ML20004D090
| ML20004D090 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/02/1981 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| 720, GL-81-04, GL-81-4, TAC-43940, NUDOCS 8106080345 | |
| Download: ML20004D090 (12) | |
Text
9 TOLEDO Docket No. 50-346 EDISON License No. NPF-3 Ro.4ao P. Case va pm Serial No. 720 Junc: 2, 1981 o\\\\ x/
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Mr. John F. Stolz, Chief g'
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Division of Licensing U. S. Nuclear Regulatory Cocnission Y j, Washingtcn, D. C. 20555
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Dear Mr. Stolz:
This letter is in response to Generic Letter 81-04, dated February 25, 1981, (Log No. 666), concerning the licensce's ability to deal with a station blackout.
Although Toledo Edison considers a station blackout to be an extremely abnormal occurrence, Davis-Besse Nuclear Power Station Unit No. 1 has adequately prepared its operators to act appropri-ately during a station blackout event.
Each specific concern listed in your February 25, 1981 letter is addressed in Attachment 1.
Yours very truly, ffk=W '
RPC:SCJ CC:
NRC DB-1 Resident Inspector hol5
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8106080)L' THE TOLEDO EDISON COMPANY EDISCN PLAZA 300 MADISON AVENUE TCLEDO CHIO 43652
10 CRF 50.54 (f)
SUBMITTAL IN RESPONSE FOR DAVIS-BESSE NUCLEAR POWER STATION UNIT 1 FACILITY OPERATING LICENSE NO. NPF-3 This letter is submittal.in conformance with 10 CFR 50.54 (f) relating to Mr. Darrell C. Eisenhut's letter of February 25, 1981. This deals with Emergency Procedures and Training for Station Block Event (Generic Letter 81-04).
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a Vice-President, Nuclear Sworn to and subscribed before me this 2nd day of June, 1981 4
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Docket No. 50-346 License No. NPF-3 Serial No. 720 June 1, 1981 ATTACHMENT 1 ITEM (a): The actions necessary and equipment available to maintain the reactor. coolant inventory and heat removal with only DC power available,. including consideration of the unavailability of auxiliary systems such as ventilation and component cooling.
RESPONSE TO ITEM (a):
AB 1203.02, " Loss of all AC Power", directs the actions necessary to provide for heat removal from ti.e reactor coolant system, utilizing available equipment with only DC power available.
The main effort in AB 1203.02 is directed toward the restoration of AC power.
If restoration of AC is delayed, instructions are provided for the reduction of *he DC loads by selective load sheddfeg of DC loads on the station batteries. Concurrent with the attempt to restore AC power, reactor coolant system heat removal will be accomplished by auxiliary feedwater pumps supplying auxiliary feedwater to the steam generators and by manual control of the atmospheric vent valves.
Davis-Besse Unit No. I has a redundant safety grade auxiliary feedwater (AFW) system. Train 1 is independent of AC power sources, as required in NPF-3 License Condition 2.C.'3)(f).
This independence includes its safety grade automatic initiation and level control system. The station procedure also has AFW Train 2 manually lined up to supply auxiliary feedwater to its steam generator. Reactor coolant system average temper-
Docket No. 50-346 License No. NPF-3 Serial No. 720 June 1, 1981 ature (Tave) and steam pressure are controlled by manual throttling of the atmospheric vent valves.
ITEM (b): The estimated time available to restore AC power and its basis.
1 RESPONSE TO ITEM (b):
The loss of AC power including the extended loss of all offsite power 4
sources and the continued failure of both safety-related emergency diesel generators is not a design basis event. However, in order to evaluate the effects of such an abnormal condition, the times availabe to restore AC power has been calculated based on the following two concerns:
i 1.
Eventual loss of subcooling in the re mor coolant system l-(RCS) due to the loss of the pressurizer heaters.
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2.
Temperature rise of the equipment above their qualified temperature, due to unavailability ot AC power for ventil-ation and air conditioning system, i
Details of the above two items are as follows:
1.
The time for cooldown of the pressurizer at Davis-Besse Unit 1 until RCS subcooling is lost has been calculated to be 15.6 1
hours. The calculations to obtain the salution were based on the following assumed conditions:
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Docket No. 50-346 License No. NPF-3 Serial No. 720 June 1, 1981 No pressurizer insurge/outsurge after the first few a.
minutes of the loss of site power, i.e., assume an equilibrium RCS temperature distribution which remains constant for an extended period of time.
b.
A constant RCS leak rate of one gallon / minute.
c.
Pressurizer ambient heat losses in accordance with test data from the Davis-Besse No. 1 site.
d.
No pressurizer heaters.
e.
An initial pressurizer outsurge determined from existing field data and analyses.
i 2.
Calculations based on actual electric loads measured during tse normal plant operation, and considering the use of the Station i
Abnormal Procedure AB1203.02, indicate that the battery capacity without battery charging ability for this event is adequate for a period of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with selective shedding of DC loads. Until some AC power is restored, the ventilation systems are inoperable, resulting in elevated room temperatures.
The steady state temperatures in the areas of concern are reached over a period of time based on area heat sources.
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Docket No. 50-346 License No. NPF-3 Serial No. 720 June 1, 1981 Specific equpment areas include:
a.
The qualified temperatures for the Channel 1 inverter is slightly lower than calculated room temperatures. These differences are, however, extremely small and in our engineering judgment should not prevent the inverters from functioning, b.
The qualified temperatures for the Channel 1 and 2 Class IE fuse panels are below the calculaced room temperatures.
In effect, evaluated temperatures reduce the fuse ratings i
to about 95% of their rated values. None of the fuses l
are loaded to their full rating, and hence the higher temperatures will not affect their function.
t c.
The speed switches associated with the auxiliary feed pump turbine (AFPT) are not qualified for the increased temperature calculated for the pump room. However, the requirement for the interlock function performed by these switches is being deleted in conjunction with a system reliability modification.
d.
The AFPT governor motor appears not to be currently qualified to withstand the elevated temperatures. However, the vendor has been contacted and attempts are being made to obtain the required qualification documentation.
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Docket No. 50-346 License No. NPF-3 Serial No. 720 June 1, 1981 e.
The control room itself will be subject to a temperature rise. By calculation the maximum temperature attained in the control cabinet room within two hours was 103 F.
However, as exhibited during testing, the control room area actually reaches a temperature of 85 F in three hours. These temperatures do not exceed the operational requirements of the located equipment.
The above information indicates that during a complete loss of all of fsite and onsite AC power sources, the limiting factor is the projected two hour battery capacity. Within these two hours neither ventilation loss nor RCS subcooling is a problem.
JTEM (c): The actions for restoring offsite AC power in the vent of a loss of the grid.
RESPONSE TO ITEM (c):
The most limiting condition associated with a complete loss of grid is one i
in which there would be no start-up power assistance available from any of the power companies interconnecting with the Toledo Edison Northwest Ohio service area.
For this extreme contingency, written guides currently l
exist for the Toledo Edison Load Dispatcher and fossil plants, f
These guides plan for the fossil fueled generating units to be recovered using stored steam in their boilers.
If, for any reason, stored-steam
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- Docket No. 50-346 License No. NPF-3 Serial No.'720 June 1, 1981 recovery is unsuccessful, the Bay Shore Cas Turbine Peaker can start one Bay Shore coal-fired unit.
l" The east side of the Toledo Edison transmission system will be isolated with the fossil fueled power plants to provide a stable network of restored
.offsite power on which to start large pumps at Davis-Besse, and to expand upon as generating capability permits load restoration.
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ITEM (d): The actions for restoring offsite AC power wher. its loss is due to postulated onsite electrical equipment failures.
RESPONSE TO ITEM (d):
i Restoration of offsite AC power to the station when its loss is due to onsite equipment failures will be made in accordance with AB 1203.02.
Adequate precautions are included to assure appropriate action is taken by the operators.
4 ITEM (e): The actions necessary to restore emergency onsite AC power.
The actions required to restart diesel generators should include consideration of loading sequence and the unavailability of AC power.
RESPONSE TO ITEM (3):
AB 1203.02, Loss of All AC Power, provides actions required to restore emergency onsite AC power, including steps for the stabilization of the j
plant.and equipment recovery priorities and precautions. AB1203.02 i.,
Docket No. 50-346 License No. NPF-3 Serial No. 720 June 1, 1981 directs the operator to attempt to manually, start the emergency diesel generators and energize the 4160 V essential buses, referencing EP 1202,02, I
Station Blackout, for the energization of the buses.
EP 1202.02 provides details for the energization of the buses and restoration of AC power. EP 1202.02 provides steps for the verification of loads on the essential buses which should have automatically energized (component l
cooling water pump, service water pump, emergency instrument air compressor, 1
i if air pressure was low). Also, direction is provided for the energization of equipr.ent required for the stabilization and recovery of the plant. The operator is cautioned in regard to prevention of overloading the emergency diesel generators.
Instrumentation to the operator for monitoring these actions is available, i
l ITEM (f): Consideration of the availability of emergency lighting and any actions required to provide such lighting in equipment areas
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where operator or maintenance actions may be necessary.
RESPONSE TO ITEM (f):
In the event of loss of off-site power, selected emergency lighting is powered from the diesel generators.
In the unlikely event that both diesel power trains were not available, fixed emergency lighting is supplied from the main station batteries. Simiutaneously available are fixed, scif-contained sealed beam units with 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> minimum battery power, installed l l l
Docket No.'50-346 License No. NPF-3
. Serial No. '20 June 1, 198 throughout the plant in areas utilized to achieve cold shutdown, power restoration'and in routes utilized for access and egress for those areas.
ITEM (g): Precautions to prevent equipment damage during the return to a
normal operating conditions following restoration of AC power.
l For example, the limitations and operating sequence requirements which must be followed to restart the reactor coolant pumps following an extended loss of seal injection water should be considered in the recovery procedures.
RESPONSE TO ITEM (g):
EP 1202.02, Station Blackout, provides adequate precautions for the prevention of damage to major equipment during the return to normal operating conditions.
EP 1202.02 includes precautions for major equipment which include the following:
Reactor Coolant Pumps - Seal Injection - Seal injection is slowly reinitiated to all reactor coolant pumps following a specified sequence of actions Reactor Coolant Pumps - Lift Oil Pumps - The DC lift oil pumps are started for all reactor coolant pumps Turbine / Generator - Lift Oil Pumps - The lift oil pumps for the turbine /
generator are placed in service Control Rod Drive Motors - The control r'4 drive booster pumps (s) are Docket No. 50-346 License No. NPF-3 Serial No. 720 June 1, 1981 started to provide cooling water flow to the control rod drives 4
Turbine Plant Cooling Water - A turbine plant cooling water pump is immediately started to cool the turbine /-
generator lube oil and station air compressor i
Mechanical Hogger - When vacuum is broken and main turbine on turning gear, the mechanical hogger is locked out PARAGRAPH 11: The annual requalification training program should consider the emergency procedures and include simulator exercises involving the postulated loss of all AC power with decay heat removal being accomplished by natural circulation i
and the steam-driven auxiliary feedwater system for PWR plants, and by the steam-driven RCIC and/or HPCI and the safety-relief valves in BWR plants.
RESPONSE TO PARAGRAPH 11:
AB 1202.02, Loss of All AC Power, is covered in the Requalification Training during the Standard and Emregency Operating Procedure training. The event was included in the 1979 Simulator Requalification Training to the extent
- it can be sim. lated on the B&W simulator.
It was not included in the 1980 Simulator series, because the simulator schedule was geared to completing the NRC required items issued by H. R. Denton's letter of March 29, 1980
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1 Doc.'et No. S M 4o Lice se No. NPF-3 Serial No. 720 June 1, 1981 (Log No. 540). The 1981 simulator program is reinstating the previous training.
The procedure will continue to'be covered in the DB-1 training.
Any procedure revisions will be covered in a method appropriate to the magnitude of the revision.
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The procedure, AB 1203.02, is also covered in Specialized License Training for all new license personnel.
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