ML19256F003

Significant Deficiency Rept 369-370/79-10:on 791108,some safety-related Mechanical & Electrical Equipment in Doghouse Area Outside Containment Not Environmentally Qualified. Caused by Feedwater or Steam Line Break

ML19256F003
Person / Time
Site:	Mcguire, McGuire
Issue date:	11/08/1979
From:	DUKE POWER CO.
To:
Shared Package
ML19256F002	List: ML19256F001 ML19256F003
References
NUDOCS 7911160465
Download: ML19256F003 (2)

Text

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Duke Power Company McGuire Nuclear Station Units 1 & 2 Report No: SD 369-370/79-10 Report Date: November 8, 1979 Facility: McGuire Nuclear Station, Units 1 and 2 Description of Deficiency:

Some safety related mechanical and electrical equipment in the doghouse area outside containment is not qualified for the final environment resulting from a feedwater or steamline break. In addition, some safety related equipment is below the flood level caused by a feedwater line break.

The following safety related equipment and corresponding controls are af fected by the adverse environment.

1. Main Steam Isolation Valves

2. Main Steam Power Operated Relief Valves

3. Auxiliary Feedwater Pump Turbine Steam Supply Isolation Valves

4. Feedwater Isolation Valves Analysis of Safety Implications:

Worst case safety consequence following an auxiliary feedwater line break in a doghouse would be reduction of effective auxiliary feedwater flow from the required 450 gpm to 100 gpm. This worst case assumes the failure of both auxiliary feedwater pump turbine steam supply isolation valves to open as a result of the break environment. Additionally, a single failure of one motor driven auxiliary feedwater pump is assumed. The operating motor driven auxiliary feedwater pump would provide 100 gpm flow to only one intact steam generator, with the remainder of its flow spilling from the broken auxiliary feedwater line.

Worst case safety consequence following a steam line break inside a doghouse is reduction of auxiliary feedwater flow from the required 450 gpm to 340 gpm.

This worst case assumes the failure of both auxiliary feedwater pump turbine steam supply isolation valves to open as a result of the break environment.

Additionally, a single failure of one motor driven auxiliary feedwater pump is assumed. The operating motor driven auxiliary feedwater pump would provide 170 gpm flow to each of two intact steam generators which have been successfully isolated and remain pressurized.

}g Corrective Action:

All safety related equipment and corresponding controls listed above will either be qualified by testing or by modification fo r the worst case steam line or feedwater line break environment, or be moved to an acceptable location outside the doghouse.

7911160 Nb

_2_ .

Redundant safety grade level instrumentation will be located in the doghouse to detect a flooding condition, initiate an alarm in the control room, and' signal automatic isolation of forward feedwater flow into the doghouse, thus

, minimizing flooding to a level which will assure the protection of safety related equipment and controls.

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