ML20154N228

Responds to NRC Re Violations Noted in Insp Rept 50-219/88-15.Util Does Not Concur W/Violation.Corrective Action:Rev 2 to MPR-999 Will Be Submitted When Available,To Document Analyses Performed as Result of Questions Raised

ML20154N228
Person / Time
Site:	Oyster Creek
Issue date:	09/19/1988
From:	Wilson R GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
5000-88-1635, NUDOCS 8809290236
Download: ML20154N228 (3)

Text

f GPU Nuclear Corporation

- Nuolear c* :::; " :: = o,osa 201 316-7000 September 19, 1968 TELEX 136-482 5000-88-1635 wnter's 0: rect o at Numben U.S. Nuclear Regulatory Commission Attention:

Document Control Desk ttail Station PI-137 Washington, DC 20555

Subject:

Oyster Creek Nuclear Generating Station Docket flo. 50-219 Inspection 88-15 Notice of Violation Response Attached is GPU Nuclear's response to the Notice of Violation contained in Appendix A to your letter dated August 19, 1988 which forwarded the report for the subject inspection.

If you should have any questions concerning the attachment, please Contact fir.

f1.W. Laggart, flanager, BWR Licensing at (201) 316-7968 or the undersigned, ytrhlyyours, t.

Y

.F. ' 11 on Vice Pre ident Technical Functions

/jb4 cc: fir. William V. Johnston, Director Division of Reactor Safety U.S. Nuclear Regulatory Comission - Region !

475 Allendale Road King of Prussia, PA 19406 fir. '41111am T. Russell, Administrator So Region I SN@

U.S. Nuclear Regulatory Comission o

475 Allendale Road 8

King of Prussia, PA 19406 co NRC Resident Inspector y](

Oyster Creek Nuclear Generating Station Forked River, NJ 08731

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!!r. Alex Dronerick

$fe U.S. fluclear Regulatory Commission

!! ail Station PI-137 14ashington, DC 20555 pbl 7398f GPU NX' ear Corwat on <s a sutu ry d Geva! Putic Ut:t es Cc<wat en g

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e Attachment Violation 10 CFR 50.59 requires that licensees obtain Commission approvai for facility changes that involve an unreviewed safety question. An unreviewed safety question, as defined in 10 CFR 50.59, it an increase in the probability of occurrence of an accident or malfunction of equipment important to safety previously evaluated in a safety analysis report.

Contrary to the above, the licensee performed an evaluation per 10 CFR 50.59 that accepted a calculated redJCtion in stress margins, below levels previously established by the NRC, which represented an increase in f ailure probability for two piping systems attached to the containment suppression pool. Although more sophisticated calculations performed subsequent to the NRC inspection demonstrated that the piping stresses are below established allowable values, acceptance of the original stress calculations without NRC approval was not in accordance with the provision of 10 CFR 50.59 as stated above.

Response

GPU Nuclear does not concur with the violation stated above.

The applicable safety analysis report is the NRC staff Safety Evaluation (SE) dated January 13, 1984, which included Franklin Research Center Technical Evaluation Report (TER) C5506-319 dated August 30, 1983.

The TER documented the acceptability of calculated overstress at certain torus-attached-piping locations documented in the original p! ant unique analysis report (HPR-734) dated August 1982.

The acceptable basis considered the following conservatisms:

1) Modal responses were combined by absolute summation.

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2) Response spectrum dynamic loads were peak-broadened + 10%.

3) Tne response spectrum method used provides up to 30% higher strest than time-history analysis.

When intended modification plans to torus-attached-piping were changed subsequent to the issuance of the NRC staff's SE, reanalyses of some torus-attached-piping systems were necessary as the analysis results in HPR-734 assumed those modifications would be implemented.

The results of the reanalyses were then documented in a followup report (MPR-999).

At two locations, calculated stresses slightly exceeded Code allowables at a similae magnitude as those documented in MPR-734.

Since nodal responses were combined using square-root-of-the-sum-of-the-squares versus absolute summation during the reanalysis, one element of conservatism was removed.

However, the remaining elements of known conservatism were judged to be sufficient to conclude that no actual overstress condition would exist for the applicable loading combinations. With this understanding, the question "Is there an increase in the probability of a malfunction of equipment important to safety previously evaluated in a safety analysis report increased" can be answered no.

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p GPUN acknowledges that engineering judgement was used in the 10 CFR 50.59 determination versus reliance on explicit Code-conforming design values.

However, we believe that supportable engineering judgement which is adequately documented and prudently applied with appropriate conservatism is acceptable for 10 CFR 50.59 reviews.

In response to questions raised during the inspection, GPUN submitted a letter dated June 1,1988 which provided the detailed discussion of the conservatisms inherent in the analysis methodology.

Because NRC questioned the conclusion of our engineering judgement, GPUN also directed its consultant to reanalyze the two piping systems where the calculated overstress conditions were located. For the 6 inch south containment spray test return branch connection, piping system flexibility was more realistically modeled and the i

stresses calculated were less than the allowables.

A time-history analysis of loadings to the 6 inch nitrogen purge branch connection was performed with results indicating about a 50% stress reduction from the results documented in

!1PR-999, Revision 1.

The time-history analysis confirms GPUN's judgement regarding the calculated overstresses.

As identified at our July 26, 1988 meeting at Region I offices. GPUN, in retrospect, should have formally submitted itPR-999. Revision I to fully inform NRC of all analyses and modifications performed as a result of the liark I Containment Long-Term Program.

A review of flark I Containment Long-Term i

Program analyses indicated no other cases of calculated overstress conditions which are unapproved by the NRC. itPR-999, Revision 1 will be submitted shortly under separate cover. Revision 2 to tiPR-999 will be submitted, when availaole, to document the analyses performed as a result of the questions raised by the NRC during inspection 88-15.

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