ML20151B801
| ML20151B801 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 04/05/1988 |
| From: | Whittier G Maine Yankee |
| To: | Wessman R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20151B804 | List: |
| References | |
| 9761L-RPJ, GDW-88-80, MN-88-37, NUDOCS 8804110278 | |
| Download: ML20151B801 (2) | |
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4 MaineYankee attet ettefacir soa uwe sm $m EDISON drive e AUGUSTA, MAINE 04330.(207) 622-4868 April 5, 1988 HN-88-37 GDH-88-80 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. Richard H. Nessman, Project Director I-3 Division of Reactor Projects I/II
References:
(a) License No. OPR-36 (Docket No. 50-309)
(b) Letter, G. D. Whittier (MYAPCo) to J. R. Miller (NRC),
"Maine Yankee Thermal Shield", MN-84-89, May 17, 1984.
(c) Letter, G. D. Whittler (MYAPCo) to J. R. Miller (NRC),
"1984 Refueling Outage Thermal Shield Repair Report",
MN-84-141 September 14, 1984.
Subject:
Maine Yankee Thermal Shield Status Update Gentlemen:
During the Cycle 7/8 scheduled refueling outage, Maine Yankee performed a comprehensive inspection and repair program on the thermal shield support structure. The details of that program and the results of the inspection are reported in Reference (c).
Coincident with the inspection and repair effort, Maine Yankee developed an enhanced thermal shleid monitoring program.
This program was initiated with the Cycle 8 startup and has been in operation since that time.
The most recent assessment of the thermal shield monitoring data from 1983 to present is provided for your information as an attachment to this letter.
This assessment concludes that the positioning of the thermal shield has not changed significantly from the repair work performed in 1984; that all radial positioning pins (upper and lower) are maintaining preload at hot full power conditions; and that the thermal shield support lugs have not experienced any degradation.
It is additionally noted that the existing thermal shield monitoring program is designed to give a significant advance warning of any loss of the thermal shield support function.
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1 MaineYankee United States Nuclear Regulatory Commission Page Two Attention: Mr. Richard H. Nessman, Project Director I-3 MN-88-37 Based on this assessment, Maine Yankee has decided that the next inspection of the thermal shield should be performed concurrently with the 10 year reactor vessel inservice inspection to be scheduled for 1990.
In Reference (b) we stated that we planned to reinspect the thermal shield no later than the 1989 refueling outage. However, because of the extended outage for 1987, the refueling outage orginally scheduled for 1989 will be delayed until 1990.
He believe this schedule is consistent with the intent of our earlier plans and is also justified based on continued excellent thermal shield performance.
Furthermore, we intend to advance our next reactor vessel inservice inspection from 1992 to 1990, thereby reducing total personnel radiation exposure.
He will continue to closely monitor the thermal shield positioning system integrity.
Should the monitoring program indicate a discernible loosening of the thermal shield to that approximating the pre 1984 condition, we would re-evaluate the thermal shield inspection schedule.
1 Maine Yankee believes this approach to be reasor.able in light of the current monitoring results and trends.
Please feel free to contact us if you should have any questions or comments.
Very truly yours, I
MAINE YANKEE k8W G. D. Whittier, Manager Nuclear Engineering and Licensing G0H/bjp Enclosure cc: Mr. Hilliam T. Russell Mr. Patrick H.
Sears 4
Mr. Cornelius F. Holden l
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