ML20245B609
| ML20245B609 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/17/1989 |
| From: | Shelton D TOLEDO EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 1651, NUDOCS 8904260182 | |
| Download: ML20245B609 (6) | |
Text
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%um EDISON AQmewEmmyrsgsy DONALD C. SHELTON Docket Number 50-346 va nwem-e, (4191249.e300 License Number NPP-3 Serial Number 1651 April 17, 1989 United States Nuclear Regulatory Commicsion Document Control Desk Washington, D. C.
20555
Subject:
Response to Station Blackout Rule Gentlemen:
On July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 CFR Part 50.
A new section, 50.63, was added which requires that each light-water-cooled nuclear power plant be able to withstand and j
recover from a station blackout (SBO) of a specified duration.
Utilities are expected to have the baseline assumptions, analyses and related information used in their coping evaluation available for NRC review.
It also identifies the factors that must be considered in specifying the station blackout duration.
Section 50.63 requires that, for the station blackout duration, the plant be capable of maintaining core cooling and appropriate containment integrity.
Section 50.63 further requires that each licensee submit the following information:
1.
A proposed station blackout duration including a justification of the selection based on the redundancy and reliability of the onsite emergency AC power sources, the expected frequency of loss of offsite power, and the probable time needed to restore offsite power; 2.
A description of the procedures that vill be implemented for station blackout 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 procedures necessary for the specified SB0 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 Initiative Addressing Station Blackout At Light Vater 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.
W THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652 l
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-8904260182 890417 PDR ADOCK 05000346 P
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Docket Numbar 50-346
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Licensa Number NPF-3 Serial Number 1651 Page 2 Table 1 of RG 1.155 provides a cross-reference between RG 1.155 and NUMARC 87-00 and notes where the RG takes precedence.
Toledo Edison has evaluated Davis-Besse Unit 1 design features against the requirements of the SB0 rule using guidance from NUMARC 87-00 except where RG 1.155 takes precedence. The results of this evaluation are provided in the l
Attachment. The plant modifications and associated procedure changes identified in Parts A, B and C of the Attachment to this letter vill be completed by the end of the 7th Refueling Outage, currently scheduled to begin on September 1, 1991.
If you have any questions concerning this matter, please contact Mr. R. V.
Schrauder, Nuclear Licensing Manager, at (419) 249-2366.
Very truly yours,
/
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EBS/dlm cc:
P. M. Byron, DB-1 NRC Resident Inspector A. B. Davis, Regional Administrator, NRC Region III T. V. Wambach, DB-1 NRC Senior Project Manager I
Dock 2t Numbar 50-346
' Licdnsa Numb:r NPF-3 Serial Number 1651 Attachment Page 1 TOLEDO EDISON RESPONSE TO STATION BLACK 0UT RULE (Applicable NUMARC 87-00 Sections are shown in parenthesis.)
A.
Proposed Station Blackout Duration NUMARC 87-00, Section 3 was used to determine a proposed Station Blackout (SBO) duration of four hours.
The following plant factors vere identified in determining the proposed station blackout duration:
1.
AC Power Design Characteristic Group is P1 based on:
Expected frequency of grid-related loss of off-site power events a.
(LOOPS) - does not exceed once per 20 years (Section 3.2.1, Part 1A, P. 3-3);
b.
Estimated frequency of LOOPS due to extremely severe weather places the plant in Extremely Severe Veather (ESV) Group 2 (Section 3.2.1, Part 1B, p. 3-4);
Estimated frequency of LOOPS due to the severe weather places the c.
plant in Severe Veather (SV) Group 2 (Section 3.2.1, Part 1D, p.
3-7);
d.
The offsite power system is in the 11/2 (Section 3.2.1, Part 1D,
- p. 3-10);
2.
The emergency AC power configuration group is C based on: (Section 3.2.2, Part 20, p. 3-13)
There are two emergency AC power supplies not credited as a.
alternate AC power sources (Section 3.2.2, Part 2A, p. 3-15);
b.
One emergency AC power supply is necessary to operate safe shutdown equipment following a loss of offsite power (Section 3.2.2, Part 2B, p. 3-15).
3.
The target Emergency Diesel Generator (EDG) reliability is 0.95.
A target EDG reliability of 0.95 was selected based on having a a.
nuclear unit average EDG reliability for the last 100 demands greater than 0.95, which is consistent with NUMARC 87-00, Section 3.2.4.
4.
An alternate AC (AAC) power source vill be utilized at Davis-Besse which meets the criteria specified in Appendix B to NUMARC 87-00.
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Dockst Nunb:r 50-346
" Licinsa Numbar NPF-3 Serial Number 1651 Attachment Page 2 The AAC power source vill be available within ten minutes of the onset of the station blackout event and vill have sufficient capacity and capability to operate systems necessary for coping with a station blackout for the required SB0 duration of four hours to bring ar.d maintain the plant in a safe shutdown condition.
It is noted that Class 1E battery capacity, compressed air and containment isolation need not be addressed.
An AAC power source with adequate capacity to power all systems I
required to cope with SB0 vill be installed at Davis-Besse. It vill have the capability to be started and aligned from the Control Room and vill be connectable but not normally connected to non-essential bus D2 (See Figure 1) which will be aligned to provide power to either essential bus C1 or D1, as required.
B.
Procedure Description Plant procedures have been reviewed and modified, as appropriate, 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; 2.
Severe weather per NUMARC 87-00, Section 4.2.3.
Site specific actions necessary to restore AC power are addressed by DB-PF-02000 (Emergency Procedure), and DB-OP-02521 (Loss of AC Bus Power Sources). Toledo Edison load dispatchers have been instructed to give the highest possible priority to restoring power to Davis-Besse in the event of a loss of power. Toledo Edison is in the process of developing formal guidelines to assure the appropriate mechanism is in place so that the highest priority is given to restoration of offsite power to Davis-Besse j
(guidelines for load dispatchers and transmission line repair crews).
l These guidelines vill be issued by May 31, 1989.
Severe Veather
(
guidelines for Davis-Besse are provided in Emergency Plan procedure I
EP-4100, Tornado and Emergency Classification Procedure, HS-EP-01500.
Plant procedures have been reviewed and changes necessary to meet NUMARC 87-00 vill be implemented by the end of the 7th refueling outage in the following areas:
1.
Station blackout response per NUMARC 87-00, Section 4.2.1; 2.
Procedure changes associated with any modifications required after assessing coping capability per NUMARC 87-00, Section 7.
C.
Proposed Modifications and Schedule The AAC source has the capacity and capability to power the equipment necessary to cope with a SB0 in accordance with NUMARC 87-00, Section 7 for the required coping duration determined in accordance with NUMARC 87-00, Section 3.2.5.
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Docket Number 50-346
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- Lic~n e Numbar NPF-3 Serial Number 1651 Attachment Page 3 An AAC source consisting of a diesel generator and required support systems with indications and controls to support remote operation from the Control Room vill be installed at the Davis-Besse site during the seventh refueling outage (7RF0) (currently scheduled to begin September 1, 1991).
New procedures and changes to existing procedures vill be generated to support the operation, testing and maintenance of the AAC equipment.
1.
Condensate Inventory for Decay Heat Removal (Section 7.2.1)
It has been determined from Section 7.2.1 of NUMARC 87-00 that approximately 62,000 gallons of water are required for decay heat removal for four hours. The minimum permissible condensate storage tank level per Technical Specifications provides 250,000 gallons of water, which exceeds the required quantity for coping with ; four-hour station blackout.
2.
Effects of Loss of Ventilation (Section 7.2.4)
The AAC power source provides power to HVAC systems serving dominant areas of concern. Therefore, the effects of loss of ventilation were not assessed.
No modifications and/or procedures are required to provide reasonable assurance for equipment operability.
3.
Reactor Coolant Inventory (Section 2.5)
The AAC source powers the necessary primary side make-up systems to maintain adequate reactor coolant system inventory to ensure that the core is cooled for the required coping duration.
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