ML19322A598
| ML19322A598 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/05/1977 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 7911210677 | |
| Download: ML19322A598 (4) | |
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Duke Power % v ATTN: Mr. William O. Parker Jr.n ORD Yice Pmsident - Stoast Production OI&E (3)-
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VStello Gentlemen:
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On February 15, 1977. a meeting was held in which you and Babcoct &
Wilcox provided the status of the recent steam generator tube led problems at the Oconee Nuclear Station. During and subsequent to the meeting, we identified certain information which we need to help us assess the Oconee Once-Through Steam Generator tube leak-occurrences and potential safety problems.
It is requested that you provide the infomation requested within 30 days of receipt of this letter.- '
Sincerely.
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A. Schwencer, Chief-Operating Reactors Branch 01 Olvision of Operating Reactors Enclosures
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Request for Additional. '
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s Duke Power Company April 5, 1977 cc:
Mr. William L. Porter Duke Power Company P. O. Box 2178 422 South Church Street Charlotte, North Carolina 28242 J. Michael McGarry, III, Esquire DeBevoise & Liberman 700 Shoreham Building 806-15th Street, NW.,
Washington, D.C.
20005 Oconee Public Library 201 South Spring Street Walhalla, South Carolina 29691 1
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,.s REQUEST FOR ADDITIONAL INFORMATION RELATED TO OCONEE STEAM GENERATORS 1.
It was stated during the meeting on February 15, 1977, that defective and plugged tubes were stabilized down to the top support plate if the defect was found near the top tube sheet.
Assess the consequence of po:sible failures of these defective tubes at lower or un-stabilized sections.
2.
Provide a re-evaluation of past ECT records to show whether or not there were tube defects that might have led to initiation of tube cracking.
3.
Due to failure in all the affected units at nearly the same point in time, indicate any change in operating procedures or other possible incidents that might have led to tube failures in Oconee steam generators.
4.
Indicate any plan to perform ECT examinations of periphery tubes.
5.
Provide analytical calculati6ns and/or tests to justify that the crack length, in the circumferential directions, associated with the proposed leakage rate will not increase in an unstable fashion under normal operating and accident conditions.
6.
During the rece
.g with the NRC staff, it was indicated that there is 0.4% -
.aur content in the sediment depos ts.
Provide i
an assessment on the effect of the high sulphur content to the tubes in terms of possible chemical reactions.
7.
Provide the micro-hardness test results of both virgin and cracked tubes to determine any evidence of plastic cyclic straining that may initiate the cracks.
8.
Provide accident consequence analyses assuming:
a.
A certain number of tube failures, that can be tolerated, concurrent with a LOCA.
b.
The equivalent number of tubes failures that can be tolerated during a MSLB in terms of off site dosage.
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Provide analytical and/or test data to assure tube integrity by demonstrating the capability of degraded tubes (circumferential1y partial cracked tubes) to withstand accident induced loads.
NRC's positions on this matter were delineated in Regulatory Guide 1.121 which was published for comment in August 1976.
10.
Indicate B&W's on-going and planned future programs associated with tube failure, i.e., tests on mechanical strengths and fatigue strengths of degraded tubes.
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