05000298/LER-1980-047, Forwards LER 80-047/03L-0.Detailed Event Analysis Also Submitted

Forwards LER 80-047/03L-0.Detailed Event Analysis Also Submitted

ML20004D557
Person / Time
Site:	Cooper
Issue date:	12/16/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20004D558	List: 05000298/LER-1980-047, Forwards LER 80-047/03L-0.Detailed Event Analysis Also Submitted 05000298/LER-1980-047-03, /03L-0:on 801117,RHR Loop a Suppression Pool Cooling Inboard Throttle Valve Found Inoperable.Caused by Key Failure Between Motor Pinion Gear & Shaft Due to Wrong Key Matl Installed.Motor,Pinion Gear & Key Replaced
References
CNSS800732, IEB-80-17, NUDOCS 8106090529
Download: ML20004D557 (2)

LER-1980-047, Forwards LER 80-047/03L-0.Detailed Event Analysis Also Submitted

Event date:
Report date:
2981980047R00 - NRC Website

text

__ _ _..

~

f.

d g,,*u COOPER NUCLEAR STATION

- K ; Nebraska Public Power District

" *

• l'A*E ?*o0%l;%'."^i

' * ^ " " '

.CNSS800732 December 16, 1980

~

r DEC 2 21980 Mr. K. V. Seyfrit, Director

.,y

. i U.S. Nuclear Regulatory Commission 1

Office of Inspection and Enforcement Region IV JJ' l.[q ' }\\

[,

611 Ryan Plaza Drive

,D Suite 1000

!(

9 A,Y 0 81981 -

Arlington, Texas 76011 u.

Dear Sir:

UsD%

This report is submitted in accordance with Section 6.7.2.B.2 of t

^

Technical Specifications for Cooper Nuclear Station and discusses a

. ; ic-reportable occurrence that was discovered on November 17, 1980.

In i

eccordance with the requirements of IE Bu'lletin 80-17, Mr. Spangler was notified while he was on site November 18, 1980.,A licensee event report for1n is also enclosed.

Report No.:

50-298-80-47 Report Date:

December 16, 1980 Occurrence Date: November 17, 1980 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Conditions which may have led to operation in a degraded mode permitted by a limiting condition for operation as delineared in Section 3.5.B of the Technical Specifications.

Conditions Prior to Occurrence:

Reactor was in cold shutdown.

Description of Occ,urrence:

During normal operation of RHR motor operated valves for torus cooling while in cold shutdown, RHR-MO-34A, the "A" Loop suppres-sion pool cooling throttle valve would not operate.

Designation of Apparent Cause of Occurrence:

The operator is'a Limitorque SMB-4 The motor was removed and the key between the motor pinion gear and the motor shaft was found sheared.

T 8106000699 s3 l

~'

l I

~.

Mr. K. V. Seyfrit December 16, 1980 Page 2.

I Analysis of Occurrence:

RHR-MO-34A is the RHR "A" Loop suppression pool containment valve which isolates the torus from the RHR system.

It is a normally closed valve.

If open during LPCI initiation, it receives a close signal. The subject valve failed iri che closed position.

Had the subject valve faihd in the open position, RHR-MO-39A, the outboard isolation valve, would have closed allowing LPCI injection with the "A" Loop. The torus cooling mode of the "A" Loop of RER was in-operable, however torus cooling could have been supplied by the "B" RER Loop. During this event, both diesel generators and the re-dundant loop of RHR were operable.

This occurrence presented no adverse consequences from the standpoint of public health and safety.

Carrective Action:

The motor, motor shaf t pinion gear, and motor shaft pinion gear key l

were replaced.

The motor shaft and pinion gear were worn due to the motor shaft rotating inside the pinion gear.

This is a re-petitive occurrence, reference LER's 7,6-14, 77-11, and 80-30.

The key was sent to' the manufacturer. Limitorque Corporation, j

for analysis. The results of that analysis indicates that Limitorque installed a key of improper hardness. Machinery history records I

indicated that this operator had never had any maintenance per-t formed on it that would have necessitated removal of the motor.

As was reported on LER 80-30-1, all sizes of Limitorque operators use standard key stock except for sizes SMB-3, 4, and 5.

RHR-MO-34A is a SMB-4.

The proper key stock is 4140 s* eel with a hardness of between 280/320 Brinell.

The failed key had a hardness of 250 The' proper key material was used for the repair.

Brinell.

This failure points out a potential area for concern for other SMB-3's, 4's, and 5's.

Lismisorquewill review-all~cperators-installed,rt g n,,,.3.

'eceedn-

- bio

- f-these operatorswic-e--'-

tu=y

---A

• be harder keyn.

Limitorque uses the hardened key in all SMB-3, 4, and 5's to reduce parts inventory as all operators do not need the hardened key.

Wh== >h4

'4=* aF muhiectsvalves 4 -

g,no m -

_ _pr -

--4.-_..,7s.

m411 s-1,.peeted-end-chfe -sample

.ineresse if ouy vihermoperata= - '--- *k= yran= 't y _--"a v4 = L Anm.

l upd. m

- m a,. - '

'-e C arm 414n-i

• k-_-

7 M ar.oca==

=d 1

ek- ---

't-

'" hee-dnspection The % edu.: h -,_e-yleting t.his s

iasp--*4aa u4

4 p==A

_uh=* "-lves ara _ suspect-and-our-abilit-y,,,

na to eek m m hT m ; ui vf.eervice-during operation.

l Sincarely.

5 L. C. Lessor Station Superintendent Cospar Nuclear Station LCL:cg

. I Attcch.

9