ML20127D664
| ML20127D664 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 06/17/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18029A593 | List: |
| References | |
| GL-83-28, TAC-52901, TAC-52902, TAC-52903, TAC-53737, TAC-53738, TAC-53739, TAC-53964, TAC-53965, TAC-53966, NUDOCS 8506240295 | |
| Download: ML20127D664 (5) | |
Text
'og UNITED STATES y',.(
g NUCLEAR REGULATOF1Y COMMISSION
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WASHINGTON, D. C. 20555 k.v...-
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUbATION
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e TENNESSEE VALLEY AUTHORITY p
BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2 AND 3 DOCKET NOS. 50-259, 50-?60 AND 50-296
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CENERIC LETTEP 83-28. ITEM 1.1 - POST-TRIP REVIEW (PROGRE DESCRIPTI0t. AND PROCEDURES)
'I.
INTR 0 DUCTION
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OtrFebruary 25',* 1983, both of the scram circuit breakers at Unit 1 of the Salem Nuclear Power Plant failed to open upon en 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 Me 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, aa automatic trip signal was 2}
generated based on steam generator low-low level durino plant start-up.
In F.- -
this~ case, the reactor was tripped manually by the operator almost
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coincidentally with the automatic trio. Following thesa incidents, on p.g February 28, 1983, the NRC Executive Director for Operations (ED0), directed
,h the staff to investigate and report on the generic implications of these occurrences at Unit 1 of the Saler Nuclear Power Plant.
The results of the staff's inquiry into the generic implications of the Salem unit incidents are e,
reported in NUREG-1000, " Generic Implications of ATWS EvPnts at the Salem huclear Power Plant." As a result of this investigation, the Commission (NRC) requested (by Generic Letter 83-28 dated July 8, 1983) all licensees of W
operating reactors, applicants for an operating license, and holders of
-construction permits to respond te certain generic concerns. These concerns are categorized into four areas:
(1) Post-Trip Review, (2) Eouipment Classification and Vendor Interface, (3) Post-Maintenance Testing, and
%g (4)- Reactor Trip System Reliability Improvements.
- e The first action item, Post-Trip Review, consists of Action -Item 1.1,
" Program Description and Procedure" and Action Item 1.2. " Data and l
Information Capability." This safety evaluation report (SER) addresses Action Item 1.1 only.
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-2 11.
REVIEW GUIDELINES i'
The following review guidelines were developed after the initial. evaluation of various utility responses to Item 1.1 of Generic Letter 83-28 and incorporate the best features of these submittals. As s'uch, 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 guidel.ines:
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.A.
The. licensee or applicant should have systematic safety assessment 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 i
of the trip.
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t-e The post-trip review team has performed an analysis and determined h.-
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 potealidl safety cancern (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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B.
The responsibilities and authorities of the personnel who sill perform the review and analysis should be well defined.
h 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
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and data needed for the post-trip review.
A second person on the review team should be an STA or should hold
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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
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prevent restart until the trip has been reviewed by the PORC or r
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equivalent organization.
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C.
The licensee or applicant should indicate that the plant response to the
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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 t1p FSAR.
An analysis of the sequence of events to verify the pr.oper
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functioning of safety related and other important equipment. Where possible, comparisons with previous similar events should be made.
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D.
The licensee or applicant should have procedures to ensure that all t
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 throuch D.
As a minimum, these should include the following:
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The criteria for determining the acceptability of restart m
The qualifications, responsibilities and authorities of key
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personnel involved in the post-trip review process t
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.
T-III.
EVALUATION AND CONCLUSION h.:
,b, By letter dated November 7, 1983, the licensee of Browns Ferry Nuclear Plant, Units 1, 2 and 3, provided information regarding its Post-Trip Review Program and Procedures. Additional information relating to the Post-Trip Review Program and Procedures is described in an Inspection Report (Letter from D. M. Verrelli dated January 16,1985). We have evaluated the licensee's program and procedure against the review guidelines 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:
A.
The licensee has established the criteria for determining the acceptability of restart. We find that the licensee's criteria
conformswiththeguidelinesasdescribedintheaboveSechonII.A, and, therefore, are acceptable.
P B.
The qualifications, responsibilities, and authorities of the personnel who will perform the review and analysis have been clearly defined.
We have reviewed the licensee's chain of command for responsibilities for post-trip review and evaluation and find it acceptable.
C, The licensee has acceptable methods and criteria for comparing the -
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m event information with known or expected plant behavior. Pertinent data obtained during the post-trip review will be used to verify proper operatica of the systems or equipment. Where possible, i
comparisons with previous similar events will be made.
D.
With regard to the criteria for determining the need for independent assessment of an event, the licensee has indicated that if the cause
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of the trip cannot be detemined, an independent assessment of the event will be perfomed.
In addition, the licensee has established f
procedures to ensure that all physical evidence necessary for an
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independent assessment is preserved. We find that these actions to be h:
taken by the licensee conform with the guidelines as described in the U
above Sections II.C and D.
E.
The licensee has provided a systematic assessment program to assess unscheduled reactor trips.
Based en our review, we find that this program is acceptable.
IV. CONCLUSION
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Based on our review, we conclude that the Post-Trip Review Progrfm and Procedures for the Browns Ferry Nuclear Plant, Units 1, 2 and 3 peets our guidelines and is acceptable.
Principal Contributor: D. Shum Dated:
June 17,1985