ML19344E054

Forwards LER 80-022/03L-0

ML19344E054
Person / Time
Site:	Cooper
Issue date:	07/22/1980
From:	Lessor L WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19344E055	List: ML19344E054 ML19344E072
References
CNSS800450, NUDOCS 8008260561
Download: ML19344E054 (2)

Text

COOPER NUCLEAR STATBoN Nebraska Public Power District "' "

• 1"E" o*"J'hi"f *".T^ "'"

CNSS800450 July 22, 1980 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection' and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.2 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that w'as discovered on June 29, 1980. A licensee event report form is also enclosed.

Report Nc.: 50-298-80-22 Report Date: July 22, 1980 Occurrence Date: June 29, 1980 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 s

Identification of Occurrence:

Conditions leading to operation in a degraded mode permitted by a limiting condition for operation as delineated in Section 3.7.D of the Technical Specifications.

Conditions Prior to Occurrence:

Steady state power operation at approximately 99% reactor power.

Description of Occurrence:

During routine discharge of water from the Residual Heat Removal System (RRR) to radwaste, the inboard throttle isolation valve (RHR-MO-57) failed to close either remotely or manually.

Designation of Apparent Cause of Occurrence:

The subject 4", 300#, motorized, globe valve was disassembled to determine the cause of the occurrence. Upon disassembly the valve seat, which is screwed into the body of the valve, had become unthreaded from the body and had lodged itself between the disc and body so that the valve disc could not move. Normally, the close fit of the threads is sufficient so that the seat does not work f (76[1 itself free; however, in this case system vibration was sufficient s to produce the failure.

//)/

8e0s20o Sq

Mr. K. V. Seyfrit July 22, 1980 Page 2.

Analysis of Occurrence:

As described, RHR-MO-57 is the inboard throttle isolation on the RHR drain to radwaste. Upstream of RHR-MO-57 is RER-MO-67 which is the outboard isolation valve which was operable. In the event the valves had received an isolation signal RHR-MO-67 would have closed.

This occurrence presented no adverse consequences from the stand-point of public health and safety.

Corrective Action:

Immediate action upon identification of occurrence was to tag shut RER-MO-67 in accordance with the Technical Specifications. The damaged seat was removed and a new seat was installed. To prevent recurrence, the seat was tack welded into place.

Sincerely,

,,cM : -)

((. .

L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.

, , , , , --,-<gm-c- -

.mr-- y m-e