ML20140B936

Safety Evaluation Supporting Util Responses to Items 3.1.1, 3.1.2,3.2.1,3.2.2,4.1 & 4.5.1 of Generic Ltr 83-28 Re post-maint Testing & Reactor Trip Sys Reliability

ML20140B936
Person / Time
Site:	Millstone
Issue date:	03/18/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20140B925	List: ML20140B921 ML20140B936
References
GL-83-28, TAC-52936, TAC-53080, TAC-53773, TAC-54083, NUDOCS 8603250037
Download: ML20140B936 (4)

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o UNITED STATES NUCLEAR REGULATORY COMMISSION

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION GENERIC LETTER 83-28, ITEM 5 3.1.1, 3.1.2, 3.2.1, 3.2.2, 4.1 AND 4.5.1 NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE HUCLEAR POWER PLANT, UNIT 2 DOCKET NO. 50-336 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 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 automatic 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',i on February 28, 1983, the NRC Executive Director for Operations (ED0), directed the staff to investigate and report on the generic implications of these. occurrences at Unit 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 oparating reactors,

. applicants for an operating license, and hciders,of construction permits to respond to certain generic concerns. These are categorized into four areas; (1) Post-Trip Review (2) Equipment Classification and Vendor Interface, (3) Post-Maintenace Testing, and (4) Reactor Trip System (RTS)

Reliability Improvements. Within each of these areas vaiious specific actions were delineated, e

This safety evaluation (SE) addresses 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 Modif,1 cations) 4.5.1, Reactor Trip System Reliability (System Functional Testing) 8603250037 860318 PDR ADOCK 05000336 P PDR

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+ By a letter dated November 8, 1983, Northeast Nuclear Energy Company (NNECo.) described their planned or completed actions regarding the above items for Millstone Nuclear Power Plant, Unit 2.

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 regarding Actions 3.1.1, 3.1.2, 3.2.1, 3.2.2, 4.1 and 4.5.1 for Millstone Unit 2 are presented in the sections that follow.

2.2 Actions 3.1.1 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 conducted and that the testing demonstrates that the equipment is capable of performing its safety functions before being returned to service.

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 a review of all test and maintenance procedures and Technical Specifications indicate that post-maintenance operability testing of reactor trip components is required in all cases. In general, this is accomplished as part of the restoration sections of procedures, retests required after maintenance, or performance of surveillance procedures as required by Technical Specifications.

The licensee's response also confirms that all known vendor and engineering recommendations have been included in test and maintenance procedures. The licensee further states that no -

recommendation involved potential changes to Technical Specifications.

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.

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c 2.3 Actions 3.2.1 and 3.2.2, Post-Maintenance (All Other Safety Related Components)

Position Licensees and applicants shall submit a report documenting the extending of test and maintenance procedures and Technical Specifications 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 is capable of performing its safety function'before being returned to service.

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 and maintenance procedures or the Technical Specifications, where required.

Discussion The licensee's response stated that the review of. test and maintenance procedures and Technical Specifications for all other safety related equipment is required in all cases. The licensee response also confirmed that a check of vendor and engineering recommendations was conducted to ensure they have been included in test and maintenance procedures or Technical Specifications.

Based on the above, the licensee has complied with the NRC staff ~

position for Actions 3.2.1 and 3.2.2 of Generic Letter 83-28, 2.4 Action 4.1, Reactor Trip System Reliability (Vendor-Related Modifications)

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

For example, the modifications recomended-by Westinghouse in NCD-Elect-18 for the DB-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. .

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1 Discussion The reactor trip circuit breakers at Millstone Unit 2 are General Electric Type AK-2-25. The licensee responded that General Electric Company was contacted and that no modifications for the reactor trip 4 breakers are required. Additionally, during the refueling outage from May 1983 to January 1984, the licensee inspected the reactor trip circuit breakers and found them to be in the vendor recommended configuration.

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 4.5.1, Reactor Trip System Reliability (System Functional Testing)

Position 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 rectifiers on B&W plants; and the scram pilot valves and backup scram valves (including all initiating circuitry) on GE plants.

Discussion The licensee's response stated that on-line testing conducted for the reactor trip system consists of the I&C Department monthly matrix testing which simultaneously actuates the undervoltage and shunt trip devices. The maintenance department performs trip bar torque testing on a quarterly basis. Shunt trip and undervoltage trip features are independently . tested every eighteen months.

Based on the above, the licensee has complied with 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, 3.2.2, 4.1 and 4.5.1 of Generic Letter 83-28. ,

Date: March 18, 1986 Principal Contributor:

John A. Schumacher DRP:RI

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