ML19225B831
| ML19225B831 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 06/22/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19225B813 | List: |
| References | |
| SER-790622, NUDOCS 7907260094 | |
| Download: ML19225B831 (2) | |
Text
[p* *E%qh UNITED STATES
' ^g NUCLE AR REGULATORY COMMISSION y " }) <.-q W ASm NGTON, D. C. 20555 j
o
%...+ /
+
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0.41 TO FACILITY OPERATING LICENSE NO. NPF-1 PORTLAND GENERAL ELECTRIC COMPANY THE CITY OF EUGENE, OREGON PACIFIC POWER AND LIGHT COMPANY TROJAN NUCLEAR PLAfqT DOCKET NO. 50-344 I nt roduct i on As result of our ongoing review of the events associated with the fia rch 28, 1979 accident at Three Mile Island Unit 2, the NRC Office of Ins.nection and Enforcement issued a number of IE Bulletins describing actions to be taken by licensees.
IE Bulletin 79-06 (April 11, 1979) called for licensees with Westinghouse PWRs to instruct operators to manually initiate safety injection whenever pressurizer pressure indication reaches the actuation setpoint whether or not the pressurizer level indication has dropped to the actt.ation setpoint.
IE Bulletin 70-06A (April 14,1979) further Cdlled for these licensees to trip the low pressurizer level bistables such that, when the pressurizer pressure reaches the low setpoint, safety injection would be initiated regardless of the pressurizer level.
IE Bulletin 70-06A Revision 1 (April 18,1979) aodified the action called for in 79-06A by allowing pressurizer level bistables to be temporarily returned to their nomal (untri pped) operating positions during the pressurizer pressura channel functional surveillance tests so that these tests can be conducted without causing a false safety injection actuation.
Discussion and Evaluation Tripping the pressurizer low level histables, which are nomally coincident with the pressurizer low pressure bistables, has the effect of reducing this safety injection actu;cion logic to a one-out-of-th ree l ogic.
A single instrument failure of one of the three low pressure bistable channels could therefore result in an 436 3l?
790726 0 09y unwanted safety injection. To prevent this, the licensee proposed, in a June 6,1979 ietter (supplemented June 20,1979), a design modification which would align the ex' sting pressurizer low pressurc bistables in a two-out-of-three logic, and delete low pressurizer level as a safety injection actuation signal.
This change is consistent with the action called for in the Bulletin, and has been recently approved on a nucher of other Westirpouse-designed PWRs.
The proposed modification to the safety injection actuation system consists of removing the pressurizer level signal frm each of the pressurizer level / pressure channel trips and converting the system to a two-out-of-three logic based on the pressurizer low pressure trips alone. The instrumentation logic would receive pressurizer pressure signals frm three pressure transmitters and would initiate a safety injection actuation when two of the three signals reach the low pressure setpoint. This modification does not involve a change in the setpoint, or any increase in actuation time for safety injection actuation.
The modification will satisfy the requirements of IEEE 279-1971.
Basef on our review of the licensee's submittal, we conclude that he modification to the safety injection actuation system logic is acceptable and that the associated changes in the Technical Specifications are correct, and are therefore also acceptable.
Enviro mental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that, pursuant to 10 CFR 51.5(d)(4), an environmental statement, or negative-declaration and environmental impact appraisal, need not be prepa ed in connection with the issuance of this amendment.
Conclusion We have concluded, based on the ronsiderations discussed above, that:
(1) because the change does not involve a significant increase in the probability or consequences of accidents previonly considered and does not involve a significant decrease in a safety margin, the change does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in tne proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulat;ons and the issuance of this amendment will not be inimical to the common defense and security or the the health and safety of the public.
Date: June 22, 1979 436 320