ML19209A330
| ML19209A330 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 08/29/1979 |
| From: | Ippolito T Office of Nuclear Reactor Regulation |
| To: | Berry G POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK |
| References | |
| NUDOCS 7910030613 | |
| Download: ML19209A330 (3) | |
Text
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August 29, 1979 Decket No. 50-333 Mr. George T. Berry General Manager and Chief Engineer Power Authority of the State of New York 10 Columbus Circle New York, New York 10019
Dear Mr. Berry:
The results of a geologic and rock mechanics investigation recently con-ducted at the Niagara Mohawk Corporation's Nine Mile Point Unit 2 site indicated that relatively high in-situ stresses existed in'the site bed-rock. These' stresses resulted in closure of the walls of newly opened excavations, and differential movements along bedding planes and fractures in the rock. This phenomenon is commonly known as rock squeeze.
Rock squeeze in the Lake Ontario region has been recognized in rock excava-tions for structures, quarries, and as having occurred naturally as pop-ups.
Rock wall closure in man made excavations ranges from a fraction of an inch up to the maximum known closure in the region, which is 9 inches in a bridge abutment at Lockport, New York. The Nine Mile Point, Unit 2 was designed to accommodate up to 12 inches of rock excavation closure, based on a study of case histories in the region and the rock mechanics investigations at the site.
To our knowledge this subject has not been addressed by the Power Authority of the State of New York in any of the fomal submissions to the NRC.
Therefore, you are requested to demonstrate that the high residual stresses that are known to exist at the site do not represent a hazard to the Category I structures and facilities of the FitzPatrick plant. This should be accom-plished by answering the following questions and by adding any additional information that supports that conclusion:
1.
Describe the extent to which plant Category I structures and components were designed and constructed to accommodate high bedrock stresses.
What were the bases for this design if such was taken into account?
If not, what were the bases for not designing for high rock stresses?
2.
Other than the tepee fold found in the turbine building excavation, have there been any other indications of deformations encountered that could be attributed to rock squeeze, such as cracked walls, floors, or foundations, floor heave, etc.
1085 198 7910080 pg g
Mr. George T. Berry August 29, 1979 3.
Has PASNY conducted any program at the site to monitor rock movements?
If so, provide the results.
4.
A minor fault was discovered in the drainage ditch on the boundary between the Niagara Mohawk and PASNY properties.
It is believed that this fault is a continuation of the tepee fold beneath the turbine building.
Evidence indicates minor adjustments have occurred on that fault within the last 12,000 years.
Data also suggest that minor adjustments are possible in the future due to the presence of high bedrock stresses.
Do any Category I structures or components overlie this feature? If so, evaluate the effects of possible future adjust-ments along this feature on those Category I structures which are inter-sected by it.
Niagara Mohawk Power Corporation has also been requested to respond to questions concerning this subject.
Therefore, we recommend that PASNY and Niagara Mohawk consult with each other about their respective findings.
Please advise if we can be of further assistance.
Sincerely,
/I
,M Thomas ' Ippolito, Chief Operating Reactors Branch #3 Division of Operating Reactors cc:
See next page 1085 199
Mr. George T. Berry Power Authority of the State August 29, 1979 of New York
-3 cc:
Mr. Vito J. Cassan Assistant General Counsel Po.ver Authority of the State of New York 10 Columbus Circle New York, New York 10019 Mr. Peter W. Lyon Manager - Nuclear Operations Power Authority of the State of New York 10 Columbus Circle New York, New York 10019 Mr. J. D. Leonard, Jr.
Resident Manager James A. FitzPatrick Nuclear Power Plant P. O. Box 41 Lycoming, New York 13093 Director, Technical Development Programs State of New York Energy Office Agency Building 2 Empire State Plaza Albany, New York 12223 Oswego County Office Building 46 E. Bridge Street Oswego, New York 13126 George M. Wilverding, Licensing Supervisor Power Authority of the State of New York 10 Columbus Circle New York, New York 10019 1085 200
.