ML19256F607
| ML19256F607 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 12/14/1979 |
| From: | Clayton F ALABAMA POWER CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0578, RTR-NUREG-578 TAC-12391, TAC-12963, NUDOCS 7912190556 | |
| Download: ML19256F607 (7) | |
Text
5 Alabama Powe. Company 600 North 18th Street Post Office Box CS41 Birmingham, Alabama 35291 Telephone 205 323-5341 A
hb cW.4ki,"cnt AlabamaPower the Southern eWITC System M r 14, 1979 Director, Nuclear Reactor Regulation U. S. Nuclear Ibgulatory Oxnission Washington, D. C.
20555 Attentio.a: Mr. A. Schwencer
Dear Mr. Schwencer:
Re: Telecopied Bequest for Mditional Information on Iessons Learned W _ndations 2.1.7a and b.
Attached is additional information on the subject itans re-quested by your staff on Decerber 10, 1979.
Yours very truly, z.;
_t.
F. L. Clayton, Jr.
FICjr/'INE/mrb Attachment cc: Mr. R. A. 'Itxxnas Mr. G. F. Trowbridge 1625 542 Ao39 s
79121oo $3
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j Description of Farley Nuclear Plant Auto Initiation of the Auxiliary Feedwater System (AFWS):
NUREG 0578/2.1.7a:
Consistent with satisfying the requirements of General Design Criterion 20 of Appendix A to 10CFR Part 50 with respect to the timely initiation of the auxiliary feedwater system, the following requirements shall be implemented in the short-term:
Position 1: The design shall provide for the automatic initiation of the auxiliary feedwater system.
Response: With the control switches in the auto position, the motor-driven auxiliary feedsater pumps will automatically start on any of the following signals:
(1) Tripping of both steam generator feed pumps; (2) Low-low water level signals from two-out-of-three level transmitters on any one steam generator; (3) Any of the conditions as defined in FSAR Section 7.3 that cause a safety injection signal; or (4) Ipss of Off-Site Powr Operation of the turbine-driven auxiliary feedwater pump is initiated by the opening of the steam supply valves to the turbine drive.
Steam from the main steam heaf ar is automatically admitted to the turbine drive on either of the following signals:
(1) Loss of power signal (2/3 reactor coolant pump bus under-
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voltage), or (2) Low-low water level signals frcn two-out-of-three of the level transmitters of any two-out-of-three steam generators.
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, Details of the emergency operation of the auxiliary feedwater system are contained in FSAR Sections 6.5.2.2.5 and 6.5.2.3.3.
Instrumentation and controls for the system are shown on drawings D-175007, D-175033, 0-177186, D-177188, 0-177189, D-177590, D-177591, and D-177857.
Position 2: The automatic initiation signals and circuits shall be designed
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so that a single failure will not result in the loss of auxiliary feedwater system function.
Response: The auxiliary feedwater system is designed to meet the single failure criteria so that no single failure will prevent the supply of sufficient feedwater to at least two of the three steam generators. A detailed design evaluation is contained in FSAR t
Section 6.5.3.
A failure analysis of the auxiliary feedwater system is provided in Table 6.5-2.
Position 3: Testability of the initiating signals and circuits shall be a feature of the design.
Response-In order to ensure the operability of the auxiliary feedwater system, periodic testing of the system is performed in accordance with the Farley Nuclear Plant Standard Technical Specifications Section 3/4.7.1.2.
These technical specifications list the limiting conditions for operation and the surveillance requirements for the emiliary feedwater system. These surveillance requirements ersure that both the motor-drivenpumps and turbine-driven pump are operable and develop at least 93% of design discharge pressure; each valve in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position; and that the motor-driven and 1625 344
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- turbine-driven pumps start automatically upon receipt of a test signal which simulates emergency operation of the system.
Position 4: The initiating signals and circuits shall be powered from the emergency ouses.
Response: The initiating signals and circuits for the auxiliary feedwater system are powered from the emergency buses, D-177001, D-177005 & D-177006.
Manual capability to initiate the auxiliary feedwater system Position 5:
from the control room shall be retained and shall be implemented so that a single failure in the manual circuits will not result in the loss of system function.
Response: The auxiliary feedwater system can be operated locally from the hot shutdown panel or remotely from the control room. The operation of the system is described in FSAR Section 6.5.2.3.
The system is designed to meet the single failure criteria and a failure analysis of the system is contained in Table 6.5-2.
Position 6: The a-c motor-driven pumps and valves in the auxiliary feedwater system shall be included in the automatic actuation (simultaneous and/or sequential) of the loads onto the emergency buses.
Response
The a-c motor-driven pumps and valves in the auxiliary feedwater system are included in the automatic actuation of the loads onto the emergency buses as indicated on the emergency load sequence drawings D-177001, D-177005, and D-177006.
Position 7: The automatic initiating signals and circuits shall be designed so that their failure will not result in the loss of manual capability to initiate the AFWS from the control room.
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- Response: The auxiliary feedwater system can be operated locally from the hot shutdown panel or remotely from the control room as detailed in FSAR Section 6.5.2.2.5.
Instrunentation and controls for the system are shown on P & ID drawing D-175007 and the initiating logic on Figure 7.2-14.
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l Description of Farley Nuclear Plant Auxiliary Feedwater Flow Indication to Steam Generators NUREG 0578/2.1.7.b:
Consistent with satisfying the requirements set forth in GDC 13 to provide the capability in the control room to ascertain the actual perform-ance of the AFWS when it is called to perform its intended function, the following requirements shall be implemented.
Position 1: Auxiliary feedwater flow indication to each steam generator shall satisfy the single failure criterion.
Response: Local and control room indication of auxiliary feedwater flow to each of the steam generators is provided by flow orifices in the auxiliary feedwater supply lines, located just upstream of the auxiliary feedwater stop check valves. The auxiliary feedwater flow
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indication is backed up by redundant safety-grade steam generator level channels.
Instrumentation and controls for the system are shown on P & ID drawing D-175007.
Position 2: Testability of the auxiliary feedwater flow indication channels shall be a feature of the design.
Response: Testing of the auxiliary feedwater flow indication is performed on 18-month intervals by injection of a test signal at the primary sensor. The instruments are calibrated if the output signals do not meet the required accuracy for the instrtment.
Position 3: Auxiliary feedwater flow instrument channels shall be powered from 1625 547 the vital instrument buses.
Response: The auxiliary feedwater flow instrumentation channels receive their power from the vital instrument bus. The Bechtel Corporation
, drawing A-177076 gives a block diagram of the steam generator feedwater flow indication loop and the power supply is indicated on drawing D-177024.
Position 4: Each auxiliary /eedwater channel should provide an indica-tion of feed flow with an accuracy on the order of 10%.
Response: The present control grade system has transmitters with a i 5%
full scale accuracy. The Westinghouse power supply has a gain accur-acy of
.1% of full scale and the control board indicator has an accuracy of f 1.5% of full scale. The additive accuracy of the flow loop is i 2.1% of full scale which is well within the i 10%
range.
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