ML20071M348

Final Deficiency Rept Re Potential Failure Mode for Robertshaw Controls Thermostatic Valves,Resulting in Diesel Generator Engine Jacket Cooling Water Sys Overcooling. Initially Reported on 820525 Per Part 21

ML20071M348
Person / Time
Site:	Seabrook
Issue date:	09/20/1982
From:	Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE, YANKEE ATOMIC ELECTRIC CO.
To:	Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
REF-PT21-82 10CFR-050.55E, 10CFR-50.55E, SBN-327, SNB-327, NUDOCS 8209270086
Download: ML20071M348 (2)

Text

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SEABR S U I IPUEBLIC BERVICE Companyof New Hampshw e 1671 Worcester Road Framingham. Mossochusetts 01701 (617) - 872 - 8100 September 20, 1982 SBN-327 T.F. Q 2.2.2 United States Nuclear Regulatory Commission Region I 631 Park Avenue KLng of Prussia, PA 19406 Attention: Mr. Richard W. Starosteckt, Director Division of Resident and Project Inspection Re f e re nces : (a) Construction Permit CPPR-135 and CPPR-136, Docket No s . 50-443 and 50-444 (b) Telecon of August 20, 1982, J. DeVincentis (YAEC) to W11ter Brunack (NRC Region I)

Subject:

Final 10CFR50.55(e) Report; Robertshaw Controls Thermostatic Valves

Dear Sir:

On August 20, 1982, a reportable 10CFR50.55(e) Ltem was reported

[Ref erence (b)] reg arding a potential f ailure mode for certain Robertshaw Controls thermostatic valves which could result in overcooling of the diesel generator engine jacket cooling water system and subsequent engine damage.

This item was reported to the NRC by Colt Industries on May 25, 1982, and June 28, 1982, pursuant to 10CFR2l.

The f ollowing inf ormttlon is provided per 10CFR50.55(e)(3) and is considered to be the final report on this item.

DESCRIPTION OF DCFICIENCY Diesel generator sets manuf actured by Colt uttllze a Robertshaw Controls thermostatic valve in the Jacket Water Cooling System. These valves incorporate an overrun assembly which absorbs excessive movement of the theru t assembly. The overrun length Ls set by an axial bolt and nut. If the not is not secured in place, and La able to backoff the bolt, the overrun assembly allows an increase in valve stroke. This additional valve stroke ukes the thermal assembly control at a lower temperature.

8209270086 820920 PDR ADOCK 05000443 S PDR

United States Nucisar Ragulatory Co2=lssion Saptember 20, 1982 Attent io n: Mr. Richard W. Starostecki. Page 2 a

ANALYSIS OF SAFETY IMPLICATIONS Laproper torquing of subject bolting may result in excessive and undestrable vibration of the generator shaf t. Also, operating vibrations and load cycling may result in further loosening of improperly tightened bolts.

These conditions, if undetected and/or corrected, could render the D-G set inoperable.

CORRECTIVE ACTIONS BPS has established a test plan for shop. equipment to determine if an equipment or procedure problem exists. BPS has also provided notification to end users of D-G sets Ln question via Mallgram dated 4/22/82 (VU-28221). This notification incluied a preliminary corrective procedure to preclude any p ro blems.

BPS has submitted a formal Colt procedure (11876749; FP 23204) by letter of 6/30/82 (VU-29801) which has been issued for record distribution and field action by UE&C letter of 7/29/82 (SBU-59276; FM 21532). Per this procedure, the final torque value has been increased to 5000 f t. Ibs. The completion and results of this corrective procedure are to be reported back to Colt / BPS -for confirmation and record of new torque values.

ANALYSIS AND EVALUATION The corrective procedure provided by BPS / Colt will preclude potential problems resulting from possLble misapplication of torquing equipment .in the shop. The higher. final torque values to be used will further reduce the potential of loosening the bolts under operating vibration and load cycling.

All of the Seabrook D-G sets -were shop tested prior to shipment, with no indication of the problems noted above. Further testing is to be done on site per established pre-operations 1 startup, and inservice operations. Even Lf the corrective procedure provided by BPS is not followed, it is expected that, if this deficiency existed, it would be detected long before a possible D-G fatture could occur. However, application of the corrective procedure will fully eltminate this potential problem.

Very truly-yours, YANKEE ATOMIC ELECTRIC COMPANY l ,J-4 0 9 J. DeVincentis Project Manager ALL/dd '