ML20126C422
| ML20126C422 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 06/07/1985 |
| From: | Whittier G Maine Yankee |
| To: | John Miller Office of Nuclear Reactor Regulation |
| References | |
| 5623L-FWS, GDW-85-165, GL-83-28, MN-85-110, NUDOCS 8506140414 | |
| Download: ML20126C422 (2) | |
Text
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.1 EDISON DRIVE MAIRE HARHEE ATOMloPOWER00MPARUe avausra, ua,ne oasas
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June 7, 1985 MN-85-110 GDW-85-165 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. James R. Miller, Chief Operating Reactors Branch No. 3 Division of Licensing
References:
(a) License No. [PR-36 (Docket No. 50-309)
(b) MYAPCo Letter to USNRC dated November 10, 1983 (MN-83-232)
(c) MYAPCo Letter to USNRC dated January 25, 1985 (MN-85-14)
Additional Information Regarding Generic Letter 83-28 (d) U3NRC Letter to MYAPCo. dated April 19, 1985, Request for Additional Information following Preliminary Staff Review of Licensee Responses to Generic Letter 83-28
Subject:
Generic Letter 83-28, Items 4.5.2 and 4.5.3 Gentlemen:
In Reference (d), you requested that Maine Yankee submit additional information on several items in Generic Letter 83-28.
This letter is in response to Items 4.5.2 and 4.5.3, the other questions will be dealt with in a separate communication.
Item 4.5.2 Maine Yankee was one of the first plants to undertake on-line testing for both the undervoltage and shunt trip devices. We have been doing such testing since late 1983. By use of existing slide links and a detailed procedure (submitted as an attachment to Reference [c]), we have been able to independently time test the shunt trip and undervoltage devices. We originally believed a design change would be required, however this proved not to be necessary, and your request for details of the design change are not applicable.
We have been actively involved in the CE Owner's Group RTB Subcommittee and currently (as indicated to the NRC at a meeting in 1984) are providing the results of this testing to CE for assessment and trending.
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United States Nuclear Regulatory Commission MN-85-110 Mr. James R. Miller, Chief Page Two Item 4.5.3 With regard to the matter of test frequency, we currently carry out functional tests of the RTB's monthly as required by our Technical Specifications.
In addition, the undervoltage trip is time tested on a quarterly basis and the shunt trip is time tested each refueling.
Given our current, improved understanding of the basic underlying cause of slow response time of the undervoltage device (that of hardening of the grease in the trip shaft bearings and latch roller bearing), the fact that Maine Yankee has refurbished or replaced all of our trip breakers, and the fact that we are involved in a data gathering program with other CE-NSSS owners, the prospect of freezing test intervals (other than the monthly functional test) in Technical Specifications is premature.
As indicated above, Maine Yankee has diligently pursued resolution of problems and questions associated with the Reactor Trip Breakers. We feel confident that we understand the cause of the earlier slow breaker opening times and we are confident that the RTBs will function properly when called upon.
As previously noted in Reference (d), Maine Yankee intends to reassess our undervoltage time test frequency as we near the end of Cycle 8.
Based upon the data collected during this cycle, it is our plan to increase the interval to a semi-annual test. We will continue to perform time tests prior to start-up following refueling.
If you are in need of any additional information, please feel free to contact us.
Very truly yours, MAINE YANKEE ATOMIC POWER COWANY bh AY G. D. Whittler, Manager Nuclear Engineering & Licensing GDW/bjp cc: Dr. Thomas E. Murley Mr. Cornelius F. Holden 3623L-FWS t