ML18142A344
| ML18142A344 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/01/1985 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML18142A343 | List: |
| References | |
| GL-83-28, NUDOCS 8504170656 | |
| Download: ML18142A344 (5) | |
Text
f i i Enc 1 osure 1 SAFETY EVALUATION FOR i
GENERIC LETTER 83-28, ITEM I.I - POST:TRIP REVIEW (PROGRAM DESCRIPTION AND PROCEDURE)
SURRY POWER STATION, UNITS 1 AND 2 DOCKET NOS.:
50-280/281 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_,; { EDO), 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 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 Class.ificatiaon 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 initial evaluation of the various utility responses to Item I.I of Generic Letter 83-28 and incorporate the best features of these submittals.
As such, these review guidelines in effect represent a "good practices 11 approach to post-trip review.
We have reviewed the licensee's response to Item 1.1 against these guidelines:
A.
The 1 icensee should have systematic safety ~-~se_ssment procedures established that will ensure that the following restart criteria are met before restart is authorized.
0 0
0 0
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).
0 If any of the above restart criteria are not nl~t, 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.
e B.
The rP.sponsibilitiP.s and authorities of the personnel who will perform the review and analysis should be well defined.
0 0
0 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 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 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/reconmendation 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 ~hould 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:
0 0
A verification of the proper opP.ration of plant systems and equipment by comparison of the pertinent data obtained dor¥ng ltie 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~ons with previous similar events should be made.
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e D.
The licensee should have procedures to ensure that all physical evidence necessary for an independent assessment is preserved.
E.
Each licensee should provide in its submittal, copies of II I.
the plant procedures which contain the information required in Items A through D.
As a minimum, these should include the following:
0 0
0 0
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.
EVALUATION AND CONCLUSION
~Y letter dated November 4, 1983, the licensee of Surry Power Station, 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 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 guideli~es is provided below:
~~
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'A.
The licensee's criteria for determining the acceptability of restart include: a verification that the reactor protection system and the engineered safety features and systems which are important to reactor safety have performed as required; a verification of the cause of the
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I I trip and the adequacy of the subsequent corrective action taken; and the conduct of an analysis to evaluate the plant transient behavior.
We find that 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 in the licensee's respons_e-.
We have reviewed the licens~e-'s chain of command for responsibilities for post-trip review and evaluation, and find them acceptable.
C.
The licensee has described the methods and criteria for comparing the event infonnation with known or expected plant behavior.
Based on our review, we find them to be acceptable.
D.
With regard to the criteria for detennining the need for independent assessment of an event, the licensee has indicated that if *the cause of the trip cannot be positively detennined, an independent assessment of the event will be perfonned by the Station Manager and the Station Nuclear Safety and Operating Committee.
In addition, the licensee 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.C. and D.
E.
The licensee has provided for our review a systematic safety assessment program to assess unscheduled reactor trips. Based on our review, WP
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find that this program is acceptable.
Based on our review, we conclude that the licensee's Post-Trip Review Program and Procedures for Surry Power Station, Units land 2, are acceptable.