ML20028C727
| ML20028C727 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 12/20/1982 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 2NRC-2-047, 2NRC-2-47, 82-03, 82-3, NUDOCS 8301140042 | |
| Download: ML20028C727 (4) | |
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a, 8 di ulte 210 Pittsburgh, PA 15205 December 20, 1982 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. 2 Gentlemen:
This letter is Interim Report No. 2 concerning Significant Deficiency 82-03,
" Robertshaw Thermostatic Control Valves".
On August 17, 1982, Beaver Valley Power Station - Unit No. 2 (BVPS-2) submitted Interim Report No. 1 on this subject.
Since that time, Robertshaw Controls Company has continued to work on the development of a procedure for correcting the deficiency.
When details of the corrective action taken are available, BVPS-2 will issue another report on this subject.
It is expected that this report will be submitted to Region I by August 30, 1983.
DUQUESNE LIGHT COMPANY hjgOCKoO42 821220 E.J.86lhver 05000412 Vice President S
l PDR JMM:tav Attachment l
I cc: NRC Document Control Desk Mr. G. Walton, NRC Resident Inspector (w/ attachment)
Ms. L. Lazo, Project Manager (w/ attachment)
SUBSCRIBED AND SWORN TO BEFORE ME THIS a3 A40AY OF O(2 pet /dA/, 1982.
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Notary Public JUDITH M. Nill. NOTA 3Y PUBllC ROSS TOWNSHIP. ALLEGHE.NY COUNTY MY COMMISSION EXPfRES MAY 28,1984 gd Member. Pennsylvanta Assocahon of Notanes
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~. United States Nuclear Regulatory Commission Page.2 COMMONWEALTH'0F PENNSYLVANIA
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COUNTY OF ALLEGHENY
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-On this J3 day of b>M,
/9 M, before 'me, a Notary--Public in and for said Commonwealth -'and ' County,. personally appeared E. J.
Woolever, ho 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 foregoingt 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.
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f JU0ifff M N!iL NOTAHY PUDllC -
ROSS 70WNSEP. AtiEchENV County MY COMMIS$l0N EXPIRES MAY 28,1984 -
Member. Pennsylvania Assvoation of Notanes t
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. BEAVER VALLEY; POWER STATION iUNIT NO. 2:
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...DUQUESNE'_ LIGHT COMPANYf.
. REPORT ON POTENTIAL DEFICIENCY-0F EMERGENCY _
-DIESEL-GENERATOR THERM 0 STATIC CONTR0L: VALVES 1.
ISUMARY z
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1 Colt Industries has reported that the diesel engines of the.BVPS-2 Emergencyl
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f Diesel Generator Sets are equipped' with potentially-defective thermostatic centrol valves manufactured by Robertshaw Controls Company.. Malfunction #
of these. valves could cause extreme overcooling with attendant risk of.
engine damage.
2.
IMEDIATE 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.
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 thennal 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 b'e satisfactory in actual operating conditions.
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ANALYSIS OF SAFETY IMPLICATIONS l
The Emergency Diesel Generators are required during design basis events to supply electric power to the safety-related components when offsite I
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..
O 5.
' CORRECTIVE ACTION TO REMEDY DEFICIENCIES Robertshaw Controls Company, working in conjunction with Colt Industries,
-is-in the process of developing a procedure for correcting the deficiency-by swage locking -the nut in position cri the overrun assembly.
ADbITIONAL; REPORTSg 6.
Duquesne Light-Company will issue another 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 August 30, 1983.
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