ML20248B136
| ML20248B136 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 06/01/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20248B124 | List: |
| References | |
| NUDOCS 8906080268 | |
| Download: ML20248B136 (3) | |
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NUCLEAR REGULATORY COMMISSION y
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.131 TO FACILITY OPERATING LICENSE N0. DPR-59 POWER AUTHORITY OF THE STATE OF NEW YORK l
JAMES A. FITZPATRICK NUCLEAR POWER PLANT DOCKET N0. 50-333 INTRODUCTION By letter dated August 5,1986 (JPN-86-37), the Power Authority of the State of New York (PASNY or the licensee), submitted a proposed change to the James A. FitzPatrick Nuclear Power-Plant Technical Specification (TS). The change would delete the TS requirement (Section 3.9.B.3) to disconnect an emergency bus from the normal power supply (auxiliary transformer) and connect it to the reserve power supply (offsite power) when its associated Emergency Diesel Generator is inoperable. Based on a review of this proposed change, a Request for Additional Information (RAI) was transmitted to the licensee by letter dated June 14, 1988. The PASNY letter of January 6,1989 (JPN 89-001) responded to the RAI.
DESCRIPTION AND ANALYSIS Under normal operating conditions, the normal AC service power source (the main generator via the station service transformer) supplies the inplant buses, with.the offsite reserve AC power source available to supply each of the two emergency buses if needed and also when the plant is shutdown. Under normal conditions, the transfer of power between these sources is accomplished by the operators in the main control room by paralleling across the oncoming source by closing the breaker, and then opening the offgoing source breaker. The emergency diesel generator system is available if power is lost from both of these sources.
The diesel generator system consists of two diesel generators per emergency bus, operating in parallel. The autcmatic start sequence for each pair includes closure of a tie breaker at the output of the diesel generators when their speed is approximately 25 percent of rated speed to tie the two outputs together. Upon reaching full speed, if the associated emergency bus voltage is below normal, the two diesel generator output breakers close and then the tie breaker opens.
Loads are then automatically and manually sequenced onto the bus.
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Ever since the original TS were incorporated, the requirement to transfer i
emergency bus power from the normal source to the reserve source when the i
associated diesel generator system was inoperable, has been in effect. While l
this condition does not occur frequently, the present TS amendment submittal requests that this requirement be deleted. The licensee has stated that the l
requirement is unnecessary and may result in large currents, in excess of equipment ratings, existing for several seconds when slow manual transfers i
are made between the normal and reserve power supplies when both breakers are j
closed at the same time.
These excess currents could be caused by a phase difference between the power sources which could be as large as 25 degrees at full power and 17 degrees at low power. Additional excess current would be caused by the amplitude differences between the voltages of the two power sources.
Licensee Event Report 85-019-00 dated August 16, 1985, describes a manual transfer event which resulted in a reactor scram.
It occurred while transferring power from the reserve to the normal power source and may have been caused by high circulating currents resulting from leaving the busses paralleled too long during the manual transfer.
The licensee has stated that the requirement is unnecessary since automatic transfer of the power supply is provided for all equipment required for a safeguard function and, where automatic transfer of power is provided, the l
transfer equipment is designed so that the normal source breaker or contactor i
must open before the alternate source breaker or contactor can close.
Because this occurs within a few cycles, power is not lost to the equipment. Since the paralleled condition does not occur for fast automatic bus transfers, circulating currents will not exist.
1 The proposed change to the TS would eliminate the requirement for performing
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manual bus transfers when the diesel generators are inoperable. The staff l
agrees with the licensee that this elimination is desirable because it would l
reduce the frequency of actions which have the overall affect of potentially j
destabilizing the electrical system, needlessly challenging protective functions, and damaging equipment. Therefore, in consideration of this, and the demonstrated reliability of the emergency diesel generators, the staff finds the proposed TS change acceptable.
It is also noted that the problems associated with offsite and onsite power systems, and the associated transfer of power between buses, is being addressed by an ongoing Safety System j
Functional Inspection, ENVIRONMENTAL CONSIDERATION This amendment involves a change in the installation or use of a facility I
component located within the restricted area as defined in 10 CFR Part 20.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that I
r; 3-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 this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eli for categorical exclusion set forth in 10 CFR Sec 51.22(gibility criteria 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 this amendment.
CONCLUSION 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 this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
June 1, 1989 PRINCIPAL CONTRIBUTORS:
C. Morris D. LaBarge
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