ML17216A381
| ML17216A381 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 12/17/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17216A380 | List: |
| References | |
| GL-83-28, NUDOCS 8512230274 | |
| Download: ML17216A381 (5) | |
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UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION GENERIC L IP REVIEW INTRODUCTION On February 25, 1983, both of the scram circuit breakers at Unit I of the Salem Nuclear Power Plant (SNPP) failed to open upon an automatic reactor trip signal from the reactor protection system.
This incident occurred during 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, an automatic trip signal occurred during start-up of SNPP, Unit I, 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.
On February 28, 1983, the NRC Executive Director for Operations directed the staff to investigate and report on the generic implications of these occurrences.
The results of the staff investigation are reported fn 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 operating license, and holders of construction permits to respond to certain generic concerns.
These concerns are categorized into the following four areas:
(I)
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 l.l, "Program Description and Procedure" and Action Item 1.2, "Data and Information Capability."
This safety evaluation addresses Action Item l.l only.
The following review guidelines were developed after the initial evaluation of several utility responses to Item 1.1 of Generic Letter 83-28 and incorporate the best features of these submittals.
Therefore, these review guidelines effectively represent a "good practices" approach to post-trip review.
The staff reviewed the licensee's response to Item l.l against these guidelines:
A.
The licensee or applicant should have systematic safety assessment procedures established that will ensure that the following restart
. crite~ia 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.
8512230274 851217 PDR ADOCK 05000335 P
Near term corrective actions have been taken to remedy the cause of the trip.
I The post-trip review team has performed an analysis and determined that the ma)or 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.
.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 SRO license on the plant.
The team leader should be charged with over'a11 responsibility for directing the post-trip review, including data gathering and data assessment, and 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 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.
D.
The licensee or applicant should have procedures to ensure that all physical evidence necessary for an independent assessment is preserved.
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E.
V Each licensee or'pplicant 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 tfie FSAR The criteria for determining the need for an independent review.
EVALUATION By letters dated November 8, 1983 and October ll, 1985, the licensee provided information regarding its Post-Trip Review Program and Procedures for St. Lucie Plant, Unit Nos.
1 and 2.
The staff evaluated the licensee's program and procedures against the review guidelines developed and described above.
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.
B.
C.
D.
The licensee has established the criteria for determining the acceptability of restart.
The staff finds that the licensee's criteria
'conform with the guidelines and are acceptable.
The qualifications, responsibilities and authorities of the personnel who will perform the review and analysis have been clearly defined.
The staff reviewed the licensee's chain of comnand for responsibility for post-trip review and evaluation and finds it acceptable.
The licensee has addressed the methods and criteria for comparing the event information with known or expected plant behavior.
Based on its review, the staff finds them to be acceptable.
With regard to the criteria for determining the need for independent assessment of an event, the licensee has indicated that if the cause of the trip cannot be determined by the Nuclear Plant Supervisor, the unit will not be returned to power until an independent review of the event has been performed by the Facility Review Group.
In addition, the licensee has established procedures to ensure that all physical evidence necessary for an independent assessment is preserved.
The staff finds that these actions to be taken by the licensee conform to the guidelines as described and are acceptable.
'I The licensee has provided for our review a systematic safety assessment program to assess unscheduled reactor trips.
Based on its review, the staff finds that this program is acceptable.
4-CONCLUSION Based on the above discussion, the staff concludes that the licensee's Post-Trip Review Program and Procedures for St. Lucie Plant, Units Nos.
1 and 2, are acceptable and no further action is required on Generic Letter 83-28 Action Item 1.1.
Date:
December 17, 1985 Principal Contributors:
D. Shum D. Sells
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