ML20086G573

Ninth Interim Deficiency Rept Re Inconsistencies in Pipe Break LOCA Analysis.Initially Reported on 801121.Review of B&W Alternate Approaches to Resolve Problem in Progress.Also Reported Per Part 21.Next Rept by 840630

ML20086G573
Person / Time
Site:	Bellefonte
Issue date:	01/05/1984
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-PT21-83 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8401120289
Download: ML20086G573 (2)

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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374ot 400 Chestnut Street Tower II January 5, 1984

'U.S. Nuclear Regulatory Commission Regior: II Attn:

Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - ATTACHED PIPING POTENTIAL SAFETY CONCERN - NCR BLN NEB 8008 - NINTH INTERIM REPORT On November 21, 1980, R. W. Wright, NRC-0IE Region II, was informed tc.

• the subject nonconformance was determined to be reportable in accordance with 10 CFR 50.55(e). This was followed by our interim reports dated December 19, 1980, April 2 and July 17, 1981, February 17, June 22, and October 14, 1982 and May 23 and November 17, 1983 Enclosed is our ninth interim report. We consider 10 CFR Part 21 to be applicable to this nonconformance. - We expect to submit our next report by June 30, 1984.

If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.

Very truly yours, TENNESSEE VALLEY AUTHORITY 8401120289 840105

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PDR ADOCK 05000438 L. M. Mills, nager S

PDR Nuclear Licensing Enclosure cc'(Enclosure):

Mr. Richard C. DeYoung, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.

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Babcock'& Wilcox Company 30, p

P.O. Box 1260 hp.I Lynchburg, Virginia 24505 Attention:

Mr. H. B. Barkley Records Center Institute of Nuclear Power Operations

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1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 77 1983-TVA SOrH ANNIVERSARY

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An Equal Opportunik Employer

ENCLOSURE

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BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 ATTACHED PIPING POTENTIAL SAFETY CONCERN NCR BLN NEB 8008 10 CFR 50.55(e)

NINTH INTERIM REPORT Description of Deficiency Babcock and Wilcox (B&W), Lynchburg, Virginia, has uncovered an inconsistency between the assumptions relative to pipe breaks in the loss-of-coolant accident'(LOCA) analysis and the structural analysis of certain. connecting pipes in the affected or broken loop.

The LOCA analysis does not assume a consequential failure of piping caused by a LOCA pipe break.

Certain piping and instrumentation connections to the Reactor Coolant System (RCS) may not be adequately designed to maintain function or to resist consequential failures as a result of the LOCA break in the Reactor Coolant System. Consequential failures of these piping connections could represent an inconsistency with the ECCS analysis performed for Bellefonte.

Interim Progress As indicated in previous interim reports, all piping analyses have been completed except for the incore piping. The completed analyses all show that the stress levels in the piping are acceptable.

Therefore, the piping is adequately _ designed to maintain function or resist consequential failures as a result of a LOCA break in the reactor coolant system.

The refined incore piping analysis scheduled for completion by

' November 18, 1983, in Report No. 8 was terminated before completion.

As the analysis develtped, it became apparent that the analytical refinements would not reduce the piping stresses to acceptable levels.

B&W has identified the following alternate approaches for resolving this problem:

1.

Mechanically test an incore pipe configuration to see if the pressure boundary can be maintained when the reactor vessel insulation loads are imposed on it.

2.

Consult with the insulation manufacturer (Mirror Insulation) to consider modifications to the existing insulation structure to restrict horizontal motion.

3 Further analysis involving a combined structural-stress approach using nonlinear finite element transient analysis of the insulation /incore piping.

TVA is now reviewing the above alternatives in order to inform B&W of which approach TVA prefers to pursue.