ML20076C007
| ML20076C007 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 07/21/1983 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 2NRC-3-049, 2NRC-3-49, 82-03, 82-3, NUDOCS 8308220141 | |
| Download: ML20076C007 (4) | |
Text
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I o 2NRC-3-049 (412) 787 - 5141 e
(412)923 -1960 Telecapy (412) 787-2629 July 21, 1983 Nuclear Construction Division Robinson Piara, Building 2, Suite 210 Pittsburgh, PA 15205 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTION:
Dr. Thomas E. Murley Administrator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Potentially Defective Robertshaw Thermostatic Control Valves Significant Deficiency Report No. 82-03 Gentlemen:
Pursuant to the requirements of 10CFR50.55(e), the " Final Report on Potentially Defective Robertshaw Thermostatic Control Valves" is at t ached for your review.
If there are any questions concerning this report, ple ase contact the Beaver Valley Unit No. 2 Project Office.
DUQUESNE LIGHT COMPANY By Y. f. Woolever Vice President
'JMM/wjs At tachment cc:
Mr. R. DeYoung, Director Of fice of Inspection and Enforcement (3) (w/a)
NkC Document Control Desk (w/a)
Mr. G. Walton, NRC Resident Inspector (w/a)
Ms. L. Lazo, Project Manager (w/a)
INPO Records Center (w/a)
SUBSC BED AND S TJ) BEFORE ME THIS
, ~2/, DAY OF
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, 1983.
b AM
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Notary Public lll ELVA G. LESONDAK, NOTARY PUBLIC 8308220141 8307 MY COMMISSION EXPIRES OCTOBER 20,1986 h
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United Stctes Nuclear Rsgulatory Commission Dr. Thomas E. Murley page 2 COMMONWEALTH OF PENNSYLVANIA )
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COUNTY OF ALLEGHENY
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On this //
day of d/
/ [ k 8, before me, a Notary Public in and for Md C[monwealth and County, pe rsonally appeared E. J.
Woolever, dio being duly sworn, deposed and said that (1) he is Vice President of Duquesne Light, (2) he is duly authorized to exe-cute and file the fo regoing S ubmit t al on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct to the best of his knowledge.
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/ Not ary Pub'lTc ELVA G. LESONDAK, NOTARY PUBLIC ROBINSON TOWNSHIP, ALLEGHENY COUNTY MY COMMISSION EXPIRES OCTOBER 20,1986 l
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...A BEAVER VALLEY POWER STATION - UNIT NO. 2 DUQUESNE LIGHT COMPANY Final Report on Potential Deficiency of Emergency Diesel Generator Thermostatic Control Valve "Lowe r Ove rrun As semb ly" 1.
SUMMARY
Colt Industries has repo rt ed that the diesel engines of the BVPS-2 emergency diesel generator sets are equipped with potentially defective thermostatic control valves manu factured by Robe rt shaw Contr ols Com-pany. Malfunction of these valves could cause extreme overcooling with a t tendant 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 ins pect ion of the BVPS-2 emergency diesel ge nerato r sets which con-firmed that the diesels are equipped with the pot ent ially de fect ive valves.
Ou. 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 Of fice of Ins pect ion and Enforcement.
3.
DESCRIPTION OF DEFICIENCY The diesel engine of each BVPS-2 emergency diesel generator is equipped with a Robert shaw Model I-1285-S25 thermostatic control valve.
The 5-inch, 3-way control valve is loca t ed in _ the engine's intercooler water system.
The valve's design incorporates a lower overrun assembly which absorbs movement generated by thennal as semb lies under certain condi-i t ions. - The ove rrun as semb ly cons is ts of'a spring res trained between two end pieces whose length and " breakdown" is set by an axial bolt and nut.
Under normal condit ions, this ' assembly act s as a rigid member.
Should the nut not be firmly af fixed in place and "b ack of f,"
the longer length of the overrun assembly result s in a valve stroke which is not generated by the thermal assembly.
This additional stroke makes l
the thermal. assembly control at a lower temperature, thus ' overcooling l
the sys tem.
In order to prevent the nut from backing of f 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 so lde red to the axial bolt.
Neither of these designs has proved to be satisfactory in actual operating conditions.
4.
ANALYSIS OF SAFETY IMPLICATION l
The emergency diesel generators are required during design basis events to supply electric power to the safety-related components.
The pot en-tial malfunct ion of the the rmos tat ic control valve and subseque nt
!~
extreme overcooling of the diesel engine could cause the diesel genera-tor to be unavailable or fail while carrying emergency load s, and, therefore, could adversely af feet the safety of operations.
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, +.
5.
CORRECTIVE ACTION TO REMEDY DEFICIENCIES Robe rt shaw Controls Com pa ny, working in conj unct ion with Colt Ind u s-tries, has presented a procedure for correct ing the de ficiency by utilizing cotter pins to ke ep the nut in position on the ove r run as semb ly.
6.
FINAL REPORT The corrective action is completed. The modification, utilizing cot ter pins ' to keep the nut in position on the ove rrun as semb ly, has be en completed.
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