ML20203C260

Final Deficiency Rept Re Defect in Overlap Modeling Techniques.Initially Reported on 840801.Rigorous Analysis Handbook Revised to Incorporate Techniques in NUREG/CR-1980. Corrective Actions Will Be Done 6 Months Before Fuel Load

ML20203C260
Person / Time
Site:	Bellefonte
Issue date:	04/08/1986
From:	Gridley R TENNESSEE VALLEY AUTHORITY
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
RTR-NUREG-CR-1980 NUDOCS 8604210072
Download: ML20203C260 (2)

Text

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• TENNECCEE VALLEY AUTHORITY '

CHATTANOOGA. TENNESSEE 37401 L

e SN 157B Lookout Place j j pqljlj 8pfp8643

'Bl.RD-50-438/84-43

-BLRD-50-439/84 U.S. Nuclear Regulatory Commission

-- Region II Attn: Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia- 30323

Dear D. Grace:

BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - DEFICIENCY IN OVERLAP MODELING TECHNIQUES -'BLRD-50-438/84-43, BLRD-50-439/84 FINAL REPORT The subject. deficiency was initially reported to NRC-0IE Inspector P. E. Fredrickson on August 1, 1984 in accordance with 10 CFR 50.55(e) as NCR BLN CEB 8412. This was followed by our interim reports dated August 28, 1984 and March 19, 1985. Enclosed is our final report.

If you have any questions, please get in touch with R. H. Shelf ct i

FTS 858-2688.

Very truly yours, TENNESSEE VALLEY AUTHORITY h

., h hW

. L. Gridley Manager of Licensing Enclosure cc: Mr. James Taylor, Director (Enclosure)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Records Center (Enclosure)

Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 8604210072 860408 '

gDR ADOCK 05000438 '

PDR ,

• l An Equal opportunity Employer

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- t ENCLOSURE ~

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BELLEFONTE NUCLEAR PLANT UNITS 1.AND 2

.OEFICIENCY IN OVERLAP MODELING TECHNIQUES

, NCR BLN CEB 8412-BLRD-50 438/84-43, BLRD-50-439/84-39 10 CFR 50.55(e)

FINAL REPORT Descrip' tion of Deficiency TVA.has identified that.the Bellefonte Nuclear Plant (BLN) MA-3 Rigorous Analysis / Handbook (RAH):was deficient in overlap modeling techniques before March:15, 1984. -(Part of Unresolved Item 390/82-27-09, Hatts Bar Nuclear Plant.) The aforementioned procedure,'section P-2, does' not meet HUREG/CR-1980 in that: seismic response spectra of two or more problems being overlapped were not required to be enveloped and support loads in t_he lap region were~envelcped but were not increased by ten percent.

A similiar condition was reported on Watts Bar Nuclear Plant as NCR HBN CEB

8221-(CDR # 390,391/83-03). Other TVA plants are not affected by this condition.

, 'The apparent cause of this deficiency stemmed from two conditions: (1) the Bellefonte MA-3 handbook.-section P-2, was written in 1978 in accordance with a previous NRC recommendation (NUREG/CR-1980 did not exist at the time) and (2) lack of underctanding by the analysis section that all deviation from the-techniques defined in the rigorous analysis handbook must be addressed and

!_ documented as acceptable.

Safety Implications The use of nonconservative analyses in the design of seismic piping supports

-could result in. inadequate support designs and installations. Therefore, if this condition had remained uncorrected, the safe operation of the' plant could have been adversely affected.

Corrective Action All. analysis problems have been reviewed and.those deficient in overlap modeling have been identified (50 problems). Approximately 50 percent of these problems will only require a documentation change, and the remainder will. require reanalysis. To date, 12 problems have been corrected. Support redesign ~and rework may be required for those problems which require reanalysis.- -

All action to correct the deficient condition for units 1 and 2 will be-

-_ complete six months before fuel loading of the respective unit.

The Rigorous Analys;s Handbook was revised to incorporate the modeling ,

technique reflected in NUREG/CR-1980. Analysts and checkers were notified of l 1 the new modeling technique and also of the requirement that any exception to l

. -the RAH. requirements must be addressed and documented as acceptable. Also, l~ with_the implementation of Office of Engineering Procedures (CEPs) in June ,1 1985, TVA employees were. trained in the requirement to document exceptions as j governed by Office of Engineering Procedure (0EP) -10, Review. Tris completes  !

the action required to prevent recurrence.

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