel components.

The items subject to ISI ultrasonic examination are the reactor coolant pump's casing, olbows in the main reactor coolant piping and portions of severed valves. The balance of the items subject to ISI ultrasonic examinations are olther wrought stainless stool or clad carbon steel vossols.

Wisconsin Electric has attempted to examine various cast stainless stool materlats installed at PBNP.

The examinations have had varied results. The procedures also vary with the individual item's fabrication processes, material thicknesses, ultrasonic transducers and signal processing. No single procedure has produced reliable results on all of our cast stainless steel applications. Wisconsin Electric has been, and will continue to be, receptive to new techniques which are demonstrated to be rollable.

The reactor coolant pump casings are SA 351 Grado CF-8, with a nominal wall of 9 inches. To dato, no ultrasonic methods have been capable of interrogating the full thickness These castings have a large grain structure and contain small casting flaws. Sound entering the casting is scattered and attenuated within the first three to four inches of material. WisconMn Electric currently does not utlitze ultrasonic techniques for the reactor coolant pump casing examinations. A rollef request has boon submittod for the RCP wolds examinations.

The cast stainless stool elbows used in the main reactor coolant loop piping are Static Cast A 351, Grade CF 8M. The wall thicknesses range from 2.7 inchos to 3.1 Inches. The procedure for ultrat,onic examination of these elbows utilizes a refracted 'L' wave with a pitch-catch technique. Transducers with a nominal frequency of 1.4 MHZ produce the best signal-to-noise ratlos from calibration reflectors.

Required ISI ultrasonic examinations, which involve cast stainless steel valves, are wolds betwoon the wrought piping materlais and valve bodies, except for valve body welds in two (2) valves. The procedure for examining theso areas use conventional shoar wave techniques, including the valve body wolds. Due to the geometry of the valve body welds, those weld examinations are supplemented with rei, acted 'L' wave scans. '

fitantl93 tem 11 The reactor vessol safety injection safe end to nozzio welds (RC-04 SI 1001-33 and RC44 SI 100219) are located below the rofueling cavity floor between the reactor vessel and the biological shle J wall.

There is no access to the outside diameter surfaces of these wolds. The insido surface of these wolds is accessible through the 3,44 inch diameter nozzle from the reactor vessel. Examination performod from this surface requires the use of remote tooling.

Those t.afo ord to nc'zzle wolds are ASME Category B.F Item B5.10. The code required area of examination is the O D. Surface and the inner one-third volumo. It is not practical to perform a surfaco examination of these wolds within the limits of access designed into the Point Beach Nuclear Plant.

There are no design or access considerations to prevent performing a volumetric examination of the ccrJo requittd Inner one-third volume, as well as the entire weid volume, including heat affected zone.

The volumetric rnothod for exarnining the safety injection safe end to nozzlo wold is ultrasonics.

Wisconsin Electric Request for Rollef RR 142 proposes the ultrasonic examination of the entire wold vo!ume, including the heat affected zono, in llou of the ccdo requirod surface examination No other alternato examination is practical.

O.D. Surface connected notches of a size similar to the acceptance limit of ASME Section XI, Tables IWB 3514 t and IWB 3514 2 can be detected by the ultrasonic procedures for examining these wolds. The ASME Code,Section XI,1980 Edition does not require procedures to be demonstrated with laboratory test blocks containing cracks.

Wisconsin Electric cannot verify that small defects within the detection limits of a surface examination method, such as dye penetrant, would also be within the detection capabiktles of an ultrasonic examination, with respect to the safety injection safe-end to nozzle welds.

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Rup_Qme to item 2K:

Relief Request No. RR 1-08 requested relief from performance of the code required surface and volumetric examinations of welds Tn the safety injection system piping located between the reactor vessel and the bioshicld wall. These welds are inaccessible. There is currently no viable, alternative examination method.

The centerline of the Si norries is on the 34 foot 5-3/8 inch elevation. A plan view of this elevation in Bechtel Drawing C 325 shows orientation of the sleeves through the bioshield wall.

The sleeves are 16 inch diameter with approximate lengths of 15 feet and 17 feet. The annulus area between the reactor vessel and the bioshield wall is 811/32 inches at the norrle elevation.

There are no removable sand (shield) plugs above the SI piping similar to thoso at the inlet and outlet norrle locations.

Dose rates below the sand plugs for the inlet and outlet norrles are typically 300 500 MR/HR at 18 inches from the pipe surface. Similar dose rates would be expected at the SI piping. No dose rate measurements have been made at the SI piping since it is not accessible for such measurements or by personnel.

As stated in Relief Request No. RR 1-08, no alternate examination is possible and no partial examination of code required area is possible.

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Besnomulu 2M:

The pages missing frorn relief requests RR 111 and RR 1+12 are attached.

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ER-1-11 REQUEST FOR RE!!EF WITHORAWN (EXAM NOT APPLICABLE TO THIRD INSPECTION INTERVAL) l ATTACHB. DOC B-19

RR-1-12 COMPONENT Regenerative Heat Exchanger - Primary Side Welds EXAM AREA

1. RHE Head to Shell

2. RHE Shell to Tubesheet

3. RHE Head to Shell

4. RHE Shell to Tubesheet

5. RHE Head to Shell

6. RHE Shell to Tubesheet

7. RHE-N1 - Inlet Nozzle to Shell

8. RHE-N4 - Shell to Outlet Nozzle

9. RHE-N5 - Inlet Nozzle to Shell

10. RHE-NB - Shell to Outlet Nozzle

11. RHE-N9 - Inlet Nozzle to Shell

12. RHE-N12 - Shell to Outlet Nozzle ISOMETRIC or COMPONENT DRAWING Figure 1 - ISI-PRI-1107 d

ASME SECTION XI CATEGORY B-B B-D ASME SECT'a" 11 ITEM NUMBER 92.51 B2.80 B3.150 ASME SECTION XI EXAMINATION RE0VIREMENT A volumetric examination of 100% of all three circumferential head welds, three tubesheet to shell . welds and six nozzle to shell welds during the third 10-year interval.

ATTACHB. DOC B-20

l ALTERNATIVE EXAMINATION PBNP proposes to utilize the ' multiple stream" concept by performing a volumetric examination of accessible portions of all circumferential head welds, tubesheet to shell welds and nozzle welds equivalent to one of the three identical sections of the regenerative heat exchanger during the third 10-year interval . Specifically, PBNP proposes to examine to the extent practical the circumferential head weld RHE-01, shell to tubesheet weld RHE-02, inlet nozzle to shell weld RHE-N1, and shell to outlet nozzle weld RHE-N4.

In addition, PBNP proposes to perform a VT-2 visual examination of all regenerative heat exchanger tubesheet and nozzle areas during system leakage tests and hydrostatic pressure tests in accordance with IWA-5000 and Table IW8-2500-1.

BEASON FOR LIMITATIM

Background

The regenerative heat exchanger (RHE) provides the major single source of radiation exposure accumulated during a normal refueling outage inservice inspection. The RHE is actually three shell and tube heat exchanger's connected in series. The RHE is designed to recover heat from the reactor coolant system letdown stream during normal operation. Tha letdown stream flows through the shell side of the heat exchanger. The shell side of the RHE is ISI class I while the tube side is ISI Class 2.

To ensure adequate coverage of the ISI Class I component welds and minimize exposure, the multiple stream concept will be implemented as it is for 151 Class 2 welds. By extending the multiple stream concept to the 131 Class I welds of the RHE, a good representative sample of the welds will be examined while a significant reduction in radiation exposure to personnel is achieved.

The welds that PBNP proposes to examine volumetrically are all located on the bottom heat exchanger (see Figure 1 for an outline of the regenerative heat exchanger that depicts the weld locations).

The bottom heat exchanger welds should be the ones to be examined for two reasons. First, the bottom heat exchanger operates at the highest temperature of the three and is therefore the most highly stressed. Typical operatirq temperatures for letdown flow are 538'F into the bottom shell and 252'F oulL.of the top shell. Second, the bottom heat exchanger welds can generally be more extensively examined than the other heat exchanger welds due to ease of access. This is reflected in the tables contained in Southwest Research Institute letter 17-7472(22), dated January 9, 1985, from Rodney M. Weber (SwRI) to Steve P111tns (WE).

Not only does this letter show the best welds to be examined, it shows that some of the welds for which relief is being requested are limited in the amount of crea that can be examined. For example, using the terminology contained in the referenced letter, only 25% of weld RHE-N9 can be examined by OL, 45, and 60 techniques.

ATTACHB.000 B-P.1

Supporting Information Radiation levels Currently, the average dose rates at the regenerative heat exchanger are:

1.5 R/Hr general area (at 18")

4.0 R/Hr insulation surface (on contact) 7.0 R/Hr shell surface (on contact under the insulation) lotal Estimated Man-Rem Exoosure involved in the Examination Considering the tasks associated with conducting an examination on a particular examination area, the following time intervals have been required in the past:

0.2 Man-Hrs for insulation removal 0.1 Han-Hrs for weld cleaning and preparation 0.7 Han-Hrs for conducting the examination 0.2 Han-Hrs for insulation replacement Using the preceding dose rates and times, the following whole body and extre.nity exposures can be calculated per examination: ,

Whole Body (using general area dose rates):

0.2 Han/ Hrs for insulation removal at 1.5 R/Hr = 0.3 Mar @n 0.1 Man-Hrs for weld cleaning and preparation at 1.5 R/Hr 0.15 Fun-kn 0.7 Man-Hrs for conducting the examination at 1.5 R/Hr = 1.05 Hn&n 0.2 Han-Hrs for insulation replacement at 1.5 R/Hr = 0.3 Hn&n Total Whole Body Dose per RHE Exam = 1.8 Hn&n Extremities (hands, using contact dose rates):

0.2 Man-Hrs for insulation removal at 4.0 R/Hr = 0.8 Hnen

! 0.1 Man-Hrs for weld cleaning and preparation at 7.0 R/Hr = 0.7 Hn&n 0.7 Man-Hrs for conducting the examination at 7.0 R/Hr 4.9 Hn&n 0.2 Man-Hrs for insulation replacement at 4.0 R/Hr - 0.8 Hn&n Total Extremity Dose per RHE Exam - 7.2 Hn&n The exposure savings per inspection interval, by a reduction of eight examinations, would be 14.4 Man-Rem Whole Body and 57.6 Man-Rem Extremities.

Shieldina The general area dose rates are reduced by approximately 50% by plsci.,q lead blankots and shields over non-examination areas. However, the hig:'es; dose rates are encountered during an inservice inspection. Also, the exam).Nr who is conducting the examination does not have the benefit of the shielding.

ATTACHB. DOC B-22 l

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Previous Insoection Results Simply stated, all indications recorded during inspections to this point were found to be either insignificant or geometric in nature. An insignificant indication is either a non-relevant indication or an indication which is equal to or greater than the examination recording level but less than the evaluation level.

Consecuences_pf Weld Failure The consequences of a weld failure of one of the RHE welds has essentially been addressed in the plant's Final Safety Analysis Report (FSAR). In the FSAR, to evaluate chemical and volume control system (CVCS) safety, failures or malfunctions were assumed concurrent with a loss of coolant accident (LOCA) and the consequences analyzed. A LOCA and a concurrent RHE weld failure is included in the more general category of a rupture in the CVCS line inside containment. During such an occurrence, the remote-operated valve located near the main coolant loop, upstream of the RHE, is closed on low pressurizer level to prevent supplementary loss of coolant through the letdown line. The RHE would also eventually be isolated, with leakage being confined to the containment, in the case of a weld failure without a LOCA.

g ATTACHS.D0C B-23 l

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