ML20236K949
| ML20236K949 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 07/07/1998 |
| From: | Cruse C BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9807100151 | |
| Download: ML20236K949 (4) | |
Text
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CHARLES II. CRIJSE Baltimore Gas and Electric Company Vice President Calvert Cliffs Nuclear Power Plant Nuclear Energy 1650 Calvert Cliffs Parkway Lusby. Maryland 20657 410 495 4155 July 7,1998 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Information Concerning Diesel Generator Loading In response to your request made during a phone call on May 20,1998, we are providing information concerning the Control Room ventilation system and the No. l A Emergency Diesel Generator (EDG).
1.
Provide a simph) led diagram ofthe Control Room ventilation system.
See Figure 1.
2.
Is there a delayed start of the Control Room ventilation system when required to support an accident response?
//
The Control Room ventilation system has two trains. Each train is powered by one EDG from each k d unit (see Figure 2). When both units are operating, each train of the ventilation system would automatically start as a sequenced load of the EDG, if the EDG is needed for accident response.
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When one unit is operating and one unit is shut down, the Control Room ventilation train powered from the EDG on the operating unit would start automatically as a sequenced lead if the EDG is needed for accident response. If the EDG on the operating unit should fail, the Control Room ventilation train powered from the EDG on the shut down unit would be manually started post-accident, because the automatic start feature and the sequencer are not required during a shutdown condition. This delayed start has been evaluated and found to provide adequate operator protection and temperature control.
3.
What are the TechnicalSpecification requirementsfor the EDGs on a shut down unit?
Technical Specification 3.8.1.2 [ Improved Technical Specification (ITS) 3.8.2] requires one operable EDG during Modes 5 and 6 (and during fuel movement under ITS). Sequencers are not required. Either EDG on the shut down unit is capable of fulfilling this function. The ITS also requires one EDG operable from the shut down unit to support the Control Room ventilation system 9807100151 900707 PDR ADOCK 05000317 P
Document Control Desk July 7,1998 Page 2 for the operating Unit (ITS 3.8.1). Only the EDG connected to the same bus as the Control Room ventilation system can fulfill this function.
4.
What is the core damagefrequencyfor a scenario where Unit I has a loss-of-coolant accident and the No. IA EDG is out-of-service?
The estimated core damage frequency increase associated with having the No. I A EDG out-of-4 service during a plant trip is 3x10. This is a 7% increase in the total core damage frequency. This evaluation does not assume that a loss-of-coolant accident (LOCA) has occurred, but that a LOCA initiating event (plant trip) has occurred. If a LOCA were assumed to occur when the No. l A EDG is out-of-service, then the core damage frequency would be higher and is dependent on the type of LOCA assumed (i.e., large, small, etc.).
Should you have gaestions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, f
Znr
,,gm CHC/ PSF /bjd cc:
R. S. Fleishman, Esquire IL J. Miller, NRC J. E. Silberg, Esquire Resident Inspector, NRC S. S. Bajwa, NRC R. I. McLean, DNR A. W. Dromerick, NRC J. H. Walter, PSC l
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CONTROL ROOM HEATING, VENTILATION, & AIR CONDITIONING
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- A Supply and Return Fan of the same train is normally operating.
- The NSR chiller is normally aligned to the operating train and providing the necessary cooling for the Control Room.
- The associated safety related refrigeration _ cycle (which includes the compressor and the roof top condenser units) is in auto. The thermostats of the chiller and the safety related refrigeration cycle are offset so that the chiller will provide the cooling load. If the chiller trips off, the SR refrigeration cycle will start automatically and pick up the cooling load
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