ML20236D548

Safety Evaluation Accepting Util Response to Generic Ltr 83-28,Item 4.5.2 Re Reactor Trip Sys Reliability

ML20236D548
Person / Time
Site:	Brunswick
Issue date:	03/17/1989
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20236D536	List: ML20236D533 ML20236D538 ML20236D548
References
GL-83-28, NUDOCS 8903230153
Download: ML20236D548 (2)

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1. 'o UNIT ED STATES 8" ~k NUCLEAR REGULATORY COMMISSION g3 E WASHINGTON, D. C. 20655

,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 & 2 DOCKET NOS. 50-324/325 REGARDING GENERIC LETTER 83-28, ITEM 4.5.2 REACTOR TRIP SYSTEM RELIABILITY

1.0 INTRODUCTION

On February 25, 1983, both of the scram circuit breakers at Unit 1 of the Salem Nuclear Power Plant failed to open an automatic reactor trip signal from the reactor protection system. This incident was terminated manually by the operator about 30 seconds after the initiation of the automatic trip signal. The failure of the circuit breakers was determined to be related to the sticking of the undervoltage trip coil.

Prior to this incident, on February 22, 1983, at Unit 1 of the Salem Nuclear Power Plant, an automatic trip signal was generated based on steam generator low-low level during plant start-up. In this case, the reactor was tripped manually by the operator.

Following these incidents, on February 28, 1983, the NRC Executive Director for Operations directed the staff to investigate and report on the generic implications of these occurrences at Unit 1 of the Salem l Nuclear Power Plant. The results fo the staff's inquiry into the generic l implications of the Salem unit incidents are reported in NUREG-1000, l

" Generic Implications of the ATWS Events at the Salem Nuclear Power Plant." As a result of this investigation, the commission (NRC) requested (by Generic Letter 83-28 dated July 8,1983) all licensees of operating reactors, applicants for an operating license, and holders of construction permits to respond to generic issues raised by the analyses of these two ATWS events.

l This is an evaluation of the response submitted by Carolina Power & Light Company, the licensee for Brunswick Steam Electric Plant Units 1 and 2, (Brunswick) for Item 4.5.2 of Generic Letter 83-28.

Item 4.5.2 requires licensees with plants not currently designed to permit on-line testing to justify not making provisions for such testing.

Alternatives to on-line testing proposed by the licensees will be considered if the objectives of high reliability can be met in another way. This review will:

1. Confirm that the licensee has identified those portions of the Reactor Trip System (RTS) that are not on-line testable. If the entire RTS is verified to be on-line testable, with those exceptions addressed above, no further review is required.

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2. Evaluate modifications proposed by the licensee to permit on-line-testing against the existing criteria for the design of the protection systems for the plant being modified.

3. Evaluate proposed alternatives-to on-line testing of the RTS where the impracticality of the-modifications necessary to permit on-line testing exists.

2.0 EVALUATION-The. licensee for Brunswick responded'to the requirements of GL 83-28, j- Item 4.5.2, with a submittal dated November 7, 1983. In that response, the licensee stated that the. Brunswick RTS, with the exception of the backup scram valves, is designed to allow on-line testing and that such '

tests are performed at the frequencies defined in the Technical  !

Specifications. On-line testing of the backup scram valves will not be performed during plant operation because there is only one pair of backup scram solenoid valves. The logic for this pair of valves is arranged so the repositioning (energizing) of either backup scram solenoid will cause a plant scram. However, the valves will be independently tested during each refueling outage.

3.0 CONCLUSION

Based on our review of the licensees response, we find that the Brunswick RTSjas designed with the exception of backup scram valves, permits on-line testing. In addition, the licensee has justified not performing on-line testing of the backup scram valves. Therefore, this licensee response meets the requirements of Item 4.5.2'of the GL 83-28 and is  ;

acceptable. j Principal Contributor: D. Lasher Dated:

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