05000298/LER-1981-002, Forwards LER 81-002/03L-0.Detailed Event Analysis Encl

Forwards LER 81-002/03L-0.Detailed Event Analysis Encl

ML20008F716
Person / Time
Site:	Cooper
Issue date:	03/13/1981
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20008F717	List: 05000298/LER-1981-002, Forwards LER 81-002/03L-0.Detailed Event Analysis Encl 05000298/LER-1981-002-03, /03L-0:on 810213,brass Filings Found in Oil Sump of Outboard Motor Bearing of RHR Svc Water Booster Pump. Caused by Loose Inboard Motor Fan & Set Screw.Fan Repaired & Second Set Screw Added
References
CNSS810146, NUDOCS 8104210531
Download: ML20008F716 (2)

LER-1981-002, Forwards LER 81-002/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2981981002R00 - NRC Website

text

- o-COOPER NUCLEAR STATION Nebraska Public Power District

• • " * "i"E" J/JM";"I,""^A" "

CNSS810146 March 13, 1981 cv et rg tt.

A r5 g *'

Q Mr. K. V. Seyfrit, Director U.S. Nuclear Regulatory Commission I-y *.

t/

Office of Inspect; ion and Enforcement O'-

D o.

/

\\

Region IV g/

g/

/.

611 Rjan Plaza Drive

%/TM \\/

Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in recordance with Section 6.7.2.B.2 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on February 13, 1981. In accordance with the requirements of IE Bulletin No. 80-17, Mr. Dennis DuBois was notified on the same date. A licensee event report form is alao enclosed.

Report No.:

50-298-81-02 Report Date:

March 13, 1981 Occurrence Date: February 13, 1931 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Conditions leading to operation in a degraded mode permitted by a limiting condition for operation as delineated in Section 3.3.B.1 of the Technical Specifications.

Conditions Prior to Occurrence:

Steady state power operation at approximately 98% reactor power.

Description of Occurrence:

During routine preventative maintenance activities, brass filings were found in the lube oil sump for the outboard motor bearing of the "B" Residual Heat Removal Service Water Booster Pump.

@)

l S

//

b

e*

Mr. K. V. Seyfrit March 13, 1981 Page Designation of Apparent Cause of Occurrence:

Zhr aubject motor is a 1000 HP Type G Allis Chalmers Induction Motor. The motor has an inboard bearing and motor fan and an outboard bearing and motor fan. The motor was disassembled and the inboard motor fan was found free of the rotor shaft. Filings worn from the brass fan were blown in the outboard bearing. The subject fan is shrunk on the shaft and locked with a set screw. The set screw for this fan was not properly engaged, and the rotor shaft was undersized by 0.003" which would produce less than the recom-mended shrink fit. This caused the failure. This is a repetitive occurrence on this same motor which initially occurred in 1974.

That occurrence was net reported to the NRC at that time.

Analysis of Occurrence:

The RHR Service Water System provides cooling water to the RER Heat Exchangers and provides emergency core flooding capability in the event the engineered safeguard systems are inoperative during a loss of coolant accident. The system consists of *wo independent Iceps with two pumps per lesp, each capable of satisfying the design criteria. The redundant loop was operable as well as both diesel generators. This event presented no adverse consequences from the standpoint of public health and safety.

Corrective Action

The motor fan was repaired and reinstalled on the rotor per the manufacturer's recommendations. An additional set screw was added which corresponds to the recent motor designs. The roter was bal-anced and reinstalled. Upon successful completion of tra repair, the pump was proven operable. The bearing sumps for tr_s ;nree other pumps were inspected and no abnormalities were found.

Sincerely, W

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