ML20245A883
| ML20245A883 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 04/17/1989 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-89-043, CON-NRC-89-43 TAC-68586, TAC-68587, VPNPD-89-216, NUDOCS 8904250427 | |
| Download: ML20245A883 (9) | |
Text
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1 WISCONSIN Electnc powca coupan 231 W. MICHIGAN,P O BOX 2046 MILWAUKEE,WI53201 (414)221 2345 VPNPD-89-216 NRC-89-043 April 17, 1989 Document Control Desk 10 CFR 50.63 U.S.
NUCLEAR REGULATORY COMMISSION Mail Station Pl-137 Washington.
D.C.
20555 Gentlemen:
DOCKET NOS. 50-266 and 50-301 RESPONSE TO 10CFR50.63., TAC. NOS. 68586 AND 68587 LOSS OF J.LL ALTERNATING CURRENT POWER POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Effective July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 CFR, Part 50 to add a new section, 50.63, which requires that each light-water-cooled nuclear power plant be capable of withstanding and recovering from a station blackout (SBO) of a specified 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 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 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 coping with and recovering from a SBO of the specified duration.
The NRC has issued Regulatory Guide 1.155, " Station Blackout," which describes a means acceptable to the NRC Staff for meeting the requirements of 10 CFR 50.63.
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 8904250427 890417 l >g[fD PDR ADOCM 05000266 P
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4 NRC Document Control Desk April 17, 1989 Page 2 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.
Wisconsin Electric Power Company (WE) has evaluated the Point Beach Nuclear Plant Units 1 and 2 against the requirements of the SBO rule i
using the appropriate guidance from RG 1.155 and NUMARC 87-00.
The results of this evaluation are detailed in the enclosure to this-letter.
Using the methodology provided in RG 1.155, Point Beach Nuclear Plant is categorized as an eight hour coping duration plant.
Although several modifications and associated procedure changes are identified in Parts A, B and C of the enclosed report, we do not believe they are required to satisfy 10 CFR 50.63 and they are not to be considered commitments to satisfy 10 CFR 50.63.
Alternate AC power capability is already available at Point Beach Nuclear Plant via an onsite 20 MW gas turbine generator (GTG).
Wisconsin Electric is evaluating the installation of a Class IE diesel generator as an installed spare for either one of the two existing Emergency Diesel Generators.
The risk associated with station blackout would be further reduced by having this reliable Class IE diesel generator power source available most of the time within 10 minutes or less from the onset of a station blackout event.
We would be pleased to answer any questions regarding the above information or the enclosed report.
Very truly yours, 0W7 C.
W.
Fay Vice President Nuclear Power Enclosure Copies to NRC Regional Administrator, Region III NRC Resident Inspector NUMARC i
y r
s e
4/17/89
~
EVALUATION OF STATION BLACKOUT DURATION'AND COPING ABILITY AT POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2, AS REQUIRED BY 10 CFR 50.63
)
1 A.
Proposed Station Blackout Duration' Regulatory Guide (RG) 1.155, " Station Blackout,".was used to
.j determine a proposed SBO duration of eight. hours for Point Beach Nuclear Plant.
l The following plant' factors were identified ~in' determining the.
j proposed-station blackout duration, as specified by RG 1.155,. Tables
)
2 through 7:
1.
AC Power Design Characteristic Group is P2 based on:
q a.
Expected frequency of grid-related loss of offsite power does not exceed once per 20 years; b.
Estimated frequency of loss of offsite power due to extremely severe' weather places the plant in Extremely Severe Weather (ESW) Group 4; c.
Estimated frequency of loss'of offsite power due to severe weather places the plant in Severe Weather (SW)
Group 2; d.
The independence of the offsite power system places Point Beach Nuclear Plant in the Independence of Offsite Power System Group II/2.
2.
The emergency AC (EAC) power configuration. group is'D based on:
a.
There are two-(2)' emergency AC power supplies not credited as alternate AC power sources; b.
One (1) emergency AC power supply is necessary to operate safe shutdown equipment for both units following a loss of offsite power.
l 3.
The target Emergency. Diesel' Generator (EDG) reliability is 0.975.
The target EDG reliability of 0.975.was selected based on EDG reliability data for the last 100 demands that was evaluated using the methodology in NSAC-108, l
" Reliability of Emergency Diesel Generators at U.
S.
l Nuclear Power Plants."
l 4.
An onsite, 20 megawatt, 13.8 kV generator driven by a 25 Megawatt gas turbine is available at Point Beach Nuclear Plant, Units 1 and 2, as an alternate AC (AAC) power
v source.
This gas turbine generator (GTG) is capable of supplying power through either or both Low Voltage Station Auxiliary Transformers (lX04 and 2X04).
The Low Voltage Station Auxiliary Transformers are the normal power supplies to the 4160 volt emergency buses (lA05, lA06, 2A05 and 2A06, see figure 1).
The 4160 volt emergency buses provide power to the 480 volt emergency buses (lB03, 1B04, 2B03 and 2B04,-see figure _1).
This AAC power source is available within one hour of the onset'of the station blackout event and has sufficient capacity and capability to operate systems necessary for coping with a station blackout for the required SBO duration of eight (8) hours, to bring the-plant to and maintain the plant in a safe shutdown condition.
An AC-independent coping evaluation was performed for the one hour required to bring this AAC
-power source on line.
The reliability of the GTG is approximately 0.91 as determined by NSAC-108 methodology.
New testing and maintenance requirements for the GTG are being implemented to improve the GTG reliability.
WE is evaluating the installation of an additional AAC power source at Point Beach Nuclear Plant.
A new 4160 volt diesel generator (DG) may be installed to provide AC power to the 4160 volt emergency buses (lA05 and 2A05 or 1A06 and 2A06). The new DG would be capable of supplying power to emergency buses within 10 minutes of the onset of station blackout.
This would further reduce the risks associated with SBO because a second independent and reliable source of.AAC would be available most of the time l
and because of the more rapid start and' load capability of I
the new DG as compared to the existing GTG.
The additional DG at Point Beach Nuclear Plant would be used as an installed backup emergency diesel generator.
If one of the existing Emergency Diesel Generators is declared inoperable or placed out-of-service, the new DG could be placed~in an automatic mode to enable it to replace that EDG.
When the new DG would be in the automatic mode, the GTG would be relied upon as the AAC l
power source.
1 B.
Procedures for Coping and Recovery The following Emergency Operating Procedures (EOPs) for Station l
Blackout are in place at Point Beach Nuclear Plant:
ECA 0.0 Loss of All AC Power ECA 0.1 Loss of All AC Power Recovery Without SI Required ECA 0.2 Loss of All AC Power Recovery With SI Required These procedures were developed from the Westinghouse Owners Group Emergency Response Guidelines (WOG ERGS).
The WOG ERGS were l l
m.
a reviewed and approved by the NRC.
WE implemented the WOG ERGS based station blackout procedures and performs operator training as committed to in response to NRC Generic Letter 81-04, " Emergency Procedures and Training for Station Blackout Events."
The method and schedule for implementation of the GL 81-04 recommendations was proposed in Sol Burstein (WE) to R. A.
Clark (NRC) letter dated September 11, 1981.
The NRC accepted the WE plan via letter from R.
A. Clark (NRC) to Sol Burstein (WE) dated September 29, 1982.
ECA 0.0 directs the operators to restore power to the emergency buses by offsite power, the gas turbine generator, or the other unit by cross-tie after the blackout condition has been identified and restart of the Emergency Diesel Generators has failed.
Once AC power is restored, ECA 0.0 and ECA 0.1 provide guidance for recovery from the station blackout condition without safety injection required.
These procedures will be reviewed and revised to account for the installation of the new DG AAC power source, if the new DG is installed.
Testing procedures will be developed to verify the ability to provide AAC from the new EDG to the emergency buses within 10 minutes under station blackout conditions.
The new DG will also be maintained and tested regularly to insure its reliability.
The reliability will meet or exceed the levels of reliability required for Point Beach Nuclear Plant Emergency Diesel Generators.
C.
Proposed Modifications and Schedule The plant does not need to be modified to utilize the existing 20 MW GTG as an alternate AC power source.
Installation of an additional DG, however, is being evaluated.
A new DG, if WE decides to install one, would be expected to be installed and operational within 4 years.
A new DG AAC power source would have the capacity and capability to power the equipment necessary to cope with a SBO for the required coping duration of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, as required for' Point Beach in accordance with RG 1.155.
The 13.8 kV distribution system is currently being modified (as shown by Figure 2 attached) to improve its reliability and the separation of the Unit 1 and Unit 2 offsite EAC power sources.
These modifications are expected to be completed by the end of 1990.
D.
Summary of Coping Evaluations The following items were evaluated as required by 10 CFR 50.63(a)
(2).
No plant modifications or procedure charges are required to ensure the ability to cope with a SBO at Point Beach Nuclear Plant.
I 1.
Condensate Inventory for Decay Heat Removal i
The minimum permissible condensate storagc tank inventory per Point Beach Nuclear Plant Technical Specifications is 10,000 gallons per operating unit.- This water, along with 3-
/
i 1
l the initial steam generator fluid inventory, is adequate to maintain steam generator decay heat removal capability for the one hour required to restore AC power by starting a
and loading the GTG.
At that time, service water from j
Lake Michigan would be available to provide water to the j
suction of the auxiliary feedwater pumps, if required.
No j
plant modifications or procedure changes are needed to j
utilize plant service' water as an additional source of auxiliary feedwater, i
2.
Capacity of Class lE Batteries The PBNP Staticn batteries were originally designed to carry DC loads for one hour.
A new battery capacity
(
calculation will be performed to verify that the Class 1E-
)
1 batteries have sufficient capacity to meet station blackout loads for at least one hour.
i 3.
Compressed' Air I
No air-operated valves are required to operate to cope with a station blackout for one hour.
i l
4.
Effects of Loss of Ventilation j
Alternate AC' power is expected to be available within one I
hour of the onset of station blackout.
Therefore, l
ventilation systems would be restored within one hour.
j The expected temperature rises in the main areas of concern (auxiliary building, containment building and the i
i control building) are not' expected to adversely affect equipment operability in that time.
Additional evalua-tions will be performed ~to confirm this conclusion.
5.
Containment Isolation The plant list of containment isolation valves has been reviewed.
Containment isolation is attainable and-l maintainable under station blackout conditions.
l Indication and control of 10 containment isolation valves (5 per unit) would be lost due to the loss of the 480 VAC emergency buses.
Eight of.these 10 valves are motor operated valves in the component cooling water system.
They do not receive automatic isolation signals.
The Point Beach Nuclear Plant FSAR classification of these penetrations states that manual isolation capability for these penetrations is adequate.
These penetrations would be used during the station blackout to supply component cocling water to the reactor coolant pump thermal barriers, once AC power is restored from the AAC source.
Two of the ten valves are motor operated valves in the chemical and volume control system.
These valves do receive automatic isolation signals.
There is an automatic air-operated isolation valve inside containment _ _ _ _ _ _ _ _ _ _ _ _ - - _ _ _ _
for these penetrations that would remain operable.
The Point Beach Nuclear Plant-FSAR allows for redundant manual isolation for this class of penetration.
6.
Reactor Coolant Inventory RCS inventory would be reduced by RCP seal leakage, but adequate initial RCS inventory is available for the one hour necessary to bring the AAC power source on line.
The AAC source powers the necessary primary make-up systems to maintain adequate reactor coolant system inventory to ensure that the core is cooled for the required coping duration of eight hours.
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