ML20079P175
| ML20079P175 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 02/28/1983 |
| From: | Harrington W BOSTON EDISON CO. |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| 83-58, NUDOCS 8303040548 | |
| Download: ML20079P175 (2) | |
Text
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BOSTON EDISON COMPANY 500 BOYLSTON STREET -
BOSTON. MASSACHUSETTS D2199 U.'.,'.'.* *.I ".^."."U *' "
February 28, 1983 a5=
BECo Letter No. 83-58 Mr. Domenic B. Vassallo, Chief Operating Reactors Branch #2 Division of. Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 License No. DPR-35 Docket No. 50-293
Subject:
Aerial Surveillance of Main Breakwater
Reference:
NRC letter dated February 3,1981, from Mr. T. A. Ippolito to Mr. A.V.
Morisi
Dear Sir:
In the Reference, the NRC accepted Boston Edison's method of adopting an NRC recommendation to employ a photographic survey, both ground-based and aerial, to monitor the structural integrity of the main breakwater at Pilgrim Station.
A Baseline photographic surveillance was established by BECo in 1981, and subse-quent photographic surveillance data can be compared to the 1981 Baseline to detect any major damage to the Breakwater or movement of the stones along it.
A comparison and assessment of the data conveyed in the 1981 and 1982 photographs, and the photographic techniques used, indicates the following:
(a) That aerial photographs only provide an inventory of surface features (general configuration or geometry).
Unless there is a discontinuity in the Main Breakwater that results in the complete severing of the structure, that is, the breakwater is no longer a monolithic structure when viewed in plan, there is no additional information concerning the structural integ-rity provided by aerial photography.
(b) That the ground-based photographs indicate the position of each visible leeward stone along the length of the Main Breakwater.
Survey data that defines the land-based camera locations relative to the benchmarks along the Main Breakwater is also provided.
As a result, any shift in the general configuration (displacement in the horizontal plane) of the structure can be identified by comparison to previous survey data without the need for an aerial survey.
/]OO/
8303040548 830228 yDRADOCK 05000293 PDR
ECCTON EDCON COMPANY Mr. Domenic B. Vassallo, Chief February 28, 1983 Page 2 We believe these findings demonstrate that a yearly aerial survey is not neces-sary, and is merely a time consuming way of acquiring redundant data.
- Instead, we propose that the aerial survey be conducted only when the need for it is demonstrated by one of the following criteria:
(a)
If severance in the breakwater is observed by "walkdown" inspections. These walkdowns shall be required prior to the initiation of the photographic survey.
(b)
If there is any substantial difference in the distance measured between fixed camera locations and the stations along the Main Breakwater for two consecutive years.
In this way, the aerial photograph will serve as a verification of existing adverse conditions, whether such conditions exist in the structure or the survey-ing technique, and will use the aerial photography in its most productive way.
Should such an aerial photograph be taken at anytime in the future, we will use the 1981 record as a basis for comparison.
We do not believe this change will reduce the effectiveness of our surveys to ensure the structural integrity of the breakwater.
We do believe, however, that this method will remove the most burdensome portion of the survey, and thereby allow the monitoring program to be conducted in a more expeditious fashion.
We currently plan to conduct the annual survey in April.
Please apprise us if this proposal is acceptable so that we may incorporate it into the survey.
We appreciate your attention to this proposal.
Should you require further information concerning this submittal, please contact us.
Very truly yours, l
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