ML20072D821

Supplements Discussing Alternative to Automatic Isolation of V-79 Exhaust Sys When Radiation Detected,Per NUREG-0737,Item II.F.1.1.Explanation of Why Alternatives to Proposed Mod Investigated Discussed

ML20072D821
Person / Time
Site:	Palisades
Issue date:	06/17/1983
From:	Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.1, TASK-TM NUDOCS 8306230413
Download: ML20072D821 (3)

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cen rei office,: 194s w.n e rnan no.d.a.cu,on, MI 4o201. (st7) 7ss-osso  ; OL ) pg June 17, 1983 James G Keppler, Administrator Region III US Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - NUREG-0737 ITEM II.F.1.1 " NOBLE GAS EFFLUENT MONITOR SUPPLEMENT" Consumers Power Company letter dated February 2, 1983 stated that an alterna-tive to automatic isolation of the V-79 exhaust system when radiation is detected. The information contained in this supplement letter explains why alternatives to the originally proposed modification were investigated, the objectives of the investigation, and the conclusions.

The reasons for pursuing alternatives to the originally proposed modification of the Auxiliary Building for V-79 are explained below.

1. Possible overloading of the existing ventilation system.

As proposed in the original modification, the discharge of the V-79 fan would have been routed to the suction of the V-6A and V-6B fans. A review of the current design flows for the Auxiliary Building ventilation shows that the addition of the V-79 flow would require V-6A or V-6B to operate above their rated capacity. As a result, either both fans would be re-quired to operate at all times, or V-6A and V-6B would be replaced with fans of sufficient capacity to provide the additional ventilation flow.

2. Originally proposed modification did not satisfy the objectives of NUREG-0737 Item II.F.1.1.

The requirement to monitor all potential release paths would s not necessarily be met by the originally proposed modification since several other areas exist which represent a potential 8306230413 830617 PDR ADOCK 05000255 JUN 2 01983 P PDR OC0683-0011A-NLO2 SY

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. l J:mes G Kapplsr, Administrator 2 Palisades Plant _

, NUREG-0737 Item II.F.1.1

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June 17, 1983 discharge path. Therefore, in the event of a high energy line break accident, ventilation provided by the modified V-79 fan would probably not be effective.

In light of these concerns, a review of potential sources of radioactivity

. release to the room serviced by the V-79 fan (ie, Component Cooling Room) and the identification of unmonitored release paths was undertaken. The following potential sources of release were identified and evaluated.

a. Main Steam Lines - The event of a main steam line break or lifting of the steam generator relief valves would create the potential for the release or radioactive steam to the Component Cooling Room. The main steam lines, however, have now been provided with on-line monitoring capabilities. In addition, the relief valve stacks are monitored by detectors. Therefore, since these potential release paths are monitored, any modifi-cation of the V-79 fan would not provide a significant increase in surveillance capabilities.

b. Containment Purge Lines - These purge lines are currently routed directly to the Plant stack which is provided with radiation monitors. Also, the release of radioactivity inside containment, ie, the origin of radioactivity in the containment purge lines, is monitored. Therefore, this potential release i source appears to be adequately monitored without the need for modifications to the V-79 fan,

c. Safety Injection Refueling Water'(SIRW) Tank Recirculation / Heat Exchanger - This component is considered a source of low-level radioactivity release only since the SIRW tank is currently vented to the atmosphere. Accordingly, any leakage in the Component Cooling Room would not constitute a release problem that would require monitoring this release path.

d. Component Cooling Room Equipment Drains - There is a concern that equipment and floor drains from various areas within the

Auxiliary Building could backup into the Component Cooling Room. If this were to occur during a major accident, a potential for the unmonitored release from highly contaminated water to the atmosphere could exist. The drain system is the only available path for highly contaminated water to enter this room since all doors are water tight.

As a result of these evaluations, Consumers Power Company intends to reroute floor drains such that the drains could be isolated in the event of an accident. This modification is expected to be complete by then end of the OC0683-00llA-NLO2

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Jr,mes G Kcpplar, Administrator 3 Palisades Plant NUREG-0737 Item II.F.1.1 June 17, 1983 1983 Refueling Outage, scheduled to begin August 13, 1983. Consumers Power Company also concludes that this modification is more acceptable from an ALARA standpoint than the originally proposed modification since rerouting of the drain lines would prevent the release of radioactivity rather than providing for the release to be monitored. In this way, Consumers Power Company believes that the objectives of NUREG-0737 Item II.F.1.1 will be satisfactorily met.

Brian D Johnson Staff Licensing Engineer CC . Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement NRC Resident Inspector - Palisades

'OC0683-0011A-NLO2