05000277/LER-1981-025, Forwards LER 81-025/01T-0.Detailed Event Analysis Submitted

Forwards LER 81-025/01T-0.Detailed Event Analysis Submitted

ML20003H291
Person / Time
Site:	Peach Bottom
Issue date:	04/24/1981
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20003H292	List: 05000277/LER-1981-025, Forwards LER 81-025/01T-0.Detailed Event Analysis Submitted 05000277/LER-1981-025-01, /01T-0:on 810413,seismic Analysis of Torus to Reactor Bldg Vacuum Breaker Valves Revealed That Valve Operator Mounting Brackets Did Not Meet Seismic Requirement. Valve AO-2502B Upgraded by Addition of Snubber
References
NUDOCS 8105050493
Download: ML20003H291 (3)

LER-1981-025, Forwards LER 81-025/01T-0.Detailed Event Analysis Submitted

Event date:
Report date:
2771981025R00 - NRC Website

text

.

t7 PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET v

.i P.O. BOX 8699 PHILADELPHI A. PA.19101

/

1881 -198 4

..,~,.

s (2isi e4i.4ooo

/. 'y [',,j j q-/,s Q.

L. f,,,M,j j j ) K.,;

u' '. -

%u,,..q

' 0.: yAl % l:'

'Q u,;p:q c

'n -i.

Aoril 24, 198*

...:w -

for. Bo yce H. Grier, Director Office of Inspection and En forcem ent Region I US Nuclear Regulatory Commission 631 Park Avenue Kin 6 of Prussia, PA 19406

SUBJECT:

LICENSEE EVENT REPORT MARRATIVE DESCRIPTION

Dear Mr. Crier:

The following w..

reported to Mr. C. Co wgill, Region I, Office of Inspection and E.Torcenent on April 13, 1981.

Reference:

Docket No. 50-277 Report Io.:

2-81-25 /1T Report Date:

April 24, 1931 Occurrence Date:

April 13, 1981 Facility:

Peach Bottom Atomic Power Station RD #1, Delta, PA 17314 Technical Specification Reference:

Tecnnical Specification 6.9.2.a(9) requires prompt reporting of "Per form ance of structures, systems, or components that require remedial action on corrective measures to prevent operation in a manner less conservative than assumed in the accident analysis in the safety analysis report or Technical Specification that require remedial action or corrective measures to prevent the existence or development of an unsafe condition."

Technical Specification 3.7. A.3 governs the Reactor Beilding to pressure suppression chamber (torus) vacuum breaker.

In particular, 3. 7. A. 3.b permits operation for seven days with one vacuum breaker inoperable.

00 3 S

/ I 8105050I'73 p

I Page 2 Description of the Event Peach Bottom site personnel were informed on April 13, 1981, by

[

the Engineering Department, that a seismic analysis of the i

Reactor Building to Torus vacuum breakers ( AO-2502 A and B) revealed that the mounting brackets for the air operators did not meet the Design Basis Earthquake (DSE) requirements.

The results of the analysis were that the brackets could i

withstand 0.8g acceleration.

The DBE requirement is 1.21g whereas and Operating Basis Earthquake (OBE) wo uld subject this bracket to 0.5g acceleration.

The redundant, 100% capacity, vacuum breakers are provided to protect containment from collapse during a negative pressure event.

These normally closed valves automatically open when the containment pressure reaches minus 0.5 + 0.25 psig.

The normal operating pressure for containment is plus 0.3 + 0.25 psig.

The 3

containment can become negative only during purging operations or following a LOCA which requires the use of the manually initiated containment spray system.

i Probable Consequence of the Occurrence The analysis shows that the valves would function properly up to an acceleration of 0.8g.

This represents a 60% margin over the OBE accelerations.

Greater accelerations may result in failure of the bracket, however, the final position of the valve (open or closed) is indeterminant.

Failure of the bracket would preclude actuation of the valve.

In addition, purging is not permitted during operations and the likelihood of a LOCA occurring which requires the use of containment spray is low.

i

cause of the Event

The valve operator brackets were not designed to meet the seismic-j requirements.

I I

Immediate Corrective Actions

A temporary amendment to Technical Specification 3.7. A.3.b was applied for and granted which permitted continued operation with both valves in the degraded condition until 5: 00 p.m. EST on April 20, 1981.

Provided that one valve was operational by this time, continued operation was permitted until 5: 00 p.m.

EDT on April 27, 1981.

One of the valves ( AO-25028) was seismically upgraded by the installation of a snubber on April 18, 1931.

Page 3 Future Corrective Actions Upgrading of the second valve ( AO-2502A) requires the installation of a snubber and inodification to the support system.

The Unit was removed from service for other reasons, on April 22, 1981.

The required upgrading will be completed prior to the startup o f the Unit.

Very truly yours,

h 97/TC M.

J. Cooney Superintendent Generation Division - Nuclear Attachment cc: Director, NRC - Of fice of Inspection and Enforce:nent Mr. Norman M.

Haller, NRC - Office of Management &

Pro ram Analysis t

I 4

L I

a l