ML20147E074

Interim Deficiency Rept CP-87-40 Re Electrical Isolation Between Class 1E & Non-Class 1E Equipment.Initially Reported on 870715.Appropriate Devices to Separate Equipment Will Be Installed.Next Rept Will Be Submitted by 880408

ML20147E074
Person / Time
Site:	Comanche Peak
Issue date:	01/11/1988
From:	Counsil W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
CP-87-40, TXX-88060, NUDOCS 8801210012
Download: ML20147E074 (2)

Text

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. Log & TXX-88060 File # 10110 r = 907.5 1UELECTRIC U$'"id7,",i, January 11, 1988 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION DOCKET NOS. 50-445 AND 50-446 ELECTRICAL ISOLATION BETWEEN CLASS 1E AND NON-CLASS 1E EQUIPMENT SOAR: CP-87-40 (INTERlH REPORT)

Gentlemen:

On July 15, 1987, we verbally notified your Mr. Ian Barnes of a deficiency involving electrical isolation. Our most recent report, logged TXX-6754, was submitted September 18, 1987. After further evaluation, we have concluded that this deficiency is reportable under the provisions of 10CFR50.55(e). The required infonnation follows.

DESCRIPTION OF DEFICIENCY Class IE radiation monitoring devices (1-RE-6290A and 1-RE-62908) interface with non-Class IE radiation monitors (1-RE-6259A, -6292, -6296, and -6298).

The non-Class 1E monitors' cornunication cables are isolated from the Class IE monitors utilizing isolators mounted on the microprocessor of the associated Class 1E monitor. These isolators are only qualified for low energy circuit separation. However, the non-Class 1E low energy communication cables are routed with non-Class IE 120V ac control circuit cables. This configuration exposes the non-Class IE low energy circuit comunication cables to f aults which may be induced by the 120V ac control circuit. Such an occurrence could cause the isolators on the Class IE radiation monitors to fail, consequently degrading the Class 1E circuit and the entire monitor communication loop.

The Class 1E versus non-Class IE separation requirements are also violated where non-Class IE cables are bundled in the radiation monitor common wireway with Class IE cables. The common wireway joins the junction box to the associated monitor microprocessor. The same cables mentioned above also terminate in the monitor junction box with less than the minimum acceptable distance between safety related and non-safety related cables. A similar condition also exists wherein there is a direct connection between the non-Class IE fire Detection System and the Class IE Atmospheric Cleanup Units fire Protection Panels.

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TXX-88060 January 11, 1988 Page 2 of 2 This deficiency apparently resulted from an inappropriate application of electrical separation criteria as defined in the CPSES FSAR. lhis type of deficiency could exist in any Class 1E to non-Class IE interface.

SAFETY IMPLICATIONS Following a LOCA, the monitors are provided to measure radiation levels. Ilad this condition remained uncorrected, the failure of the non-Class 1E 120V ac circuit could have adversely affected the Class lE monitors. Similarily, a failure in the non-Class lE Fire Detection System could have adversely affected the Class lE Atmospheric Cleanup Units Fire Protection Panels.

These conditions violate separation criteria and represent a significant deficiency in final design as approved and released for construction such that the design does not conform to the criteria and bases stated in the FSAR.

CORRECTIVE ACT10ft in order to correct the above condition, appropriate isolation devices will be installed to adequately separate non-Class 1E from Class IE to ensure Class IE circuit integrity is not degraded, in order to preclude recurrence, the design criteria for electrical separation have been established and documented in design basis document DBD EE-057, "Electrical Separation."

Our next report on this issue will be submitted no later than April 8,1988.

Very truly yours, f 14W W. G. Counsil VIP /grr c- Mr. R. D. Martin, Region IV Resident inspectors, CPSES (3)

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