05000321/LER-1980-115-01, /01T-0:on 801031,util Notified That Nine Masonry Block Walls in Control Bldg Show Local Stresses Above Allowable Codes.Caused by Equipment Mounted on Walls After Original Installation.Walls Will Be Reinforced

/01T-0:on 801031,util Notified That Nine Masonry Block Walls in Control Bldg Show Local Stresses Above Allowable Codes.Caused by Equipment Mounted on Walls After Original Installation.Walls Will Be Reinforced

ML19339C773
Person / Time
Site:	Hatch
Issue date:	11/11/1980
From:	Coggin C GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19339C771	List: 05000321/LER-1980-115, Forwards LER 80-115/01T-0 05000321/LER-1980-115-01, /01T-0:on 801031,util Notified That Nine Masonry Block Walls in Control Bldg Show Local Stresses Above Allowable Codes.Caused by Equipment Mounted on Walls After Original Installation.Walls Will Be Reinforced
References
LER-80-115-01T, LER-80-115-1T, NUDOCS 8011190422
Download: ML19339C773 (2)

LER-1980-115, /01T-0:on 801031,util Notified That Nine Masonry Block Walls in Control Bldg Show Local Stresses Above Allowable Codes.Caused by Equipment Mounted on Walls After Original Installation.Walls Will Be Reinforced

Event date:
Report date:
3211980115R01 - NRC Website

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DOCKET NUMBER ES 89 E 'ENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION ANO PROBABLE CONSEouENCES h l o 2 On 10-31-80, with the Unit 2 reactor in told shutdown and the Unit 1 1

g Ireactor in normal power operation at 630 MWe, the plant was notified byI loTTl I CSI that 9 masonry block' walls in the Plant Hatch control building show 1 S

F5Tsl llocal stresses above code allowables during an OBE and/or DBE.

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Iols]loverstressed condition was determined in the process of responding to 1

o 7 lIEB 80-11.

This is a nonrapetitive occurrence.

There were no effects 1

1 [5Til ion public health and safety.

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lio lThese stresses were caused by equipment mounted on the walls after theirl l lTTTl I ori oi nal installation.

A complete and specific report was submitted toI Ithe NRC by GPCo on Tuesday, 11-4-80.

In that recort it was determined i

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50-321/1980-115 Licensee:

Georgia Power Company Facility Name:

Edwin I.

Hatch Docket #:

50-321

Narrative

Report for LER 50-321/1980-115 On 10-31-80, with the Unit 2 reactor in cold shutdown and the Unit I reactor in normal power operation at 630 MWe, the plant was notified by SCSI that 9 walls in. the Plant Hatch control building show local stresses above code allowables during an OBE and/or a DBE.

In responae to IEB 80-11, SCSI surveyed a total of 166 walls.

64 of these required no reevaluation because they were constructed of

concrete, had no safety-related equipment attached or in the immediate proximity, or were adequately supported by external steel frames.

Of the 102 remaining walls requiring reevaluation, 93 were shown to require no modification.

Modifications to the remaining 9

walls will be c om'pl e t e d as soon as design and materials are available.

This is a nonrepetitive occurrence.

There were no effects on public health or safety.

ca' sed by equipment mounted on the walls These stresses were u

after original installation of the walls.

A complete and specific report was submitted by GPCo to the NRC on 11-4-80.

It was determined that these walls would not fail during an OBE and/or DBE by the following consid' rations:

e 1.

The overstress condition identified is a

localized condition only.

2.

The overstress condition is based on code (HCI-531-79) allowables, not material yield stresses or ultimate stresses.

3.

As local yielding takes place, the wall will lose some of its ability to carry load at the point of local yielding, and the stresses will be distributed to adjacent elements via the reinforcing and masonry, thus spreading out loads.

4.

If local cracking develops in the masonry during an earthquake, the wall loses its ability to transmit stresses across the discontinuity of the crack; therefore, dampening is increased and earthquake forces are not as readily transmitted throughout the wall.

5.

The maximum wall displacement expected due to this overstressed condition during an earthquake is less than

.5";

therefore, the integrity of conduits and cable trays on or in the vicinity of the wall wi,11 not be affected.

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The 9

walls will be reinforced tuch that they meet code (HCI-531-79) allowable stresses as soon as design and materials are a'vailable, t