ML19242D021

Deficiency Rept Re Svc Water Supply Pressure for Containment Air Coolers.Corrective Action Will Be Taken to Ensure That Boiling Does Not Occur in Containment Air Coolers & That Design Conforms to SAR

ML19242D021
Person / Time
Site:	Midland
Issue date:	08/02/1979
From:	Massing D BECHTEL GROUP, INC.
To:
Shared Package
ML19242D016	List: ML19242D015 ML19242D021
References
MCAR-30, NUDOCS 7908140366
Download: ML19242D021 (2)

Text

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. Howe-219-79 Bochtel Assoc:ated ProiossionalCorporation Attachment to BLC-7971

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S U r,.l CCT - trAR 30 (issued 7/11/79)

Service Water Supply Pressure for the Containment Air Coolers INTdRIM REPORT 1 ,

DATE: August 2, 1979 PROJECT: Consumers Power Company Midland Plant Units 1 and 2 Bechtel Job 7220 Introduction This report is submitted to advise of the interin status af the project's actions relating to the service water supply pressure for the containment air coolers.

Designation of Deficiency Duri1g final systen design review, p roj ec t engineering discovered that the service water supply pressure to the containacnt air coolers following a lons-tl-coolant accident (LCCA) or main steam line break (MSLB) is less t aan 40 psig (54.7 psia) at the outlet of the air cooling unit as stated in FSAR subsection 6.2.2.2.3. The final calculations indicate that the service water pressure at the containment air cooler outlet could be as low as 13 to 14 psia under caergency operation, with the ultimate heat sink at its design elevation of 604 feet (see FSAR subsection 9.2.5). The post-accident environ =ent inside the containment reaches approximately 30 and causes the service water inside the air coolers to boil, resulting in reduced performance of the containment air coolers.

Consequently, the containment air coolers could not remove heat at the rate as described in FSAR subsections 6.2.2.2 and 9.2.1.3 following an MSLB or LOCA.

Potential Safety Tmplications If the deficiency had not been detected, there would have been no effect on the nornal safe operation of the plant. With the service water system as designed, the containment air coolers are capabic of removing heat from the containment for all power generation modes. However, under post-LOCA or MSLB conditions, the containmeat air coolers would not have been able to meet their safety design bases to remove heat from the containment f ollowing a LOCA or MSLB. Analysis of the effects of complete loss of containment air cooler heat removal capability is incompic_te, but the following preliminary conclusions can be drawn:

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13echtel /\ssociatus Prolossional Corporation Attachment to ELC-7971 MCAR 30 Interim Report 1 August 2, 1979 Page 2

1. Containment pressures and tenperatures following a LOCA sprays and MSLB operating v'.;.a no air coolers and only one train of containment Therefore, containment are within the containment design basis.

integrity would not be jeopardized.

2. Following a MSLB or LOCA, the containment prcosure and temperatures decrease more slowly when one spray train is used rather than one spray and one air cooler train. The temperature and pressure environmental qualification envelopes of various components insideTherefore, the contain=cnt may be exceeded for LOCAs and large MSLDs.

the longer-tera availability of various safety-related equipment and post-accident monitoring components cannot be ensured. Because this is a significant deficiency in the design as stated in the this item is reportable safety analysis report, it is concluded that in accordance with 10 CFR 50.55(c) .

Corrective Action occur in Corrective action will be taken to ensure that boiling does not the design conf orms to the safety the containment airSpecifically, coolers andathat pump will be provided in each service analysis report.

water supply line to the containment air coolersthe to boost the service outlet of the air coolers.

water pressure to a minimum of 40 psig at A suitable flow control device will be provided to throttle the excess pressure before returning the service water to the main return header.

Normally, the pump will not be running, it will start outom:_tically on a reactor building cooling actuation signal.

Design for this corrective action is proceeding and is expected of additional componentsto be has Procurement complete started. by September, 1979.The cause of the interin deficiency and other corrective actions ar report.

under review and will be discussed in the next Signed by: p m

1 u., m(Sh (f Approved by: _

f Concurrence by: #

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