05000298/LER-1981-005, Forwards LER 81-005/03L-0.Detailed Event Analysis Submitted

From kanterella
(Redirected from ML20004C351)
Jump to navigation Jump to search
Forwards LER 81-005/03L-0.Detailed Event Analysis Submitted
ML20004C351
Person / Time
Site: Cooper Entergy icon.png
Issue date: 04/16/1981
From: Lessor L
NEBRASKA PUBLIC POWER DISTRICT
To: Seyfrit K
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20004C352 List:
References
CN55810222, NUDOCS 8106030233
Download: ML20004C351 (2)


LER-1981-005, Forwards LER 81-005/03L-0.Detailed Event Analysis Submitted
Event date:
Report date:
2981981005R00 - NRC Website

text

.

M

/

Coof ER NUCLEAR STATaoN 9

Nebraska Public Power District "A"E, 3 R M Gh"."^A" "

CNS 10222

.R April 16, 1981

$'\\

Sh

  • y k'

!Y,., ~ '> n ~

^ '

Mr. K. V. Seyfrit, Director 3LU

.\\%

d U.S. Nuclear Regulatory Commission

/ /4 10ffice of Inspection and Enforcement D

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 was discovered on March 20, 1981. A licensee event report form is also enclosed.

Report No.:

50-298-81-25 Report Date:

April 16, 1981 Occurrence Date: March 20, 1981 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which lead to operation in a degraded mode permitted by the limiting condition for operation established in Section 3.12.B.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was operating at a steady state power level approx-imately 95% of rated thermal power.

Description of Occurrence:

During Surveillance Procedure S.P. 6.3.16.3, Reactor Building Closed Cooling Water pump 1D tripped when started.

Designation of Apparent Cause of Occurrence:

A minimally sized fuse was installed in the control circuit of RBCCW pump 1D.

003 s

ll 8106080 N s

r m

v+--e

' - =

.r r

~

Mr. K. V. Seyfrit April 16,-1981-Page 2.

l-k

' Analysis of Occurrence:

l The Reactor Building Closed'Coolir.g Water. System (RBCCW) consists l

of 'two independent closed loups. = It:is designed with sufficient l

' redundancy so_that no single active system component failure nor any single active component failure in any other plant-sys tem can i

- Prevent it from achieving its safety objective. Each loop has two

[-

pumps discharging to one reactor building cooling water heat ex-changer. The two Toops can be' interconnected through crosstie equipped with isolation valves..Either: reactor building closed cooling water loop has sufficient capacity with one puni operating to transfer the essential services design cooling load-during-postulated-transient or accident conditions.

Each-RBCCW pump'has a size 4 motor-starter protected by a control power fuse.. The undersized control power fuse (3 amp) blew when

. pump,.lD was started,which made' the pump inoperable for about 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. 'The subject motor starters were initially supplied with a 4 amp style AB fuse. The AB style fuse has been discontinued by the fuse manufacturer and style ABC has been supplied. Style ABC is available in 1, 2,-3, 5, 6,..

20 amp capacity. It is apparent that the original 4. amp style AB fuse had been replaced with a 3 any style ABC fuse. This was'a conservative action however and the 3 amp fuse on occasion failed during the instantaneous control circuit in-rush current during' motor starter actuation.

Redundant systems were available and operable. This occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action

A spare size 4 motor starter was bench tested, its in-rush current measured, and was found to be the same as the measured in-rush current on the subject matcr starter.

Based on the motor starter manufacturer recommendation and a revised fuse specification sheet, a 5 amp control power fuse was specified'for installation in the subject size 4 motor starter. Control power fuses in all size 4 motor starters for ECCS components were checked and undersized fuses replaced. Equipment history did not reveal similar problems with control fuses in sizes 1, 2, & 3 motor starters for ECCS equipment.

Sincerely, L. C. Lessor

' Station Superintendent Cooper Nuclear Station LCL:cg Attach.

- r.

,,,.,,,,,,...,,......,_..w,,,,...mw

-, y