ML18152A763

Requests Discretionary Enforcement by NRC Re Use of Temporary 30-inch Svc Water Line for Two 72 H Periods. Justification for Continued Operation,Including Description of Sys Involved & Technical Considerations Evaluation Encl

ML18152A763
Person / Time
Site:	Surry
Issue date:	02/23/1988
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
88-045, 88-45, NUDOCS 8803010164
Download: ML18152A763 (14)

Text

e e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 W. L. STEWART February 23, 1988 VICE PRESIDENT NUCLEAR OPERATIONS U, S. Nuclear Regulatory Commission Serial No.88-045 Attention: Document Control Desk NO/RPC:vlh RS 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 COMPONENT COOLING HEAT EXCHANGERS UTILIZATION OF TEMPORARY 30 INCH SERVICE WATER LINE In preparation for the Surry Power Station Unit 1 refueling outage scheduled to begin April 2, 1988, provisions are being made to install a temporary service water flow path which will supply the Component Cooling Water Heat Exchangers while certain valves are being replaced. This valve replacement project represents a portion of a comprehensive program of maintaining plant equipment in original design condition. In order to avoid affecting the concurrent operation of Unit 2, an alternate 30 inch pipe must be used during two 72-hour periods to provide service water to the Component Cooling Water Heat Exchangers. This plan of action requires that the definition of operability for the Component Cooling Water Heat Exchangers be clarified for the limited period when the temporary service water line is used.

We seek discretionary enforcement by the NRC with regard to the use of the temporary 30 inch service water line for the two 72-hour periods. Our justification for continued operation (JCO) of Unit 2 during these periods of time is attached. The JCO describes the systems involved, an evaluation of technical considerations, the constraint of operational limits, and compensatory measures which will be in place to respond to anticipated circumstances. The JCO has been reviewed and approved by the Station Nuclear Safety and Operating Committee.

If you have any questions, or require any additional information, please contact us immediately.

Very truly yours, LOlffi3 W. L. Stewart Attachments PDR ADOCK 05000280 3-.----,1

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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

JUSTIFICATION FOR CONTINUED OPERATION SURRY POWER STATION UTILIZATION OF A TEMPORARY 30 INCH SERVICE WATER LINE BACKGROUND Cast iron butterfly valves in the main condenser inlet and outlet piping and in the service water piping servicing the bearing cooling water, recirculation spray, and component cooling water heat exchangers have experienced degradation due to graphitic corrosion of the cast iron in a brackish water environment.

Twelve motor-operated valves will be replaced in each unit and eight manually-operated valves will be replaced in Unit 1. The valves, .identified below, will be replaced during four upcoming outages:

UNIT 1 REFUELING OUTAGE - Spring 1988 Condenser inlet valves MOV-CW-106A,B,C,D CCW heat exchanger isolation valves MOV-SW-I02A,B CCW heat exchanger inlet valves l-SW-25, 29, 33, 37 UNIT 1 REFUELING OUTAGE - Fall 1989 Condenser outlet valves MOV-CW-lOOA,B,C,D Bearing cooling heat exchanger isolation valves MOV-SW-I01A, B CCW heat exchanger outlet valves l-SW-27, 31, 35, 39 UNIT 2 REFUELING OUTAGE - Fall 1988 Condenser inlet valves MOV-CW-206A,B,C,D Service water pump suction isolation valves MOV-SW-202A,B UNIT 2 REFUELING OUTAGE - Spring 1990 Condenser outlet valves MOV-CW-200A,B,C,D Bearing cooling heat exchanger isolation valves MOV-SW-201A,B The existing cast iron valves are being replaced with epoxy lined ductile iron valves. The ductile iron is a material suitable for seismic qualification and the epoxy lining will inhibit corrosion.

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This project is one of several being actively pursued during the upcoming outages to ensure the continued operability of the systems. Replacement of these valves will provide continued assurance of our ability to isolate the service water and circulating water systems in accordance with their safety-related functions. The MOV-SW-103's, which isolate service water to the recirculation spray heat exchangers, were replaced in a previous refueling outage.

In addition to valve replacements, repairs to the 96" circulating water piping will also be completed. This work was begun for both units in previous outages and should be completed during the upcoming Unit 1 refueling outage. We are currently formulating a plan to repair the balance of service water piping, but this work will proceed at a later date.

Replacement of the Unit 2 valves will be accomplished during a Unit 2 outage by providing normal system realignment and draining. However, since Unit 1 contains the component cooling water (CCW) heat exchangers which provide cooling to both units, a temporary service water flow path to the CCW heat exchangers is required in order to isolate and replace the following Unit 1 valves while allowing Unit 2 to remain operational.

CCW heat exchanger isolation valves MOV-SW-102A,B CCW heat exchanger inlet valves 1-SW-25, 29, 33, 37 EVALUATION Technical Specification Requirements The component cooling system is an intermediate cooling system which serves both reactor units. It transfers heat from heat exchangers containing reactor coolant, other radioactive liquids, and other fluids to the service water system. The component cooling water system has four CCW heat exchangers. Each of the CCW heat exchangers is designed to remove the entire heat load from one unit plus one-half of the heat load conunon to both units during normal operation. The capacity of one CCW heat exchanger is sufficient to remove the total heat load from Unit 2 during Unit I valve replacements. Two heat exchangers are normally operated during the removal of residual and sensible 2

heat from one unit during cooldown. Failure of any one component of the system may extend the time required for cooldown, but will not affect the safe operation of the station. Abnormal procedures are in place which address a loss of component cooling water.

Technical Specification 3.13.A.l requires that for one unit operation, two component cooling water heat exchangers shall be operable. If one of these heat exchangers becomes inoperable, it must be made operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the operating reactor shall be placed in the hot shutdown condition.

Technical Specification 3.14.A.2.B makes a corresponding requirement that service water shall be operable to the extent of being able to establish flow to and from the component cooling heat exchangers required by Specification 3.13.

Valve Replacement Activities Due to the existing piping configuration, replacement of valves MOV-SW-102A,B, and l-SW-25, 29, 33, and 37, requires the normal service water flow path to the CCW heat exchangers to be temporarily isolated. Since the CCW heat exchangers must still perform a cooling function, a temporary 30 inch service water supply line will be installed to provide the cooling water. Use of the temporary 30 inch line will be confined to two 72-hour time periods during replacement of the six service water valves. The activities to be performed during these two 72-hour periods have been scheduled such that the work required during the clock is minimized. Three valves will be replaced during each time period by three separate maintenance teams.

For clarification, the two time periods are referred to as Activity No. 1 and No. 2. Valves MOV-SW-102B, l-SW-25, and l-SW-29 will be replaced during Activity No. 1. Valves MOV-SW-102A, l-SW-33, and l-SW-37 will be replaced during Activity No. 2. Activity No. 1 will be performed first. Activity No. 2 will not be initiated until at least seven days after the completion of Activity No. 1.

The following work steps are accomplished in each activity:

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Activity No. 1 Replacement of MOV-SW-102B, 1-SW-25, and l-SW Refer to Figure No. 1

1. Stop logs and blank plates are installed upstream of line 96"-WC-4-10 at the high level intake structure.

2. The 30 inch temporary line is put into service by opening temporary valves V-3, V-4, and V-5.

3. Valves MOV-SW-102B~ 1-SW-25, and l-SW-29 are isolated by closing valves MOV-SW-102A, 1-SW-495, 1-SW-33, 1-SW-35, l-SW-37, and l-SW-39.

4. Valves MOV-SW-102B, l-SW-25, and l-SW-29 and their adjacent rubber expansion joints are replaced and tested.

5. Normal service water flow to the CCW heat exchangers is reestablished by opening MOV-SW-102A and the appropriate heat exchanger isolation valves, and then closing temporary valves V-3, V-4, and V-5.

6. Stop logs and blanks are removed as required.

NOTE: The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> JCO period starts at step 2 and ends at step 5. The construction effort includes approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> for isolation and valve replacement and 10-15 hours for testing of the valve prior to declaring operability of the system. The amount of time from when the old valve starts to be lifted from the system to the point where the new valve is lowered into place is expected to be 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

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Activity No. 2 Replacement of MOV-SW-102A, l-SW-33 and l-SW-37 Refer to Figure No. 1

1. Stop logs and blank plates are installed upstream of line 96"-WC-2-10 at the high level intake structure.

2. CCW heat exchangers 1-CC-E-lA and 1-CC-E-lB are isolated and blank pipe line flanges are installed downstream of valves l-SW-33 and l-SW-37.

3. The 30 inch temporary line is put into service by opening temporary valves V-3, V-4, and V-5

4. Valves MOV-SW-102A, l-SW-33, and l-SW-37 are isolated by closing valves MOV-SW-102B and l-SW-11, l-SW-35, and l-SW-39.

5. Valves MOV-SW-102A, l-SW-33, and l-SW-37 and their adjacent rubber expansion joints are replaced and tested.

6. Normal service water flow to the CCW heat exchangers is reestablished by opening MOV-SW-102B, l-SW-25, l-SW-29, and then closing temporary valves V-3, V-4, and V-5.

7. Stop log and blanks are removed as required.

NOTE: The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> JCO period starts at step 3 and ends at step 6. The construction effort includes approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> for isolation and valve replacement and 10-15 hours for testing of the valve prior to declaring operability of the system. The amount of time from when the old valve starts to be lifted from the system to the point where the new valve is lowered into place is expected to be 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

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Design Considerations of the Temporary 30" Line The 30 inch temporary service water supply line to the CCW heat exchangers has been designed with the following features:

1. The line is fabricated and installed in accordance with Surry plant piping Specification NUS-20 for safety-related piping and pipe class design standard STD-MEN-0004 for Class 151 .piping.

2. Class 151 (150 lb carbon steel) is suitable for the design condition of 25 psig and 95°F. Carbon steel is suitable for use with service water in this application. Corrosion of carbon steel is not a concern since the line will be in service for short durations.

3. Piping materials are specified to ASTM requirements. CMTRs are required for all pressure retaining components.

4. The temporary line is tested prior to use in accordance with the design change package requirements.

5. Line generally meets the "safety related" requirements of service water piping to CCW heat exchangers, except line is not seismic downstream of valve V-5 and is not missile protected.

6. The 30 inch line up to and including valve V-5 is seismically designed and installed, thus allowing the line to be isolated and preventing any flooding due to a seismic event.

The rationale for accepting the temporary 30 inch line as operable although nonseismic and nonmissile protected is based on the following considerations and expected plant conditions when the line is in service:

1. The service water system is a moderate energy system, and postulated failure to the piping is limited to through wall cracks. The impact of the flooding of safety-related components due to failure of the circulating water piping has been evaluated in the UFSAR and exceeds the potential flooded volume of the temporary line and is therefore bounding.

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2. Because Unit 1 is shut down when the 30 inch temporary line is in use, the only high energy lines in the vicinity of the 30 inch temporary lines containing high energy fluid are three 3 inch steam generator blowdown lines from Unit 2, located near the CCW heat exchangers. These lines have a minimal nonrupturing impact on the existing plant equipment and by equivalence have a minimal nonrupturing impact on the 30" line.

3. Use of the 30 inch line will be limited to two 72-hour periods. The probability of a seismic event during this period is small.

Construction Considerations The temporary 30 inch line will be utilized during two 72-hour time periods.

Construction work requiring the use of this line will be completed within this time period due to the following considerations:

1. Replacement equipment will be on hand prior to starting work.

2. The six valves and expansion joints have flanged ends facilitating installation and joint makeup.

3. Flange fasteners will be replaced on a one-for-one basis prior to replacing the valves to ensure rapid joint disassembly.

4. The valves being replaced in each activity are physically located such that they can be worked on simultaneously.

5. Hour by hour schedules will be used and dry run training of the valve replacements will be conducted for the construction personnel.

6. Valve staging will be performed to ensure the prompt replacement of the valve. If necessary to interupt the activity in order to restore component cooling, this method of replacement (staging) will facilitate prompt recovery. Prompt recovery measures will be included in the general training of construction personnel.

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Operational Considerations The potential impact of a loss of service water to component cooling to Unit 1 in a cold shutdown condition utilizing the Residual Heat Removal system and to Unit 2 at 100% power has been reviewed. Use of the manual valve in the temporary 30" line to provide system isolation has also been reviewed. The following actions will be taken to reduce the vulnerability to a loss of component cooling event and to ensure the required isolation features are provided:

1. An operator will be assigned to the manual isolation valve, V-5, on the temporary supply line. In the event of a pipe rupture, a seismic event, or a design basis event, the operator will be available to close V-5 as directed by the Control Room.

2. Prior to entering the 72-hour JCO periods, the operating shifts will be briefed on the Abnormal Procedures and Emergency Operating Procedures that would be used upon loss of component cooling. The actions would involve a reactor trip and securing the reactor coolant pumps on Unit 2 with resulting natural circulation cooling. Pressure control would be provided by alternate pressurizer spray from the charging pumps. On Unit 1, the loss of component cooling would affect the decay heat removal capability requiring the initiation of an Abnormal Procedure.

3. To avoid any concern about mid-nozzle operation, Activities 1 and 2 shall not be performed during that condition.

Based on the above considerations and the estimated time to replace components and reestablish a cooling path if required, sufficient time would be available to initiate the necessary actions.

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Unreviewed Safety Question Considerations Installation of the temporary service water supply line to the component cooling heat exchangers does not constitute an "Unreviewed Safety Question" as defined in 10CFR50.59. Operation of the alternate service water flow path does not:

1. Increase the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety and previously evaluated in the UFSAR.

Failure of the temporary line would cause a loss of service water to the CCW heat exchangers and would result in a loss of component cooling. This has been evaluated in the UFSAR. Unit 2 would be brought to hot shutdown using existing Station Abnormal and Emergency Operating Procedures.

The probability of a loss of component cooling water is not significantly increased since the temporary line will be installed and operated in accordance with the compensatory measures identified in the JCO which establishes relative equivalence for the 30" line.

2. Create a possibility for an accident or malfunction of a different type than any previously evaluated in the UFSAR.

The possibility for accidents or malfunctions created by these activities has been evaluated in the UFSAR. Flooding of safety-related components due to failure in the circulating water system has been evaluated in the UFSAR.

The flooding source which would result from a crack in the temporary line is a bounded by the current evaluation. For a LOCA coincident with a seismic event the temporary line will have to be isolated to conserve intake canal inventory. A manual valve will be installed in the temporary line as close as possible to the circulating water lines for isolation.

Piping between the 96 in. circulating water line and the manual valve is seismically analyzed and installed. During use of the temporary line, the intake canal level will be maintained at a level that would maintain the required water inventory for a sufficient duration to allow for manual isolation actions before minimum allowable level is reached.

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3. Reduce the margin of safety as defined in the basis for any Technical Specification.

The temporary line will be used only for short periods of time when Unit 1 is in cold shutdown. Operation of the temporary line under the conditions imposed will provide sufficient service water flow to meet the design basis requirements for single unit operation. A break in this temporary line would not reduce the flow to the recirculation spray heat exchangers during an accident condition. Administrative controls will be provided to close the isolation valve to the temporary line if required.

Construction of the temporary line will be accomplished in accordance with applicable station procedures to ensure that plant safety is maintained.

CONCLUSION Due to the corrosion, the service water butterfly valves require replacement.

During certain valve replacements, the normal service water supply to the CCW heat exchangers must be isolated and drained. In order to keep the CCW heat exchangers functional, a temporary 30 inch service water supply line will be utilized. This line is used during two 72-hour time periods which is consistent with the standard service water system technical specification LCO time periods as detailed in the Standard Technical Specifications for Westinghouse Pressurized Water Reactors (NUREG-0452). The 30 inch line is designed to provide full flow to one CCW heat exchanger, is constructed with safety-related material, is hydrostatically tested prior to use and is seismic up through the first isolation valve. Use of this line will provide the cooling water necessary for Unit 2 to remain operational. In the event the line requires isolation and is nonfunctional, Unit 2 can be brought to hot shutdown using existing station procedures. This evaluation has shown that the intent of the relevant technical specifications has been met by providing an alternate flow path with design and operational considerations provided for a non-missile protected and non-seismic line. Therefore, these measures provide the justification for continued operation of Unit 2 using the temporary service water supply to the CCW heat exchangers.

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