ML20245B338
| ML20245B338 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 04/17/1989 |
| From: | Fitzpatrick E GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8904260039 | |
| Download: ML20245B338 (9) | |
Text
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l GPU Nuclear Corporation
': : M Imar one Upper Pond Road E
EW swWu Parsippany, New Jersey 07054 201-316-7000 l
TELEX 136-482 Writer's Direct Dial Number:
1 April 17,1989 l
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Director Office of Nuclear Reactor Regulation U.
S.
Nuclear Regulatory Commission Washington, D.C.
20555 Attn: Document Control Desk Dear Sir Subjects Oyster Creek Nuclear Generating Station Docket No. 50-219 Station Blackout Rule Response On July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 C.F.R.,
Part 50.
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 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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1 GPU Nuclear Corporation is a subsidiary of General Pubhc Utihties Corporation
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Oyster Creek Nuclear Generating Station Station Blackout Rule Response Page 2 The NRC has issued Regulatory Guide 1.155 " Station Blackout" which describes a means acceptable to th0 NRC Staff for meeting the requirements of 10 C.F.R. 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 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 NUEARC 87-00 and notes where the RG takes precedence.
GPU Nuclear has evaluated the Oyster Creek Nuclear Cenerating Station (OCNGS) against the requirements of the SDO 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.
The following plant factors were identified in determining the proposed station blackout duration:
1.
AC Power Design Characteristic Group is P2 based ont 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 4.
c.-
Estimated frequency of LOOPS due to severe weather places the plant in SW Group 1.
d.
The offsite power system is in the II/2 Group.
2.
The emergency AC power configuration group is C based one a.
There are two emergency AC power supplies not credited as alternate AC power sources.
b.
One emergency AC power supply is necessary to operate safe shutdown equipment following a loss of offsite power.
Oyster Creek Nuclear Generating Station Station Blackout Rule Response Page 3 3.
The target EDG reliability is 0.975.
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.
4.
An alternate AC (AAC) power source will be utilized at Oyster Creek which meets the criteria specified in Appendix B to NUMARC 87-00.
Two commercial-grade, industrial-type combustion turbines are currently under construction immediately adjacent to the OCNGS site.
The approximate location of the combustion turbines is depicted on the attached OCNGS site plan (FSAR Figure 1.2-1).
These units will normally be used as peaking units for the grid. Each of the two combustion turbines will have blackout start capability, independent of the outside electric interconnection.
OCNGS will use isolation condensers to maintain a hot shutdown condition. This is defined as the SHUTDOWN CONDITION or REFUEL MODE (with all operable control rods fully inserted) by Oyster Creek Technical Specifications.
As the coping analysis developed, it was determined that an AAC source would improve station blackout response.
The decision was then made to utilize the combustion turbines as the AAC source.
The AAC source enables use of the preferred source of isolation condenser make-up and provides RCS make-up capability.
It will also eliminate the need to strip loads from the station batteries.
The AAC power source will be available within one hour of the onset of the station blackout event and will have sufficient capacity and capability to operate systems necessary for coping with a station blackout for the required S30 duration of four hours to bring and maintain the plant in safe shutdown. An AC-independent coping analysis was performed for the one hour required to bring the AAC power source on line.
Under the conditions of station blackout as defined in NUMARC 87-00, one of the two combustion turbines (each unit is capable of supplying the full station blackout load) will be connected to either 4160 VAC Emergency Bus 1C via 4160V Bus lA or 4160 VAC Emergency Bus ID via 4160V Bus l'8.
See attached Sketch 3A-SK-E v200 for a one line diagram of the combustion turbine connection.
The sketch shows the combustion turbine connection to 4160V Bus lA for illustrative purposes only.
The combustion turbines will be started and brought to operating conditions at intervals not longer than three months. Once every refueling outage, a timed start and SBO load capacity test will be performed to verify that the AAC source is capable of providing power to the safe shutdown bus within one hour.
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1 e
Oyster.Crask Nuclear Gansrating Station Station Blackout Rule Response Page 4 1
1 A target reliability goal of 0.95 per demand, as determined using methodology consistent with NSAC-108, will be set for the AAC system l
(2 units).
i B.
Procedure Description Plant procedures have been reviewed and modified, if 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:
JCP&L System
. Restoration Plan is sufficient as it currently exists.
2.
Severe weather per NUMARC 87-00, Section 4.2.3:
High Winds Procedure, 2000-ABN-3200.31 has been reviewed and modified.
Plant procedures have been reviewed and changes necessary to meet NUMARC 87-00 will be implemented in the following areas:
1.
Station blackout response per NUMARC 87-00, Section 4.2.1:
A station blackout response procedure is expected to be complete by the first quarter of 1990.
2.
Procedure changes associated with the modifications described in Section C below will be made on a schedule consistent with complation of the modifications.
C.
Proposed Modifications The connection of the combustion turbines to Emergency 4160 VAC Bus 1C (1D) will be accomplished by disconnecting Startup Transformer SA (SB) via a new disconnect switch, and feeding 4160 VAC Bus 1A (lB) from one of the two combustion turbines.
Besides the new disconnect switch, three new circuit breakers and a new stepdown transformer will be required.
4160 VAC Bus lA (lB) normally feeds 4160 VAC Emergency Bus IC (lD) via a normally closed circuit breaker (trips on LOOP). The operator then can manually apply thost loads necessary to bring and maintain the plant in safe shutdown. All cable connections and other equipment necessary to complete the Alternate AC cource tie-in will be protected against the effects of likely weather-related events as required by NUMARC 87-00.
Procedures will be developed to connect the combustion turbines to the plant 4160 VAC buses following a station blackout event accounting for various conditions of operation of the two units; i.e. both operating normally, one operating and one shutdown, both shutdown, etc.
Also, OCNGS procedures will be either modified or supplemented by new procedures to reflect the capability of the AAC source to power response equipment during a SBO.
The AAC source will have the capacity and capability to power the equipment necessary to cope with a SBO in accordance with NUMARC 87-00, Section 7 for the required coping duration determined in accordance with NUMARC 87-00, Section 3.2.5.
i,
Oybter Creek Nuclear Generating Station Station Blackou ; Rule Response i
Page 5
!n order to monitor the functional requirement of decay heat removal via g
L the isolation condensers, reactor pressure indication must be provided.
This indication should be available in the control room to facilitate isolation condenser operation.
There currently is no DC-backed instrument-which can be used.
Therefore, a modification to provide a DC-powered reactor pressore indication will be performed.
1.
Condensate Inventorv For Decay Heat Removal-l It-has been determined per Section.7.2.1 of NUMARC 87-00 that.42,700 gallons of water are required for decay heat removal for four (4) hours. The minimum permissible condensate storage tank level per plant operating procedures provides a minimura of 250,000 gallons of-water, which exceeds the required quantity for coping with a four (4) hour station blackout.
No plant modifications or procedure changes are needed to utilize these water sources.
2.
Class 1E Batterv Capacity Battery capacity has been reviewed pursuant to NUMARC 87-00, Section 7.2.2 to verify that the Class 1E battery has sufficient capacity to meet station blackout loads for one hour. Battery chargers will be l
powered by the AAC source.
3.
Comoressed Air.
l Air-operated valves relied upon to cope with a station blackout for four hours can either be operated manually or have sufficient backup sources independent of the preferred and blacked out unit's Class 1E power supply.
Valves requiring manual operation or that need backup sources for operation will be identified in plant procedures.
4.
Effects Of Loss Of Ventilation The assumption in NUMARC 87-00, Section 2.7.1 that the control room will not exceed 120*F during a station blackout has been assessed.
The HVAC System serving the contro4 room will not be available until AAC power is established. iiowever, the control room at Oyster Creek ooes not exceed 120*F during a station blackout and therefore is not a dominant area of concern.
l Oyster Creek Nuclear Generating Station Station Blackout _ Rule Response Page 6
/
The steady state ambient air temperature (four hour AC-independent duration) has been calculated for the following dominant areas of concern since the HVAC systems for these areas need not be available when AAC power is established.
AREA TEMPERATURE Reactor Building El. 51'-3" 108'F Reactor Building El. 75'-3" 108*P Reactor Building El. 95'-3" 108'F Reasonable assurance of the operability of station blackout response equipment in the above dominant areas of concern has been assessed using Appendix F to NUMARC 87-00 and/or the Topical Report.
No modification or associated procedures are required to provide reasonable assurence for equipment operability.
5.
Containment Irolation The plant list of contair.mont isolation valves has been reviewed to verify that valves which must be capable of being closed or that must-be operated (cycled) under station blackout conditions can be positioned (with indication) independent of the preferred and blacked-out unit's Clacs lE power supplies. No plant modifications and/or associated procedure changes were determined to be required to.
ensure that appropriat<a containment integrity can be provided under SBO conditions.
6.
Reactor Coolant Inventor;y 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 isolation condensers will be used to maintain the plant in a hot standby condition.
Isolation condenser shell-side water inventory will be sufficient until the make-up system is powered by the AAC source.
Oyster Creek Nuclear Generating Station Station Blackout Rule Response-Page 7 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 14R.
The l
14R outage is currently scheduled for the fall of 1992 and is the second refueling outage from the date of this submittal. This schedule.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) within 12 months of the date of this letter. The schedule constraints are necessary to ensure that sufficient time is allowed for engineering and design. Final scheduling will be established cenciatent with the Oyster Creek Integrated Schedule.
Sincerely, E. E.
Fitzpatrick Vice President & Director Oyster Creek EEF/gd cci NUMARC Regional Administrator Region I U.
S.
Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Resident Inspector Oyster Creek Nuclear Generating Station Mr. Alex Dromerick U.S.
Nuclear Regulatory Commission Mail Station Pl-137 Washington, DC 20555
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