NSD-NRC-96-4813, Responds to Telcon Questions Re Main Control Room Emergency Habitability Sys

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Responds to Telcon Questions Re Main Control Room Emergency Habitability Sys
ML20117K532
Person / Time
Site: 05200003
Issue date: 09/04/1996
From: Mcintyre B
WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To: Quay T
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
DCP-NRC0597, DCP-NRC597, NSD-NRC-96-4813, NUDOCS 9609110341
Download: ML20117K532 (3)
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Westinghouse Energy Systems Box 355 Electric Corporation Pittsburgh Pennsylvania 15230 0355 i

NSD-NRC-96-4813 DCP/NRC0597 Docket No.: STN-52-003 1

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September 4,1996 i

Document Control Desk l

U.S. Nuclear Regulatory Commission l

Washington, D.C. 20555 i

j ATTENTION:

T.R. QUAY

SUBJECT:

RESPONSES TO NRC QUESTIONS RELATED TO TIIE MAIN CONTROL ROOM EMERGENCY IIABITABILITY SYSTEM i

Dear Mr. Quay:

i Attached are responses to NRC questions related to the main control room emergency habitability l

system. The questions resulted from a phone call with the NRC and are identified by the Open Items j

Tracking System item number. This response completes our actions on these four questions and will j

permit the staff review of Section 6.4 and preparation of the Final Safety Evaluation Report input.

Please contact Donald A. Lindgren on (412) 374-4856 if you have additional questions.

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i Brian A. McIntyre, Manager Advanced Plant Safety and Licensing i

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Attachment i

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W. C.1luffman - NRC i

N. J. Liparulo - Westinghouse (w/o attachments) j Ew/,

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9609110341 960904 PDR ADOCK 05200003 C

PDR 4

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Attachment to NSD-NRC-96-4813 These questions resulted from a phone call with the NRC staff to discuss the main control room emergency habitability system (VES, Section 6.4). The issues are identified by the Open Items Tracking System Database item number.

2892 Provide additional information on modeling of the annex building and turbine building temperatures in the GOTillC evaluation of main control room temperature rise. Provide information on modeling - specifically: 1) initial temperature, 2) basis for model, 3) how temperature rise is limited to 15 F.

Response

1) The initial temperatures for the room heatup calculations (i.e., thermal analysis) performed with the GOTHIC code conservatively use the upper bound of the applicable room temperature range, plus an uncertainty for instrument / channel inaccuracy. Specifically, the annex building is modeled as a separate volume with an initial air temperature of 80 F (78 F+2 uncertainty), while the turbine building is represented by a separate volume with an initial air temperature of 108 F (105 F+

3 F uncertainty).

2) The GOTHIC model for the room heatup calculation is a lumped parameter model, consisting of 32 volumes connected by approximately 40 flowlinks representing doors, corridors, and air delivery lines. Heat conduction is modeled through the use of over 100 conductors representing walls, floors, and ceilings through which heat transfer occurs. The majority of the rooms on the " clean" side of the auxiliary building are included in the model, which is used to predict the room air temperature during VES operanon.
3) The temperature rise in the main control room (MCR) is limited by the rate of heat transfer to the surrounding structures through the walls, floors, and ceilings. To enhance the transfer of heat into these structures, both the MCR and I&C equipment rooms are constructed with finned ceilings. See SSAR Rev. 7, subsection 3.8.4.1.2 and Figure 3.8.4-6 for additional details concerning finned ceiling construction.

2893 Demonstrate that expected humidity response with VES operating during the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is not a problem for I&C equipment.

Response

The environmental qualification test profile for the Class IE electrical equipment rooms have been provided in Revision 5 of the SSAR, in Figure 3D.5-1, sheets 2 through 5.

These figures show that the equipment will be qualified to a 95% relative humidity environment for a duration of 5 days. This bounds the design condition, in that the design condition is initialized at 60% relative humidity. Since there is no source of humidification within the room (i.e., no human presence producing moisture through respiration), the relative humidity of the room will not increase to that which the equipment is qualified. Thus, the electrical equipment room relative humidity would be bounded by that of the test envelope.

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2895 Confirm that I&C equipment qualification is consistent with the 120 degree F room temperature

Response

Design conditions and testing conditions for equipment including I & C equipment subject to elevated temperatures not resulting from pipe break environments during abnormal conditions is outlined in Appendix 3D. Please see subsection 3D.5.1 and Figure 3D.5-1.

2896 Address operator action of shutting down nonsafety-related loads at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Staff thinks "it is not wise" to turn off indication channels powered through batteries during station blackout. Discuss instrument overheating during the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period issues related to elevated temperature as a result of loss of IIVAC.

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Response

To control I&C room temperatures, the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> battery loads are terminated at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in the thermal analysis. This is accomplished only after all required safety functions have been completed. For post-accident monitoring, the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> batteries continue to supply power, so there is no loss of surveillance capability if the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> batteries are secured.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> battery loads would only need to be terminated at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in the event of VES system initiation if the I&C room temperature approaches 120 *F. This is not predicted to occur before the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the event. It provides adequate margin to the l

environmental qualification temperature limit of 125 F.

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