ML18152A908

Provides Details Re Concerns of Potential Dependence of Component Cooling Water HXs on Plant Vacuum Priming Sys.Sys Can Operate at Any Intake Canal Water Level,Per Tech Specs & Vacuum Priming Not Required for Continued Operation

ML18152A908
Person / Time
Site:	Surry
Issue date:	04/26/1988
From:	Cruden D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
88-209, NUDOCS 8805030271
Download: ML18152A908 (2)

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VIRGINIA ELECTRIC AND POWER COMPANY' RICHMOND, VIRGINIA 23261 Apri 1 26, 1988 U. S. Nuclear Regulatory Commission Serial No.88-209 Attention: Document Control Desk NO/RPC:vlh R4 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 I AND 2 COMPONENT COOLING WATER HEAT EXCHANGER OPERABILITY As a result of recent concerns regarding the potent i a1 dependence of the Component Cooling Water Heat Exchangers (CCHX) on the Station Vacuum Priming System, this letter provides details of the CCHX Service Water System.

The CCHX are installed in the Unit 1 Turbine Building at centerline elevations of 23 ft.-7 in. (1-CC-E-lA,B) and 14 ft.-10 in. (1-CC-E-lC,D). The minimuni elevation of the intake canal level is 18 ft.-0 in. per Technical Specifica-tion. Service Water (SW) flow throOgh the heat exchangers is dependent on the siphon created when the system is full and flowing. The Station Vacuum Priming System is utilized to initiate the siphon action when placing the heat

_exchangers in *service.

The primary purpose of the Station Vacuum Priming System is to remove non-condensabl e gases from the Main Condenser waterboxes during operation.

Priming of the CCHX and the Bearing Cooling Water Heat Exchangers is a secondary function served by the system. The Vacuum Priming System ties into each CCHX at the top of the inlet and outlet channel heads, which are the high points of the port ion of the SW system that supp 1i es the heat exchangers.

Piping from the two channel head connections combines below a fl oat/check valve that serves to prevent SW from entering the Vacuum Priming system and air from entering the CCHX. The Vacuum Priming System has normally been valved in, except when the heat exchangers are opened for maintenance.

The design of the CCHX SW piping system does not require that the Vacuum Priming System remain operable. Once the siphon has been initiated and flow is established, the velocities experienced in the SW system are sufficient to purge any entrained non-condensable gases, gases *liberated by the transfer of heat to the

• SW or subatmospheric conditions in the heat exchanger, and any normal (by design consideration) air inleakage that may be occurring in the SW piping system. Station records show that actual conditions have included an extended period of days when CCHX A and B (both upper elevation) operated while the Station Vacuum Priming System was removed from service.

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During ~evi ew of the CCHX and vacuum priming system design, a potent i a1 adverse seismic interaction between the systems was identified. In the event of a piping failure in the vacuum priming system, it was determined that air ingress could break the siphon in the upper two CCHXs rendering them i noperab 1e. Based on that determination, a station deviation was filed and the CCHXs were declared inoperable. Corrective actions to restore the. CCHXs to operability included seismically anchoring the vacuum priming system piping of each channel head connection up to the manual isolation root valves (l-VP-57, 58, 60, 61, and 66) and maintaining the valves closed. These actions were completed within the time constraints of Technical Specifications 3.0.1. Additional evaluations will be performed to assess the necessary design changes to permit future CCHX operation with the vacuum priming system valved-in.

As a result of discussions between our staffs, the intake canal level will be administratively controlled at an elevation of at least 27 ft.-0 in.

throughout the balance of the Unit 1 refueling outage while CCHX A & Bare the only CCHXs in service. This action will provide additional assurance of continued system operation for the periods of time when CCHX C and D (both lower elevation) are removed from service.

In summary, the Component Cooling Water System can be operated at any Intake Cana 1 water 1eve 1 consistent with the Techni ca 1 Specifications and Vacuum Priming is not required for continued system operation following flow initiation.

Very truly yours, Vice President - Nuclear 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 Mr. Chandu P. Patel NRC Surry Project Manager Project Directorate II-2 Division of Reactor Projects - I/II