ML20244D037
| ML20244D037 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 04/14/1989 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.155, RTR-REGGD-1.155 NUDOCS 8904210112 | |
| Download: ML20244D037 (5) | |
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BALTIM ORE GAS AND ELECTRIC CHARLES CENTER P. O. BOX 1475 BALTIMORE, MARYLAND 21203 GEORGE C. CREEL Vect PatsrocNT NucLean Ewcnoy (300 aco-d ess April 14,1989 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 Response to Station Blackout Rule: 10 CFR 50.63 Gentlemen:
i On July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 CFR 50. A new section, 50.63, was added which requires that each light-water-cooled nuclear power plant be able to withstand and recover from a station blackout l
(SBO) of a specified duration. It also identifies the factors that must be considered in specifying the SBO duration. Section 50.63 requires that, for the S00 duration, the plant be capable of maintaining core cooling and appropriate containment integrity.
Section 50.63 further reouires that we submit the following informatiore 1.
A proposed SBO duration including a justification for the selection based on the redundancy and reliability of the on-site emergency AC power sources, the expected frequency of loss of off-site power, and the probable time needed to restore offsite power; 2.
A description of the procedures that will be implemented for SBO events for the duration (as determined in 1. above) and for recovery therefrom; and 3.
A list and proposed schedule for any needed modifications to equipment and associated procedure necessary for the specified SBO duration.
The NRC has issued Regulatory Guide (RG) 1.155, " Station Blackout," which describes a means acceptable to the NRC Staff for meeting the requirements of 10 CFR 50.63.
Regulatory Guide 1.155 states that the NRC Staff has determined that NUMARC 87-00,
" Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors" also provides guidance that is in large part identical to the RG 1.155 guidance and is acceptable to the NRC Staff for meeting these requirements.
Our baseline assumptions, analyses and related information used in the coping evalua-tion is available for NRC review.
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Document Control Desk Aprtl 14,1989 Page 2 Table I to RG 1.155 provides a cross-reference between RG 1.155 and NUMARC 87-00 and notes where the RG takes precedence.
Baltimore Gas and Electric has evaluated Calvert Cliffs Units 1 and 2 against the requirements of the SBO rule using guidance from NUMARC 87-00, except where RG 1.155 takes precedence. The results of this evaluation are detailed below.
A.
Pronosed Station Blackout Duration NUMARC 87-00, Section 3 was used to determine a proposed SBO duration of four hours. The following modifications will be implemented to attain the proposed coping duration category: (1) At least one additional diet.el generator will be installed, and (2) The battery room IIVAC system will be upgraded.
The following Plant factors were identified in determining the proposed SBO duration:
1.
AC Power Design Characteristic Group is P2 based on:
a.
Expected frequency of grid-related Loss of Offsite Power (LOOPS) does not exceed once per 20 years; b.
Estimated frequency of LOOPS due to extremely severe weather places the plant in ESW Group 4; c.
Estimated frequency of LOOPS due to severe weather places the plant in SW Group 2; d.
The off-site power system is in the 11/2 Group; c.
Plant-specific pre-hurricane shutdown requirements and procedures which meet the guidelines of Section 4.2.3 of NUMARC 87-00 have been implemented.
2.
The emergency AC power configuration group is D based on:
a.
There are three emergency AC power supplies not credited as alternate AC power sources; b.
Two emergency AC power supplies are necessary to operate safe 1
shutdown equipment following a loss of off-site power.
3.
The target Emergency Diesel Generator (EDG) reliability is 0.975.
a.
A target EDG reliability of 0.975 was selected based on having a nuclear unit average EDG reliability for the last 100 demands greater s
than 0.95, consistent with NUMARC 87-00, Section 3.2.4.
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Document Control Desk Aprf1 14, 1989 3
Page 3 i
l B.
Procedure Dacription Plant procedures have been reviewed and modified, if necessary, to meet the guidelines in NUMARC 87-00, Section 4 in the following areas:
1.
AC power restoration per NUMARC 87-00, Section 4.2.2; Electrical Systems Restoration Procedures.
2.
Severe weather per NUMARC 87-00, Section 4.2.3; Emergency Response Plan Implementing Procedure 3.0.
Plant procedures have been reviewed and changes necessary to meet NUMARC 87-00 will be implemented in the following areas:
1.
Station blackout response per NUMARC 87-00, Section 4.2.1; Emergency Operating Procedure 7, Station Blackout; 2.
Procedure changes associated with modifications required after assessing coping capability per NUMARC 87-00, Section 7.
C.
Proposed Modifications and Schedule The ability of Calvert Cliffs Units 1 and 2 to cope with a SBO for four hours in accordance with NUMARC 87-00, Section 3.2.5 and as determined in Section "A" above; was assessed using NUMARC 87-00, Section 7 with the following results:
1.
Condensate Inventory for Decav Heat Removal (DHR) (Section 71])
It has been determined from Section 7.2.1 of NUMARC 87-00' that 98,000 gallons of water are required for DHR for eight hours for one unit. The f
minimum permissible condensate storage tank level per Technical Specifications provides 300,000 gallons of water total for both units, which exceeds the required quantity for coping with an eight-hour SBO.
a.
No plant modifications or procedure changes are needed to utilize these water sources.
2.
Class IE Batteries Canacity (Section 7.2.2 )
A battery capacity calculation has been performed pursuant to NUMARC 87-00, Section 7.2.2 to verify that the Class IE batteries have sufficient capacity to meet SBO loads for four hours.
3.
Comoressed Air (Section 7.2 Air-operated valves relied upon to cope with a SBO for four hours can be operated manually. Valves requiring manual operation are identified in plant procedures, l l
s Document Control Desk Apr'il 14,1989 Page 4 4. Effects of Loss of Ventilation (Section 7.2.4) a. AFW Pump Room The calculated steady state ambient air temperature for the steam-driven AFW pump room (the dominant area of concern for a PWR) during a SBO-induced loss of ventilation is 137 F. b. Control Room Complex The assumption in NUMARC 87-00, Section 2.7.1 that the Control Room will not exceed 120 F during a SBO has been assessed. The Control Room at Calvert Cliffs does not exceed 120 during a SBO. Therefore, the Control Room is not a dominant area of concern. Reasonable assurance of the operability of SBO response equipment in the l f above dominant area of concern has been assessed using Appendix F to NUMARC 87-00 and/or the Equipment Operability Topical Report. No modifications or associated procedures are required to provide reasonable assurance for equipment operability. 5. Containment Isolation (Section 7.2.5) The plant list of containment isolatio-valves has been reviewed to verify that valves which must be capable of being closed or that must be operated (cycled) under SBO conditions can be positioned (with indication) independ-ent of the preferred and blacked-out Unit's Class IE power supplies. No plant modifications and/or associated procedure changes were determined to be required to ensure that appropriate containment integrity can be provided under SBO conditions. 6. Reactor Coolant inventory (Section 2.5) The ability to maintain adequate reactor coolant system inventory to ensure that the core is cooled has been assessed for four hours. A plant-specific analysis was used for this assessment. The expected rates of reactor coolant inventory loss under SBO conditions do not result in core uncovery during an SBO of four hours. Therefore, makeup systems are not required to maintain core cooling under natural circulation (including reflux boiling), i The modifications and associated procedure changes identified in Parts A, B and C above will be completed within five years after the notification provided by the Director, Office of Nuclear Reactor Regulation, in accordance with 10 CFR 50.63(c)(3).
1 +. gg.' l Document Control Desk.' lf .. ; April - 14,.- 1989 Page 5.' Should 'you have any; further questions regarding this matter, we will be ' pleased to discuss them with you. - I Very1 t uly yours, / e GCC/ PSF / dim. cc: D.. A. Brune, Esquire J. E. Silberg, ' Esquire R. A. Capra, NRC - S. A.McNeil, NRC W. T. Russell, NRC - ' H. Eichenholz/V. L. Pritchett, NRC T. Magette, DNR 1 l J}}