ML20042F886
| ML20042F886 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 05/08/1990 |
| From: | Hood D Office of Nuclear Reactor Regulation |
| To: | Tucker H DUKE POWER CO. |
| References | |
| IEB-88-002, IEB-88-2, TAC-76654, NUDOCS 9005100114 | |
| Download: ML20042F886 (3) | |
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N og UNITED STATES p
NUCLEAR REGULATORY COMMISSION n
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q j-WASHING TON, D. C. 20566
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MAY 0 81939
' Docket No. 50-370 i
e Mr. H. B.-Tucker Vice President Nuclear Production Department Duke Power Company
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'422 South Church Street i
Charlotte, North Carolina 28242 j
Dear Mr. Tucker'
SUBJECT:
REASSESSMENT OF BULLET 1H 88-02 FOR MCGUIRE NUCLEAR STATION, T
UNIT 2 (TAC 76654)
LBy letter of February 27, 1089. I advised you of the completion of the NRC's y
review of your actions to resolve NRC Bulletin 88-02, " Rapidly Propagating F:tigue Cracks in Steam Generator Tubes," for McGuire Unit 2.
Based on the satisfactory resolution of the bulletin issues, the letter noted your option to terminate your commitment to the enhanced primary-to-secondary leak rate
' monitoring program described in your June 10, 1988, letter and encouraged you to review the leak rate monitoring procedures to ensure the continued effectiveness of these procedures for the timely detection, monitoring, and L
trending of rapidly increasing. leak rates.
During subsequent review of analyses performed by Westinghouse on behalf of I
a number of other PWR licen mes, the NRC staff discovered a pattern of-deficiencies that appear'to be generic to Westinghouse analyses completed before November 1988.-
The deficiencies involve lack of adequate considerations of flow peaking factor sensitivity-to the measured locations of the anti-vibration bars (AVBs),.and AVB measurement uncertainties. These' deficiencies i
can lead to non-conservative estimates of'the flow peaking factor and, hence, l
to non-conservative conclusions as to which tubes are acceptable for. continued service. -' Accordingly, by the' enclosure, Westinghouse has informed the NRC
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staff Lof plans ~ to reassess these analyses and forward results to plant owners.
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L McGuire Unit 2 is'among nine plants to be reassessed by Westinghouse over the next 3'to 4 months. Until the current uncertainties regarding.the adequacy of your response to the bulletin are resolved for Unit 2, we request that you D l reinstate your commitment to the enhanced leak rate monitoring program discussed in item C.1-of the bulletin, and inform us of your reinstatement within 30 days of receipt of this letter. We also request that you forward the Westinghouse
-reassessment'for Unit 2 to us for review and approval once received from Westinghouse.
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x 9005100114'900508 PDR-ADOCK 05000370 t
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Mr. H. B.-Tucker Duke Power Company McGuire Nuclear Station j
4 cc Mr. A.V. Carr, Esq. -
Dr. John M. Barry i
Duke Power Company Department of Environmental Health P. O. Box 33189 Mecklenburg County-l
-422 South Church Street 1200 Blythe Boulevard Charlotte, North Carolina. 28242 Charlotte, North Carolina 28203 1
County Manager of Mecklenburg County Mr. Dayne H. Brown, Director f
720 East Fourth Street-Department of Environmental, Charlotte, North Carolina 28202 Health and Natural Resources Division of Radiation Protection q
P.O. Box 27687 Mr. J. S. Warren Raleigh. North Carolina 27611-7687 Duke Power Company l
Nuclear Production Department Mr. Alan R. Herdt, Chief P. O. Box 33189
. Project Branch.#3 Charlotte, North Carolina 28242 ti.S. Nuclear Regulatory Comission j
101 Marietta Street, NW, Suite 2900 4
'J. Michael McGarry, III, Esq.
Atlanta, Gcorgia 30323 i
Bishop Cook, Purcell and Reynolds 1
1400 L Street, N.W.
Ms. Karen E.,Long Washington, D. C.
20005 Assistant Attorney General N. C. Department of Justice J
Senior Resident Inspector P.O. Box 629 I
c/o U.S. Nuclear Regulatory Commission Raleigh, North Carolina -27602 i
12700 Hagers. Ferry Road i
Huntersville, North Carolina-28078 o
Regional Administrator, Region II
.l U.S. Nuclear Regulatory Comission 101 Marietta Street, N.W., Suite 2900 l
Atlanta, Georgia 30323
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Ms. S. S. Kilborn Area Manager, Mid-South Area 1
ESSO Projects Westinghouse Electric Corporation MNC West Tower - Bay 239 P. O. Box 355 Pittsburgh, Pennsylvania 15230 t
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-,y MAY 0 81990 Mr. H. B. Tucker,
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If you have any questions regarding this matter, please contact me at (301) 49?.1442. The subject TAC should be included on all future relevant correspondence.
The reporting arid /or _recordkeeping requirements of this letter affect fewer than ten respondeat" therefore, OMB clearance is not required under P.L.96-511.
Sincerely, 1s/
1 Darl S. Hood, Project Manager Project Directorate 11 3 Division of Reactor Projects 1/11 Office of Nuclear Reactor Regulation
Enclosure:
3/27/90 W. Johnson 1tr. to NRC cc w/ enclosure:
See next page DISTRIBUTION; e.Dectat illev NRC POR
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D. Matthews-D. Hood R. Ingram C. Y. Cheng 4
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OFFICIAL RECORD COPY-Document Name:
LTR TUCKER 76654
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A ENCt.0SURE Westinghouse Energy Systems e8' 8?83" Electric Corporation
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Box 355
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U.S. Nuclear Regulatory Commission ATTN: Document Control Desk NS NRC 90 3498 Washington, D.C. 20555 March 27, 1990 ATTENTION:
Mr. J.E. Richardson Director, Division of Engineering Technology
Subject:
Steam Generator Tube Fatigue Evaluations Update I
Dear Mr. Richardson:
This letter outlines a plan and the basis for this plan to update steam generator tube fatigue evaluations performed by Westinghouse in-response to NRC Bulletin 88 02. As these evaluations progressed from
".t late 1987 to,- in particular, late 1988, metho'ds for defining.AVB position uncertainties improved and a larger flow peaking test data base showed increased sensitivity to AVB positions. On this basis, it is prudent-to review some of the earlier completed analyses.
To date, reevaluations of earlier reports have been completed for six plants and a reevaluation partially completed for a seventh plant. These efforts have led to the identification of'a total of two tubes requiring corrective action that were not included in the original assessment.
In one case, Diablo Canyon Unit 1, a tube was identified for corrective action as a consequen~ ce of an error in transposing graphical AVB data that was supplied by another vendor.
Following this occurrence all other plants.that used graphical input to prepare AVB maps were, reviewed and no other case of a transposition error was identified..For plants having the eddy current review for. AVB positions performed by Westinghouse, AVB depth projections are used as an independent check on AVB positions'which further minimizes the potential for an AV8 mapping error.-
For Salem Unit 1, the reassessment completed to date has identified one
- additional tube requiring corrective action.
In this case, increased adjustments of-AVB positions further away from the best estimate positions to account for position uncertainties resulted in a higher flow peaking factor than the original evaluation.
The larger data base on flow peaking factors permits identification of more limiting AVB positions than possible for the earlier assessments.
This situation t
forms the basis for the planned review of the tube fatigue evaluations completed. prior to November 1988.
Evaluations completed since this date have included increased efforts to establish AVB positions to maximize flow peaking based on extensive flow peaking tests. Consequently, these 4
later evaluations do not require a reevaluation.
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The existing cusluations completed prior to November 1988 have identified the most probable, limiting tubes relative to tube fatigue sensitivity.
The later assi.sments and planned reevaluations more extensivo1y
' incorporate.loveh probability AVB positions in the evaluation to increase the confidence that all potentially affected tubes have been identified.
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A total of 3 tc 4 months are necessary to complete the reevaluttion.
In the interim, Westinghouse is not recommending that any action be taken by the identified plants.
To identify the tube fatigue analyses requiring review, the plants for which Westinghouse has completed the evaluations have been grouped into six categories.
These categories are identified in Table 1 Categories 1 to 4 do not require reevaluation for the reasons (attached).
noted in the table; therefore, the associated plant names are not listed.
The reevaluations have been completed for the Category 5 plants and the results transmitted to the respective utilities.
As noted above, one tube in Diablo Canyon Unit I for the Category 5 plants was identified for corrective action.
There are 9 plants in Category 6 for which reevaluation will be performed.
To date in this group, one tube in Salem Unit I has been identi Med for corrective action.
Westinghouse intends to complete the reevaluation for the Category 6 plants over the next 3 to 4 months.
A letter summarizing the results of these assessments will be transmitted to the plant owners upon completion of these activities.
If there are any questions on this transmittal, please contact T.A. Lordi (412 374-4311) of my staff.
Si cerely,,
W ohn n, Manager Nc ar S fety Department
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ra IABLE 1 PLANT CATEGORIES FOR TUBE FATIGUE EVtLUATION CATEGORY P ANTS 1.
Plants with AVB Modifications o Performed with projecticas o Small uncertainty on Ai2 positions Negligible flow peaking effects o
o Reevaluation not required 2.
Plants with large margins o
Re'. valuation not required 3.
Plants with round bars Round bars do : lot snow high o
peaking factors or sensitivity as found for square bars o Reevaluation not required 4
Evaluation performed since late 1988 Sensitivity to AVBs fully recognized o
o Conservative evaluations performed o Reevaluation not required 5.
Reevaluation already completed Otablo Canyon 1 and 2 o Sensitivity analysis performed Sequoyah 1 and 2 Trojan Point Beach 2 5.
Reevaluation should be per'--med Indian Point 2 o Evaluation performed or so 11/B8 Kewaunee o Sensitivity analysis to
.e performed Zion 1 o 9 plants McGuire 2 Beaver Valley 1 and 2 Salem 1 and 2 Ginna