ML17199G023
| ML17199G023 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 03/09/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17199G021 | List: |
| References | |
| GL-83-28, NUDOCS 8703120267 | |
| Download: ML17199G023 (2) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SJ!.FETY EVALUATION BY THE OFFICE OF NUCLEAR RE.l\\CTCR REGULATION SUPPORTING GENERIC LETTER 83-28, ITEM 4.5.2 REACTOR TRIP SYSTEM RELIABILITY COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION UNIT NOS. 2 AND 3.
DOCKET NOSr 50-237, 249
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 upon an automatic reactor trip signal from the reactor pro'tection system. This incident was tenninated manually by the operator about*30 seconds after the initiation of the automatic trip sional. The failure of the circuit breakers was determined to be related to th~ sticking of the undervoltage trip coil. Prior to.this incident, on February 22, 1983, at Unit 1 of the Salem 'Nuclear Pow~r Plant, ~n automatic.
trip signal was generated based on steam generator low-low level during ~lant start-up.
In this case, the reactor was tripped ~anually by the operator...
- Following these incidents, on February 28, 1983, the NRC Exec~tive Director.
for Oper~tions (EDD),. directed the staff tb investigate and report on the*'
generic implications of these occurrences at Unit 1 of the Salem Nuclear Power Plant.
The results of the staff's inquiry into the generic implications of the Salem unit incidents are reported in NUREG-1000, "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 pennits.to respond to generic is~ues raised b~.the analyses of these two ATWS events. This report is an evaluation of the response submitted by Col11llonwealth Edison, the licensee for Dresden 2 & 3, for.Item 4.s~2*of Generic Letter 83-28.
The act~al documents reviewed as part of this evaluation are listed in the references at the end of this report.
2.0 REVIEW CRITERIA Item 4.5.2 requires licensees with plants not currently designed to permit on-line testing to justify not making provisions for such testing. Alter-natives 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
- 1.
{.. Confirm that th:
~ i censee has i den ti fi ed those portions of the Reactor Trip System that are not on-line te£teble.
Jf the entire Reactor Trip System is verified to be on-lirr testable, with those exreptions arldressPd
~bove, no further review is required.
Evaluate modification~ proposed by the license'? to permit on-line testir.g against the existing criteria for the design of the protection systems for the plant being modifierl.
Evaluate proposed alterretives tc on-line testing of the Reactor Trip System where the impracticality of the modifications necessary tn permit on-line testing exists.
- 3. 0 EVALUATION The licensee for Dresder ? & 3 responded to the requirements of 4.5.2 with submittals dated November 5, 1983 and June l, 1984.
!n the responses, the licensee stated that the Dresden reactor trip system, with the exception o' the backup scram valves, is designed to allow on-line testing and that such tes~s are performed at t~e frequencies defined in the Technical Specifications.
Except for the backup scram valves, this meets the requirements of Item 4.5.2.
On-line testing of the backup scram valves will not be performed curing plant operation because there is only one pair of backup scram solenoid valves and the logic arranged is such that the repositioning (energizing) of either backup scram solenoid will cause a plant scram.
However, the valves will be indepen-dertly tested during each refueling outage.
We conclude that this is acceptable.
4.0 CONCLUSION
~ased on our review of the licensee's responses, Wf find that the Dresden reactor trip system with the exception of backup scra.m valves pennits on-lir~
testing. The licensee has justified not perfonning on-line testing of the backup scram valves.
Thi$ meets the requirements of Item 4.5.2 of the GL 83-28 ard is, therefore, acceptable.
5.0 REFERENCES
- 1.
NRC Letter, n. G. Eisenhut to all Licensees of Operatin~ Peactors, ftpplicants for Operatin9 License, anc µolcers of Construction Permits, "Required A.ctions Basf'c! on Generic Implication~ of Salem A.Tli.'S Events (Generic Letter 83-28),",1lJ1y 8, 198~.
- 2.
Letter, P. L. Rarnes, Commonwealth Edison to ~arold R. Denton, l'JRC, November 5, 1983.
- 3.
l.P.t:ter, P. L. Barnes, Commonwealth Edison to Har01d R. Denton, NRC, June 1, 1984.
Contributnr~: N. Trehan, H. Garg, R. Marcus Dated: March 9, 1987