ML20137S578

SER Approving Licensee 831104 & 0715 Responses to Generic Ltr 83-28,Item 1.1 Re post-trip Review.Program & Procedures for Restart from Unscheduled Reactor Trip Acceptable

ML20137S578
Person / Time
Site:	Summer
Issue date:	09/24/1985
From:	NRC
To:
Shared Package
ML20137S566	List: ML20137S561 ML20137S578
References
GL-83-28, NUDOCS 8509300432
Download: ML20137S578 (5)

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

VIRGIL C. SUMMER NUCLEAR STATION DOCKET NO.: 50-395

-I . INTRODUCTION On February 25, 1983, both of the scram circuit breakers at Unit 1 of the Salem Nuclear Power Plant (SNPP) failed to open upon an automatic reactor j 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. On February 22, 1983, during start-up of SNPP, Unit 1, an automatic trip signal occurred as the result of steam generator low-low level. 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. The results of the staff's inquiry into these 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 requested (by Generic Letter 83-28 dated July 8,1983) all licensees of operating -reactors, applicants for an l

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-Maintenance Testing, and (4) Reactor Trip System Reliability Improvements.

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

" Program Description and Procedure," and Action Item 1.2, " Data and  ;

Information Capability." This safety evaluation report (SER) addresses Action Item 1.1 only.

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II. REVIEW GUIDELINES The following review guidelines were developed after the initial' evaluation of various utility responses to Item 1.1 of Generic Letter 83-28 and

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incorporate the best features of these submittals. As such, these review I 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:

A. The licensee or applicant should have systematic safety assessment l procedures established that will ensure that the following 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.

I . b B. 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 for the plant. The team leader should be charged with overall responsibility for directing the l 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.

i The team leader and the STA (Engineer) should be responsible to l 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 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, compari. sons with previous similar events should be made.

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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 i in the FSAR The criteria for determining the need for an independent review.

III. EVALUATION AND CONCLUSION By. letters dated November 4, 1983, and July 15, 1983, the licensee of Virgil C. Summer Nuclear Station provided information regarding its Post-Trip Review Program and Procedures. We have evaluated the licensee's program and procedure against the review guidelines 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:

A. The licensee has established the criteria for ' determining the acceptability of_ restart from any unscheduled reactor trip. We find that the licensee's criteria conform with the guidelines described in Section II.A and, therefore, are acceptable.

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B. The qualifications, responsibilities and authorities of the personnel who will perform the review and analysis have been clearly defined. 3 43 have, reviewed the licensee's chain of command for responsibility for post-trip review and evaluation and find it acceptable.

C. The licensee has addressed 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 following an unscheduled reactor _ trip, the Shift Supervisor together with the Control Room Foreman and the Reactor Operator will conduct an assessment of the event and prepare the Reactor Trip Report. The Shift Technical Advisor will also conduct an assessment of the event independently. The Reactor Trip Repcrt will then be reviewed separately by the Independent Safety Review Group and the Plant Safety Review Committee. In addition, the licensee has established procedures to ensure that all physical evidence necessary for an independent assessment is preserved. We find these dCtions conform with the guidelines described in Sections II.A and D.

E. The licensee has provided a systematic safety assessment program to evaluate unscheduled reactor trips. We have reviewed this program and find it acceptable.

Based on our review, we conclude that the licensee's Post-Trip Review Program l

and Procedures for Virgil C. Summer Nuclear Station are acceptable.

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