ML19317F882
| ML19317F882 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/10/1977 |
| From: | Mattimore J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19317F875 | List: |
| References | |
| NUDOCS 8002210612 | |
| Download: ML19317F882 (3) | |
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SACRAMENTO MUNICIPAt. UTILITY elSTRICT U 6201 S Street. Scx 15830. Sacramento. California 95813: (916) 452 3211 O
January 10, 1977 Mr..R. H. Engelken Docket No. 50-312 Directorate of P.egulatory Operations Recian V U.'S. Nuclear Regulatory Commission 1990 North California Boulevard
- alnut Creek, California 94596 Rancho Seco Nuclear Generating Station No.1 IE Investigation Report No. 76-01
Dear Mr. Engelken:
In accordance with your request covering the investigation of the Rancho Seco replacement fuel storage racks, we are taking the follow-ing action to correct the nonconformance listed as Appendix A:
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Accendix A v
Based on the results of the NRC investigation conducted dur-ing the period October 21, 1976 to November 11,1976, it appears that certain of your activities were not conducted in confomance to your commitments to the Commission as indicated below:
1.
Contrary to the December 19, 1975 request for a license amend-ment which described the design of the replacement fuel storage racks and the design specification and drawings which set forth the acceptance standard for the construction of the storage racks :
a.
Seventeen of eighteen fuel guide to structural clip welds in fuel rack 0 were found unacceptable when they were liquid penetrant tested by our inspectors. The inspectors used test methods and acceptance standards described in the design specification.
b.
The spot welds that were used to form the fuel guide tubes were not tested as described in the design specification.
A description of the action initiated by the District is-out-lined to ensure conformance to our December 19, 1975 recuest for a license amendment.
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R. H. Engelken January 10, 1977 Item a. - All of the replacement fuel storage racks have 3
either been returned to the fabricator (Precision Metal Fabricators, Sherwood, Oregon) or will be in the near future. The A/E (Exxon Nuclear Company, Richland, Washington) has prepared a Technical Specification, XN-NS-5-006, Specification for Reexamination of Spent Fuel Storage Racks for Rancho Seco Unit #1, which has been reviewed and approved by the Sacramento Municipal Utility District (SMUD). A repair program consistent with this specification has been initiated. As an added precaution, the a
SMUD metallurgical / welding engineer will be-in attendance for welder and welding procedure qualification. An increased level of surveillance during repair of the racks will be maintained by SMUD and Exxon quality assurance personnel.
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.The approved Technical Specification also outlines the increased level of visual and liquid penetrant inspection to ensure proper repairs have been made. This specification, XN-MS-S-006._ Specification for Reexamination of Spent Fuel Storage Racks for Rancho Seco Unit #1, is available for your review.
Item b. questioned the acceptability.of the spot welds used to fom the fuel guide tubes.
Each spot weld on the reverse side from the i
spot weld exhibits a heat trace mark of variant size. A correlation will be made between the heat trace mark size and spot welding macnining amper-age current on a limited number of samples.
The sample welds will be sectioned, etched and inspected for weld soundness. The resultant corre-lation studies will be used to evaluate weld soundness.
It is not anti-cipated that the allegation of poor spot welding will be substantiated.
You also expressed concern about the implementation of our quality assurance program that pemitted these deficiencies to occur.
We have reviewed the philosophy that pemits acceptance of parts and com-ponents based on review of certifications, inspection reports and aon-destructive examination results and have arrived at the conclusion our quality assurance program must extend its receiving inspection to include a limited surveillance sampling of nondestructive examinations. We will 4
provide this additional inspection to establish a confidance level that i
i the original examinations were properly conducted and the test results
- l were not falsified before acceptance of parts and components for use at Rancho
- Seco.
l We will increase our level of source inspection into the arev of witnessing-a. higher number of examinations where acceptance criter ia is difficult to judge after parts and components are delivered to r.4ncho Seco.
Consistent with the above stated philosophy, the Exxon Nuclear Company has modified its Quality Assurance Program with respect to fabri-cation service vendors in the following respects:
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O R. H. Engelken' January -10,1977 1.- Quality control overcheck, features will be introduced, such that a sample of the key quality control steps will be duplf-cated independently by Exxon Nuclear Company personnel.
2.
The Exxon Nuclear Company quality assurance audit program of fabricators will include a mixture of announced and unannounced audits.
3.
With respect to the existing rack fabrication vendor and vendors with similar nuclea'r fabrication experience and qualifications, Exxon Nuclear Company Quality Control personnel will be present at the fabricators shop on a nearly full-time basis when weld-ing and other initial fabrication processes are underway.
If there are any further questions regarding the actions taken,
, please contact the District.
Sincerely yours, W
A.
O J. J. Mattimoe Assistant General Manager and Chief Engineer i
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