ML18150A002
| ML18150A002 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 03/03/1987 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 86-801, GL-85-12, NUDOCS 8703100365 | |
| Download: ML18150A002 (4) | |
Text
e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 March 3, 1987 W. L. STEWART VICE PRESIDENT NucLEAR OPERATIONS U. S. Nuclear Regulatory Commission Serial No.86-801 Attn: Document Control Desk NO/ETS:vlh Washington, D. C. 20555 Docket Nos. 50-280 50-281 License Nos. DPR-32 DPR-37 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 USE OF INADEQUATE CORE COOLING MONITOR FOR RCP TRIP In our letter dated December 6, 1985 (Serial No. 85-510B), Virginia Electric and Power Company provided a response to Generic Letter 85-12, concerning reactor coolant pump trip criteria and instrumentation. This letter supplements our response, addressing the use of the recently installed Inadequate Core Cooling Monitor (ICCM) instrumentation to monitor the core subcooling margin parameter used for RCP trip. The design details of this system were provided by previous correspondence. The ICCM can now use either core-exit thermocouples or the wide-range loop RTDs as input to subcooling margin.
The ICCM system was installed at Surry Units 1 and 2 to satisfy the requirements for detection of Inadequate Core Cooling contained in NUREG-0737,Section II.F.2. The core subcooling margin monitor subsystem of the ICCM is being used to monitor core subcooling margin, which is the parameter used to determine reactor coolant pump trip requirements in the Surry Emergency Operating Procedures. With the installation of qualified core-exit thermocouples completed, the ICCM uses the core-exit thermocouples as the normal input for temperature to the core subcooling margin monitor subsystem.
Attachment 1 provides the associated supplemental information for the additional instruments and uncertainties. The remainder of the items addressed in our December 6, 1985 response to Generic Letter 85-12 remain applicable.
Should you have any questions concerning this information, please contact us at your earliest convenience.
Very truly yours,
~~*
W. L. Stewart Attachment 870310036~870303 PDR ADOCK 05000280 p PDR
cc: U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station
e ATTACHMENT 1 USE OF THE INADEQUATE CORE COOLING MONITOR FOR MONITORING RCP TRIP SUBCOOLING PARAMETER SURRY POWER STATION
e Section IV.A.I - Identify Required Instrumentation For the Surry plant, RCS subcooling has been chosen as the criterion for manually tripping reactor coolant pumps (RCPs).. The primary means of subcooling indication is the subcooling margin monitor subsystem of the Inadequate Core Cooling Monitor (ICCM), which receives temperature input from the core exit thermocouples. Backup temperature indication is available from the hot leg RTDs. Emergency Operating Procedure setpoint values are being revised to include adequate uncertainties to accommodate subcooling indication from either source. Use of the subcooling criterion requires the following instrumentation: 1) wide range RCS pressure transmitters, 2) core exit thermocouples and 3) Inadequate Core Cooling Monitor. The channel mark numbers and instrument model numbers are provided below. The required subcooling value for RCP trip will be read directly from the ICCM display.
Mark No. Instrument Make/
Parameter Channel A Channel B Model No.
Wide Range RCS Pressure PT-402 PT-402-1 Rosemount/1153GD9 Core Exit Temperature CET (25 total) CET (25 total) Westinghouse/WL-24295 RCS Subcooling ICC Train A ICC Train B Westinghouse Section IV.A.2 - Identify Instrumentation Uncertainties Listed below are the specific normal and adverse instrument uncertainties for the portion of the instrument loop which is input to the ICCM subcooling margin monitor. The overall channel accuracy for subcooling includes these individual instrument uncertainties combined with uncertainties associated with processing and reading the subcooling indication. The adverse containment parameters were selected to bound the plant Environmental Zone Descriptions for the area in which required instrumentation is located.
Instrument Uncertainty for These Containment Conditions Parameter Normal Adverse Wide Range RCS Pressure +/- 52 psi +/- 352 psi Core Exit Temperature +/- 21.1°F +/- 27.8°F