ML20094F521

Part 21 Rept Re Defect in Amot Control Corp Safety Trip Valves for Use in Edgs.Defective Overspeed Trip Valve Removed from DG 1.Replacement & Existing Amot Overspeed Trip Valve on DG 2 Inspected & Determined Not to Contain Defect

ML20094F521
Person / Time
Site:	Cooper
Issue date:	02/18/1992
From:	Horn G NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-92 NSD920193, NUDOCS 9202250182
Download: ML20094F521 (4)

Text

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NSD920193 February 18, 1992' Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 Centlemen:

Subject:

Report of Defect in Accordance with 10CFR21 Cooper Nuclear Station NRC Docket No. 50-298, DPR-46 Attached please tind a report submitted in accordance w'.th 10CFR21.21(c)(1).

This rcrort details defects in AMOT safety trip valves supplied to the Nebraska Public Power District's Cooper Nuclear Station for use in each of the Emergency Diesel Generators.

l Should you have any questions or concerns regarding the enclosed report, please contact me l

Sincerely, l

lw G. s 1orn Nuc ear Power Group Manager

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Attachment ec: NRC Regional Administrator USNRC - Region IV Cooper Bessemer Reciprocating Group AMOT Control Corporation

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' U. S.' Nuclear Regulatory Commission  ;

February 18, 1992 Attachment  ;

Page 1 of 3 >

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10CFR21 Rc nort t

Defects in AMOT Safety Trio Valves Two AMOT safety trip valves, supplied by AMOT Control Corporation, for use in each of the Cooper Nuclear Station (CNS) Emergency Diesel - Generators, as mechanical overspeed devices, have been identified as containing defects. One unit was installed, _-and was subsequently . removed upon -its . failure while troubleshooting engine operation. The other unit was procured under the same purchase order and was not installed at the time- the defect was discovered.. Tha identified defects could have created a substantial safety hazard,.if the AMOT valve installed in Emergency Diesel Generator 1 (DG1) had failed along with a -

single failure of DG2. The following information is provided pursuant to the >

requirements of 10CFR21.21(c)(4) .

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1, 10CFR21.21(c)(4)(1) Name and address of the individual or individuals informing the-Commission:

Guy. R. Horn Nuclear Power Group Manager Nebraska Public Power District P. O. Box 499 Columbus, NE 68602-0499

2. 10CFR21.21(c)(4)(ii) Identification of the facility, the activity, or the basic component supplied for such facility or such activity _. within the United States which fails to comply or contains a defect.

Basic Component Containinz - Defect  : Safety. trip. valve for the Emergency Diesel Generators '

Facility Suonlied to - Cooper Nuclear Station

3. 10CFR21.21(c)(4)(iii) Identification . of . the firm constructing - the facility or suppi,ing the basic component which fails to comply:or contain a defect.

i Supplier: Cooper Energy Services Cooper Bessemer Reciprocating Group 150. Lincoln-Ave.

Grove City, PA -16127 Manufacturer: AMOT Control. Corporation P.O. Box 1312 l-Richmond, CA 94802 .

4. 10CFR21.21(c)(4)(iv) Nature of the: defect or-failure to. comply and the safety haurd which is created 1 or could- be- created, by such . defect. 'or failure to co.nply.

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U. S; Nuclear Regulatory Commission

^ February 18, 1992 Attachment Page 2 of 3 i

i On October 25, 1991, the AMOT overspeed trip valve, DG-SV.DG1 was ,

. replaced with a new AMOT valve (Model 1476B/0212A3). Four days

later, on October 29, 1991, this new AMOT control valve was removed

! from DG-1, due to confirmed binding in the lifting spring / loading

l. spring / piston area. The binding was not allowing this~ assembly to

! function properly during the resetting phase of the operation, j Visual inspections of the piston iden ified some markings similar to adhesive wear. There was no evidence of internal lubrication of the moving components. Discussions with the manufacturer indicated that i the lower cylinder assembly of the valve should have been lubricated during the manufacturing and assembly process. The lack - of j lubrication in the valves as supplied to Cooper Nuclear, Station i indicates the . lubrication was apparently _ missed in the assembly

. process. An identical valve, procured under the same purchase order, showed indications of the potential for developing the_same

{ problems if put in service.

4 The safety impact of these components not working is that if the

component failed while in service, the diesel generators would not have started or operated. as designed. The loss of.' both diesel j geLerators could have occurred if the AMOT valve installed in DG1 j wculd have failed in addition 'to the single failure ' of DG2 i postulated for accident scenarios. This potential for the loss of

i. both emergency-diesel generators is considered t., he a substantial i safety hazard.

l 5, 10CFR21.21(c)(4)(v) The date on whict the information of such defect or j failure to comply was obtained.

f February 17, 1992 i 6 10CFR21.21(c)(4)(vi) In the case of a basic component which contains a l defect or fails to comply, the. number and location of all such components in use at, supplied for, or being supplied for one-or more facilities.or activities subject to the regulations in this part.

Two units total - One unit was initially installed on DC1, and was subsequently removed from service, Both units are under the control-of the Nebraska Public Power District.

a 10CFR21.21(c)(4)(vii) The corrective action which has been,lis being, or 7.

will he taken; the nate of the_ individual or organization responsible for the actions; and the length - of--time' that- has been . or will be : taken to complete the action.

Corrective Action -

The ; defec tive AMOT overspeed trip- valve was -

removed - from- DGl. - Its replacement, and _the existing AMOT_~ overspeed trip valve on DG2, have been inspected and determined to not contain this identified defect. Contact was made with the_ manufacturer in determining the cause of failure. CNS is aware of only one other station, Zion, which uses a trip system: similar. to this.

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• U. S'. Nuclear Regulatory Commission February 18, 199z Attachment -

Page 3 of 3 Information regarding this defect was provided to Zion station personnel at the Cooper Besse:ner Owners Group meeting, Responsible Orranization - Nebraska Public Power District Length of Time to Comnlete - All corrective ax . sns regarding the l identification and root cause determination of the above identified defect have been completed. This effort took approximately 60 man.

hours.

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8. 10CFR21.21(c)(4)(viii) Any advice related to the defect or failure to comply about the facility, activity or basic component that has been, is being, or will be given to purchasers or licensees.

Not applicable. The supplier and manufacturer have teen informed-through previous correspondence and-will be further advised of the District's evaluation by copy of this notification.

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