ML19317G079
| ML19317G079 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 08/15/1978 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML19317G080 | List: |
| References | |
| NUDOCS 8002210772 | |
| Download: ML19317G079 (2) | |
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SACRAMENTO MUNICIPAL UTILITY OtSTRICT Q 6201 S Street. Box 15830, Sacramento, Califomia t
i 95813; (916) 452-3211
\\j Aught 15,1978 Director of Regulatory Oper.stions ATIN:
Mr. R. H. Engelken NRC Operations Office Region V 1990 North. California Boulevard
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Walnut Creek Plaza, Suite 202 Walnut Creak, California 94596 Re: Operating License DPR-54 Docket No. 50-312 Reportable Occurrence 78-8
Dear Mr. Engelken:
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In accordance with Technical Specifications for Ri$1cho Seco Nuclear Generating Station Section 6.9.4.l(h), and Regulatory Guide 1.16, Revision 4, Section C.2.a(8), the Sacramento Municipal Utility District is hereby sub-
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mitting a fourteen day follow-up report to Reportable Occurrence 78-8, which was ini+"~ reported to your office August 4,1978, via a telephone j
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call and a e mon letter on August 7,1978.
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On August 4.,1978, B&W, 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,'
d conjunction with the B&W owner's group program for evaluation of reactor vessel material properties, they discovered that weld filler wire atypical,
of the subnerged are veld filler wire used by B&W in the construction of nuclear pressure vessels was unknowingly mixed by the supplier with a shipment of Ma-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 B&W. This vire sixture (Mn-Mo-Ni filler wire plus the atypical filler wire) may have been used in the construction of seven B&W reactor vessels.
The veld locations of interest in the B&W vessels where the wire nrixture may have been used are in the follewing areas:
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'.1 a)
Closure head-to-flange b)
Outlet nozzle-to-nozzle belt c)
Beltline belt 2.
-1 A technical evaluation has been perfor=ed on B57 reactor vessels assuming the atypical =aterial is in each of these three reactor vessel p
T locations.
The results of these evaluations demenstrated that the structural g o o2 210 772 f
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Director of Regulatory Operations. Augus t 15,1978 integrity of the reactor vessels has not been cocpromised by the possible presence of the atypical material. However, for those reactor vessels with the atypical wald material assumed to be present, future operation may be governed by more restrictive pressure temperature operating limits.
3 B&W has supplied the District with drafts of required Technical Speci-fication changes for Rancho Seco Unit 1 assuming the atypical weld material j
is present. The analytical procedures of BAW-100046A Revision 1 have been
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employed in the formulation of these changes with the exception of circum-ferential velds in the beltline region.
For these welds, the postulated
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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 longitudfcal stress. The hoop stress component is used g
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
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Mr. Reid on August 11, 1978.
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Respectfully, 14.
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J. Mattimoe Assistant General Mant.ger atf Chief Engineer JJM:EH:sc Enclosure es: Director, MIPC (3)
Director, IE (30)
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