ML17195A894
| ML17195A894 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/25/1985 |
| From: | Shum D Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17195A893 | List: |
| References | |
| GL-83-28, NUDOCS 8507300407 | |
| Download: ML17195A894 (5) | |
Text
e UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATIO~! BY THE OFFICE OF NUCLEAR REACTOR REGUL.A.TION RELATED TO LICENSEE RESPONSE TO GENERIC LETTER 83-28 COMMONWEALTH EDISO~ rOMPANY DRESDEN NUCLEAR POWER STATION, UNIT NOS. 2 AND 3 DOCKET NO. 50-237, 50-249.
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 ~rotection 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 determinP.d tn 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 implicaiions 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 lmplications*of ATWS Events at the Salem Nuclear Power Plant." As a result of this investigation, the Commission
(~RC) requested (by Generic Letter 83-28 dated July 8, 1983) all licenseP.s of operating reactors, applicants for an operating license, and ho1ders of construction pennits 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 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 safet.y evaluation (SE) addresses Action Item 1.J only.
2.0. REVIEW GUID~LINES 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 t~ese submittals.
As such, these review guidelines in effect represent a "good practices" approach to post-trip review.
The staff has reviewed the licensee's response to Item 1.1 against these guidelines:
A.
The licensee should have systematic safety assessment procedures.
established that will ensure that the following restart criteria are met before restart is authorized.
0 The post-trip review team has determined the root cause and seauence of events r~sulting in the plant trip.
Near term corrective actions have been taken to remedy the cause of the tr:ip.
The post-trip review team has performed an ana*lysis 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)
- If any of the above restart criteria are not met, then an independent assessment of the event is performed by the Plant Opere1tions 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.
n The post-trip re~1ew team leader should be a member of plant management at the shift supervisor level or above and should hold or shouln have held a senior operator 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 a shift technical advisor (STA) or should hold a relevant engineering degree with special transient analysis training.
0 The team leader and the STA (Engineer) should be responsible to concur nn 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 equiyalent organization.
C. *The licensee should indicate that the plant response to the trip event will he evaluated and a detennination made as tc whether the plant response was within acceptable 1imits. The evaluation should include:
A verification of the proper operation of plant systems and equipment by comparison of the pertinPnt. data obtained during the post-trip review to the applicable data provided in the Final Safety Analysis Report (FSAR).
An analysis of the sequence of events to verify the proper functionin~ of safety-related and other important equipment.
Where possible, comparisons with previous similar events should be made.
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 the plant procedures which contain the information required in Items A through D.
As a minimum, these should include the following:
- 3. 0 EVALUATION 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 detennining 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.
By letters dated November. 5, 1983, and June 5, 1985, the licensee of Dresden Nuclear Power Station, Units 2 anp 3, provided information regarding its Post-Trip Review Program and Procedures.
The staff has evaluated the licensee's program and procedures against the review guidelines developed as described in Section 2.0. A brief description of the licensee's response end the staff's evaluation of the response ag~inst each of the review guidelines are provided below:
A.
With regard to the criteria for determining the acceptability of *restart, the licensee referred to a Corporate Directive, "Plant Start~up After
- Trip, 11 which provides guidance for post-trip analysis, determination of root cause and approval for start-up. The licersee indicated that prior to the authorization of restart, the Corporate Directive requires: a determination of the root cause of the event; a satisfactory evaluation
, of equipment performance; and an understanding of the cause of any degraded, abnormal, or unexpected performanr.e of safety-related equipment.
The staff finds that the licensee's criter.ia for determining the acceptability of restart conform with the guidelines as described in Section 2.A and, therefore, are acceptable.
B.
The licensee indicated that a Shift Supervisor has the responsibility and authority to obtain all* necessary personnel and any special assistance considered necessary to ensure a thorough post-trip review.
The Station Supervisor has the final authority to authorize plant restart.
The personnel performing the review and analysis will be shift management personnel (i.e., Shift Engineer, Shift Fore~an and Station Control Room Engineer). These are all senior operator licensed shift positions.
The staff finds that the qualifications, responsibilities and authorities of the personnel who will authorize the restart and/or perform the post-trip review and analysis have been clear1y defined and are acceptable.
C.
The licensee has addressed the methods.and criteria for comparing the event information with known or expected.plant behavior.
Based on a review, the staff finds them to be acceptable.
D.
With regard to the criteria for the need of independent assessment of a~
- event, the licensee indicated that as required by the Administrative Controls Section of the Technical Specifications, all unscheduled reactor trips are assessed by the Onsite Review and Investigative Function and again by the Offsite Review and Investigative Function.
In adrli~ion, 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 with the guidelines as described in the above Sections 2.A and D.
E.
The licensee has indicated that the above cited Corporate Directive provides a systematic safety assessment program to ~ssess unscheduled reactor trips. Based on a review, the staff finds it to be acceptable.
Based.on an overall review, the staff concludes that the licensee's Post-Trip Revie~ Pr6gram and Procedures for Dresden Nuclear Power Station, Units 2 and 3, are acceptable.
4.0 CONCLUSION
The staff concludes that the programs and procedures outlined in the licensee's submittals adequately address the requirements of Generic Letter 83-28 for the area specified in this Safety Evaluation.
/' 5.0 ACKNOWLEDGEMENT This Safety Evaluation was prepared by D. H. Shum.
Dated: July 25, 19~5.