ML20090D313
| ML20090D313 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 11/01/1977 |
| From: | Dise D NIAGARA MOHAWK POWER CORP. |
| To: | Lear R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19289B256 | List: |
| References | |
| NUDOCS 8302280009 | |
| Download: ML20090D313 (2) | |
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O IE PTLE COPY NIAGARA MOHAWK POWER CORPORATION NI AGAR A MOHAWK 300 ERIE SOULEV ARD. WEST
$YR ACU SE. N. Y.13 202 November 1, 1977 4
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$ ul*% wy 2 Director, Nuclear Reactor Regulation Attn:
Mr. George Lear, Chief Operating Reactors p
Branch #3 4
0 U. S. Nuclear Regulatory Commission
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Washington, D. C.
20555 Re:
Nine Mile Point Unit 1 Docket No. 50-220 DPR-63 Gentlemen:
On October 18, 1977 Niagara Mohawk notified the Office of Inspection and Enforcement, Region I, of a potentially reportable condition relating to relief valve actuation for Nine Mile Point Unit 1.
Since then a meeting was held on October 27, 1977 with members of the Nuclear Regulatory Commission and the Mark I Owners Group in Bethesda, Maryland.
The purpose of that meeting was to discuss the effects on the Mark I containment.
General Electric has made a survey of operating experience which indicates that many isolation events (greater than 100) have occurred both during normal operation and start up tests.
The survey showed that in only two (2) cases has greater than one (1) valve experienced 2nd actuation.
No evidence of detrimental effects on the suppression chamber have been observed.
General Electric's analysis for Nine Mile Point Unit 1 showed that there is no safety concern even if three (3) valves experience a second actuation.
The Mark I Containment Short Term Program acceptance criteria strength ratio of 0.5 was used as a guideline.
The strength ratio for the highest stressed portion of the sup-pression chamber support structure (inner column) was 0.2.
In addition, the shell stress was only 3.73 ksi.
773110107 8302280009 771101 PDR ADOCK 05000
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'Mr. Georg*e Lear Page Two U. S. Nuclear Regulatory Commission November 1, 1977 Continued operation of Nine Mile Point Unit 1 is justified throughout the duration of the Long Term Program.
Such operation will not result in undue risk to the health and safety of the public.
Very truly yours, NIAGARA MOHAWK POWER CORPORATION l
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,Om,,.;;A_c Lee w Donald P. Dise Vice President-Engineering 4
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