ML20113C915
| ML20113C915 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/25/1985 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 2NRC-5-050, 2NRC-5-50, 85-01, 85-1, NUDOCS 8504120106 | |
| Download: ML20113C915 (4) | |
Text
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v Duquesne U! fit lgc,g; Pao 21 9234 960 Nuclear Construction Division Telecon W 2) 787-2629 Robinson Plaza, Building 2. Suite 210 Pittsburgh, PA 15205 March 25, 1985 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 Inadequately Torqued Bolts for Electrical Support Connections Potentially Significant Deficiency Report No. 85-01, Final Report Gentlemen:
This Final Report is in reference to the potentially reportable Significant Deficiency relating to the " Inadequately Torqued Bolts for Elec-trical Support Connections." Pursuant to the requirements of 10CFR50.55(e),
it is anticipated that a subsequent repo rt on this matter will not be necessary.
DUQUESNE LIGHT COMPANY By J. (,T.Uarey Vice President MAH/wjs A t t achment.
Mr. R. DeYoung, Director (3) (w/a) cc:
Mr. B. K. Singh, Project Manager (w/a)
Mr. G. Walton, NRC Resident Inspector (w/a)
INPO Records Center (w/a)
NRC Document Control Desk (w/a)
SUBSCRIBED AN RN,TO EFORE ME THIS M AY OF p
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q United States Nuclear Regulatory Commission Dr. Thomas E.
Murley Potentially Significant Deficiency Report No. 85-01, Final Report Page 2 COMMONWEALTH OF PENNSYLVANIA )
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, before me, a On this Notary Public in and for said Commonwealth and County, personally appeared J.
J. Carey, 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.
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k BEAVER VALLEY POWER STATION UNIT NO. 2 DUQUESNE LIGHT COMPANY Potential Significant Deficiency Report No. 85-01
" Inadequately Torqued Bolts for Electrical Support Connections" 1.
SUMMA RY Bolts with spring nuts are used fo r electrical suppo rt connections at BVPS-2.
These bolts have been installed " uptight," not to minimum torque values.
2.
IMMEDIATE ACTION TAKEN A sample of 50 bolts, one-half inch in di ameter, were torque tested by Duques ne Light Company (DLC) Site Quality Control (SQC) using a cali-brated torque wrench.
Thirty percent of these installed bolts were found to be to rq ued to less than the manufacturer's and SWEC corporate guide-lines of 50 ft-lbs, with a lowest value of 20 ft-lbs.
Following the collection of these torque data, an analysis of the safety implications of this deficient condition was complete (refer to Section 4, ANALYSIS OF SA FETY IMPLICATIONS).
On February 26, 1985, S.
D.
Hall, Acting Manager of Duquesne Light Company's (DLC) Regulatory Af fairs Department, notified Lowell Tripp of NRC Region 1 Office of this pot ent ially reportable deficiency.
3.
DESCRIPTION OF DEFICIENCY installed by construction to an unspecified Bolts with spring nuts we re torque be cause applicable BVPS-2 engineering documents did not specify the minimum acceptable torque values recommended by the manuf acturer and by SWEC corporate guidelines.
A bolt torqued to less than these minimun requirements might not provide adequate load carrying capability parallel to the axis of the support channel.
4.
ANALYSIS OF SAFETY IMPLICATIONS The installation torque of bolts with spring nuts in cold-formed channel sections af fects only one of the three degrees of freedom of the bolts, ar.d the typical raceway structures using these bolts are s up port ed in a redundant manner. These considerations and analysis of the data generated from the torque testing of the 50 installed bolts indicated it was unlikely that the deficient condition of inadequately torqued bolts fo r elect rical support connections could have caused the failure of any elec-trical raceways under any applicable loading conditions. However, because the sample size of 50 bolts was small compared to the total number of spring nuts used for electrical sup po rt connec t ions at BVPS-2, this determination was considered a preliminary conclusion pending the collec-tion and analysis of additional installed torque data.
These additional data were to be generated as part of the spring not retorquing program that DLC was planning to initiate (refer to Section 5, 00RRECTIVE ACTION TO REMEDY DEFICIENCY, for a description of this retorquing program).
Subsequent to the above preliminary conclusion, DLC determined that the content of the electrical support retorquing program would not include
P tre generation of "as found" torque data fo r bolts with spring nuts.
Without these data, the completed torque tests of the 50 bolt samples are insufficient to support a statistical de terminat ion, with the required c onf idence level, that the subject deficient condition would not have resulted in the failure of an elect rical raceway. Thus, DLC has concluded that, due mainly to the large number of spring nuts at BVPS-2 that were torqued to an unspeci fied value (approximately 130,000), the deficient condition of the inadequately torqued bolts fo r electrical support connections, if le f t uncorrected, could have adversely impacted the safe operations of the plant.
5.
CORRECTIVE ACTION TO REMEDY DEFICIENCY To correct the po t ent ial significant deficiency regarding inadequately torqued bolts for electrical support connections at BVPS-2, the fo llowing actions have been taken.
Appropriate torque requirements for bolts with spring nuts have been issued via E&DCR 2PS-3207B, the electrical instal-lation s peci f ic at io n (2BVS-931) has been mdified to incorporate these torque values, and a 100 percent retorque program fo r existing Seismic Category I electrical support connections will be initiated and completed prior to fuel load.
These corrective actions will ensure that BVPS-2 electrical support connections using bolts with spring nuts will be properly torqued, and electrical raceways will pe rfo rm their intended safety functions.
6.
ADDITIONAL REPORTS This report rega rding the po t ent i al significant deficiency of inad e-quately to rqued bolts for electrical support connections is a final report.
Any further correspondence regarding this matter will be issued related Unresolved NRC Inspection Item as part of the activities for a (UNR 84-16-03) and will be made available to the Senior Resident Inspec-tor upon request.