ML20245A716
| ML20245A716 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 04/17/1989 |
| From: | Kuncl L NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS-8900153, NUDOCS 8904250353 | |
| Download: ML20245A716 (6) | |
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GENERAL OFFICE 1
p Nebraska Public Power District "LeW!#&"f ^1*eP""
fi NLS 0900153 April 17, 1989 U.S.
Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555 Gentleman:
Subject:
Response to Station Blackout Rule, 10CFR50.63.
Cooper Nuclear Station NRC Docket No. 50-298, DPR-46 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 each light-water-cooled nuclear power plant be able to withstand and recover from a station blackout (SBO) of a specified duration.
The new rule specifies the factors that must be considered in determining 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 for the selection based on the redundancy and reliability cf 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 will 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 SBO duration.
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NLS 8900153 Page 2 U.S.
Nuclear Regulatory Commission The NRC has issued Regulatory Guide 1.155 " Station Blackout" which describes a means acceptable to the NRC Staff for meeting the requirements of 10CFR50.63.
Regulatory Guide (RG) 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.
Table 1 to RG 1.155 provides a cross-reference between RG 1.155 and NUMARC 87-00 and notes where the RG takes precedence.
The Nebraska Public Power District has evaluated the Cooper Nuclear Station (CNS) 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.
Proposed Station Blackout Duration NUMARC 87-00, Section 3, was used to determine a proposed SBO duration of four hours.
No modifications were required to attain this proposed coping duration category.
The following plant factors were identified in determining the proposed station blackout duration:
1.
AC Power Design Characteristic Group is P2 based on:
a.
Expected frequency of grid-related LOOPS - does not exceed once per 20-years.;
b.
Estimated frequency of LOOPS due to extremely severe weather places the plant in ESW Group 3; c.
Estimated frequency of LOOPS due to severe weather places the plant in SW Group 3; and d.
The offsite power system is in the 11/2 Group.
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t We are presently evaluating site-specific data on wind speeds.
This data may change the CNS AC Power Design Characteristic Group to Pl.
The Commission will be notified of any changes to the information provided herein that result from this site-specific data.
2.
The emergency AC power configuration group is C based on:
a.
There are two emergency AC power supplies not credited as alternate AC power sources; and b.
One emergency AC power supply is necessary to operate safe shutdown equipment following a loss of offsite power.
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'3.
The target EDG reliability. is' O. 975.
The target. EDG
. reliability _will change.to.0.95 if an AC Power. Design Characteristic Group of;P1 is' justified based on ' site l
l:
specific' data.
l A target EDG reliability of 0.975 was selected based on having a CNS average EDG reliability for the last-100 demands greater than 0.95,' consistent with NUMARC 87-00,
'Section 3.2.4..
B.
Procedure Description Plant procedures have been reviewed and revisions drafted, as necessary, to-meet the guidelines in NUMARC 87-00, Section 4, in:the following areas:
l 1.
AC power restoration per NUMARC 87-00, Section 4.2.2, except guideline (5);
2.
Severe weather per NUMARC 87-00, Section 4.2.3.
Plant procedures to address these two areas have been drafted and ar_e in the approval cycle. - They will be implemented prior to October 1, 1989.
Plant procedures have been reviewed and changes necessary to meet NUMARC 87-00 will be implemented'in the following area:
Station blackout response per NUMARC 87-00, Section 4.2.1.
These procedure changes will be completed 6 months after the notification provided by the Director, Office of Nuclear Reactor Regulation, in accordance with 10CFR50. 63 (c) (3).
C.
Pronosed Modifications and Schedule The ability of Cooper Nuclear Station to cope with a station blackout for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, 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 Decay Heat Removal It has been determined from Section 7.2.1 of NUMARC 87-00 that 52,668 gallons of water are required for decay heat removal for a required coping duration category of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The minimum permissible condensate storage tank level identified in the CNS Updated Safety Analysis Report provides 100,000 gallons of water, which exceeds
NLS 8900153 Page 4 U.S.
Nuclear Regulatory Commission-the required quantity for coping with a 4-hour station blackout.
2.
Class lE Batteries Capacity A
battery capacity calculation has been performed pursuant to NUMARC 87-00, Section 7.2.2,-to verify that the Class 1E batteries have sufficient capacity to meet station blackout loads for four hours.
3.
Compressed Air Compressed air is not relied upon at CNS to cope with a station blackout for four hours.
4.
Effects of Loss of Ventilation a.
The steady state ambient air temperature has been calculated for the following dominant areas of concern:
AREA TEMPERATURE RCIC Room 130 F DC Switchgear Rooms 127 F The HPCI Room and Main Steam Tunnel are not dominant areas of concern at CNS.
Although the HPCI System will be available, it is not required to respond to a station blackout and no credit is taken for its operation.
With regard to the Main Steam Tunnel, there is no high temperature cutout of the RCIC System based on tunnel temperature at CNS.
b.
Control Room Complex The assumption in NUMARC 87-00, Section 2.7.1, that the control room will not exceed 12 0 F during a station blackout has been assessed.
The control room at CNS does not exceed 120 F during a station blackout.
Therefore, the control room is not a dominant area of concern.
Reasonable assurance of the operability of station blackout response equipment in the above dominant areas of concern has been assessed using Appendix F, Revision 1, dated October 1988 to NUMARC 87-00 and/or Appendix F Topical
- Report, dated October 1988.
No modifications or associated procedures are required to provide reasonable assurance for equipment operability in the dominant areas of concern.
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Containment Isolation-The plant list of containment isolation valves has been reviewed to determine those valves which must be capable of being closed or that must be operated-(cycled): under station blackout conditions, with indication, independent of.the preferred and blacked-out Class lE AC 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 The ability to maintain adequate reactor coolant system inventory has been assessed for four hours.
The generic analyses listed in Section 2.5.2 of NUMARC 87-00 were used for this assessment and are applicable to the
.. specific design of CNS..The expected rates of reactor coolant inventory loss under SBO conditions do not result in more.than a' momentary core uncovery in a SBO of four hours..
Therefore, makeup systems other than those currently available under SBO conditions are not required to maintain core cooling.
If further information is required, please contact ry office.
Sincerely, 86 L.
G.
Kuncl-Nuclear Power Group Manager LGK/mtb:caa18-1(NLS) cc:
U.S.
Nuclear Regulatory Commission Region IV Arlington, TX NRC Senior Resident Inspector Cooper Nuclear Station NUMARC l
NLS 8900153
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Nuclear Regulatory Commission j
STATE OF NEBRASKA)) ss PLATTE COUNTY
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Kuncl, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District, a public corporation and political subdivision of the State of Nebraska; that he is duly authorized to srbmit this response on behalf of Nebraska Public Power District; and that the statements contained herein are true to the best of his knowledge and belief.
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Kuncl Subscribed in my, esence and sworn to before me on this /7k (l,yW day of 1939.
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