ML17333A441
| ML17333A441 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 04/30/1996 |
| From: | Fitzpatrick E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| AEP:NRC:0969A0, AEP:NRC:969A, NUDOCS 9605060344 | |
| Download: ML17333A441 (11) | |
Text
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CATEGORY ly REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9605060344 DOC.DATE: 96/04/30 NOTARIZED: NO DOCKET FACIL:50.-33,5 Donald C.
Cook Nuclear Power Plant, Unit 1, Indiana M
05000315 50-3f6 Donald C.
Cook Nuclear Power Plant, Unit 2, Indiana M
05000316 AUTH.NAME AUTHOR AFFILIATION FITZPATRICK'.
Indiana Michigan Power Co. (formerly Indiana 6 Michigan Ele RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Forwards addi info in support of augmented RV insp relief request submitted 950728.
DISTRIBUTION CODE:
IE10D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: 50 Dkt Augmented Inspection Team (AIT) Reports/Correspondence NOTES:
RECIPIENT ID CODE/NAME PD3-1 PD INTERNAL: AEOD/DO C
RS FILE CENTER FB NRR/DRPM/PECB NRR/DRPW NUDOCS-ABSTRACT OEDO RES/DSR/HFB EXTERNAL: INPO RECORD CTR NRC PDR COPIES LTTR ENCL 1
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1 RECIPIENT ID CODE/NAME HICKMANgJ AEOD/SPD/RAB DEDRO NRR/DISP/PIPB NRR/DRPM NRR/DRPM/PERB NRR/DSSA/DIR OE/DIR OGC/HDS2 RGN3 FILE 01 NOAC COPIES LTTR ENCL 1
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0 NOTE TO ALL "RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE!
CONTACT THE DOCUMENT CONTROL DESK/
TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 27 ENCL 27
indiana Michiga~
Power Company~
P.O. Box 16631 Columbus, OH 43216 Z
INQIAitM NICHIGA&I IaOWM April 30, 1996 AEP'NRC:0969AO 10 CFR 50.55a Docket Nos.:
50-315 50-316 U.
ST Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D. C.
20555 Gentlemen:
Donald C.
Cook Nuclear Plant Units 1 and 2
REQUEST FOR RELIEF FOR AUGMENTED REACTOR VESSEL IN-SERVICE INSPECTION ADDITIONALINFORMATION The purpose of this letter is to provide additional information in support of our augmented reactor vessel inspection relief request which was submitted July 28,
- 1995, (AEP:NRC:0960AI).
The addi.tional information is included as an attachment to this letter.
As is noted in our response to NRC request number two, during the examination of the unit 1 reactor vessel we found that there were three additional welds (RPV-VCl, RPV-VC2, and RPV-VC3) for which we could not obtain the required 90% examination coverage.
Ve are revising our relief request to include these additional welds.
This revised request is scheduled for submittal by May 3, 1996.
The information regarding the reduced amount of the examination coverage and its causes is given in our response to the request.
If necessary, the unit 2 relief request will be similarly modified following the evaluation of the data taken during its augmented examination.
Sincerely, E.
E. Fitzpatrick Vice President llg Attachment OGO> 'r) 9605060344 960430 PDR ADOCK 05000315 8
U. S. Nuclear Regulatory Commission Page 2
AEP:NRC:0969AO CC:
A. A. Blind G. Charnoff H. J. Miller NFEM Section Chief NRC Resident Inspector
- Bridgman J.
R. Padgett
Attachment to AEP:NRC:0969AO
Response
to Additional Information Request 10 CFR 50.55a Code Relief For the Augmented Reactor Pressure Vessel Shell Weld Examinations for Cook Nuclear Plant Unit 1
Attachment to AEP:NRC:0969AO Page 1
This attachment provides supplemental information to the previously submitted relief requests related to the augmented examination of the reactor pressure vessel shell welds (ASME Code,Section XI,>
Category B-A, Item Bl.10 welds).
These questions were provided to us by the NRC on March 26,
- 1996, and they were discussed in a telephone conference on March 29, 1996.
The individual NRC requests and our responses are given below.
C Re uest 1
Provide more quantitat':
information on the expected coverage increase and impact of OD examinations for welds RPV-D (both units).
EPSC Res onse The original submittal of this code relief.request was based on estimates of examination coverages.
We presently have the results from the unit 1 RPV examinations conducted in October 1995.
The estimate for RPV-D (lower shell to lower head circumferential weld) for unit 1 submitted originally in July 1995 was 76% compared to 69% actual obtained during the examination (See Table 1).
As we discussed in the March 29th conversation, it is not feasible to examine the unit 1 RPV-D weld from the OD for the purpose of obtaining improved coverage.
At this location, the gap between the RPV OD surface and the concrete biological shield wall ID varies between 6 inches and 9 inches.
The RPV shell has approximately 3
inches thick mirror insulation mounted on it.
This insulation was installed as the reactor pressure vessel was lowered into the cavity and the removal of the insulation could only be accomplished by the removal of the RPV from the cavity.
We therefore believe, as previously stated, that examination of the RPV-D weld from the OD will be an undue hardship and significant economic burden without commensurate increases in safety, quality, and additional information.
The radiation exposure at this location is extremely high.
Since weld examination from the OD surface is not a feasible alternate, we did not develop the anticipated dosage value associated with insulation removal, examination from OD and re-installation of insulation.
Attachment to AEP:NRC:0969AO Page 2
C Re uest Discuss the possibility of increasing coverage on the VA welds@,
(nozzle interferences) during the performance of the code-required nozzle examinations.
AEPSC Res onse During the unit 1 examinations in October
- 1995, every effort was made to maximize volumetric coverage.
Equipment set-up was optimized to gain as much coverage of the longitudinal welds in the vicinity of the integral nozzle extensions by starting and finishing the exam scans as close to the integral extensions as equipment design would allow.
This increased the examination time on the vessel due to the careful approach of the equipment to the extensions so as not to damage the vessel and/or equipment.
Table 1 compares the estimated coverages for the reactor pressure vessel shell welds with the actual coverages obtained for 1995 unit 1
examination.
The actual examination coverage was 62% for the RPV-VA-2, and the reason is that this longitudinal weld is located tangential to the integral nozzle extension which resulted in more examination interference.
Additionally, the radial location of the core support lugs with respect to the lower shell longitudinal welds (1RPV-VC1, 2
6 3) resulted in examination coverages of less than 90%.
These limitations were not anticipated during the preparation of the original relief request.
The coverage obtained for these three welds was 80%
(See Table 1) with a best effort examination.
As stated in our response above to NRC Concern No.
1, alternative examination from the OD surface will require removal of the RPV from the cavity and removal/re-installation of the mirror insulation.
This is not practically feasible and will impose on us undue hardship and significant economic burden without commensurate increase in safety and quality.
By separate letter (AEP:NRC:0969AP) we willmodify our relief request to include these welds.
As an alternate, we conducted a best effort exam from the inside surface using techniques, tools, and reduced speeds which permitted maximized percentage coverage of these welds.
C Re uest 3
Discuss how data from recent unit 1 examinations confirms the estimate coverages in Table 1 (from original relief request) and the need for quantitative coverage limits for unit 2.
Attachment to AEP:NRC:0969AO Page 3
EPSC Res onse We have provided a comparison of the unit 1 estimated values versus the actual values in Table 1.
Additionally in Table 1,
we have
- provided, as requested, a more quantitative estimate for unit 2
shell welds, based on the weld configuration, review of possible examination interferences, and unit 1 results.
NRC Re uest 4
Discuss how many other Item Bl.10 welds are being examined and their amount of examination coverages.
AEPSC Res onse Table 2 lists all the Item B1.10 shell welds for units 1 & 2 which are subjected to the augmented examination.
Also shown are the actual coverage for unit 1 and the estimated coverage for unit 2 based on the weld configuration, possible
'xamination interferences, and unit 1 examination results.
Addit onal Re uests NRC/INEL also requested a total coverage statistic for unit l.
Table 3 provides the total linear length of the circumferential and longitudinal welds on the RPV and also the total length of all welds.
The total percentage coverage for all unit 1
RPV shell welds subjected to the mandated 10 CFR 50.55 examination has been calculated to be 88.8%.
Attachment to AEP:NRC:0969AO Page 4
Weld I.D.
RPV-D RPV-VA1 RPV-VA2 RPV-VA3 RPV-VC1 RPV-VC2 RPV-VC3 Unit 1 estimate submitted with 7/95 relief re 85'90'90'90'90%
Unit 2 estimate submitted with 7/95 relief re Unknown Unknown Unknown Unknown
>90'90@
Unit 1 Actual results 10/95 exam 69%
808 62@
99'0880'0'nit 2
Updated Estimate 70'0%
80'0'90'90' Shell weld does not exist for Unit 2.
Table 1
Summary of examination coverage estimates and actual results for the Cook Nuclear Plant Reactor Pressure Vessel Shell Welds where actual Unit 1 coverages were less than or equal to 90't. (ref.
ASME Section XI, Cat B-A, Item B1.10 welds).
Attachment to AEP:NRC:0969AO Page 5
Veld Z.D.S RPV-B RPV-C RPV-D RPV-VA1 RPV-VA2 RPV-VA3 RPV-VB1 RPV-VB2 RPV-VB3 RPV-VC1 RPV-VC2 RPV-VC3 Unit 1 Actuals (10 95 100%
100%
69%
80%
62%
99%
100%
100%
100%
80%
80%
80%
Unit 2 Updated Estimate 100%
100%
70%
80%
80%
80%
100%
100%
100%
100%
- Shell weld does not exist for Unit 2.
Table 2
Units 1
and 2
RPV shell velds which are sub)act to 10 CFR 50.55a augmented examination.
Attachment to AEP:NRC:0969AO Page 6
Unit RPV-B RPV-C RPV-D Tot. circ welds RPV-VA1 RPV-VA1 RPV-VA1 RPV-VB1 RPV-VB2 RPV-VB3 RPV-VC1 RPV-VC2 RPV-VC3 Total length of longitud.
welds Total weld len th Length of weld (ft) 48.67 48.67 48.67 146.01 8.25 8.25 8.25 9.08 9.08 9.08 8.92 8.92 8'2 78.75 224.75
% exam covers e
100 100 69 80 62 99 100 100 100 80 80 80 Covered length (ft) 48.67 48.67 33.58 130.92 6.6 5.12 8.17 9.08 9.08 9.08 7.14 7.14 7.14 68.55 199.47 Remarks Total 8 coverage for circ. welds - 89.78 Tot.
0 coverage for Longitud. welds - 87%
Tot.
8 coverage for all RPV welds - 88.8%
Table 3
Unit 1 RPV Shell Welds Subject to 10 CFR 50.55a Augmented Examination