ML20245A660
| ML20245A660 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/17/1989 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C311-89-2018, TAC-68615, NUDOCS 8904250321 | |
| Download: ML20245A660 (7) | |
Text
7.
1 GPU Nuclear Corporation 1
Nuclear
=, ors =8o Middletown, Pennsylvania 17057 0191
)
717 944 7621 i
TELEX 84 2386 j
Writer's Direct Dial Number:
j i
April 17,1989
)
C311-89-2018 1
)
U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C.
20555 Gentlemen:
Three Mile Island Nuclear Generating Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Station Blackout Rule Response On July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10CFR50. 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 (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 for the selection based on the redundancy and reliability of the onsite emergency AC power sources, the expected frequency of loss of offsite power (LOOP),
and the probable time needed to restore offsite power; 2.
A description of the procedures that will be implemerited for station blackout events for i.rq 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 1.155 " Station Blackout" which describes a means acceptable to the NRC Staff for meeting the requirements of 10CFR50,63 l
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 l
Staff for meeting those requirements.
o I
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation 8904250321 890417 PDR ADOCK 05000289 P
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- 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.
GPU Nuclear has evaluated TMI-1 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 detailed below.
l A.
Proposed Station Blackout Duration NUMARC 87-00, Section 3 was used to determine a proposed SB0 duration of four hours.
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 2; d.
The offsite power system is in the 11/2 Group.
2.
The emergency AC power configuration group is C based on:
a.
There are two emergency AC p'ower supplies not credited as alternate AC power sources; I
b.
One emergency AC power supply is necessary to operate safe shutdown equipment following a loss of offsite power.
3.
The target EDG reliability is 0.975.
a.
EDG reliability will be determined in accordance with NSAC-108 methodology. This represents a change from GPUN's commitment to Regulatory Guide 1.108 operational and failure data records as described in our October 17, 1984 response to NRC Generic Letter 4
84-15.
b.
A target EDG reliability of 0.975 was selected based on having a nuclear unit average EDG reliability for the last 100 demands greater than 0.95, consistent with NUMARC 87-00, Section 3.2.4.
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- 4.
An alternate AC (AAC) power source will be utilized at TMI-1 which meets the criteria specified in Appendix B to NUMARC 87-00. AAC power capability will be provided by modifying and utilizing one of the TMI-2 Emergency Diesel Generators to provide power to TMI-1 electrical buses.
The AAC power source will be available within ten minutes 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 SB0 duration [four hours] to bring and maintain the plant in safe shutdown.
Circuit breakers necessary to bring power to a safe shutdown bus will be capable of being actuated in the control room within that period.
This will be demonstrated by an initial test. It is noted that Class 1E battery capacity, compressed air and containment isolation need not be addressed.
In accordance with 10 CFR 50.63(c)(2) and NUMARC 87-00, Section 7.1.2, no coping assessment is required.
The AAC system configuration is shown on Attachment 1 and is similar to "AAC Configuration 1B" shown in NUMARC 87-00, Appendix C.
The AAC system and components are not required to meet Class 1E or safety system requirements. Components and subsystems will be physically protected against the effects of likely weather-related events that may initiate the loss of offsite power event. The AAC power source is located in the TMI-2 Diesel Generator Building which is a Seismic Category I concrete structure.
Electrical cable between the AAC source and the TMI-1 buses will be run within plant structures and therefore adequately protected from weather-related events.
The normal position of 4KV (4160 volts) breakers is shown on Attachment 1.
The breakers on the 4KV alternate AC feeder to buses IC, ID and IE i
(breakers #1, 2 and 3 respectively on Attachment 1) are interlocked so that not more than one breaker can be closed at any time.
Note that two breakers; one that is Class 1E (#2 or 3) and one that is non-Class 1E (#4) separate the AAC Supply from the 4KV ES buses.
In the event of a station blackout the breakers on 4KV buses IC, ID and IE, that are connected to the preferred power system as shown on Attachment 1, will either trip open on undervoltage or be already open.
Undervoltage will automatically start the AAC Supply.
The operator in the control room can provide power from the AAC Supply to either 4KV Bus 1E or 10 by manually closing the corresponding 4KV breaker
(#3 or #2 respectively on Attachment 1). The AAC system will not automatically load shutdown equipment on the ES buses.
Either 4KV ES Bus can be manually loaded by the operator with the loads necessary to bring and maintain the plant in safe shutdown.
Once the AAC Supply is providing power to 4KV ES Bus IE or 10, the operator actions are essentially identical to that under a loss of offsite power with only one Emergency Diesel Generator operating, except for restoration of offsite power.
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Failure of AAC components will not adversely affect Class 1E AC power systems. The AAC source will not normally be connected to the preferred or on-site 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.
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 procedures. Although not yet finalized, an electrical tie to Unit 2 electrical busses may be employed for test purposes only.
If this configuration is implemented, appropriate administrative or electrical interlocks will be provided. This potential tie to Unit 2 busses is not shown on the attached sketch as the sketch is intended to only show how the AAC source will provide power to the Unit i busses in a station blackout condition. 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 subjected to maintenance will be tested prior to returning the AAC power system to service.
Consistent with the NRC Proposed Policy on Technical Specification Improvement, Technical Specification requirements are not applicable to the AAC power system.
GPUN will set a target reliability goal of 0.95 per demand, as determined in accordance with NSAC-108 methodology, for the AAC system.
The applicable portions of the QA guidance contained in Reg. Guide 1.155, Appendix A will be implemented for the AAC system.
B.
Procedure Description Plant procedures have been reviewed and modified, as 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; Met-Ed System Restoration Procedure (File #394) is sufficient as it currently exists.
2.
Severe weather per NUMARC 87-00, Section 4.2.3; EP 1202-33 is sufficient as it currently exists.
Plant procedures have been reviewed and changes necessary to meet NUMARC 87-00 have been or will be implemented in the following areas:
1.
Station Blackout response per NUMARC 87-00, Section 4.2.1; ATP 1210-1, ATP 1210-10, EP 1202-2A are sufficient as they currently exist for the time prior to AAC power availability.
2.
Procedure changes associated with the modifications described in Section C below will be made on a schedule consistent with completion of the modifications.
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i C.
Proposed Modifications The AAC power capability will be provided by modifying what is currently a TMI-2 Emergency Diesel Generator so that it 1) is independent of TMI-2 services, e.g. TMI-2 Nuclear Services cooling water and 2) can power either TMI-1 4KV ES Bus 1E or ID (see Attachment 1).
Electrical modifications at the AAC Supply are necessary so that the diesel' generator auxiliaries (heaters, air compressors, etc.) are normally fed by TMI-1 BOP electrical power. DC power, independent of that used for TMI-1 ES functions, will be used to supply the AAC source and its associated breaker control (#4 on ). The cable that will connect the output of the AAC Supply l
(#4 on Attachment 1) to the breakers on 4KV buses IC, ID and IE (#1, 2 and 3 respectively on Attachment 1)'also must be installed. The breaker i
control switches for the 4KV alternate AC feeder (breakers #1, 2 and 3 on ) physically exist on the TMI-1 control console, although modifications will be necessary to make them operational.
Plant procedures will be modified, consistant with the modification, to provide direction on the use of the AAC Supply.
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.
1.
Condensate Inventory For Decay Heat Removal It has been determined from Section 7.2.1 of NUMARC 87-00 that 56,804 gallons of water are required for decay heat removal for four hours.
The minimum permissible condensate storage tank level per technical specifications provides 150,000 gallons of water for each of two tanks, which exceeds the required quantity for coping with a four hour station blackout.
No plant modifications or procedure changes are needed to utilize these water sources.
2.
Effects of Loss of Ventilation The AAC power source will provide 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 l
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.
1 l
l
C311-89-2018 )
The modifications and associated procedure changes identified in Parts A, B and C above are expected to be completed by the end of refueling outage 9R, which j
is currently scheduled for the Fall of 1991. This is based on receipt of the notification provided by the Director, Office of Nuclear Reactor Regulation in accordance with 10 C.F.R. 50.63(c)(3) on or before October 17, 1989. The schedule constraints are necessary to ensure that sufficient time is allowed for engineering and design.
Further scheduling will be established consistent
{
with the TMI-1 Integrated Schedule amendment process.
]
Sincerely, h
H.D. Huh11 Vice President & Director, TMI-1
/Im1 - GPUN Dwg. No. 1A-SK-E-194, Rev. O cc: R. Hernan, USNRC W. Russell, USNRC, Region I J. Stolz, USNRC F. Young, USNRC, TMI-1 NUMARC 7927f i
1 1
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ATTACHMENT 1 l
l l
I SWITCHYARD 1
AUX.TRANSF.
ww aw AUX.TRANSF.
^
(Tm(TP 18 hh LLUJJLJ mm PPP (T m (T m f
il MAIN TURBINE GENERATOR NC NO NO NC 6.9KV BU'S 1A 6.9KV BUS 18 4KV 4KV 4KV 4KV 4KV BUS BUS __
__ BUS __
BUS
_ _ BUS _
NO 1A NC NO 18 NC NC 1C NO NC 1D NO NO 1E NC T
1 1
1 T
~ BOP ~
~ BOP ~
BOP E.S.
E.S.
- 1 NC
- 2 NO NO
- 3 Nb Ud EDG EDG 1A 18 WW N4 NO mm 480V AAC LEGEND:
SUPPLY AAC AUX. BUS NO = NORMALLY OPEN (NON-CLASS 1E)
NC = NORMALLY CLOSED EXISTING AAC REVISIONS GPU Nuclear CONCEPTUAL TMi-1 ALTERNATE AC CONFIGURATION (NON-CLASS 1E DIESEL GENERATOR)
CAD FILE f 1ASKE194 DWG.NO 1A-SK-E-194 REV.
scin g.
Maw l
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