ML20147B271

Forwards LER 78-008/02T-0

ML20147B271
Person / Time
Site:	Rancho Seco
Issue date:	08/15/1978
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20147B275	List: ML20147B271
References
NUDOCS 7810100061
Download: ML20147B271 (2)

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gsuun SACRAMENTO MUNICIPAL UTILITY DISTRICT D 6201 S Street, Box 15830, Sacramento, California 95813; (916) 452-3211 August 15, 1978 Director of Regulatory Operations ATTN: Mr. R. H. Engelken G3 MRC Operations Office Ul Region V c7 1990 North California Boulevard Ed Walnut Creek Plaza, Suite 202 ,

(n Walnut Creek, California 94596 -

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Re: Operating License DPR-54  !!

j Docket No. 50-312 8 C' , 27 Reportable Occurrence 78-8 5 fo b

Dear Mr. Engelken:

In accordance with Technical Specifications for Rancho Seco Nuclear Generating Station Section 6.9.4.1(h), and Regulatory Guide 1.16, Revision 4, Section C.2.a(8), the Sacramento Municipal Utility District is hereby sub-mitting a fourteen day follow-up report to Reportable Occurrence 78-8, which was initially reported to your office August 4,1978, via a telephone call and a confirmation letter on August 7, 1978.

On August 4, 1978, B6W, the NSS supplier for Rancho Seco Unit 1, informed the District of the following potential discrepancy:

As a result of chemical analysis performed on archive weldments in conjunction with the B6W owner's group program for evaluation of reactor vessel material properties, they discovered that weld filler wire atypical of the submerged are weld filler wire used by B6W in the construction of nuclear pressure vessels was unknowingly mixed by the supplier with a shipment of Mn-Mo-Ni filler wire. The atypical weld wire has high Silicon and low Nickel contents which are outside of the typical range for the Mn-Mo-Ni filler wire specified by B6W. This wire mixture (Mn-Mo-Ni filler wire plus the atypical filler wire) may have been used in the construction of seven B6W reactor vessels.

The weld locations of interest in the B6W vessels where the wire mixture may have been used are in the following areas:

a) Closure head-to-flange b) Outlet nozzle-to-nozzle belt c) Beltline belt A technical evaluation has been performed on B6W reactor vessels assuming the atypical material is in each of these three reactor vessel locations. The resulto of these evaluations demonstrated that the structural 78 ///gh6/ M gg0ajg a nw w r v, - vn >- . n .

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Director of Regulatory Operations August 15,1978 integrity of the reactor vessels has not been compromised by the possible presence of the atypical material. However, for those reactor vessels with the atypical weld material assumed to be present, future operation may be governed by more restrictive pressure temperature operating limits.

B&W has supplied the District with draf ts of required Technical Speci-fication changes for Rancho Seco Unit 1 assuming the atypical weld material is present. The analytical procedures of BAW-100046A Revision 1 have been employed in the formulation f these changes with the exception of circum-ferential welds in the beltiine region. For these welds, the postulated flaw as specified in BAW-10046A has been orientated in the circumferential direction. The component of stress due to pressure used in the fracture analysis is then the longitudinal stress. The hoop stress component is used for postulated flaws in the longitudinal area.

The resultant Technical Specification changes were submitted as revision 1 to Technical Specification Amendment No. 59 in a letter to Mr. Reid on August 11, 1978.

Respectfully,

. Lct

( J. Yattimoe Assistant General Manager and Chief Engineer JJM:HH:sc Enclosure es: Director, MlPC (3)

Director, IE (30)