ML20128J993

SER Re Util 831107 & 840430 Responses to Generic Ltr 83-28, Item 1.1, Post-Trip Review. Program & Procedures Acceptable

ML20128J993
Person / Time
Site:	Sequoyah
Issue date:	05/21/1985
From:	NRC
To:
Shared Package
ML20128J979	List: ML20128J977 ML20128J993
References
GL-83-28, NUDOCS 8505310062
Download: ML20128J993 (5)

Text

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Enclosure 1 SAFETY EVAI.UATION REPORT FOR GENERIC LETTER 83-28, ITEM 1.1 - POST-TRIP REVIEW (PROGRAM DESCRIPTION AND PROCEDURE)

SEQUOYAH fiUCLEAR PLANT, UNITS 1 AND 2 DOCKET N05.: 50-327/328 I. 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 start-up 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 under voltage 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 start-up. 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 (ED0), directed the staff to 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 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 l operating reactors, applicants for an operating license, and holders of construction permits to respond to certain generic concerns. These concerns are categorized into four areas: (1) Post-Trip Review, (2) Equipment Classification and Vendor -Interface, (3) Post-Mainter.ance Testing, and (4) Reactor Trip System Reliability Improvements.

o The first action item, Post-Trip Review, consists of Action Item 1.1,

" Program Description and Procedure" and Action Item 1.2. " Data ind Information Capability." This safety evaluation report (SER) addresses Action Item 1.1 only, u 8505310062'B5g0y p.

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2 II. REVIEW GUIDELINES The following review guidelines were developed after initial evaluation of the various utility responses to Item 1.1 of Generic Letter 83-28 and 3 incorporate the best features of these submittals. As such, these review guidelines in effect. represent a " good practices" approach to post-trip review. We have reviewed the licensee's response to Item 1.1 against these guidelines:

O A. The licensee or applicant should have systematic safety assessment procedures established that will ensure that the fellowing restart criteria are met before restart is authorized.

The post-trip review team has determined the root cause and sequence of events resulting in the plant trip.

Near. term corrective actions have been taken to remedy the cause of the trip.

The post-trip review team has performed an analysis and determined that the major safety systems responded to the event within specified limits of the primary system parameters.

The post-trip review has not resulted in the discovery of a potential safety concern (e.g., the root cause of the event occurs with a frequency significantly larger than expected).

If any of the above restart criteria are not met, then an independent assessment of the event is performed by the Plant Operations Review Committee (PORC), or another designated group with similar authority and experience.

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8. The responsibilities and authorities of the personnel who will perform the review and analysis should be well defined.

The post-trip review team leader should be a member of plant management at the shift supervisor level or above and should hold or should have held an SR0 license on the plant. The team leader should be charged with overall responsibility for directing the

- post-trip review, including data gathering and data assessment and he/she should have the necessary authority to obtain all personnel and data needed for the post-trip review. -

A second person on the review team should be an STA or should hold a relevant engineering degree with special transient analysis training.

The team leader and the STA (Engineer) should be responsible to-concur on a decision / recommendation to restart the plant. A nonconcurrence from either of these persons should be sufficient to prevent. restart until the trip has been reviewed by the PORC or equivalent organization.

C. The licensee or applicant should indicate that the plant response to the trip event will be evaluated and a determination made as to whether the plant response was within acceptable limits. The evaluation should include:

A verification of the proper operation of plant systems and 4

equipment by comparison of the-. pertinent data obtained during the

-post-trip review to the applicable data provided in the FSAR.

An analysis of the sequence of events to verify the proper functioning of safety related and other important equipment. Where {

possible, comparisons with previous similar events should be made.

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,. t D. The licensee or applicant should have procedures to ensure that all physical evidence necessary for an independent assessment is preserved.

E. Each licensee or applicant should provide in its submittal, copies of the plant procedures which contain the information required in Items A through D. As a minimum, these should include the following:

The criteria for determining the acceptability of restart The qualifications, responsibilities and authorities of key personnel involved in the post-trip review process The methods and criteria for determining whether the plant variables and system responses were within the limits as described in the FSAR The criteria for determining the need for an independent review.

I I' I . EVALUATION AND CONCLUSION By letters dated November 7, 1983 and April 30, 1984, the licensee of Sequoyah Nuclear Plant, Units 1 and 2, provided information regarding.its-Post-Trip Review Program.and Procedures. We have evaluated the licensee's program and procedures against the review guiaelines developed as described in Section II. A brief description of the licensee's response and the staff's evaluation of the response against each-of the-review guidelines is provided below:

r A. The licensee has established the criteria for determining the acceptabilityofrestart.Basedonourreview,wefindtha)the

licensee's criteria for determining the acceptability of restart are acceptable.

B. The qualifications, responsibilities and authorities of the personnel who will perform the review and analysis have been clearly described.

We have reviewed the licensee's chain of command for responsibility for post-trip review and evaluation, and find it acceptable.

G. The licensee has described the methods and criteria for comparing the event information with known or expected plant behavior. Based on our review, we find them to be acceptable.

D. With regard to the criteria for determining the need for independent assessment of an event, the licensee has indicated that if the root cause of the trip cannot be determined or unexpected operations occurred during the trip, additional investigations by plant personnel and/or plant management will be conducted. In addition, as a post-trip assessment, the PORC will perform an independent assessment of the event. The licensee also has established procedures to ensure that all physical evidence _necessary for an independent assessment is preserved.

We find that these actions to be taken by the licensee conform to the guidelines as described in the above Sections II.A. and D.

E. The licensee has indicated that its plant operating procedures which contain the above actions and information provide systematic assessment procedures and adequately establish a complete evaluation of the event.

Based on our review, we agree with the licensee that plant operating procedures will ensure that systematic assessment of the events will be I accomplished.

Based on our review, we conclude that the licensee's Post-Trip Review Program and Procedures for Sequoyah Nuclear Plant, Units 1 and 2, are acceptable. t

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