ML20005A297
| ML20005A297 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/23/1981 |
| From: | Heider L YANKEE ATOMIC ELECTRIC CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| FYR-81-94, GL-81-04, GL-81-4, NUDOCS 8106300168 | |
| Download: ML20005A297 (5) | |
Text
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- YANKEE AT0f]IC ELECTRIC COMPAtlY
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2.C.2.1 FYR 81-94 Qh 1671 Worcester Road, framingham, Massachusetts 01701 YANKEE June 23, 1981
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United States Nuclear Regulatory Commission
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O Washington, D. C. 20555
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-r Attention:
Mr. Darrell C. Eisenhut, Director F
Division of Licensing 9A p*
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f Office of Nuclear Reactor Regulation 4
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References:
(a) License No. DPR-3 (Docket No. 50-29).
(b) USNRC Letter to YAEC dated February 25, 1981.
Subject:
Emergency Procedures and Training for Station Blackout Events (Generic Letter 81-04).
Dear Sir:
Reference (b) required us to review our current plant operations to determine our capability to mitigate a station blackout event. We were also required to implement, as necessary, emergency procedures and a training program for station blackout events.
The attachment to this letter has been prepared in response to your request in Referencr (b).
We have reviewed our emergency procedures and our training program as they pertain to station blackout. We conclude that our emergency procedures and our training program are sufficient in detail and no further action is required at this time.
We trust this information is satisfactory, however, should you desire additional information, please feel free to contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY L'
Whf6t's W L. 11. lleide r Vice President COMMONWEALTil 0F MASSACilUSETIS)
)ss MIDDLESEX COUNTY
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- Then personally appeared before me, L.11. Ileider, who, being duly sworn, did state that he is a Vice President of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing request in the came and on the behalf of Yankee Atomic Electric Company, and that the statements therein are true to the best of his kno edge and belief.
N obert 11. Groce Notary Public 61063 My Commissir,n Expires September 14, 1984 h
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- e 6/19/81 YANKEE ATOMIC ELECTRIC COMPANY Attachment Response to' Generic Letter 81-04 The following responses answer, in sequence, the items discussed in reference (b).
- 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
The actions necessary and equipment available to maintain the reactor coolant inventory and heat removal with only DC power available are outlined in emergency procedure OP-3251, " Loss of AC Supply," which are described below:
1.
The control room operator will trip closed the bleed line trip valve from the main control board which isolates the main coolant system. This valve is air operated and closes by removal of the air supply, a
2.
When the main generator frequency, during coastdown, reaches 58 Hertz, the control room operator will open the 124ACB and 448ACB.
These ACB's remain closed until 58 Hertz to insure two (2) main coolant pumps remain in operation for initial decay heat removal from the core.
The design of the main coolant pumps (canned rotor pumps) is such that they can be operated for this time period (approximately two (2) minutes) without component cooling water being supplied.
3 The control room operator opens the 224, 324, 548 and 648 ACB's and opens or checks open the 1224, 1324, 4548 and 4648 ACB's.
The operator also places all the pump control switches on the main control board in the " trip pull out" or " trip" position as appropriate. These actions are performed to insure that no loads are inadvertantly energized when either on-site or off-site power is restored.
4.
The auxiliary operator, upon notification that a total loss of AC has occurred, will place the emergency nitrogen bottle in service to insure steam is available for the steam driven emergency boiler feed pump operation.
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5.
The auxiliary operator then starts the steam driven emergency boiler feed pump and commences feeding all four steam generators in order to maintain the heat' sink for the main coolant system.
'6.
The auxiliary operator also places the emergency nitrogen ' bottle in service for the atmospheric steam dump valve. This action will initiate a steam dump to the secohdary stack insuring a
~ heat removal path from the steam generators.
Upon loss of. voltage to the three emergency busses, the three emergency AC diesel generators will be started by their DC starting motors powered from three independent 125 volt DC battery busses.
These emergency diesels will then be available for backfeeding the station busses and supplying power to selected station equipment as necessary and specified in the emergency procedure.
Item b.
The estimated time available to restore AC power and its basis.
Response
The plant has as a minimum fifteen hours in which to restore AC power. -This is based on the amount of water available for makeup to
- the steam generators. With the primary system intact, the steam driven emergency boiler feed pump can supply the makeup requirements for decay heat removal and the core will be protected. The plant is required by its Technical Specifications to maintain 85,000 gallons of water for system makeup.
Based on the steam driven emergency boiler feed pump flow rate of 90 gpm, sufficient water inventory will be available'for fifteen (15) hours.
Item c.
The actions for restoring AC power in the event of a loss of the grid.
Response
The actions required for restoring AC power are outlined in emergency procedure OP-3251, " Loss of AC Supply." The operators would perform the steps outlined in response to item a above and, in addition, they would utilize the emergency diesel generators to energize the three
-480 volt busses and back feed one of the 2400V/480V station service transformers'to energize one of the 2400 volt busses. This action will make available auxiliary equipment including a charging pump, component cooling pump and service water pump.
Item d.
The actions for restoring off-site AC power when its loss is due to postulated on-site equipment failures.
Response
- The postulated on-site equipment failure which initiates this event will'be isolated by plant protective relay and breaker operation.
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, The actions for restoring off-site AC power are outlined in the YAEC Electrical Operating Instructions in which the operators at Harriman Station and Cabot Station will reclose their OCB in 5 minutes, energizing the Z-126 line and the Y-177 line, respectively, which will restore off-site AC power to the plant. The plant will then utilize procedure OP-2501, "Bestoration of Normal AC Power af ter a Total Loss of AC," to transfer the station service loads from the emergency diesel generators to the normal off-site circuits.
Both of the off-site circuits are supplied from hydroelectric generating stations which would assure a quick response even if the units were not operating at the time of the line loss. The off-site AC power system has been very reliable based on 20 years of operation in which there has never been a loss of both lines due to on-site equipment failures.
Item e.
The actions necessary to restore emergency on-site AC power. The actions required to restart diesel generators should include consideration of loading sequence and the unavailability of AC power.
Response
The emergency diesel generators start automatically on a loss of AC power to the emergency busses. The emergency diesel generators are started by DC powered starting motors.
Each emergency diesel generator breaker is automatically closed to supply its emergency bus and les associated sar ty injection pump loads.
After verification e
that safety injection is not required, the control room operator will load the diesel generators manually from the control room in accordance with emergency procedure OP-3251, " Loss of AC Supply."
Item f.
Consideration of the availability of emergency lighting, and any actions required to provide such lighting, in equipment areas where operator or maintenance actions may be necessary.
Response
The plant has an installed emerge 4.
y ghting system located in all areas where operatcr or maintenance actions may be necessary. The emergency lighting system is normally supplied power by the A.C.
lighting transformer panel and in the event of a loss of AC power the emergency lighting is automatically transferred to the #2 station battery bus.
Item g.
Precautions to prevent equipment damage during the return to normal operating conditions following restoration of AC power.
For example, the limitations and operating sequence requirements which muet be followed to restart the reactor coolant pumps following an extended loss of seal injection water should be considered in the recovery procedures.
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Response
The plant would follow procedure OP-2501, " Restoration of Normal AC Power after a Total Loss of AC."
Once normal AC power was restored, the plant personnel would follow normal operating procedures.
These procedures detail the operating sequence requirements to preclude equipment damage.
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