ML19318B689
| ML19318B689 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 06/13/1980 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8006270307 | |
| Download: ML19318B689 (2) | |
Text
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(.eneral Orfaces: 212 West Michigan Avenue, Jackson, Micnagan 49201
- Area Code 517788 0550 V
June 13, 1980 Director, Nuclear Reactor Regulation Att Mr Dennis M Crutchfield, Chief Cperating Reactors Branch No 5 U S Nuclear Regulatory Cc==ission
'4ashington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - CONTAINME7T ISCLATION VAIVES - MODIFICATION TO ASSURE OPERABILITY Licensee Event Reports (LERs) 79-28 and 80-13, sub itted December 26, 1979, and May 23, 1980, respectively, reported design deficiencies involving Big Rock Point containment ventilation isolation valves.
In each case, corree-tive action involved placing the valves in a partially-closed condition to assure they could adequately perform their functions under design basis accident conditions. These acticas have resulted in a significant reduc-tien in containment vnetilation air flow rates with attendant concerns about the ability to control the temperature of critical ec=penents in het weather.
These concerns vill be alleviated by a modification to the operators of the sving check valves (C7 h09h and CV h096).
As reported in LIR 80-13, the design deficiency involving the check valves is a potential for overpressurization of the air cylinders of the valve operaters. These cylinders vill be enlarged to prevent this overpressuriza-tien. This modification vill enable the valves to be returned to their full-open position (h5 seat-to-disc are) while assuring that the valves and oper-0 ators vill not be damaged during closure under the transient conditions assoc-iated with a design basis accident.
All contain=ent ventilation valves vill be closed during modification verk, thereby assuring containment integrity. Since the air supply to the valve operators =ust be interrupted to perform the modification, the valves will be incapable of opening to accceplish their function of vacuum relief while verk is in progress. One isolatien valve vill be installed in each air supply line for each set of valves (butterfly and check) to permit the associated valve train to be individually isolated for =cdification work; this will limit to four hours (the ti=e necessary to install the isolation valves) the period during which all automatic vacuum relief vill be incapacitated. The entire
=odification package is expected to take less than ene week to i=plement.
g 8006270307
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Director, :iuclear Reacter Regulatien 2-Big Rock Point Plant June 13, 1980 s
4' Appropriate precautions and procedures will be imple=ented to reduce the pcssi-bility of a vacuu: being created within containment during this period.
These =cdifications and the procedures to implement the= have been reviewed in accordance with 10 CFR 50 59 Review of this change has deter =ined that the increased risk to the health and safety of the public is insignificant and the
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Plant Review Cc==ittee has ccncluded that this verk involves no unreviewed d
safety question. This letter is intended to infor ycu of current plans which differ frc= the information previously submitted regarding partial closure of the ventilation isolatica valves.
David P Hofftan (Signed)
I David P Hoffban 4.
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- iuclear Licensing Administrator i
C0 JGKeppler, USiRC
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!RC Resident Inspector - Big Rock Point
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