ML20063B937
| ML20063B937 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 08/17/1982 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| REF-PT21-82 NUDOCS 8208260329 | |
| Download: ML20063B937 (4) | |
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(412)923 - 1960 Telecopy (412) 787-2629 Nuclear Construction Division August 17,1982 Robinson Plaza, Building 2, Suite 210 Pittsburgh, PA 15205 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTION:
Mr. R. Haynes Administrator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Potentially Defective Robertshaw Thermostatic Control Valves Significant Deficiency 82-03, Interim Report No. 1 Gentlemen:
This letter is Interim Report No. 1 concerning Significant Deficiency 82-03.
On July 26, 1982, Lowell Tripp of your of fice was notified by tele-phone of a potential significant deficiency in thermostatic control valves manufactured by Robertshaw Controls Company and provided for Beaver Valley Unit No. 2.
This was determined to be reportable in that had it remained uncorrected, it could have adversely affected safe operation of the plant.
The attached report provides a more detailed description of the problem.
Duquesne Light Company will issue either another interim or final report on this subject when details of the corrective action taken are available.
It is expected that this report will be submitted to Region I by January 10, 1983.
DUQUESNE LIGHT COMPANY 8208260329 820817 By PDR ADOCK 05000412 E. JyWoolever S
PDR Vice President JMM/wjs Attachment cc: NRC Document Control Desk Mr. G. Walton, NRC Resident Inspector (w/ attachment)
Ms. E. Doolittle, Project Manager (w/ attachment)
SUBSCRIBED AND SWORN TO BEFORE BE THIS / 7 DAY OF 4v#
_, 1982.
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I{ h At A14 s. ems. NMm Faeuc Notary Public NSIGN PAP.. Atttcriar conry Vf COWMA EXP;PC5 april !?. IM6 V*:rW.P:nntvam A%wat A 0t Ftctsys
3-United States Nuclear Regulatory Commission page 2 COMMONWEALTH OF PENNSYLVANIA )
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COUNTY OF ALLEGHENY
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On this /7 day of A(/8-
, /7 7d, before me,-
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NA M4 6, a Notary Public in and for said Commonwealth and County, personally appeared E. J. Woolever, who being duly sworn, deposed, and said that (1) he is Vice President of Duquesne Light, (2) he is duly authorized to execute and file the foregoing Submittal on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct to the best of his knowledge, information and belief.
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LNotary Public.
ALAN B. BANAS, NOTARY F06 tlc ROBINSON TWP., AlttGHINv C00miY
.MV COMMIS$t0N EXP!RES APRIL 12,1986 Weeber.Penosvivania Association of hie
6 BEAVER VALLEY POWER STATION'- UNIT NO. 2 DUQUESNE LIGHT COMPANY REPORT ON POTENTIAL DEFICIENCY OF EMERGENCY DIESEL CENERATOR THERM 0 STATIC CONTROL VALVES 1.
SUMMARY
Colt Industries has reported that the diesel engines of the BVPS-2 Emer-gency Diesel Generator Sets are equipped with potentially defective thermostatic control valves manufactured by Robertshaw Controls Company.
Malfunction of these valves could cause extreme overcooling with atten-dant risk of. engine damage.
2.
IMMEDIATE ACTION TAKEN Upon notification of the problem by Colt Industries, Stone & Webster Engineering Corporation issued a report of a problem and initiated an inspection of the BVPS-2 Emergency Diesel Generator Sets which confirmed that the diesels are equipped with the potentially defective valves. On July 26, 1982, Duquesne Light Company notified the Region I office of the problem by telephone. Colt Industries.also filed a 10CFR21 report with the Director of the NRC's Region III Office of Inspection and Enforcement.
i 3.
DESCRIPTION OF DEFICIENCY The diesel engine of each BVPS-2 Emergency Diesel Generator is equipped with a Robertshaw Model I-1285-S25 thermostatic control valve. The 5-inch, 3-way control valve is located in the engine's intercooler water system.
The valve's design incorporates a lower overrun assembly which absorbs movement generated by thermal assemblies under certain conditions. The overrun assembly consists of a spring restrained between two end pieces whose length and " breakdown" is set by an. axial bolt and nut.
Under normal conditions, this assembly acts as a rigid member. Should the nut not be firmly affixed in place and " backoff", the longer length of the overrun assembly results in a valve stroke which is not generated by the thermal assembly. This additional stroke makes the thermal assembly function at a lower temperature, thus, overcooling the system. In order to prevent the nut from backing off and allowing the valve to go into the full cooling position, Robertshaw has employed a design which stakes the retaining nut in place and a design in which the nut is soldered to the axial bolt. Neither of these designs has proved to be satisfactory in actual operating conditions.
4.
ANALYSIS OF SAFETY IMPLICATION The Emergency Diesel Generators are required during design basis events to supply electric power to the safety-related components.when offsite power is not available. The potential malfunction of the thermostatic control valve and subsequent extreme overcooling of the diesel engine could cause the diesel generator to be unavailable or fail while carrying emergency loads and, therefore, could adversely affect the safety of plant operations.
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CORRECTIVE ACTION TO REMEDY DEFICIENCIES Robertshaw Controls' Company, working in conjunction with Colt Industries, is presently developing a procedure for correcting the deficiency by swage locking the nut in position on the overrun assembly.
4 6.
ADDITIONAL REPORTS Duquesne Light Company will issue either another interim report or a final report on this subject when details of.the corrective action taken-are available. Te is expected that_this report will be submitted to Region I by January 10, 1983.
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