ML19330A847
| ML19330A847 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 07/24/1980 |
| From: | Clayton F ALABAMA POWER CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8007290642 | |
| Download: ML19330A847 (7) | |
Text
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e Alabama Power Company 600 North 18th Street Post Offica Box 2641 Birmingham, Alabama 35291 Telephone 205 323-5341 k
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Alabama Power the southern eiectnc system July 24, 1980 Docket No. 50-364 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attention: Mr. A. Schwencer JOSEPH M. FARLEY NUCLEAR PLANT - UNIT 2 CORE SUBC00 LING INSTRUMENTATION Gentlemen:
As requested by the NRC staff, Alabama Power Company submits the attached information concerning core subcoolic.g instrumentation.
If you have any questions, please advise.
Yours very truly,
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F. L. Claytonj Jr.
FLCjr/RWS:sc 4
Attachments cc: fir. R. A. Thomas
~l fir. G. F. Trowbridge Mr. L. L. Kintner fir. W. H. Bradford i
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1.
Describe the incore themocouple measurement means available at FNP, their range, readout location and how they are used under nomal and abnomal conditions.
Response
The primary means of monitoring incore themocouple temperature is the core subcooling monitor system.
Each channel of the subcooling monitor receives inputs from 8 themocouples (2 per core quadrant per channel, for a total of 16 thermocouples). A digital readout of any of the 16 single thermocouple temperatures may be obtained at the s', cooling monitor panel located behind the control board. The upper limit af the readout is in excess of 2300 F.
0 The second means available for mon'toring thermocouple temperature is the incore themocouple readout panel located adjacent to the safeguards section of the main control board (MCB). !ny of the 51 incore thermocouples may be selected by toggle switch positioning and read on an analog readout. The readout range is 100 - 7000F.
If the readout should go offscale high, thermocouple temperatures may be measured directly by connecting a "Digimite" or millivolt potentiometer to the thermocouple inputs at the readout panel.
A third means available for monitoring thermocouple temperature is the plant process computer. The computer constantly monitors all 51 incore thermocouple temperature values. When any value exceeds preset alam limits (7000F hi, 0
1200 F hi-hi) the computer prints an alam message on the alarm typewriter V- -
and on the control room CRT's. Up to 51 of the themocouples can-be trended by the computer with output on the trend typewriter. Up to 26 thermocouple values may be selected.for display on either control room CRT.
The computer also is capable of detemining and displaying the highest themoccuple value on the CRT. The trend typewriter, alarm typewriter and one CRT are located in the "at the controls" area in front of the safeguards panel of the MCB.
The second CRT is installed on the center section (reactor panel) of the MCB.
Trend and display selections are controlled from the computer operators console, located between the trend typewriter and alam typewriter. The maximum computer themocouple display range is 19000F.
0 In the event that the margin to saturation decreases to less than 15 F as indicated by themocouple input to the subcooling monitor, the " core subcooling alarm" annunciator actuates and monitoring of the incore thermo-couples is initiated in accordance with FNP Annunciator Response Procedures.
If any 5 exit incore themocouples indicate a temperature greater than or equal to 12000F, action is initiated in accordance with " Inadequate Core Cooling Due To A Small Loss of Coolant Accident," a FNP Emergency Operating Procedure.
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2.
Describe the subcooling monitor to be installed by fuel load.
Response
The subcooling monitor is described in Alabama Power Ccapany's TMI-2 Action Plan response item II.F.2 dated June 20, 1980.
The current main control board readout is pressure to saturation.
Energency procedures describe the utilization of the subcooling monitor and agpended portions of the steam tables to determine subcooling conditions in F.
Alabama Power Company is pursuing with Westinghouse Electric Corporation a minor change to provide main control board readout in degrees Fahrenheit.
A description of the modification required to implement this change will be presented to the NRC prior to its completion.
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3.
D'escribe the testing program to be conducted on incore themocouple measurement means and provide results of similar tests if already conducted on Unit 1.
Response
I.
Core Subcooling Monitor A.
Initial Testing _
The core subcooling monitor is to be tested by a calibration and functional test procedure. This test is a comprehensive software and hardware perfomance verification which includes initial cali-bration of inputs and functional testing of microprocessor self test features, calculation outputs, display capabilities and alann outputs. The maximum thermocouple indication error found during testing of the Unit 1 Subcooling Monitor was 70F at 20000F in a conservative (high) direction.
B.
Periodic Retesting Retesting is to be accomplished under the Preventive Maintenance program and will be performed at refueling intervals. This test will be a full functional test as outlined in A. above.
C.
Diagnostic Capabilities
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The subcooling monitor has a range of diagnostic capabilities including channel self-test, channel processor failure, power t
failure, sensor input failure and calculational output failure.
These diagnostics along with vendor recomended maintenance will be utilized to ensure the subcooling monitor channels are operable.
II.
Incore Themocouple Readout Panel A.
Initial Testing
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Testing of the Incore Thermocouple Readout Panel was performed by functional test procedure.
Thermocouple inputs and readout panel performance was verified to be within expected tolerances.
Input
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verification was performed on each thermocouple input. Maximum thermocouple indication error over the temperature range tested was 4.50F in the conservative (high) direction on Unit 2.
B.
Periodic Retesting Retesting is to be accomplished under the Preventive Maintenance program and will be performed at refueling intervals.
C.
Diagnostic Capabilities There are no specific diagnostics internal to the Incore Thermocouple Readout Panel.
Recommended vendor maintenance procedures will be utilized to ensure operability of the readout panel.
III.
plantprocessComputer(p2500)
A.
Initial Testing The plant process computer is tested using a combined input veri-fication and acceptance test procedure. This test is a comprehensive software and hardware performance verification which includes cali-bration of inputs, individual program performance testing, and calculated value, display, and alarm outputs verification. The thermocouple program package and incore thermecouple inputs are verified and calibrated at this time.
Unit 1 preoperational test 0
results indicated errors of less than 4 F over the range tested.
B.
Periodic Retesting Incore thermocouple input verification to the process computer will be performed at refueling intervals.
C.
Diagnostic Capabilities Incore thermocouple inputs are monitored and alarmed by the process computer for sensor input failure and temperature alarm limits.
Thermocouple program outputs are also monitored by the computer for alarm limits.
Routine preventive maintenance as recommended by the vendor will be utilized to ensure process computer system operability.
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-4.
Perform an evaluation 'of the core subcooling monitor instrumentation with the requirements of R.G.1.97, Rev. 2 prior to full power operation.
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Response
' Alabama Power Company will complete such an evaluation of the core subcooling monitor instrumentation. The results of this evaluation and a report of actions to be taken by Alabama Power will be provided to the NRC prior to full power operation.
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5.
Provide a description of any additional instruments or controls needed to supplement installed equipment to provide unambiguous, easy-to-interpret indication of inadequate core cooling, procedures for use of this equipment, and analyses used to develop these procedures.
Response
Alabama Power Company's letter of July 17, 1980, from F. L. Clayton, Jr.,
to A. Schwencer addressed the addition of a reactor vessel level system for FNP 2.
A description of instruments associated with the reactor vessel level, procedures for the use of this equipment, and a summary of the analytical processes used to develop these procedures will be provided to the NRC as soon as practical after a commitment for a specific reactor vessel level system is made.
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