ML20009G853

LER 81-009/01T-0:on 810714,per IE Bulletin 80-11 Analyses, Contractor Reported That Four Control Room & Two Battery Room Walls Did Not Meet Revised Criteria for Seismic Event. Caused by Reanalysis Per Revisions.Supports Installed

ML20009G853
Person / Time
Site:	Point Beach
Issue date:	07/28/1981
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20009G852	List: ML20009G851 ML20009G853
References
IEB-80-11, LER-81-009-01T, LER-81-9-1T, TAC-42896, TAC-42897, NUDOCS 8108050149
Download: ML20009G853 (3)

Text

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LICENSEE EVENT REPORT CONTROL BLOCX: l l l l l l l PLE ASE PRINT OR 1YPE ALL REQUIRED INFORMATiON) i e jo Jid j 9lWl Il ~4NSEE 7

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REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h ITiTl l On 7/14/81 Licensee received information from the contractor conducting l

,g;3, ;IEB 80-11 " Masonry Block Nalls" analyses that stresses in four walls in g ;the control room and two walls in the battery room would exceed the ig,,, ; revised acceptance criteria in the event of an SSE. Failure of these lO l6 l l Walls Could impact safety related equipment including the plant bat-g ;teries, electrical distribution panels, and control boards.This event is

,g,g, , reportable under T.S. 15.6.9.2.A.9.

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Attachment to Licensee Event Report No. 81-009/0lT-0 Wisconsin Electric Power Company Point Beach Nuclear Plant, Units 1 and 2 Docket Nos. 50-266 and 50-301 During the afternoon of July 15, 1981, the Wisconsin Electric Power Company Nuclear Engineering Safety Review Committee met to consider information received on July 14, 1981 from the Bechtel Power Corporation regarding the investi-gation of masonry block walls at the Point Beach Nuclear Plant.

! Bechtel has been retained by Wisconsin Electric to conduct masonry wall investigations and analyses in accordance with the require-ments of IE Bulletin 80-11. On July 14, 1981 Bechtel reported by telephone that their analyses of several of the walls in the Point Beach Nuclear Plant control room and battery rooms indicated that in the event of an SSE stresses in these walls exceeded the revised acceptance criteria stress limits as established during the meeting between Licensee and the NRC Staff on June 9-11, 1981. These walls are identified as wall numbers 19 and 20 in the battery room and walls 111-1, ill-3N, 113, and 114 in the control room.

' Details of the wall locations and the proposed corrective modifications were provided to the NRC in Licensee's letter to Mr. Denton dated July 17, 1981. These modifications include installation of positive shear transfer mechanisms (clip angles) along the wall boundaries and upgrading with structural steel l supports to relieve the flexural tension overstress. Block wall 20, the north-south divider wall in the battery room, has already been modified to eliminate the SSE-induced overstress condition.

Modifications to the remaining walls will be completed in October 1981.

On July 15, 1981, the Wiscon sin Electric Nuclear Engineering Safety Review Committee evaluated this information and determined that continued operation of the Point Beach Nuclear Plant pending modifications to these walls was justified.

This determination was based on the following considerations:

For walls 19 and 20 the degree of SSE overstress l indicated by the analysis was small with respect to the factor of safety of approximately four between the stress allowed by the acceptance criteria and the ultimate strength.

The remaining walls, 111-1, lll-3N, 113, and 114 had higher SSE overstress conditions; however, it was concluded that a failure of these walls would noc preclude the ability of plant personnel to safel shut down the plant using the remote shut-down panels as necesrz,ry. It was further observed that the I

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Point Beach Nuclear Plant is located in a relatively inactive earthquake area and the probability of seismic activity with ground accelerations equaling the SSE design for the plant within the three months necessary to complete the wall modi-fications is exceedingly remote.

This event is reportable in accordance with Technical Specification 15.6.9.2.A.9.

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