ML20198Q367
| ML20198Q367 | |
| Person / Time | |
|---|---|
| Issue date: | 01/20/1998 |
| From: | Sullivan E NRC (Affiliation Not Assigned) |
| To: | Modeen D NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| PROJECT-689 GL-95-05, GL-95-5, NUDOCS 9801230004 | |
| Download: ML20198Q367 (4) | |
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UNITED STATES 1
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- i NUCLEAR REGULATORY COMMISSION s*
. WAsHINsToN, D.C. 300tHOM January'20, 1998 qg
- David.I Modeeri, Director _
Engineering, Nuclear Energy institute 1776 i Street, NW Suite 400
- Washington, D.C. 20006-3708
SUBJECT:
EPRI REPORT:' STEAM GENERATOR TUBING OUTf"OE DIAMETER STRESS CORROSION CRt CKING AT TUBE SUPPORT PLATES DATABASE FOR
- ALTERNATE REMIR LIMITS,' NP-7480-L, ADDENDUM 1, NOVEMBER 1998 -
Dear Mr. Modoen:
- In a letter dated October 28,1997, Nuclear Energy Institute (NEI) requested that the staff respond to the following five items related to the subject EPRI report: (1) an NRC decision to accept or reject the industry rationale to exclude the French data; (2) treatment of uncertainties -
regarding correlation parameters in Monte Carlo analyses; (3) the voltage-based Probability of -
Detection (POD); (4) the revised leak rate for the Virgil Summer Station tube R28C41; and (5) a revisior, to EPRI Cata Exclusion Criterion. NEl also requested that the staff provide the correct detsbase for the Generic Letter (GL) 95-05 calculations and resolve the latest issues regarding the database protocol.- The following informaticn documents the background and status of our review of NP-7480-L.
GL 95 05," Voltage-Based Repait Criteria for Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking," provides guidance on implementing voltage-based repair criteria for certain degraded stesm generator tubes. The repair criteria allow degraded tubes having outside diameter stress corrosion cracking that is predom_inately axially oriented and confined within the tube support plates to remain in service on the basis of, iri part, the results of licensees' condition monitoring and operational assessment. Licensees implementing GL 95-05 use an NRC approved database when performing GL 95-05 calculations.- The database consists of burst pressure and leakage data derived from destructive tests of laboratory specimens, and tubes that have been remcved from US cnd French nuclear plants.- The database is required to be updated periodically as additional tubes are removed from steam generators and tested as specified by GL 95-05.
On December 3,1997, the staff met with representatives of industry in Rockville, Maryland to discuss outstanding items (1) and (2) me'itioned above.-
' With regard to item (1), the staff hac concluded that at pretont the French data should rercain in the database. During the meeting on December 3,1997, the staff commented that statistical analyses alone do not provide a basis for excluding the French data and there does not appear :
to be conclusive physical evidence to demonstrate that French data should be separated from -
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domestic plant data. In addition, the' staff noted that the French deta need to be reviewed to -
' ensure that they satisfy quality assurance requirements. It is our understanding that. as a result -
F L of the meeting, the industry will review the French data and may provide additionalinformation to support its rationale for excluding the French data, j
During the meeting on December 3,1997, the staff provided an explanation for the current.
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analysis framework including the treatment of sampling uncertainties (item 2).' Staff and industry representatives jointly agreed that this analysis framework is appropriate, in this meeting, the -
staff indicated that the recent industry proposal for a one-aided p-test for the leak rate vs. voltage data correlation is appropriate. Therefore, based on thc. current database, analyses of leakage in 7/8" tubes will rely on a correlation between leak rate and voltage, b
With regard to item (3), the staff is waiting for the industry's responses to its request for
" additional information on POD dated March 31,1997.
~ On November 20,1997, NEl submitted the latest revision of the database, EPRI reports NP-7480-L V1-R2 and NP-7480-L-V2-R2, November 1997. Included in the submittal was the revised leak rate for the Virgil Summer tube R28C41 (Item 4) and revised EPRI Data Exclusion r
l Criterion (item 5).~ The staff review of these two issues is ongoing.
L With regard to the protocol, the staff finds the final version of the protocol in the NEl's letter dated October 28,1997, acceptable. We request that you notify the appropriate industry representatives that the protocol has been jointly agreed upon by NEl and the NRC and that the staff considers the protocol in effect. With the protocol in effect, utilities using the voltage-based repair criteria of GL 95-05, can determine the correct database for their analyses. However, pursuant to your request, the staff will perform a one time review of the latest database and notify NEl of the resuits of our review.
If you have any questions, please contact me at (301) 415-2795.
Sincerely, Edmund J. Sullivan, Acting Chief Materials and Chemical ' Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation ~
U.S. Nuclear Regulatory Commission'
= PROJECT NO :- 689
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ei Mr. David Modeen domestic plant data. In addit.on, the staff noted that the French data need to be reviewed to ensure that they sa'Jsfy quality assurance requirements. It is our understanding that as a result of the meeting, the industry will review the French data and may provide additional information to support its rationale for excluding the Franch data.
During the meeting on December 3,1997, the staff provided an explanation for the current analysis framework including tha treatment of sampling uncertainties (item 2). Staff and industry representatives jointly agreed that this analysis framework is appropriate, in this meeting, the staff indicated that the recent industry proposal for a one-sided p-test for the leak rate vs. voltage data correlation is appropriate. Therefere, based on the current database, analyses of leakage in 7/8" tubes will rely on a correlation between leak rate and voltage.
With regard to item (3), the staff is waiting for the industry's responses to its reouest for addi-lional information on POD dated March 31,1997.
On November 20,1997, NEl submitted the latest revision of the datacase, EPRI reports NP-7480-L-V1-R2 and NP-7480-L-V2-R2, November 1097. Included in the submittal was the revised leak rate for the Virgil Summer tube R28C41 (Item 4) and revis3d EPRI Data Exclusion Criterion (item 5). The staff will review these two issues is ongoing.
With regard to the protocol, the staff finds the final version of the protocolin the NEl's letter dated October 28,1997, acceptable. We request that you notify the appropriate industry representatives that the prctocol has been jointly agreed upon by NEl and the NRC and that the staff considers the protocolin effect. With the protocolin effect, utilitias using the voltage-based i
repair criteria of GL 95-05, can determine the correct database for their analyses. However, pursuant to your request, the staff will perform a one time review of the latest database and notify NEl of the results of our review.
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If you have any questions, please contact me at (301) 415-2795.
Sincerely, Edmund J. Sullivan, Acting Chief Materials and Chemical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission PROJECT NO.: 689 cc: C. Callaway, NEl Distribution:
EMCB RF BSheron PRush SMagruder EDebec-Mathet File Center CBeardslee SCoffin AKeim PubliC DOCUMENT NAME: G:\\TSA0\\NEILETTE.RV1 To receive a copy of tnis document. indicate in the box C= Copy w/o attachment / enclosure E= Copy with attachment / enclosure N = No copy OFFCE,
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~ Mr. David Modeon domestic plant data, in addition, the staff noted that the French data need to be reviewed to ensure that they satisfy quality assurance requirements. it is our understanding that as a result of the meeting, the industry w'll review the French data and may provide additional information to support its rationale for excluding the French data.
1 During the meeting on December 3,1997, the staff provided an explanation for the current -
analysis frwmework including the treatment of sampling uncertainties (item 2).. Staff and industry representatives jointly agreed that this analysis framework is appropriate, in this meeting, the _
staff inctAted that the recent industry proposal for a one-sided p-test for the leak rate vs. voltage data correlation is appropriate. Therefore, based on the current database, analyses of leakage in 7/8" tubes will rely on a correlation between leak rate and voltage.
With regard to item (3), the staf: is waiting for the industry'c responses to its request for
- additional information on POD dated March 31,1997,
'On November 20,1997 NEl submitted the latest revision of the database, EPRI reports NP-7480-L-V1 R2 and NP-7480-L-V2-R2, November 1997, included in th3 submittal was the revised leak rate for the Virgil Summer tube R28C41 (Item 4) ar % vised EPRI Data Exclusion
. Criterion (item 5). The staff review of these two issues is ongoir,a.
t With regard to the protocol, the staff finds the final version of the protocol in the NEl's letter dated October 28,1997, acceptable. We request that you notify the appropriate industry representatives that the protocol has been jointly agreed upon Dy NEl and the NRC and that the staff considers the protocol in effect. With the protocolin effect, uti5 ties using the voltage-based
. repair criteria of GL 95'05, can determine the correct database for their analyses. However, pursuant to your request, the staff will perform a one time review of the latest database and notify NEl of the results of our review, if you have any questions, please contact me at (301) 415-2795.
- Sincerely, I
R Edmund J. Sullivan, Acting Chief 4
Materials and Chemical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation
[
U.S. Nuclear Regulatory Commission
. PROJECT NO.: 689 cc C. Callaway, NEl es er
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