ML20059G084
| ML20059G084 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/27/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20059G073 | List: |
| References | |
| NUDOCS 9311050282 | |
| Download: ML20059G084 (2) | |
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%...s..J SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 66 TO FACILITY OPERATING LICENSE NO. DPR-21 NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION. UNIT 1 DOCKET NO. 50-245
1.0 INTRODUCTION
By letter dated July 26, 1993, the Northeast Nuclear Energy Company (NNECO) submitted a request for changes to the Millstone Nuclear Power Station, Unit 1 Technical Specifications (TS).
The requested change would increase the maximum stroke time for reactor water cleanup (RWCU) system isolation valves CU-2, 3, 5, and 28 from 18 seconds to 20 seconds in TS Table 3.7.1.
2.0 EVALUATION In the letter dated July 26, 1993, NNECO stated that the increase in stroke time from 18 to 20 seconds for RWCU valves CU-2, 3, 5, and 28 would provide a more appropriate closure limit which would aid in trending of valve performance and correcting identified valve degradation prior to exceeding the maximum stroke time allowed by the TS.
NNECO stated that historically the valves have closed within the 18-second time period, however, the margin for meeting the 18-second closure limit has always been narrow.
Trending of stroke times for these valves from 1984 to date provides illustration that this narrow margin is not indicative of valve degradation, but rather represents a random variation in the average closure time for the valves.
There has been no significant or consistent increase in closure time for these valves except for RWCU valves CU-2 and 3.
Their actuators were replaced during the 1989 refueling outage.
Subsequently, these valves have closed in a consistent and acceptable manner, but still within a narrow margin of the 18-second stroke time limit.
In support of the stroke time change, NNECO noted that loss-of-coolant accident (LOCA) calculations assume that as long as all containment isolation valves (CIVs) close within 60 seconds, calculated release rates will not increase. All reactor building environmental profiles have been developed utilizing the 20-second maximum closure time of these CIVs.
Therefore, the environmental profiles of temperature, pressure, humidity, and radiation are unaffected by this change. The 2-second increase in CIV response time would remain conservatively within the bounds of the 60-second closure limit assumed in the calculations for radiological consequences from a LOCA, and at the 9311050282 931027 PDR ADDCK 05000245 P
. closure time assumed for the environmental and radiological consequences-for an RWCU system line break outside containment (the two accident scenarios which could be impacted by the proposed change).
This increase in allowable stroke time is intended to provide more operating margin so that valve degradation can be detected and corrected prior to exceeding TS limits.
Therefore, based on the above, the NRC staff has concluded that increasing the stroke time for RWCU valves CU-2, 3, 5, and 28 is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment. The State official.had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 46238).
Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact ' statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
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Principal Contributor:
J. Andersen Date:
October 27, 1993 4