ML20135E521
| ML20135E521 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 09/11/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20135E515 | List: |
| References | |
| NUDOCS 8509160427 | |
| Download: ML20135E521 (4) | |
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~k UNITED STATES
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p, NUCLEAR REGULATORY COMMISSION
- E WASHINGTON, D. C. 20555 7i 4.***
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION IMPLICATIONS OF SALEM ATWS EVENTS, ITEM 1.1 - POST-TRIP REVIEW BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION DOCKET NO. 50-293
1.0 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 trip signal from the reactor protection system. This incident occurred during the plant startup and the reactor was tripped manually by the operator about 30 seconds after the initiation of the automatic trip j
signal. The failure of the circuit breakers has been determined to be 1
related to the sticking of the under voltage trip attachment. On February 22, 1983, during startup 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 (ED0) directed the staff to investigate j
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 Comission requested (by Generic Letter j
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 Classification and Vendor Interface, (3) Post-Maintenance Testing, and (4) Reactor Trip System Reliability a
j 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 Infonnation Capability." This Safety Evaluation (SE) addresses Action Item 1.1 only.-
l 2.0 EVALUATION The following review guidelines were developed after initial evaluation of various utility responses to Item 1.1 of Generic Letter 83-28 and incorporate the best features of these submittals. As such, 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 i
guidelines:
8509160427 850911 PDR ADOCK 05000293 p
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l 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.
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The post-trip review team has determined the root cause and sequence of events resulting in the plant trip.
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o Near term corrective actions have been taken to remedy the cause of the trip.
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o The post-trip review team has performed an analysis and I
determined that the major safety systems responded to the event l
within specified limits of the primary system parameters.
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The post-trip review has not resulted in the discovery of a potential safety concern (e.g., the root cause of the event j
occurs with a frequency significantly larger than expected).
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o If any of the above restart criteria are not met, then an independent assessment of the event is performed by the Plant Operations Review Consnittee (PORC), or another designated group with similar authority and experience.
B.
The responsibilities and authorities of the personnel who will perform l
the review and analysis should be well defined.
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r o
The post-trip review team leader should be a member of plant I
management at the shift supervisor level or above and should hold or should have held a Senior Reactor Operator (SRO) license for l
the plant. The team leader should be charged with overall responsibility for directing the post-trip review, including data
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gathering and data assessment and he/she should have the i
necessary authority to obtain all personnel and data needed for the post-trip review.
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o A second person on the review team should be a Shift Technical j
Advisor (STA) or should hold a relevant engineering degree with special transient analysis training.
o The team leader and STA (Engineer) should be responsible for-concurring 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.
l C.
The licensee or applicant should indicate that the plant response to i
the trip event will be evaluated and a detennination made as to i
whether-the plant response was within acceptable limits. The i
evaluation should include:
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A i
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A verification of the proper operation of plant systems and y
equipment by comparison of the pertinent data obtained during the r
post-trip review to the applicable data provided in the Final t
Safety Analysis Report (FSAR).
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o 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.
l 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.
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:
o The criteria for detemining the acceptability of restart.
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o The qualifications, responsibilities and authorities of key personnel involved in the post-trip review process.
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o The methods and criteria for determining whether the plant variables and system responses were within the limits as described in the FSAR.
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The criteria for detemining the need for an independent review.
By letters dated November 7, 1983 and August 13, 1985, the licensee for
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Pilgrim Station provided information regarding its Post-Trip Review Program j
and Procedures. We have evaluated the licensee's program and procedures i
against the above review guidelines. A brief description of the licensee's i
response and the staff's evaluation of the response against each of the review guidelines is provided below:
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A.
The licensee has established the criteria for determining the i
acceptability of restart. We find that the licensee's criteria i
conform to the guidelines described in Section A above and, therefore, are acceptable.
B.
The qualifications, responsibilities and authorities of the personnel
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who will perform the review and analysis have been clearly described.
We have reviewed the licensee's chain of connand for responsibility r
for post-trip review and evaluation and we find it acceptable.
l C.
The licensee has described the methods and criteria for comparing the I
event information with known or expected plant behavior. Based on our review, we find the licensee's methods to be acceptable.
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i D.
The licensee has established the criteria for determining the need f
for an independent assessment conducted by the Operation Review i
Committee.
In addition, the licensee has established procedures to ensure that all physical evidence necessary for an independent assessment is preserved. We find these actions conform with the i
guidelines described in Sections A and D above.
E.
The licensee has provided a systematic safety assessment program to assess unscheduled reactor trips. We have reviewed this program and i
find it acceptable.
3.0 CONCLUSION
S r
Based on our review, we conclude that the licensee's Post-Trip Review i
Program and Procedures for Pilgrim Station are acceptable.
t Principal Contributor:
D. Shum Dated: September ll,1985 j
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