ML20077J489
| ML20077J489 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 08/10/1983 |
| From: | William Jones OMAHA PUBLIC POWER DISTRICT |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| LIC-83-190, NUDOCS 8308160451 | |
| Download: ML20077J489 (3) | |
Text
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1 Omaha Public Power District 1623 Harney Omaha. Nebroska 68102 402/536-4000 August 10, 1983 LIC-83-190 Mr. Robert A.
Clark, Chief U.
S.
Nuclear Regula tory Commission Office of Nuclear Reactor Regulation Division of T. i c e n s i ng Operating Reactors Branch No. 3 Washington, D.C.
20555
References:
(1)
Docket No. 50-285 (2)
Letter (LIC-83-103) to R.
A.
Clark from W.
C. Jones dated April 26, 1983 (3)
Letter (LIC-83-146) to R.
A.
Clark from W.
C.
Jones dated June 17, 1983 (4)
Letter (LIC-83-189) to R.
A.
Clark from W.
C.
Jones dated August 2, 1983
Dear Mr. Clark:
Reactor Pressure Vessel Thermal Shield In the above referenced letters, the Omaha Public Power Dis-trict provided information on the Fort Calhoun Station's re-actor vessel thermal shield (RVTS).
This information in-cluded the results of inspections of the thermal shield, sup-ports, and positioning pins which were completed during the 1983 refueling outage.
These inspections were performed by j
qualified inspectors from Southwest Research Institute, Com-l bustion Engineering, and the Omaha Public Power District.
These inspections verified the structural integrity of the RVTS and supporting hardware after almost ten years of ser-vice.
Reference (4) provided the findings of a safety analysis of the effects of a dropped thermal shield.
This safety analy-sis indicates that no significant safety hazards exist in the event the thermal shield failed, as discussed in the referenced analysis.
The results of the inspections and safety analysis refer-enced above provide the basis for the District's position that no significant safety concerns currently exist for the Port Calhoun Station's RVTS.
flool 9309160451 830810 ds s'24 PDR ADOCK 05000205 iment wim Equal opponunity
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PDR Male Female
Mr. Robert A.
Clark LIC-83-190 Page Two The District is aware of and has been following, via the Fort Calhoun Station's NSSS vendor (Combustion Engineering, Inc.), the thermal shield problems at other utilities.
The identification of the causes of these thermal shield failures is of concern to the District.
Measures are being taken to obtain the available information on these failures, and the applicability of this information to the Fort Calhoun Station's RVTS will be assessed.
While determi-nation of the causes of these failures is underway, the District is taking the following actions to assure the continued integrity of the Fort Calhoun Station's RVTS.
Since the RVTS inspection at the Fort Calhoun Station, ad-ditional information has become available regarding the spe-cific areas of the RVTS experiencing problems at other utili-ties.
The District has initiated with Combustion Engineer-ing, Inc. a more detailed review of the video tapes from the 1983 Fort Calhoun Station RVTS inspection.
Particular at-tention will be directed toward those areas of the RVTS ex-periencing failures at other utilities.
It is expected that this review will be completed by October 15, 1983.
The re-sults of this review be factored into the District's plans on future activities regarding the RVTS.
Since the removal of the RVTS for inspection involves a major effort including personnel radiation exposures, ex-posure of the RVTS to damage during removal and instal-lation, and results in at least a two-week extension to the plant critical path outage time, the District is exploring other methods of performing inspections on critical portions of the RVTS.
RVTS inspection using boroscopic or fiber-optical devices through the penetrations in the core barrel flange near the reactor surveillance capsule penetrations will be assessed.
It is the District's plans to have this assessment completed on a schedule which would provide.ade-quate time to prepare for an inspection during the 1984 re-fueling outage, if it is determined that such an inspection is necessary.
l The District is also evaluating the need, cost, and benefit of upgrading the existing reactor vessel loose parts monitor-ing system.
This evaluation will include other elements of the District's activities regarding the RVTS.
This evalu-ation is scheduled to be completed by October 15, 1983.
Mr. Robert A. Clark LIC-83-190 Page Three The District fully recognizes the importance of assuring the Jintegrity of the Fort Calhoun Station's reactor vessel thermal shield.
The actions which have been taken, coupled with the comprehensive program discussed above, will provide assurance that this integrity is maintained.
Sincerely, EA h
W.
C.
Jones Division Manager Production Operations WCJ/KJM:jmm cc:
LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, D.C.
20036 Mr.
E. G. Tourigny, Project Manager Mr.
L.
A. Yandell, Senior Resident Inspector
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