ML20244B313
| ML20244B313 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 04/10/1989 |
| From: | Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8904190122 | |
| Download: ML20244B313 (3) | |
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PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 PHILADELPHIA A. PA.19101 (215)841 45oo
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APR101989 i
U. S. Nuclear Regulatory Conmission Docket No. 50-353 Attn: Document Control Desk Washington, DC 20555.
SUBJECT:
Limerick Generating Station, Unit ?
Independent Construction Assessment Inspection Report No. 50-353/88-202 I
Gentlemen:
Our Letter of March 29, 1989 provided Philadelphia Electric Company's response to the subject Nuclear Regulatory Conmission (NRC) Inspection Report dated January 23, 1989. Our response to one item was incomplete with regard to the significance of a potential deviation of allowed cable bend radius. The attactynent provides supplemental infonnation to complete our response to this concern and our response to NRC Inspection Report 50-353/88-202 for Limerick Generating Station, Unit 2.
If additional information is required, please do not hesitate to contact me.
Sincerely, h$$f Attachment ERG /dk/04058900 Copy to:
T.- J. Kenny, LGS, SenJor Resident Inspector W. T. Russell, Region 1 Administrator R. J. Clark, LGS, Project Manager ffk 0
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A. c MS d ELECTRICAL (LK-C-1904)
M SECT!ON 4.5.2.1 Concern Vendor installed cabling in several Class lE motor control centers exhibited deficiencies in the bend radius.
The teams examination of motor control centers 2AC224 and 2BC224 (control panels for the unit hydrogen recombiners) disclosed wiring between the heater breaker and the motor starter that exhibited significantly less radius than that required by industry and site standards. The wires in question were number 4 AWG (American Wire Gage) in size and were installed with a radius of approximately 1 inch. The team also noted that the insulation of these wires had buckled and pullec away from the individual conductors because of their excessive bending.
Similar deficiencies were observed in cubicle 08 of motor control center 20B212, in which vendor wiring was formed with a radius of approximately 1/2 inch.
In response to this observation, the licensee issued NCR-13910 to document and evaluate the impact of the deficiencies on :omponent and system operation.
However, based upon the frequency of this observation from a relatively small sample, it appeared that the licensee should consider conducting a review of vendor wiring in Class 1E motor control centers to determine the scope and significance of bend radius deficiencies.
Resnonse The concern identifies two conditions that are unrelated and must be addressed individually. As a means of differentiation, they are henceforth referred to as concern il and concern 82.
Renconse to Concern 41 Concur With Concern Cause The cited condition relative to the bend radius deficiencies identified in
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hydrogen recombiner power cabinets 2AC224 and 2BC224 is attributable to lack of attention to detail during the fabrication process.
Extent of Condition Panels 2AC224 and 2BC224 are power panels uniquely designed for components of the hydrogen recombiner skids, supplied by the sub-vendor Time-Trol Inc.
These are the only such power panels furnished by Time-Trol Inc. for Limerick Generat.ng Station Unit II.
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7, Significance According to G.E. catalog 4CM646, the subject cable (Vulkene XHHW) was manufactured and tested in accordance with IPCEA standard S-19-81 or S-61-402.
As part of the production tests, the cable was subjected to heat aging, moisture resistance, radiation resistance, and chemical resistance tests to demonstrate the mechanical and electrical integrity of vulkene insulation.
In Limerick application, this cable is not exposed to steam (high humidity) or high temperature environment. The required DBE radiation is 5.33 x 106 Rads (gamma and beta). According to the G.E.
7 rads without catalog, the vulkene insulation can withstand 2 x 10 any significant deterioration.
l The cable insulation is rated at 600 Volts and must withstand a 125 Volt ac/ mil high voltage withstand test, (ie. a total of 6875 volts ac for 5 minutes).
Because this cable was to be used only in a 480 volt ac application, the possible reduction in the cable dielectric properties as a result of excessive bending is judged not to be significant to affect the performance.of the cable or to result in its premature failure under normal or design basis conditions.
Corrective Action NCR-13910 was issued to document the noted deficiencies and dispositioned to replace the discrepant wires with Rockbestos firewall III cables using proper bending radius; all work is complete, and accepted.
Action to Prevent Recurrence Based upon the discussion under Extent of Condition, no further action is warranted.
Resoonse to Concern 42 Do Not Concur With Concern The cited condition relative to the bend radius deficiency identified in motor control center 20B212 is attributable to the as supplied condition of the vendor supplied equipment.
The wire in question was a 44 SIS wire with a bend radius of approximately 1/2 inch. The vendor (Cutler-Hammer) has advised us that their standard wire bending policy is that the inside bend radius is to be no smaller than the outside diameter of the cable being bent.
The 44 SIS wire has an out-side diameter of.360 inch and therefore, a.5 inch inside bend radius is acceptable.
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