ML20005E285
| ML20005E285 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/18/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20005E284 | List: |
| References | |
| REF-GTECI-A-44, REF-GTECI-EL, RTR-REGGD-01.155, RTR-REGGD-1.155, TASK-A-44, TASK-OR NUDOCS 9001040204 | |
| Download: ML20005E285 (13) | |
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'o UNITED STATES l'"
1 i' n NUCLE AR REGULATORY COMMISSION l
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c-wAsmNotoN, D c.20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RESPONSE TO THE STATION BLACKOUT RULE (10 CFR 50.63) i METROPOLITAN E0!$0N COMFANY JERSEY CENTRAL POWER & LIGHT C04PANY PENN5YLVANIA ELECTRIC COMPANY GPU NUCLEAR CORPORATION THREEMILEISLAt:0NUCLEARSTATION,UtlITN0.J DOCKET NO. 50-289,
1.0 INTRODUCTION
On July 21, 1988, the Nuclear Regulatory Comission (NRC) amended its regulations l
in 10 CFR Part 50 by adding a new section, 50.63, " Loss of I'1 titernating Current power," (1). The objective of this requirement is to asst-W t all nuclear power plants are capable of withstanding a station blackout (SBO) ard rairtaining adequate j
reactor core cooling and appropriate containnient integrity for a required duration.
This requirement is based on information developed under the Commission study of Unresolved Safety Issue A-44, ' Station Blackout" (2-6).
To provide guidance for meeting the requirements of 10 CFR 50.63, the NRC staff issued Regulatory Guide (RG) 1.155 (7). Concurrent with the development of this ReEulatory Guide, the Nuclear Utility Management and Resource Council (NUMARC) developed a document entitled, " Guidelines and Technical Basis for NUMARC Initia-l l
tives Addressing Stetion Blackout At Light Water Reactors," NUMARC 87-00 (8).
l The document provides detailed guidelines and procedures on how to assess each plant's capabilities to comply with the station blackout rule. After reviewing the NUMARC document, the NRC staff has endorsed the document as a guide for addressing the 10 CFR 50.63 requirements.
In order to achieve a consistent response to the SB0 rule and to expedite the staff review process, two generic response documents were developed by NUMARC and reviewed by the NRC staff. The plant-specific submittels using the generic format provide a summary of results of the analysis of the plants' station blackout coping capability. The licensees are expected to ensure that the baseline assumptions used in NUMARC B7-00 are applicable to their plants and to verify the accuracy of the stated results. Compliance to the SB0 rule is verified by review and evaluation of the licensee's submittal, audit review of the supporting documents l
as deemed necessary, and possible follow up NRC inspections to assure that the
- licensee has implemented the necessary hardware and procedure changes to comply with 9001040204 kW1218 PDR ADOCK 05000289 p
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the SB0 rule. A normel SB0 review does not include a concurrent site audit review of the supporting documentation. However, a limited number of concurrent site audit i
reviews were performed to obtain a benchmark for licensee conformance with the docu-mentation requirements of the SB0 rule. No audit review was performed at THI-1.
The licensee's response to the SB0 rule was provided by letter C311-89-2018 from H. D. Hukill to U. S. Nuclear Regulatory Comission, dated April 17,1989(10).
The staff has reviewed this response and prepared the following evaluation.
2.0 EVALUATION
2.1 Station Blackout Duration For the determination of the proposed minimum acceptable SB0 duration, the i
following factors are reviewed: a)offsitepowerdesigncharacteristics, b) emergency ac power system configuration, c) determination of the emergency diesel ger.erator (EDG) reliability consistent with NSAC-108 criteria (9), and d) detemination of the accepted EDG target reliability. Once these factors are known, Table 3-8 of NUMARC 87-00 or Table 2 of RG 1.155 provides a matrix l
for determining the required coping duration, l-The licensee calculated a minimum acceptable SB0 duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for the Three Mile Island Nuclear Generating Station, Unit ] (TN!-1) site. The licensee based an SB0 duration on the following factors:
1.
Offsite Power Design Characteristics l
The plant AC power design characteristic group is P2, based on:
a.
Independence of the plant offsite power system characteristics of I 1/2, b.
Expected f requency of grid-related LOOPS does not exceed once per 20 years, l
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Estimated frequency of LOOPS due to extremely severe weather places the plant in ESW group 3, l
d.
Estimated frequency of LOOPS due to severe weather l
places the plant in SW group 2, J
2.
EmergenqyAC-(EAC)PowerConfigurationGroup The EAC power configuration of the pleet is *C".
THI-1 is equipped t
with two emergency diesel generators se
- ere normally available to the unit safe shutdown equipment. One t-r-supply is necessary to operate safe shutdown equipment following a LOOP.
t 3.
Target Emergency Diesel Generator Reliability TM1-1 has selected a target reliability of 0.975. TM1-l's nuclear unit average EDG reliability has been better than 0.95 over the last 100 starts.
l After reviewing the above factors, the staff found them to be properly evaluated.
The licensee's estination of the frequency of LOOPS due to ESil and SW is consistent with the NRC provideo data given in NUMARC 87-00. The licensee provides a breakdown of the EDG reliability as follows:
EDG-1 EDG-2 t
Last 20 starts 1.00 1.00 Last 50 starts 0.96 0.96 Last 100 starts 0.97 0.97 The licensee expects continued high diesel reliability because the EDGs are continually prelubed and warmed and a formalized EDG preventive maintenance program has been effective in maintaining high EDG reliability.
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2.2 Alternate AC power Source i
i The proposed use of an alternate AC power source is reviewed to determine whether it meets the criteria and guidelines of Position 3.3.5 of RG 1.155 and Appendix B of NUMARC 87-00.
If the alternate AC source (s) meet these requirements and can be demonstrateJ by test to be available to power the shutdown buses within 10 minutes of the onset of the station blackout, then no coping analysis is required.
The licensee proposes to use an existing emergency diesel generator (EDG) that was installed for TMI-2 as the Alternate A.C. (AAC) power source for THI-1.
Mcdifications will be made so that it becomes independent of TMI services, e.g.,
THI-2 Nuclear Services cooling water. Electrical modifications would be made to provide connectability of this AAC source to the TMI-1 emergency buses 10,10 and IE (See Figure 1).
Electrical modifications will also be made so that the diesel generator (AAC source) auxiliaries (heaters, air compressors, etc.) are normally t
fed by THI-I balance of plant (B0p) electrical power. DC power, independent of i
that used for THI-1 will be used to supply the AAC source and its associated breaker control. The certrol switches for the feeder breakers to 4kV busses IC, ID and IE presently exist on the TMI-I centrol console. However, modifications will be recessary to make them operational.
The AAC power source is located in the THI-2 Diesel Generator Building which is a Seismic Category I concrete structure. Electrical cable between the AAC source and the THI-1 buses will be run within plant structures and therefore adequately protected from weather-related events.
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The normal position of the 4kV breakers are shown on Figure 1.
The feeder breakers to buses 10, ID and IE will be interlocked so that only one breaker can be closed at any time.
In the event of an SB0 the feeder breaker to buses 10, ID and IE will either trip open on undervoltage or be already open. Undervoltage will also automatically start the AAC supply.
i The operator in the control room can provide power from the AAC supply to either Bus 2E or ID by manually closing the corresponding 4kV feeder breaker. The opera-ter can then manually load the necessary shutdown loads on the appropriate Bus 1E or ID. Once the AAC supply is providing power to 4kV bus IE or ID, the operator actions are essentially identical to that under loss of offsite power with only one EDG operating.
The AAC source will be available within ten minutes from the onset of an SB0 event and has sufficient capacity and capability to operate the systems necessary for coping with a station blackout for the required SB0 duration (four hours) to bring and freintain the plant in safe shutdown. THs will be demonstrated by an initial test.
Failure of AAC componer.ts will nct adversely affect Class 1E AC power systems and the AAC source will not normally be connected to the preferred or onsite emergency AC power system.
No single active failure or weather-related event will disable both the emergency onsite AC power sources and simultaneously fail the AAC power source.
l The AAC power source will be started and brought to operating conditions (loaded) at intervals not less than a quarterly frequency in accordance with plant pro-cedures. Once every refueling period, a timed start and rated load capacity test will be performed to verify that the AAC source is capable of providing power to the safe shutdown bus within 10 minutes. Portions of the AAC power system sub-jetted to maintenance will be tested prior to returning the AAC power system to service.
GPUN will set a target reliability goal of 0.95 per demand, as detennined in accordance with NSAC-108 methodology, for the AAC syste'n.
The applicable portions of the QA guidance contained in RG 1.155, Appendix A will be implernented for the AAC system.
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.6-s After reviewing the licensee's submittal, the staff found that the submittal did not specifically address the following items of NUMARC 87-00, Appendix B.
B.B.b The AAC should have an independent air start system B.8.c The AAC should have an independent fuel oil supply l
B.B.f The AAC should not depend on any of the blacked out unit's support systems powered from the preferred power supply.
l A telecon with the licensee confirmed that the AAC source does meet the above i
criteria. Although the TM1-1 EDGs and the proposed AAC source will utilize the j
same main fuel oil storage tank, the AAC source has a separate day tank and a separate 25,000 gallon storage tank located in the THI-2 building.
The telecon also disclosed that the proposed AAC diesel generator is essentially the same size and type as the TMI-1 EDGs except that the AAC EDG has a water cooled system instead of a shaf t driven air cooled system. provisions will there-i fore be required to provide a cooling system for the AAC EDG that is independent of offsite power or Till-1 power sources. The Itcensee has not finalized the pre-ferred method for doing this. Thus, the modification will be subiect to review by the NRC.
The licensee's submittel addressed each of the other criteria of Appendix B of NUMARC 87-00 and our review of the submittel indicates that the AAC source meets all of these criteria. We therefore find that the AAC source meets the require-ments of NUMARC 87-00 and RG 1.155 and is therefore acceptable provided the AAC source is cooled independent of TNI 1 power sources.
2.3 Station Blackout Coping Capability The SB0 coping capability is reviewed to assess the availability, adequacy and capability of the plant systems and components needed to achieve and maintain a safe shutdown and recover from an SB0 of acceptable d'uration. To assure an
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7 acceptable SEO coping capability, guidelines for a coping analysis are given in RG 1.155, Position 3.2.
Using the RG 1.155 guidelines, the licensee has submitted i
and the NRC staff has reviewed the following information:
1 2.3.1 Condensate inventory for decay heat removal The licensee's analysis has shown that 56.804 gallons of water are required for decay heat removal for the proposed $B0 duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The minimum pemissible condensate storage tank (CST) level per technical specifications provides 150,000 gallons of water for each of two tanks. The licensee has indicated that no plant modifications or procedure changes art needed to utilize this water source.
Af ter reviewing the supporting documentation and the technical specifica-tions, the staff agrees with the licensee's assessment that the plant has adequate condensate invertory for the 4-hour SB0 duration.
In addition, the excess inventory available in the CST can be used to assist in SB0 recovery.
2.3.2 Effects of loss of ventilation The licensee states that the AAC power source will provide power to HVAC systems serving the dominant areas of concern, and therefore no further assessmcnt on the effects of loss of ventilation was made. The licensee also states that no modifications and/or procedures are required to pro-vide reasonable assurance for equipment operability.
Since the AAC source will be available within 10 minutes and will provide power to the HVAC systems serving the dominant areas of concern, the staff has determined that the equipment and systems necessary to cope with the SB0 will not become inoperable due to excessive heat and lack of ventila-tion. This is contingent upon the control room, which was not identified by the licensee as a dominant area of concern, being cooled by the HVAC system (s)poweredbytheAACsource.
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2.3.3 Reactor coolant inventory The licensee states that the AAC source will power the necessary make-up systems to maintain adequate reactor coolant system inventory to ensure that the core is cooled for the required coping duration.
The AAC source will be available within 10 minutes to power either division emergency bus and its associated equipnent.
In addition, the AAC source has the capacity and capability of the normal EDGs, therefore, the staff has determined that adequate reactor coolant system inventory wil'l be maintained.
2.3.4 Analysis of the remaininoyidelines as set forth in RG 1.1%
The staff has determined that in accordance with 10 CFR 50.63(c)(2) no coping analysis is required for the Class IE battery, compressed air and containnant isolation since the AAC source will be available in 10 minutes, is equivalent in capacity to the existing EDGs and can power either divi-stonel safety train.
2.4 Preposed Procedures and Training Pursuar.t to RG 1.155 and NUMARC 07-00, plant procedures and training must be revised or added to cope with an SB0 and to restore nonrel long term core cooling once AC power is restered.
The licensee states that plant procedures have been reviewed and have been or will be modified as necessary, to meet the guidelines in NUMARC 87-00, Posi-tion 4 in the following areas:
1.
AC power restoration (File #394) is sufficient as it currently exists.
2.
Severeweather(EP 1202-33) is sufficient as it currently exists.
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3.
Precedures ATP 1210-1. ATP 1210-10 and EP 1202-2A are suffi-cient as they currently exist for the time prior to AAC power availability.
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Procedure changes associated with the modifications for the AAC will be ma G on a schedule consistent with the completion of the modifications.
After rev' ewing the Itcersee's submittal, the staff found that the licensee did not specifically address training requirements for utilization of the AAC source.
However, the licensee confirmed by telecon that such training will be implemented
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consistent with the completion of the modifications. Although the staff has not actually reviewed the individual procedures, the licensee has indicated that apprcpriate procedures exist. Therefore, the staff finds the licensee's response to bc acceptable.
2.5 Proposed Modifications I
To ccmply with the guidance of RG 1.155 and NUMARC 87-00, plant modifications will be necessary. The additions required for the AAC supply are shown in Figurt 1.
The AAC supply will be provided by modifying what is currently a TM1-2 EDG so thet it is independent of THI-2 support services, e.g., TMI-2 Nuclear Services cooling water. Also, modifications are necessary so that the EDG auxil-iaries (heaters, air compressors, etc.) are nonna11y fed from THI-1.
DC power, incependent of that used for THI-1 functions, will be used to supply the EDG and its associated breaker control. The cable that will be used to connect the AAC to the existing breakers on the 4kV buses 10, ID and IE must be installed. Modi-fications are required to the existing control switches os the TMI-1 control con-sole for control of the infeed breakers to buses 10, ID and IE. These infeed breakers are interlocked so that no more than one breaker can be closed at any time.
The licensee states that the modifications and procedural changes associated with these modifications are currently scheocied for the Fall of 1991, assuming receipt of notification by the NRC of their acceptebility by October 17, 1989.
After reviewing the licensee's submittal, the staff found that the submittal did not describe the DC and AC power source that would be used for the AAC, nor the method of interlocking the infeed breakers to buses IC, ID ano IE. This was clarified by telecon. The licensee states that the breakers will be interlocked using auxiliary contacts of the breakers. The size and exact location of the AC and DC auxiliary power supplies are still under evaluation. However, they will be located in the THI-2 building.
With the above clarification, the staff finds the licensee's description of the proposed modificationc to be generally acceptable. However, specific details of the mcdificaticns will be subject to review by the NRC, including assurance that the AAC source cooling water and other equipment reeded by the AAC source following a station blackout is independent of Till-1 power sources.
2.6 Qu,ality Assurarce and Technical Specifications The licensee states that the applicable portions of the QA guidance contained in Regulatory Guide 1.155, Appendix A will be implerented for the AAC system.
With respect to Technical Specifications, the licensee states that consistent with NRC Proposed Policy on Technical Specification Improvement, Technical Specificatter, requirements are not applicable to the AAC power system.
The staff finds the licensee's commitment to the QA guidance of Regulatory Guide 1.155 to be acceptable.
The question of how specifications for SB0 equipment will be applied is currently being considered generically by the NRC in the context of the Technical Specifica-tion Inprovement program and remains as an open item at this time. However, the staff would expect that the plant procedures will reflect the appropriate testing and surveillance requirements to ensure the operability cf the necessary SB0 equip-ment.
If the steff later determines that a Technical Specification regarding SB0 equipment is warranted, the licensee will be notified of the implementation requirements.
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1 11 2.7 EDG Reliet.111ty Program The licensee's submittal on SB0 did not specifically address the comitment to implement an EDG reliability program to conform to the guidance of RG 1.155.
However, during a telecon, the licensee stated that they believed their present EDG reliability program meets the guidelines of RG 1.155. We consider this to be an acceptable commitment for the EDG reliability program.
2.8 Scope of Staff Review The station blackout rule (10CFR 50.63) requires licensees to submit a response centaining specifically defined information.
It also requires utilities "... to have baseline assumptions, analyses, and related information used in their coping evaluations available for NRC review.* The staff did not review this supporting documentoion, or the proposed hardware and procedure modifications (which are scheduled fer later impleuttation). Howr m
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- " view of the licensee response, we have identified the following t u:. ;,; *:. t r any followup inspec-d tion or assessment that may be und(rtaken by the NPC to further verify conformance with the 550 rule:
a.
The hardware and procedural modifications associated with the AAC source, b.
Assurance that the AAC source powers the control roon, area HVAC systems and the control room remains fully functional, operable and manned.
c.
The correctness of the EDG reliability data in accordance with RG 1.155, Position 1.1, d.
The preparation and the implementation of the plant SB0 l
procedures in accordance with RG 1.155, Position 3.4, and NUMARC 87-00, Position 4, l
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The requirement for operator staffing and training to follow the identified actions in SB0 procedures, and i
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The implementation of a quality assurance program and tech-nical specifications for $B0 equipment as guided in RG 1.155, Position 3.5.
3.0 CONCLUSION
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The staff has reviewed the licensee's response to the station blackout rule (10CFR 50.63) and finds that it meets the requiren nts of the rule and the criteria of NUMARC 87-00 and Regulatory Guide 1.155. We therefore find the licensee's response and proposed method of dealing with an SB0 provide reason-able assurance that full conformance with the station blackout rule will be i
attained.
The licensee has comitted to an expected completion of the required plant modi-fications and associated procedural changes and training by the end of refueling outage 9R, which is scheduled for the Fall of 1991, provided NRC acceptance of l
the proposed coping methed is received by October 17, 1989. This condition was i
met by telecon notification to the licensee prior to this date that the SB0 re-l sponse had been reviewed by the staff and found acceptable, l
4.0 REFERENCES
1.
The Office of Federal Register, " Code of Federal Regulations Title 10 Part 50.63," 10 CFR 50.63, January 1,1989.
2.
U.S. Nuclear Regulatory Commission, " Evaluation of Station Blackout Accidents at Nuclear Power Plants - Technical Findings Related To Unresolved Safety Issue A-44," NUREG-1032, Baranowsky, P.W., June
- 1988, i
3.
U.S. Nuclear Regulatory Comission, " Collection and Evaluat1or, of Complete and Partial Losses of Offsite Power at Nuclear Power Plants "
NUREG/CR-3992, February 1985.
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4 U.S. Nuclear Regulatory Comission, " Reliability of Emergency AC Power System at Nuclear Power Plants,' NUREG/CR-2989, July 1983.
5.
U.S. Nuclear Regulatory Comission, " Emergency Diesel Generator Operating Experience, 1981-1983," NUREG/CR-4347, December 1985.
6.
U.S. Nuclear Regulatory Comission, " Station Blackout Accident Analyses (Part of NRC Task Action Plan A-44) " NUREG/CR-3226, May 1983.
7.
U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research, " Regulatory Guide 1.155 Station Blackout,* August 1988.
8.
Nuclear Management and Resources Council, Inc., " Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," NUMARC 87-00, November 1987.
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j 9.
Nuclear Safety Analysis Center, "The Reliability of Emergency Diesel l
Generators at U.S. Nuclear Power Plants," NSAC-108, Wyckoff, H.,
September 19P6.
- 10. Letter from H. D. Hukill to U.S. Nuclear Regulatory Comission, GPU Nuclear Corporation, Serial No. C311-89-2018, April 17, 1989.
Principal Contributors: Faust Rosa, Argil Toalston, Gary Garten Date:
December 13. 1989 l
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