ML18153C457
| ML18153C457 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 11/29/1990 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 90-538, NUDOCS 9012070139 | |
| Download: ML18153C457 (2) | |
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VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 November 29, 1990 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 and 2 NORTH ANNA POWER STATION UNITS 1 and 2 REGULATORY GUIDE 1.97 INSTRUMENTATION Serial No.90-538 NL&PffAH R4 Docket Nos. 50-280 50-281 50-338 50-339 License Nos. DPR-32 DPR-37 NPF-4 NPF-7 In our January 31, 1984 responses (Serial Nos. 053 & 054) to Regulatory Guide 1.97 (AG 1.97), Virginia Electric and Power Company committed to providing flow indication for "containment spray flow" to ensure sufficient heat rem*oval capability from containment. This parameter was identified in our RG 1.97 variable list as Item D-23.
Because of differences in the nomenclature used in the regulatory guide and at our stations, only one of two subsystems for the "containment spray system" at North Anna and Surry was instrumented with direct flow indication. The second subsystem has only indirect flow indication. Based on our evaluation, we consider indirect indication on the second subsystem to be adequate and do not plan to take any further action.
The systems at each station and our bases for considering the indirect indication as adequate are discussed below.
The containment spray system at both Surry and North Anna is comprised of two subsystems. One subsystem takes suction from the Refueling Water Storage Tank.
This subsystem is designated "Containment Spray" (CS) at Surry and "Quench Spray" (QS) at North Anna and each has been instrumented to provide a flow status. A second subsystem takes suction from the containment sumps and is designated Recirculation Spray (RS) at both stations. Because the CS I QS subsystems provide the initial heat removal function for containment cooling, the R.G. 1.97 Type D Variable
,i_tem_23 criteria was applied to them _and not to the RS systems.
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I D.ts No. 50-280 & 50-281 50-338 & 50-339 Serial No 90-538 We have recently re-evaluated this position and have concluded that the RS system should have been included in the scope of Item D-23. However, our evaluation also concluded that installing additional direct flow instrumentation to the RS system would not provide any additional useful information to the operator that can not already be derived from existing instrumentation.
Operator actions concerning the operation of the RS system are directed by the emergency operating procedures and are based on monitoring containment pressure.
Containment pressure instrumentation is qualified to RG 1.97 Category 1 requirements.
A failure of the RS system to provide recirculation flow would be indicated by abnormal RS pump motor current, RS pump discharge pressure, and containment pressure and-ternperature, all of which indicate in the control room. As there are no operator actions to be taken on a reduced RS flow condition that would be different from a total loss of RS flow condition, we believe sufficient indication exists in the control room to monitor and determine the state of the RS system operation without need for additional direct flow instrumentation. To enhance decision-making by the emergency response organization, we are developing additional guidance to better utilize the indirect information.
Therefore, although this position represents an exception to what we now understand to be the requirements of Regulatory Guide 1.97 for the containment spray flow variable, we believe sufficient indirect indication of recirculation spray system flow exists to permit operators to take appropriate action. Based on this position, we do not plan to install direct flow instrumentation for the recirculation spray subsystem portion of the containment spray system for North Anna or Surry Power Station.
If you have questions or require additional information, please contact us.
'vV. L.
t ~art Senior Vice President - Nuclear Attachments cc: U. S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. S. Lesser NRC Senior Resident Inspector North Anna Power Station Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station