ML20154M656

Safety Evaluation Supporting Licensee post-trip Review Program & Procedures Per Generic Ltr 83-28,Item 1.1 Re Generic Implications for Salem ATWS Events

ML20154M656
Person / Time
Site:	River Bend
Issue date:	09/22/1988
From:	Paulson W Office of Nuclear Reactor Regulation
To:
Shared Package
ML20154M644	List: ML20154M640 ML20154M656
References
GL-83-28, NUDOCS 8809290052
Download: ML20154M656 (4)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO GENERIC LETTER 83-28 ITEM 1.1 POSTTRIPREVIEW(PROGRAMDESCRIPTION_ANDPROCEDURE),

GULF STATES UTILITIES RIVER BEND STATION, UNIT 1 DOCKET NO. 50-458

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 start-up and the reactor was tripped ranually by the operator about 30 seconds after the initiation of the automatic trip signal. The failure of the circuit breakers has been detertnined to be related to the sticking of the under voltage trip attachnent. Prior to this incident, on February 22. 1983, at Unit 1 of the Salem Nuclear Power Plant, an autoeatic 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 (ECO), 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 implica-tions of the Salem unit incidents are reported in NUREG-1000. "Generic Irplications of ATVS Events et the Salem Nuclear Power Plant." As a  ;

result of this investigation, the Connissior. (NRC) 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 certain generic concerns. These concerns are categorized into four areas: (1) Post-TripReview.(2)EquipmentClassificationand Vendor Interface. (3) Post-Maintenance Testing, and (4) Reactor Trip System Reliability Improverents.

The first action item. Post-Trip Review, consists of Action Item 1.1 I "Program Description and Procedure" and Action item 1.2 "Data and Infonration Capability." This safety evaluation (SE) addresses Action Item 1.1 only.

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?.0 REVIEW GUIDELINES The following review guidelines were developed after initial evaluation of the various utility responses to item 1.1 of Generic letter 83-78 and incorporate the best features of these submittals. As such, these review guidelines in effect represent a "good practices" approach to post-trip review. Ve have reviewed the licensee's response to item 1.1 against these guidelines:

A. The licensee or applicant should have systematic safety assessrent procedures established that will ensure that the following restart criteria are net before restart is authorized.

The post-trip review team has detertnined the root cause and sequence of ever.ts resulting in the plant trip.

Near tern. corrective actions have been talen to remedy the cause of the trip.

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

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 ret, then an independent assessnent of the event is perforced by the Plant Operations Feview Comittee (FORC), or another designated group with similar authority and experience.

B. The responsibilities and authorities of the personnel who will

- perforfr the review and aralysis should te well defined.

The post-trip review tur leader should be a rerber of plant managenent at the shift supervisor level or above and should hold or should have held an SRO license on the plant. The team leader should be charged with overall responsibility for directing the post-trip review, including data gathering and data assessrent and he/she should have the necessary authority to obtain all persunnel and data needed for the post-trip review. .

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

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• The team leader and the STA (Engineer) should be responsible to i concur on a decision /reconwendation 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 i whether the plant response was within acceptable limits. The evaluation i 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, cosperisons with previous similar events should be made.

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

preserved. j E. Each licensee or applicant should provide in its submitts), copies of the plant procedures which contain the information required in Items A through 0. As a minimum, these should include the following: j The criteria for detemining the acceptability of restart.

The qualifications, responsibilities and authorities of key  !

personnel involved in the post-trip review process.

l The methods and criteria for determining whether the plant I variables and system responses were within the limits as  !

described in the FSAR. f l

The criterta for detemining the need for an independent review.

I 3.0 EVALUATION AND CONCLUSION By letter dated August 3,1984. Gulf States Utilities Coepany (G5V). the l licensee of review its post-trip River Bend Station.

program Unit 1 provided and procedures. infomationtoregarding's In response the staff l June 25, 1985 request for additional infomation, by letter dated July 9 l 1985 GSU provided copies of procedures relevant to item 1.1 of Generic [

Letter 83-28.  ;

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-4 By letter dated August 11, 1928 GSV provided update / procedures A0M-0022, Revision 11. "Conduct of Operations"; A0P-0001, Revision 4. "Reactor Scram", and GOP-0003, Revision 5, "Scram Recovery." The staff has evaluated the licenste's program and procedures against the review guidelines developed as described in Section !!, above. A brief description of the licensee's response and the staff's evaluation of the response against each of the l review guidelines is provided below:

A. The licensee has systematic safety assessrent procedures for determining the acceptability of restart. Section 5.3, ADM-0022 states that the STA under the direction of the shift supervisor is responsible for compilin ,

cause(s)g of all theinformation andismaking trip. The STA the initial responsible detemination for completing theof the '

Post-Trip Chuklist and Scram Report (GOP-0003). These reports include listing any safety system functions that were supposed to actuate but did not, corrective actions, and any urespected aspect of  :

transient behavior including comparison with FSAR transient. The facility Review Comittee makes the final determination of root cause and this comittee authorizes restart if appropriate. Eased on the review of the licensee's submittal, the staff concludes that the licer,see's criteria conform to the guidelines as described in the above Section II.A. and, therefore, they are acceptable.

B. The qualifications, responsibilities and authorities of the personnel  :

d e will perform the review and analysis have been clearly described.  :

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

C. The licensee has described the rethods and criteria for comparing the event inforration with known or expected plart behavior. Eased ,

j en our review, we find them to be acceptable.

D. The licensee has established criteria for detemining the need for independent assessrent of an event. Based on our review, we find i them acceptable. In addition, the licensee has established procedures to ensure that all physical evidence necessary for an independent assessment is preserved. We find that this action to be taken by the f licensee confoms with the guidelines as described in the above Sections II.A and D.

I E. The licensee has provided for our review a systeratic safety assessment i program to assess unscheduled reactor trips. Based on our review, we find that this program is acceptable.

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] Based on our review, we conclude that the licensee's Post-Trip Review t

Program and Procedures for River Bend Station, Unit 1 are acceptable.

Dated: September 22, 1988

! Principal Contributor: W. Paulson t

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