ML20213G721
| ML20213G721 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 05/12/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20213G708 | List: |
| References | |
| NUDOCS 8705180418 | |
| Download: ML20213G721 (3) | |
Text
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NUCLEAR REGULATORY COMMISSION 5
l W ASHINGTON, D. C. 20$55
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0. 8 TO FACILITY OPERATING LICENSE NO. NPF-37 AND AMENDMENT NO. 8 TO FACILITY OPERATING LICENSE NO. NPF-66 COMMONWEALTH EDISON COMPANY BYRON STATION, UNITS 1 AND 2 DOCKET NOS. STN 50-454 AND STN-50-455 1.
INTRODUCTION For the purpose of performance testing the Byron Essential Service Water (ESW) Cooling Towers, the licensee hcs proposed a change to Technical Specification 3/4.7.5d which requires four cooling tower fans to be running in high speed when the ESW pump discharge temperature is greater than 80*F.
During additional performance testing of the ESW cooling towers, this proposed amendment would allow plant operation with the ESW pump discharge temperature greater than 80*F, but less than 98'F, with no cooling tower fans running. Operation in this condition is necessary to obtain data points near expected extreme accident and atmospheric conditions.
During a recent (4/28/87) telephone conversation with the licensee, we learned that the cooling tower performance tests will only attain about 10 to 15% of the design heat load (about 40,000,000 btu /hr vs about 540,000,000 Btu /hr) and this will only be an instantaneous peak load.
The data obtained at this lower heat load during the performance tests will be used to extrapolate cooling tower performance at the higher heat loads.
Since the perfomance testing and tower validation methodology have not been made available to the staff, we have some reservations regarding this method of trying to validate cooling tower performance. This safety evaluation does not reflect NRC acceptance of the testing methodology at this time.
The cooling tower test program is scheduled to continue through the sumer 1987 to validate and refine the tower performance estimates.
Upon completion of the test program we will review the report containing the test results in order to be assured that the cooling towers will perform as predicted under extreme accident and atmospheric conditions. Upon satisfactory acceptance of tower performance, the relief from the 80*F ESW pump discharge limit with no fans running will no longer be applicable.
2.
EVALUATION The proposed amendments involve temporary operation of the ESW system with the ESW pump discharge temperature greater than 80 F and no cooling tower fans running. The limiting previously evaluated accident 8705180418 870512 PDR ADOCK 05000454 p
t 4 which is dependent upon ultimate heat sink cooling is a large break LOCA with loss of offsite power. The probability of occurrence of this accident is not affected by operation of ESW cooling tower fans.
The consequences of a large break LOCA with loss of offsite power will not be significantly increased by operating the ESW system with ESW pump discharge temperature greater than 80 F and no cooling tower fans running. This is because the cooling tower fans are manually operated and a 20-30 minute time period is conservatively required for operator action. The 80*F alann allows 20-30 minutes for operator action before the temperature will reach 98*F.
Since the plant operators will be closely monitoring ESW pump discharge temperature during the Cooling Tower tests, the operator reaction time would be less than a minute and thus the 80*F Technical Specification limit is unnecessary. With all four cooling tower fans running there should be more than 100% capacity to handle the most severe heat load under worst case meteorological conditions. As a further precaution, the test operating procedures will b
instruct the plant operator to start the fans on a safety injection signal dt. ring the test.
Operation of the plant in accordance with the proposed amendment will 4
not change the design of the ESW system. Other systems that are J
dependent on ESW cooling will not be affected. Consequently, performance of the cooling tower testing with an ESW pump discharge temperature greater than 80*F and no fans running will not create the possibility of a new or different kind of accident.
The capability of the ESW system to remove heat will not be affected by operation of the system in accordance with the proposed amendment. As long as the cooling tower fans are started prior to reaching 98*F, the temperature limit of 98'F will not be exceeded. Therefore, the margin of safety has not been significantly reduced.
3.
ENVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of the facilities components located within the restricted areas as defined in 10 CFR 20. The staff has detennined that these amendments involve no significant increase in the amounts, and no significant change in the 4
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 these amendments involve no significant hazards consideration and there has been no public comment on such finding.
2 Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR Sec 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 these amendments.
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CONCLL'SION We have 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, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: May 12, 1987 PRINCIPAL CONTRIBUTORS:
L. Olshan and G. Staley
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