ML19259A802
| ML19259A802 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/26/1978 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| TAC-49501, NUDOCS 7901110025 | |
| Download: ML19259A802 (3) | |
Text
S UNITED STATES 3
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 3
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December 26, 1978 v
Docket No. 50-312 Mr. J. J. Mattimoe Assistant General Manager and Chief Engineer Sacramento Municipal Utility District 6201 S Street P. O. Box 15830 Sacramento, California 95813
Dear Mr. Mattimoe:
By letter of February 2,1978 we requested information regarding the possibility of the reactor cavity annulus seal plate becoming a missile as a result of a pipe break inside the reactor vessel cavity.
In your letter of March 17, 1978 responding to this inquiry, you chose to resolve this concern by comitting to store the seal plate in a position which would eliminate the possibility of it becoming a missile, following the 1978 refueling outage.
By letter dated December 14, 1978, you advised us that you had recently become aware of a design effort which you believed would provide an improved resolution of this concern. This concept would allow rigid storage of the seal plate above its present location and would obviate the need for cutting the seal plate which can cause subsequent problems in attaining a good seal. To allow evaluation of this concept prior to cutting the seal plate, you proposed to continue to store the seal plate in its present manner for one more fuel cycle.
As indicated to you on December 15, 1976 in telephone discussions between Mr. G. B. Zwetzig of our staff and your Mr. R. Dieterich, we find that there is reasonable assurance that continued operation in the manner and for the period you have proposed will not constitute an undue hazard to the health and safety of the public. Our conclusion in this regard is based on the very low likelihood of occurrence during this period of a pipe failure of the size and location that could cause the seal plate to become a damaging missile. At the same time, however, we believe this concern should be resolved at the earliest date practicable. Accordingly, it is requested that the following information be submitted within 30 days of receipt of this letter:
- 1) A description, including sketches and/or drawings, of the proposed method of storing the cavity seal ring during reactor operation.
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- 2) The design criteria for this modification.
- 3) An analysis which compares the costs of installation of the modification at the next refueling outage, and on schedules corresponding to normal and expedited procurement and design. This analysis should consider the costs of a special reactor shutdown for the modification, and for implementation of the modification during a shutdown for another purpose.
Sincerely, h jh
's_ Y, dvs Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors cc:
See next page
Sacramento Municipal Utility District cc: David S. Kaplan, Secretary and General Counsel G201 S Street Post Office Box 1583t Sacramento, Californi' 95813 Mr, Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Business and Municipal Department Sacramento City-County Library 828 I Street Sacramento, California 95814