ML20207F824
| ML20207F824 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/04/1988 |
| From: | Knighton G Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20207F807 | List: |
| References | |
| TAC-68425, TAC-68426, NUDOCS 8808230232 | |
| Download: ML20207F824 (4) | |
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0 7590-01 U.S. NUCLEAR REGULATORY COMMISSION SOUTHERN CALIFORNIA EDISON COMPANY DOCKET NOS. 50-362 AND 50-362 ENVIRONMENTAL ASSESSMENT AND FINDING OF NO SIGNIFICANT IMPACT The U.S. Nuclear Regulatory Comission (the Comission) is considering the issuance of amendments to Facility Operating License Nos. NPF-10 and NPF-15 issued to Southern Californik Edison Company, et al. (the licensee), for operation of the San Onofre Nuclear Generating Station, Units 2 and 3, located in San Diego County, California.
ENVIRONMENTAL ASSESSMENT Identification of the Proposed Action Section 3/4.1.3.4 of the Technical Specifications currently requires the Control Element Assembly (CEA) drop time, from a withdrawn position greater than or equal to 145 inches, to be less than or equal to 3.0 seconds from when electrical power is interrupted to the CEA drive mechanism until the CEA reaches its 90 percent inserted position. This drop time is required to be demonstrated through measurement prior to criticality whenever the reactor vessel head has been removed, following maintenance on the CEA drive mechanisms which could affect drop time, and every 18 sienths. The proposed change would increase the maximum allowable drop time from 3.0 secondt, to 3.2 seconds.
Need for the Proposed Action Previously each CEA was withdrawn from the cure to its full out position and dropped by opening its individual circuit breaker. Beginning with Unit 2
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Cycle 4 startup, a new method of measuring CEA drop times was used in which the reactor trip breakers are the point at which power is interrupted to the CEA gripper coils rather than the individual breakers. This new method uses the reactor trip breakers and, therefore, more accurately reflects the operation of the reactor protection system during a scram. During the Unit 2 startup tests, the CEA drop times obtained using the new method were longer than those obtained using the previous method. This has been found to be due to the fact that the ri.'uit dissipating gripper coil stored energy has a longer time constant when tripped by the reactor trip breakers than when tripped by the
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individual circuit beakers. Unit 3 is currently in a refueling outage and will hsJ the new test method during Cycle 4 startup. Since a review of previous Unit 3 CEA drop time measurements indicated that there is a potential for at least one CEA to fail to meet the 3.0 seconds requirement, the proposed change would increase the specified drop time to 3.2 seconds in order to avoid possible delay of Unit 3 restart.
Environmental Impacts of the Proposed Action The Comission has completed its evaluation of the proposed revision to the Technical Specifications and has concluded that the proposed change provides reasonable assurance that the facility can be operated safely. This change will not alter the impacts of normal operation. The proposed change does not increase the probability or consequenccs of accidents. There will be no increase in the probability of any accident because the CEA drive mechanisms have not been changed. With respect to the consequences of accidents, the increased drop time is either bounded by previous analyses or is compensated for by penalty factors or design conservatisms. Therefore, the consequences of
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previously analyzed accidents will not be increased.
No changes are being made in the types of any effluents that may be released offsite and there is no significant increase in the allowable individual or cumulative occupational radiation exposure. Accordingly, the Cosmission concludes that this proposed action would result in no significant adverse radiological environmental impact.
With regard to potential nooradiological impacts, the proposed change to the Technical Specifications involves systems located within the restricted areas as defined in 10 CFR Part 20.
It does not affect nonradiological plant effluents and has no other environmental impact. Therefore, the Connission concludes that there are no significant nonradiological environmental impacts associated with the proposed amendarents.
The Notice of Consideration of Issuance of Amer.dments and Opportunity for Hearing in connection with this action was published in the FEDERAL REGISTER on July 8,1988(53FR25711). No request for hearing or petition for leave to intervene was filed following these notices.
l Alternative to the Proposed Action l
Since the s'.ommis: ion concluded that there is no significant adverse environmental effect that would result from the proposed action, alternatives y
with equal or greater environmental impacts need not be evaluated.
The principal alternative would be to deny the requested amendments.
l' Denial of the request would not reduce environmental impacts of plant operation.
Alternative Use of Resources This action does not involve the use of resources not previously considered in the Final Environmental Statement Related to the Operation of the San Onofre Nuclear Generating Station, Units 2 and 3, dated April 1981.
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Agencies and Persons Consulted The NRC staff has reviewed the licensee's request and did not consult other agencies or persons.
FINDING OF NO SIGNIFICANT IMPACT The Coraission has determined not to prepare an environmental impact statement for the proposed license amendment.
Based upon this environmental assessment, we conclude that the proposed action will not have a significant adverse effect on the quality of the human environment.
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l For further details with respect to this action, see the application for l
amendments dated June 14, 1988 and the supplementary information provided by i
letters dated July 13 and July 25, 1988, which are available for public inspection at the Cornission's Public Docurent Room,1717 H Street, N.W.,
Washington, D.C., and at the General Library, University of California at Irvine, Irvine, California 92713.
Dated at Rockville, Maryland, this 4th day of August 1988.
FOR THE NUCLEAR REGULATORY COMMISSION 9
L 6eorge. Knighto irector Project Directorate V Division of Reactor Projects - III, IV, Y and Special Projects Office of Nuclear Reactor Regulation i