ML20245K263

Supplemental Deficiency Rept CP-88-19 Re Qualification of Instrument Cable Insulation Inside Containment.Initially Reported on 880129.No Replacement of safety-related Instruments or re-routing/replacement of Cables Required

ML20245K263
Person / Time
Site:	Comanche Peak
Issue date:	06/30/1989
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CP-88-19, TXX-89351, NUDOCS 8907050075
Download: ML20245K263 (2)

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%% Log' # TXX-89351 File # 10110

= = 908.3 1UELECTRIC June 30, 1989 William J. Caisill. Jr.

Decunve Vice President l

U. S. Nuclear Regulatory Commission Attn: Documer.i Control Desk Washincten, D. C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) l DOCKET NOS. 50-445 AND 50-446 CABLE INSULATION RESISTANCE - LOOP ACCURACY a l

SDAR: CP-88-19 (SUPPLEMENTAL REPORT) i Gentlemen:

l On January 29, 1988, TU Electric notified the NRC via final report logged TXX-88143, of a reportable deficiency involving the qualification of instrument cable insulation inside containment. The last report was logged TXX-88824, dated December 1, 1988. This report is submitted to revise the corrective actions.

The corrective action discussed under Item 3 of TXX-88143, indicated that a Design Basis Document (DBD) would be initiated to control NSSS setpoint calculations. Upon further review, it was determined that an additional DBD is unnecessary since this information is included in the Reactor Protection and NSSS Related Control Systems DBD. This DBD was recently revised to incorporate the Westinghouse Setpoint Methodology for Protection Systems which provides the methodology and criteria for NSSS setpoint determination.

With regard to the corrective action discussed under Item 4 of TXX-88143, TU Electric has completed an engineering evaluation of the adequacy of safety-related instrument loops inside the containment with existing cable insulation resistance following a postulated loss of coolant accident or main j steam line break. A calculation was performed using conservative values for .

cable lengths (i.e., cable lengths posted against pull tickets, which are longer than the as-built cable runs). The evaluation concluded that the cable leakage error for BOP instruments is very small and the impact on instrument 4 setpoints is negligible. As a result, PCHVP evaluations to identify as-built  !

cable lengths were not required. In addition, since cable leakage error j rates were negligible, no replacement of safety-related instruments or re-routing / replacement of instrument cables was required.

-l 8907050075 890630 PDR S

ADOCK 05000445 PDC h/_f(

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400 krth Olive Street LB81 Dallas, Texas 75201

l TXX-89351 (

June 30, 1989 j

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o The same calculation was submitted to Westinghouse to evaluate the cable f leakage errors of the reactor protection system and engineered safety features J actuation system instrument setpoints within their scope. The Westinghouse 4 Setpoint Methodology for Protection Systems, WCAP-12123 (Proprietary),

documents.the resulting setpoints, in which cable leakage errors were considered in the analysis.

Items 1, 2 and 5 of TXX-88143 were completed as previously described. Unit 2 {

activities will be completed prior to Unit 2 fuel load. j i

Sincerely, j i

William J. Cahill, Jr.

VPC/ddm 1

c - Mr. R. D. Martin, Region IV j Resident Inspectors, CPSES (3) i l

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