ML20030C201
| ML20030C201 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/19/1981 |
| From: | Parker W DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8108250511 | |
| Download: ML20030C201 (2) | |
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May 19, 1981 WCr Patsrotaev csj TELce.co t: Anta 704 373 4C83 S T Ca ne PmODuCTICao
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Q /, 7, Mr. James P. O'Reilly, Director
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Re: Oconee Nuclear Station b/ g 0',
j Docket Nos. 50-269, -270, -287 On May 7, 1981 your office was notified tnat a potentially reportable incident had occurred at Oconee. This incident concerned the adequacy of separation between the new spent fuel tack modules recently installed in the common spent fuel pool for Unita 1 and 2.
Since that time, a re-evaluation of the separation has been performed and Duke Power Company now considers that this incident is not reportable per the Oranee Technical Specifications. For your information, the following paragrapns provide
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a discussion of this incident.
Installation of the new Oconee spent fuel racks was performed between January and April, 1981.
Due to the "as-built" dimensional restrictions of the common spent fuel pool for Units 1 and 2, the rack modules were installed with a smaller " rack-to-rack" separation gap than had been previously considered, based upon design drawings of the pool. A review by Westinghouse, the manufacturer of the new racks, determined that installation of the racks with 0.75 inch separation between modules would be sufficient to preclude rack-to-rack interaction during a design seismic event.
l Subsequent review by Westinghouse, however, after completion of the rerack l
project, indicated that a minimum separation of 0.80 inch is required to I
assure that rack-co-rack impact does not occur during a seismic event.
By this time, spent fael had been loaded into the new racks, effectively making them " operable". Therefore, on May 6, 1981, Duke Power determined l
that the potentially insufficient separation of the modules should be l
reported to Region II of the NRC pursuant to Oconee Technical Specification 6.6.2.1.a(9) because licensing submittals made by Duke to support the approval of the reracking, as well as the NRC Safety Evaluation Report issued with the approval, implied that the racks would be in called such that impact between the racks would not occur during an earthquake.
On May 12, 1981, Duke requested Westinghouse to review their seismic analysis again to confirm the validity of the new 0.80 inch specification.
In parallel to this analytical effort, work was begun at Oconee to move all modules until a minimum spacing of 0.80 inch was achieved.
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May 19, 1981 Page 2 On May 14, 1981, Westinghouse reported to Duke that a rack-to-rack separation of 0.750 inch was acceptable for the Oconee spent fuel Based upon this finding, the racks were sufficiently separated at pool.
all times while loaded with fuel to preclude rack-to-rack interaction during an eartliquake, and Duke Power Company therefore does not consider this matter to be reportable pursuant to Oconee Technical Soecifications.
It should be noted that although the rack-to-rack spacing was questionable during this incident, the rack module-to-pool vali spacing was always sufficient to prevent rack-to-wall impact during an earthquake.
Additionally, the rack modules have now been shifted to a clear rack-to-rack spacing of 0.80 inch for an additional margin of safety.
Very truly yours, William O. Parker, Jr.
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