ML18087A713
| ML18087A713 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Salem |
| Issue date: | 03/01/1983 |
| From: | Uderitz R Public Service Enterprise Group |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML18087A711 | List: |
| References | |
| NUDOCS 8303150646 | |
| Download: ML18087A713 (5) | |
Text
Richard A. Uderitz Vice President -
Nuclear Pub!ic Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609 935-6010 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 March 1,198~
Attention:
Mr. Darrell G. Eisenhut, Director Division of Licensing Gentlemen:
REACTOR TRIP BREAKER FAILURE NO. l UNIT SALEM GENERATING STATION DOCKET NO. 50-272 The purpose of this letter is to document our investigation of two reactor trip breaker failures and provide corrective actions to be taken.
On February 22 and 25, 1983, the Salem Unit l reactor trip breakers failed to open upon receipt of a valid trip signal from the reactor protection system.
In both instances, the manual trip was used to shut down the unit.
PSE&G has determined that the reactor trip breaker undervoltage trip attachment failures were caused by a lack of proper lubrication on the latch.
Westinghouse expert opinion concurs with this based *'upon:
- a.
An inspection of the undervoltage trip attachments.
- b.
A review of PSE&G accounts of the tests performed after the failures.
- c.
Previous Westinghouse experience which indicates that the lack of lubrication has been the cause of similar previous failures.
~3e3i'~~:) I~..-
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Mr. Darrell G. Eisenhut U. S. Nuclear Regulatory Commission 2 -
3-1-83 As presented in our meeting on February 28, 1983, our investigation of these incidents is summarized herein.
(""
PSE&G has reviewed the plant data from the events of February 22 and 25, 1983 to evaluate any potential safety impact on the primary system.
Review of the primary coolant parameters did not reveal any significant perturbations and followed trends that would be expected in a normal plant trip.
The bounding case in the FSAR is the loss of normal feedwater at 102% power with only one auxiliary feedwater pump starting.
In that transient, two steam generators boil dry and the other two drop to a level where approximately 50% of the tube bundles are exposed.
This provided sufficient heat removal to preclude boiling in the primary system.
This is a more limiting case than the two recent incidents at Salem, where on February 22nd as a result of the transient, the water level in three steam generators briefly dropped to a level equivalent to approximately 20% of the tube bundle exposed.
On February 25th, the level in one steam generator again briefly dropped to approximately this same level.
On both occasions, there was automatic auxiliary feedwater initiation.
The potential for waterhammer in the steam generator feed ring exists when the feedwater flow is interrupted long enough to allow the feed ring to drain.
In both recent instances, there was no flow interruption since auxiliary feedwater was initiated automatically.
In addition, "J-tubes" have previously been installed in the feed rings.
In conclusion, the events of February 22 and 25, 1983 were within bounds of FSAR analyses and did not have the necessary prerequisites for feedwater line waterhammer.
Our review of the breaker failures has resulted in a program of corrective actions to assure that such failures will not recur.
These corrective actions are described below:
- 1.
PSE&G has verified the Salem surveillance testing meets the technical specification requirements.
Procedure PD18.l.004/5 Solid State Protection System Reactor Trip Breakers and Permissive P-4 Test Train A/B satisfy the requirements for testing the reactor trip breakers.
--1
Mr. Darrell G. Eisenhut U. S. Nuclear Regulatory Commission 3 -
3-1-83 Procedure PD18.l.008/9 Solid State Protection System Functional Test Train A/B satisfied the requirements for testing the automatic trip logic.
- 2.
A detailed maintenance procedure M3Q-2 entitled Reactor Trip and Bypass ACB Inspection and Test, which includes the undervoltage trip attachment, has been developed and approved.
This procedure is based on and references Westinghouse data letter NSD-TB-74-2, Westinghouse Procedure NDC-ELEC-18 and the Westinghouse Instruction Book for DB-50, DBF-16 and DBL-50-ACB's.
This includes electrical testing of the breaker, notification of the Technical Department of the need for post maintenance testing and appropriate QA inspection hold points.
- 3.
New undervoltage trip attachments will be supplied by Westing-house and will be installed on each of the four No. 1 Unit breakers.
Westinghouse will provide technical assistance to PSE&G to assure that_No. 1 Unit undervoltage trip attachments are installed properly and that the breakers operate p~operly.
- 4.
Proper operation of the breakers will be verified prior to placing the breakers in service.
A program to verify proper operation will be developed and completed prior to returning to service.
This program will take into consideration statistical data and recommendations to be provided by Westinghouse.
- 5.
PSE&G will verify that Westinghouse has determined that the UV attachments meet the specification requirements for the original reactor trip switchgear.
- 6.
Surveillance of reactor trip breaker operation will be increased as follows:
- a.
Main and bypass breakers will be shunt-tripped weekly.
- b.
Main breakers will be UV-tripped monthly.
Proposed technical specification changes will be submitted as appropriate.
--1
)
Mr. Darrell G. Eisenhut U. S. Nuclear Regulatory Commission 4 -
3-1-83 7.
The following tests will be performed after maintenance on reactor trip breakers to demonstrate operability prior to return of the I5'reaker to service:
- a.
Breaker will be shunt-tripped.
- b.
Breaker will be UV-tripped.
- c.
Breaker will be time-response tested.
- 8.
Emergency Instruction I-4.3, Reactor Trip, for Salem Units l and 2 will be revised to include the requirement to manually trip the reactor trip breakers on all reactor trips.
The revision to this procedure and the basis for this additional action will be disseminated to all licensed operators.
- 9.
A formal reactor trip/safety injection post trip review procedure will be developed and issued as an Operations Department Directive.
This procedure will specify the review and documentation necessary to determine the cause of the event and also determine that affected equipment performed in its intended function.* The procedure will also include management authorization requirements for startup.
All licensed operators will be informed of the requirements of this document.
- 10.
A review of LER's, deficiency reports, maintenance work sheets and work orders is in progress to identify items requiring preventative maintenance.
Our preventative maintenance program will incorporate the results of this review to be ~ompleted by January 1, 1984.
- 11.
A reactor trip and bypass breaker traceability program will be established to insure that all work performed on the breakers will be traceable to a particular breaker and its location.
This will be accomplished by April 1, 1983.
- 12.
Westinghouse has committed to provide PSE&G with a compilation of all technical bulletins, manuals, etc., pertaining to Westinghouse equipment utilized at Salem. These will be reviewed and incorporated into station documents as necessary in a timely manner.
),
Mr. Darrell G. Eisenhut U. S. Nuclear Regulatory Commission 5 -
3-1-83
- 13.
Work orders will be reviewed by QA to insure that there is proper designation of safety related items.
For safety related work, QA w~ll establish proper inspection and/or surveillance coverage.
In addition, PSE&G is undertaking a thorough review of its Operational QA Program to identify changes necessary to improve performance.
In our meeting with the staff on February 28, 1983, we were requested to clarify the safety classification of the reactor trip breakers.
The reactor trip breakers are part of the Reactor Trip System which is a safety-related system.
In the design and construction of Salem Generating Station, PSE&G considered as safety-related, those structures, systems and components that prevent or mitigate the consequences of postulated accidents that could cause undue risk to the health and safety of the public.
Salem UFSAR Section 7.1.l.l states that the Reactor Trip System consists of equipment which initiates reactor trip or activates engineered safety features.
Included is equipment from sensors to actuating devices.
The reactor trip breakers and the under-voltage attachment are safety-related.
The shunt-trip attachment is not a functional part of the reactor trip system.
Correc~ive action Items l through 9 will be completed prior to startup.
Corrective action Items 10 through 13 will be com-pleted as described therein.
We believe that accomplishment of the corrective actions identified above will preclude recurrence of these and similar events and provide adequate confidence that Salem Unit l can be safely returned to service.
Sincerely,