ML20197F008

Safety Evaluation Supporting Licensee Responses to Generic Ltr 83-28, Required Actions Based on Generic Implications of Salem ATWS Events, Items 3.1.1,3.1.2,3.2.1,3.2.2,4.1 & 4.5.1

ML20197F008
Person / Time
Site:	Yankee Rowe
Issue date:	05/07/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20197E999	List: ML20197E993 ML20197F008
References
GL-83-28, NUDOCS 8605150377
Download: ML20197F008 (5)

Text

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t SAFETY EVALUATION BY THE OFFICE OF THE NUCLEAR REACTOR REGULATION RELATED TO

, GENERIC LETTER 83-28, ITEMS 3.1.1, 3.1.2, 3.2.1, 3.2.2, 4.1 and 4.5.1 YANKEE ATOMIC ELECTRIC COMPANY  :

I YANKEE NUCLEAR POWER PLANT i DOCKET NO.50-029 i

, 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

.t startup, and the reactor was tripped manually by the operator about 30 seconds g 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 j 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 4 on steam generator low-low level during plant startup. In this case the i reactor was tripped manually by the operator almost coincidentally with the automatic trip.

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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 Unit 1 of the Salem Nuclear Plant.

l The results of the staff's inquiry into the gendric 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 re-4 quested (by Generic Letter 83-28 dated July 8,1983) all licensees of operat-

ing reactors, applicants for an operating license, and holders 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-Maintenance Testing, and (4) Reactor Trip Systera (RTS) i Reliability Improvements. Within each of these areas various specific actions j , were delineated.

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

3.1.1 and 3.1.2, Post-Maintenance Testing (Reactor Trip System Components) i --

3.2.1 and 3.2.2, Post-Maintenance Testing (All Other Safety-Related Com- '

ponents)

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

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. Safety Evaluation 2 i'

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=f 4.5.1, Reactor Trip System Reliability '(System Functional Testing)

By a letter dated November 5, 1983, Yankee Atomic Electric Company (the lic-i ensee) described their planned or completed actions regarding

.the above items I

for Yankee Nuclear Power Plant.

2.0 Evaluation i

! 2.1 General-

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! 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 2 . of licensee compliance regarding Actions 3.1.1, 3.1.2, 3.2.1, 3.2.2, 4.1

.g and 4.5.1-for Yankee are presented in the sections that follow. .j

- 6 f  ? 2.2 Actions 3.1.1 and 3.1.2, Post-Maintenance Testing (Reactor Trip.

i System Components)  :

j Position

} Licensees and appitcants shall submit'the results of their review of test l and maintenan e procedures and Technical Specifications to assure that  !

1 post-maintenance operability testing of safety-related components in the i j reactor trip system (RTS) is required to be conducted and that the test-j ing demonstrates that the equipment is capable of performing _its safety j functions before being returned to service.

4 Licensees and applicants shall submit the results of their check of ven-

] dor 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, j where required.

! Discussion i

i The licensee's response states that the requirements of Technical Speci- 1 i fications and applicable engineering and vendor recommendations have been i reviewed to assure that post-maintenance testing.of safety-related com-j ponents in the reactor trip system are required to be conducted and that j the testing demonstrates that_the equipment is capable of. performing its

safety function.

Additionally, the licensee's response states that the results of their

, review disclose that appropriate'information has.been incorporated into i applicable test and maintenance procedures to meet the requirements of j the above actions.

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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9 Safety Evaluation 3 2.3 Actions 3.2.1 and 3.2.2, Post-Maintenance Testing (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 ven-dor 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, i where required.

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Discussion The licensee's response states that the requirements of Technical Speci-fications and applicable engineering and vendor recommendations are in-corporated into test and maintenance procedures. These procedures are reviewed to ensure that post-maintenance operability testing of safety-related components is required to be conducted and that the testir.g demonstrates that the equipment is capable of performing its intended safety functions before being returned to service. Additionally, testing and maintenance procedures are developed utilizing appropriate vendor information and engineering recommendations.

The licensee's response further states that their review of vendor and engineering recommendations as required by Actions 3.2.1 and 3.2.2 sub-stantiates their belief that their system for incorporating appropriate vendor and engineering recommendations is effective and adequate.

' 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-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.

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4 For example, the modifications recommended by Westinghouse in NCD-Elec-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.

DISCUSSION The reactor trip breakers at Yankee are Westinghouse ACBs, DB-25. No modifications of these have been recommended by the vendor.

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

position for Action 4.1 of Generic Letter 83-28.

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( 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 undervoltage and shunt trip features on Westinghouse, B&W, and CE plants; the j 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 On-line testing cannot be conducted at Yankee. This action is therefore deferred to Item 4.5.2 regarding justification for no on-line testing, which will be reviewed separately. In addition, no diverse trip features (UV-trips) are installed at Yankee. The generic letter assumes that undervoltage devices are already installed in Westinghouse breakers. This is not true for Yankee breakers which have shunt trip attachments only and no undervoltage devices. Item 4.3 of Generic Letter 83-28 addresses the need for diverse trip features for breakers.

The staff's SER, provided in an August 9, 1984 letter from W. A. Paulson to J. A. Kay, found the Yankee plant design provided sufficient diversity, including provisions for reactor shutdown under loss-of-voltage conditions, to meet the requirements of Item 4.3.

Based on the above, Action 4.5.1 of Generic Letter 83-28 has been reviewed and is considered closed. However, the unique situation described above will be reviewed under Items 4.5.2 of Generic Letter 83-28.

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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: NAY 0 71986 Principal Contributor: John A. Schumacher DRP f

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