ML20214L089
| ML20214L089 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/04/1986 |
| From: | Whittier G Maine Yankee |
| To: | Thadani A Office of Nuclear Reactor Regulation |
| References | |
| 8028L, 8028L-GDW, GDW-86-206, MN-86-114, NUDOCS 8609090299 | |
| Download: ML20214L089 (2) | |
Text
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l MAIRE HARHEE ATOMICPOWERCOMPARUe
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September 4, 1986 HN-86-114 GDH-86-206 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Hashington, D. C.
20555 Attention:
Mr. Ashok C. Thadani, Director PHR Project Directorate #8 Division of Licensing
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) MYAPCo Letter to USNRC dated May 12, 1986 (MN-86-64 (c) USNRC Letter to MYAPCo dated July 21, 1986
Subject:
Reactor Coolant Pump Shaft Integrity Gentlemen:
This letter is in response to Reference (c) which requested additional information concerning Maine Yankee reactor coolant pump shafts. As noted in Reference (b), Maine Yankee has been closely monitoring industry experience and developments associated with reactor coolant pump shafts with a similar design to Maine Yankee.
He have reviewed our safety evaluation of RCP shaft integrity which was submitted in Reference (b) in light of more recent information. He have determined that our conclusions regarding the safety significance of this issue continue to be valid.
As noted in Reference (b), the design of Maine Yankee's RCP impeller bolting differs significantly from Crystal River and Davis Besse designs.
The eight-bolt design employed at Maine Yankee, vs. four bolts at Crystal River and Davis Besse, provides a much tighter impeller to shaft connection which results in significantly less cyclic stress applied to the bolts.
He believe these differences reduce the likelihood of cracking similar to that experienced at these other facilities.
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l MAINE YANKEE ATOMIC POWER COMPANY United States Nuclear Regulatory Commission Page Two Attention: Mr. Ashok C. Thadani, Director MN-86-ll4 Maine Yankee has implemented a program of replacing a reactor coolant pump motor each refueling, and refurbishing the removed motor during the following operating cycle. He are currently planning to expand this program to include the reactor coolant pump rotating assembly beginning with the next refueling outage. This program will continue until each RCP motor and rotating assembly have been refurbished. During the replacement, the portions of the pump not being replaced would be visually inspected. During the following operating cycle, the removed rotating assembly will be decontaminated, inspected and refurbished as necessary.
Should additional industry experience prior to the refueling (scheduled for April 1,1987) indicate that our pumps are more susceptible to failure, we will revise our program accordingly.
Please feel free to contact me if you should have any questions in this matter.
Very truly yours, MAINE YANKEE ATOMIC P0HER COMPANY MW G. D. Whittier, Manager Nuclear Engineering and Licensing GDH/bjp cc: Dr. Thomas E. Murley Mr. Pat Sears Mr. Corntlius F. Holden 8028L-G0H
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