ML20210Q557

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Forwards Rev 0 to Design Assessment of Dresden Units 2 & 3 Control Room Panel Mounting, in Response to 860403 Request. Background Info Re Discrepancy in Design Document & as-built Condition Discussed
ML20210Q557
Person / Time
Site: Dresden  Constellation icon.png
Issue date: 05/06/1986
From: Wojnarowski J
COMMONWEALTH EDISON CO.
To: James Keppler
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20210Q562 List:
References
1649K, NUDOCS 8605140137
Download: ML20210Q557 (2)


Text

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m; n Mr. James G. Keppler Idi Regional Administrator W U.S. Nuclear Regulatory Commission *M Region III 799 Roosevelt Road Glen Ellyn, IL 60137 subject: Dresden Station Units 2 and 3 Submittal of Control Room Panel Mounting Design Analysis and Evaluations NRC Docket Nos. 50-237 and 50-249 References (a): Dresden Station Licensee Event Report (LER)

No. 86-009-0.

(b): April 3, 1986 Telecon between NRC Region III (Danielson, Boyd, Landsman and Gavula),

Dresden Station, and Corporate Ceco (SNED, NSD).

Dear Mr. Keppler:

Enclosed for your information is a summary of the calculations which were recently used to redesign the mounting of the subject control panels. This information was requested by Region III during the referenced telecon.

Background:

A discrepancy between the design document (12E2161) and the as-built condition for control room panel mounting was identified. Specifically, the bolted connections indicated in the drawing between the floor anchored base channel and the cabinets did not exist. A look into the history on panel mounting was initiated to determine whether an alternate mounting method had previously been

evaluated and accepted (top supports, welds, etc.). On April 1, 1986, a formal walkdown of the control room panels was performed. The purpose of this walkdown was to determine if some positive anchorage existed.

8605140137 860506 t l PDR ADOCK 05000237 l PDR P '

MAY 91986 \

Mr. J. G. Keppler May 6, 1986 When it was confirmed that intentional positive anchorage was not present, and when the search into the history on panel mounting did not reveal the discrepancy had previously been identified and resolved, Dresden Unit 2 began an Lunediate and orderly shutdown. Dresden Unit 3 was in a refuel / maintenance outage, with all fuel removed from the vessel. Your staff was notified of this situation in the reference (b) telecon. Further information is provided in the reference (a) LER.

The corrective actions taken included bolting or welding of the control room panels to the floor supports. Additional supports, three lateral braces, were added to the Standby Gas Treatment Common Services panel. Corrective actions were completed for Unit 2 on April 5, 1986 prior to restarting the unit. Unit 3 fixes will be completed prior to fuel load.

A verification of the design adequacy was performed by analysis as described in the enclosure.

If you have any additional questions regarding this transmittal, please contact this office.

Very truly yours, s .

J. R. Wojnarowski Nuclear Licensing Administrator 1m cc: H. R. Denton - NRR R. A. Gilbert - NRR NRC Resident Inspector - Dresden 1649K

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