ML18139A892
| ML18139A892 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 12/12/1980 |
| From: | Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, Varga S Office of Nuclear Reactor Regulation |
| References | |
| TASK-2.E.1.2, TASK-TM 894, NUDOCS 8012160142 | |
| Download: ML18139A892 (7) | |
Text
'.
'. ~
f e
VIRGINIA ELECTRIC AND POWER COMPANY RrcHMOND,VIRGINIA 23261 December 12, 1980 Mr. Harold R. Denton, Director Office 0£ Nuclear Reactor Regulation Attn:
Mr. Steven A. Varga, Chief Serial No. 894 NO/FHT:ms Operating Reactors Branch 1 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Denton:
Docket Nos. 50-280 50-281 License Nos. DPR-32 DPR-37 AUXILIARY FEEDWATER SYSTEM AUTOMATIC INITIATION SURRY POWER STATION UNITS 1 AND 2 SUPPLEMENTAL INFORMATION In response to your letter of October 29, 1980, we are providing the attached supplemental information for Surry Power Station Units 1 and 2.
If you have any questions, please contact this office.
cc:
Mr. James P. O'Reilly re:*
~ :t.
~-'
Very truly yours, fJtf~
B. R. Sylvia Manager - Nuclear Operations and Maintenance
/)ool s
I~
- 1.
NRC Question Attachment Page 1 Is the Auxiliary Feedwater System and its automatic initiation circuitry considered to be part of the Engineered Safety Features (ESF)?
Response
No.
The Auxiliary Feedwater System (AFWS) is not considered an en-gineered safety feature at Surry Power Station.
The AFWS is described in Surry FSAR Section 10, Steam and Power Conversion System under the subheading of the Condensate and Feedwater Systems.
The AFWS is not identified in FSAR Section 6, Engineered Safeguards and is not designed as an ESF system, particularly with respect to testability and bypass alarm functions.
The automatic initiation circuitry for the auxiliary feedwater pumps originate in the Engineered Safeguards and Reactor Protection System which are designed in accordance with IEEE 279-1971.
r...
- I I.*
e e Attachment Page 2
- 2.
NRC Question Submitted by letter dated February 1, 1980 was a diagram of the automatic initiation logic.
- 1.
Describe whether redundant and independent logic trains are used
- and,
- 2.
If this arrangement satisfies the single failure criterion with regard to automatic and manual initiation of the auxiliary feedwater pumps.
Response
- 1.
The automatic initiation signals are comprised of:
- 2.
- 1.
Steam Generator Level signals.
- 2.
Safety Injection (ECCS) actuation signals.
- 3.
Undervoltage on Reactor Coolant Pump Buses (Station Service Buses).
- 4.
Undervoltage on transfer buses (Loss of Reserve Station Service Power).
- 5.
Main Feedwater Pump breakers open signals.
The level signal trains are redundant.
The input signals from Safety Injection are both redundant and independent.
Undervoltage signals on RCP Buses are not redundant.
Undervoltage signals on Transfer Buses are redundant.
The Main Feed Pump breaker signals are both redundant and independent.
This arrangement does regard to automatic and pumps.
satisfy the single failure criterion with manual initiation of the auxiliary feedwater
I
~...
e
- 3.
NRC Question e Attachment Page 3 Are there any operating bypasses associated with the automatic initiation logic/circuitry (including sensors used for auto signals) during start-up or operation of the reactor?
If so, how are these bypasses removed (automatically, procedurally, etc.)?
Respones The AFWS is automatically initiated by the following sensor channels:
2 out of 3 low-low level indications in any one steam generator, reactor coolant pump undervoltage, safety injection actuation, station blackouts and loss of main feedwater pumps.
The steam generator low-low level (SGLLL) initiation circuitry is always active and can only be bypassed by placing a particular channel in the test position.
This action is restricted by Technical Specifications.
Since these channels are always active, a bypass removal mechanism is not needed.
The reactor coolant pump (RCP) undervoltage channels which sense the voltage on the station service buses A, B and C are not provided with bypass capability during start-up or operation.
Safety Injection (SI) initiation circuitry is provided with a bypass for startup purposes and is separately alarmed in the control room.
This bypass (block) is automatically unblocked and requires no operator action.
No bypass capability is provided for the station blackout signal which senses the voltage on the station transfer buses.
Automatic initiation of the AFWS due to loss of the main feedwater (MFW) pumps is bypassed during startup by placing two of the four pump's breakers in the test position.
This prevents AFWS initiation until the breakers are procedurally taken out of the test position when the main feed system is placed in operation.
The AFW pumps may be prevented from starting by placing the pump controls in the "pull-to-lock" position.
The AFW control is procedurally returned to the "auto" position when the main feed system is placed in operation.
Reactor Coolant System loop isolation valves provid~ a signal, when closed, which prevents automatic start of Auxiliary Feedwater pumps from a Steam Generator Low-Low water level signal in the affected loop.
This signal is automatically reinstated upon reopening of the valves.
In the event this block is initiated, a permissiv.e status light is lit in the Control. Room to alert the operator of the condition.
This is, however, not considered an operating bypass since the plant operation is restricted to three-loop operation and at no time would it be operated with a loop isolated.
r-...'
I J_;;.
e
- 4.
NRC Question e Attachment Page 4 Process analog and logic channels of the automatic initiation circuitry are tested monthly up to the relay that starts the pump.
The pumps are placed in the lock position.
What indications are available to the operator in the control room which displays at the system level the inoperable status of the AFW train?
Response
Since the AFW system is not considered an engineered safeguards system, there is no direct indication that the pump has been placed in pull-to-lock position.
An alarm is sounded in the control room when a motor overload has occurred which alerts the operator to that inoperable status of the pump.
S.
NRC Question e Attachment Page S Describe the steam generator level instrumentation at the Surry Plant.
This description should include:
- a.
Type and number of level channels per steam generator including the range of each channel.
- b.
The specific source (vital bus) from which each of these channels is powered.
- c.
Capability for testing and calibration including the interval between tests.
- d.
The type of indication available in the
- control room for each channel (indicator, recorder, etc.).
Response
Sa.
Each of the three steam generators has three narrow range level transmitters and one wide range level transmitter.
All four read in 0-100% of range.
The narrow range transmitters read from just below the TI-bends of the tube bundle up to the steam dryer section.
The wide range channels read from above the tube sheet up to the steam dryer section above the tube bundle.
Sb.
Steam Generator "A" Wide Range Level Transmitter LT-1477: Vital Bus II Steam Generator "B" Wide Range Level Transmitter LT-1487:
Vital Bus III Steam Generator "C" Wide Range Level Transmitter LT-1497:
Vital Bus IV Steam Generator "A" Narrow Range Level Transmitter LT-1474 - Vital Bus I LT-1484 - Vital Bus II LT-1494 - Vital Bus III Steam Generator "B" Narrow Range Level Transmitter LT-147S - Vital Bus I LT-148S - Vital Bus II LT-149S - Vital Bus III Steam Generator "C" Narrow Range Level Transmitter LT-1476 - Vital Bus I LT-1486 - Vital Bus II LT-1496 - Vital Bus III
)
.... *~
Attachment Page 6 Sc.
The narrow range level channels are checked monthly by verification to the output comparator.
Each 2 out of 3 logic for start of the motor driven AFW pumps is tested monthly with the pump breakers in the pull-to-lock position.
5d.
Each narrow range channel is provided with an edgewise analog indi-cator in the control room.
The three wide range channels are indicated on a single strip chart recorder in the control room.
Also, the operator has on-demand capability to call up any of these narrow or wide range channels on the plant computer.