ML19351E825

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Forwards Addl Info Re TMI Requirement II.F.2,in Response to NRC Request.Includes Description of in-core Thermocouple Monitoring & Subcooling Monitor Backup Capabilities.Info Suppls Util 801204 Ltr
ML19351E825
Person / Time
Site: Summer South Carolina Electric & Gas Company icon.png
Issue date: 12/15/1980
From: Nichols T
SOUTH CAROLINA ELECTRIC & GAS CO.
To: Harold Denton
Office of Nuclear Reactor Regulation
References
NUDOCS 8012190392
Download: ML19351E825 (3)


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. south CAROLINA ELECTRIC a gas COMPANY PCST OF FIC E SOM 764 ColuMaiA, south CARO LIN A 29218 T. C. Nichots. JR.

v.ar.n .,..oom.t.cc . December 15, 1980 Nuctsas C*t nanc.s Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Subj ec t : Virgil C. Summer Nuclear Station Docket No. 50/395 TMI Requirements-lI.F.2.

Dear Mr. Denton:

As requested by Mr. Tai Huang, South Carolina Electric and Gas Company, acting for itself and agent for South Carolina Public Service Authority, provides as an attachment to this letter forty-five (45) copies of additional information regarding TMI requirement II.F.2. This information supplements that of our previous letter dated December 4, 1980.

If you have additional questions, please let us know.

Very truly yours, IY A T. C. Nichols, Jr.

RBC:TCN:glb

Enclosures:

! cc: V. C. Summer w/o enclosures G. H. Fischer w/o enclosures T. C. Nichols, Jr. w/o enclosures E. H. Crews, Jr.

O. W. Dixon, Jr.

D. A. Nauman

j O. S. Bradham
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W. A. Williams, Jr.  : -.  %.t; A. A. Smith # *~ ~

A. R. Koon be p d

yh R. B. Clary ~El 2;o J. B. Knotts, Jr. $ Pi j J. L. Skolds Q u W

ff B. A. Bursey R. Faas NPCF/Whitaker File 8012190 392. b

gr y DESCRIPTION OF IN-CORE THERMOCOUPLE MONITORING CAPABILITIES The primary means for monitoring thermocouple temperatures is the plant process computer. The computer constantly monitors all 51 in-core thermocouple temperature values over a range of 70"F to 2200*F. A spatially oriented core map can be printed en operator cemand giving the temperature at each core exit thermocouple location. This process takes less than ten minutes. A printed list of all in-core thermocouple temperatures can be obtained in less than five minutes.

When any value exceeds preset alarm limits (700*F hi 1200*F hi-hi) the computer prints an alarm message on the alarm typewriter and on the control board CRT's.

Up to 51 of the thermocouples can be trended by the computer with output on the trend typewriter. Four of the 51 in-core thermocouples may be selected for trending on computer trend recorders located on the main control board. Up to 30 thermo-couple values may be selected for continuous display on either control room CRT.

The computer also is capable of determining and displaying the highest thermocouple value and the average of all thermocouple values on the CRT. The trend and alarm typewriters are located on the computer operators console in the control room.

The two CRTs are located on the center section (reactor panel) of the MCB. Trend and display selections are controlled from the computer operators console.

The second means of monitoring in-core thermocouple temperature is the core subcooling monitor system. Each channel of the subcooling monitor receives inputs from 8 thermocouples (2 per core quadrant per channel, for a total of 16 thermo-couples). A digital readout of any of the 16 single thermocouple temperatures may be obtained at the subcooling monitor panel located in the control room. The upper limit of the readout is 2300*F.

The third means available for monitoring thermocouple temperature is the in-core thermocouple readout meter located in the in-core instrumentation panel in the control room. Any of the 51 in-core thermocouples may be celected by toggle switch positioning and read on the analog readout. The readout range is 100 - 700*F.

If the manual readout should go off scale high, or problems exist with any of these systems, thermocouple temperatures may be measured directly by connecting a millivolt potentiometer to any of the thermocouple inputs in the back of the in-core instrumentation panel in the control room.

In the event that the margin to saturation decreases to less than 15*F as indicated by thermocouple input to the subcooling monitor, the " core subcooling alarm" annunciator actuates and monitoring of the in-core thermocouples is initiated in accordance with Annunciator Response Procedures.

If any 5 exit in-core thermocouples indicate a temperature greater than or equal to 1200*F, action is initiated in accordance with the " Inadequate Core Cooling" Emergency Operating Procedures.

INFORMATION REQUIRED FOR THE SUBC001,ING MONITOR BACKUP CAPA3ILITY

1. Availability of temperature and pressure Temperature and pressure readings are available on the control board and from the computer for use in determining subcooled margin manually.
2. Availability of steam tables Saturated steam tables are available in the main control room. Emergency 0; erating Procedures (EOPs) contain instructions and curves for verifying subcooled conditions.
3. Training and Operators Operators will receive appropriate training on the use of the sub-cooling monitor and other methods to determine required subcooling conditions.
4. Procedures Emergency operating procedures contain instructions for determining 4

subcooling conditions.

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