ML20210U478

Safety Evaluation Supporting Util Responses to Generic Ltr 83-28,Items 3.1.1,3.1.2,3.2.1,4.1 & 4.5.1 Re post-maint Testing & Reactor Trip Sys Reliability.Item 3.2.2 Will Be Reevaluated After Nutac Resolution

ML20210U478
Person / Time
Site:	Maine Yankee
Issue date:	05/27/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20210U019	List: ML20210U013 ML20210U478
References
GL-83-28, NUDOCS 8606020371
Download: ML20210U478 (5)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION MAINE YANKEE ATOMIC POWER COMPANY MAINE YANKEE ATOMIC POWER STATION DOCKET NO. 50-309 GENERIC LETTER 83-28, ITEMS 3.1.1, 3.1.2, 3.2.1, 3.2.2, 4.1 AND 4.5.1

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 protection system. This incident occurred during '

the plant startup, and the reactor was tripped manually by the operator about 30 seconds after the initiation of the automatic trip signal. The failure of the circuit breakers has been determined to be related to the sticking of the undervoltage trip attachment. Prior to this incident, on ,

February 22, 1983, at Unit 1 of the Salem Nuclear Power Plant, an auto-matic trip signal was generated based on steam generator low-low level during plant startup. In this case the reactor was tripped manually by the operator almost coincidentally with the automatic trip.

Following these ' incidents,'on February 28, 1983, the NRC Executive '

Director for Operations (EDO), directed the staff to investigate and report on the generic implications of these occurrences at l' nit 1 of the Salem Nuclear 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 ATWS Events at the Salem Nuclear Power Plant."

As a result of this investigation, the Director, Division of Licensing, Office of Nuclear Reactor Regulation 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 cer-tain generic concerns. These are categorized into four areas; (1) Post-Trip Review, (2) Equipment Classification and Vendor Interface, (3) Post-Maintenance Testing, and (4) Reactor Trip System (RTS) Reliability Improvements. Within each of these areas various specific actions were delineated.

This safety evaluation (SE) addressed the following actions of Generic Letter 83-28:

3.1.1 and 3.1.2, Post-Maintenance Testing (Reactor Trip System Components) 3.2.1 and 3.2.2, Post-Maintenance Testing ( All Other Safety-Related Components) 4.1, Reactor Trip System Reliability (Vendor-Related Modifications) 4.5.1, Reactor Trip System Reliability (System Functional Testing) pg86$88uBe88@gg' P

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By letters dated November 10, 1983 and June 18 and June 25, 1985, Maine Yankee Atomic Power Company (the licensee or MYAPCo) described their plan or completed actions regarding the above items for Maine Yankee Atomic Power Station.

2.0 Evaluation 2.1 General Generic Letter 83-28 included various NRC staff positions regarding the specific actions to be taken by operating reactor licensees and operating license applicants. The Generic Letter 83-28 positions and discussions of licensee compliance recarding Actions 3.1.1, 3.1.2, 3.2.1, follow.3.2.1, 4.1 and 4.5.1 for MYAPCo are presented in the sections that 2.2 Actions 3.1.'l and 3.1.2, Post-Maintenance Testing (Reactor Trip System Components)

Position Licensees and applicants shall submit the results of their review of test and maintenance procedures and Technical Specifications to assure that post maintenance operability testing of safety-related components in the reactor trip system (RTS) is required to be con-ducted and that the testing demonstrates that the equipment is capable service. of performing its safety functions before being returned to Licensees and applicants shall submit the results of their check of

, vendor and engineering recommendations (regarding safety-related components in the RTS) to ensure that any appropriate test guidance is included in the test and maintenance procedures or the Technical Specifications, where required.

Discussion The licensee's response states that procedure revisions which specify that post maintenance operability testing of the reactor These revisions were put into s,ervice 30, 1984on Januarytrip system Additionally, the licensee's response states that a program of administrative controls to implement a vendor' interface program for reactor trip system components has been developed. This program requires annual written correspondence between the licensee and the vendor of reactor trip system components.

This review insures that vendor to date. technical information held by the licensee is complete and up June 18,1985. Details are presented in the licensee's response dated

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Based on the above, the licensee has complied with the NRC staff position for Actions 3.1.1 and 3.1.2 of Generic letter 83-28.

2.3 Actions 3.2.1 and 3.2.2, Post-Maintenance Testing (All Other Safety Related Componen.ts) ,

Position .

Licensees and applicants shall submit a report documenting the ex-tending of test and maintenance procedures and Technical Specifica-tions review to assure that post-maintenance operability testing of all safety related equipment is required to be conducted and that the ,

testing demonstrates 'that the equipment safety function before being returned to service.is capable of performing its Licensees and applicants shall submit the results of their check of vendor and engineering recommendations (regarding all other safety '

related components) to ensure that any appropriate test guidance is ,,

included in the test Specificatians, where required.and maintenance procedures or the Technical Discussinn The licensee's response dated November 10 ISS3 states that their procedures have been revised to require post maintenance testing of all safety related equipment prior to returning equipment to service.

These procedures were imolemented on June 1.1984

• Additionally, in their response dated November 10, 1983 the licensee indicated that they would develop a vendor interface program for safety related components based on the INPO Nuclear Utility Task Action Committee (NUTAC) project for safety related components. Implementation of an ,

appropriate vendor interface program by HYAPCo will be assessed after the NRC resolves the adequacy of the NUTAC effort since NYAPCo believes the NUTAC report is a sufficient and appropriate response to Action 3...2 2 Based on the above, the licensee has complied with Action 3.2.1 of Generic L:tter 83-28. I af ter NUTAC resolution. Action 3.2.2 will remain outstanding and will be -reevaluated b

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2.4 Action 4.1, Reactor Trip System Reliability (Vendor-Related Modifications)

Position All vendor recommended reactor trip breaker modifications shall be re-viewed to verify that either: (1) each modification has, in fact, been implemented; or (2) a written evaluation of the technical reasons for not implementing a modification exists.

For example, the modifications recommended by Westinghouse in NCD-Elec-18 for the 0B-50 breakers and a March 31, 1983 letter for the DS-416 breakers shall be implemented or a justification for not implementing shall be made available. Modifications not previously made shall be incorporated or a written evaluation shall be provided.

Discussion The licensee's response dated November 10, 1983 states that no modifications to Maine Yankee Subsequent Station's Reactor trip breakers are currently required.

to the November 10, 1983 submittal, some of' Maine Yankee Station's AK2-25 breakers experienced slow response times when the undervoltage trip attachments were tested independently of the shunt trip device. As a result 4

of these problems, Maine Yankee Station had breakers either refurbished, i

replaced, or upgraded with new front frame assemblies.

maintenance and surveillance frequencies were increased. Additionally, Based on the above, the licensee has complied with the NRC staff position for Action 4.1 of Generic Letter,83-28. ,

2.5 Action Testing)4.5.1. Reactor Trip System Reliability (System Functional position

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On-line functional testing of the reactor trip system, including independent testing of the diverse trip features, shall be performed.

The diverse trip features to be tested include the breaker under- ]

voltage and shunt trip features on Westinghouse, B&W, and CE plants; the circuitry used for power interruption with the silicon controlled l rectifiers on B&W plants; and the scram pilot valves and backup scram valves (including all initiating circuitry) on GE plants.

Discuss _io_n_

The licensee's response dated January 25, 1985 states that MYAPCo has installed the capability to time test breaker opening from both the (

undervoltage device and the shunt device on line. This; testing has been I performed since late 1983. l I

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Based on the above, the licensee has complied with the NRC staff positions for Action 4.5.1 of Generic Letter 83-28.

! 3.0 Conclusion Based upon the foregoing discussions, the staff concludes that the licensee is in compliance with actions 3.1.1, 3.1.2, 3.2.1, 4.1, and '

4.5.1 of Generic Letter 83-28. Action 3.2.2 will be re-evaluated at a later date.

Date: May 27, 1986 Principal Contributor: John A. Schumacher, DRP i

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