ML20207G446

Forwards Rev 1 to Response to 970219 NRC RAI Re GL 95-07, Pressure Locking & Thermal Binding of SR Power Operated Gate Valves. Rev Reflects Evaluations Which Have Changed Number of Valves That Need to Be Modified

ML20207G446
Person / Time
Site:	Catawba
Issue date:	03/02/1999
From:	Gordon Peterson DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-95-07, GL-95-7, TAC-M93446, TAC-M93447, NUDOCS 9903120077
Download: ML20207G446 (5)

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bb Duk2 Energy C:rporation L 8 kg)g g , Catawba Nudear Station 4800 Concord Road York, SC 29745 Gary R. Peterson (803) 831-4251 oH2CE Vise hident , (803) 831-3426 ux l

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March 2, 1999 l

U.S. Nuclear Regulatory Commission f Attention: Document Control Desk l Washington, D.C. 20555

Subject:

Catawba Nuclear Station, Units 1 and 2 l Dockets Nos. 50-413,40-414 Revision 1 to Request for Additional Information Regarding Generic Letter 95-07, " Pressure Locking and Thermal Binding of Safety Related Power Operated Gate Valves" TAC Nos. M93446, M93447 By letter dated February 19, 1997, the NRC requested additional information regarding Catawba actions to address the pressure locking and therma binding of selected valves. Catawba responded to this aquest on April 4, 1997 and provided the requested information. In particular, specific information was provided on which valves would be modified to address pressure locking and thermal binding concerns as well as time frames for completing the modifications. l l

Attached is Revision 1 to this response. It reflects updated i evalue..tions which have changed the number of valves that need to j be modified and the time frame when the modifications will be  !

performed. Actions described in the attachment to this letter l are considered to be regulatory commitments. I If there are any questions regarding this revised information, please contact Skip Copp at (803) 831-3622.

< g Gary R. Peterson 9903120077 990302 - -

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U.S. Nuclear Regulatory Commission Page 2 March 2,.1999 cc: (w/att achment)

Mr. Luis Reyes Regional Administrator, Region II U.S. Nuclear. Regulatory Commission 61 Forsyth Street,.S.W., Suite 23T85 Atlanta, GA 30303 Mr. Peter S. Tam U.S. Nuclear Regulatory Commission Mail Stop O-14 H25 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Darrell Roberts NRC Senior Resident Inspector Catawba Nuclear Station

Attachment Revision 1 to Response to NRC Request for Additional Information Generic Letter 95-07; Pressure Locking and Thermal Binding of Safety-Related Power Operated Gate Valves Request dated February 19, 1997

1. Valves 1ND28A, 1(2)NI136B, 1(2)NSJB, 1(2)NS18A, 2NS38B, l 1(2)NI121A, 1(2)NI152B, 1(2)NI9A, and 1(2) nil 0B Each of these valves has been or will be modified to l preclude pressure locking. The refueling outage when each valve was modified or is currently planned for modification l is listed below:

• 1ND28A and 1(2)NI136B - RHR Supply to Charging System Valve 1ND28A was modified during 1EOC10 in the Fall of 1997. The modification to 1NI136B will be performed during l refueling outage 1EOC11. Valve 2NI136B was modified during  !

the 2EOC9 refueling outage in the Fall of 1998.

• 1(2)NS1B and 1(2)NS18A - Containment Spray Pump Containment Sump Suction Both 1NS1B and 1NS18A were modified during 1EOC10 in the Fall of 1997. The modifications to valves 2NS1B and 2NS18A were made during refueling outage 2EOC9 in the Fall of 1998.

• 2NS38B - RHR Supply to Containment Spray Header l The actuator on valve 2NS38B will be replaced during refueling outage 2EOC10.

• 1(2)NI121A and 1(2)NI152B - Safety Injection Pump Hot Leg Injection 1 Revision 1

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Valves 1NI121A and 1NI152B will be modified during refueling outage 1EOC12. Valves 2NI121A and 2NI152B will be modified during refueling outage 2EOC10.

• 1(2)NI9A and 1(2) nil 0B - Charging Pump Cold Leg Cold Leg Injection Isolation Valve 1NI9A was modified during refueling outage 1EOC10 in the Fall of 1997. Valve 1 nil 0B will be modified during refueling outage 1EOCll. Valves 2NI9A and 2 nil 0B were modified during 2EOC9 in the Fall of 1998.

2. Valves 1(2)ND32A and 1(2)ND65B - RHR Hot Leg Injection

• During Catawba's initial GL 95-07 response, these valves were not evaluated for PL/TB concerns because the current UFSAR licensing basis does not take credit for RHR Hot Leg Recirculation. The following is the PL/TB evaluation for these valves:

Va.lve Application: RHR Pump Hot Leg Injection Isolation l Gate Design: Flex Wedge l

Manufacturer: Westinghouse Safety Function: Normally open for cold leg injection; closed for cold leg recirculation to provide train separation and passive failure protection in the manual alignment for cold leg recirculation. Note, only the LOCA will be addressed, since non-LOCA accidents do not require sump recirculation.

Pressure Locking / Thermal Binding Evaluation: Once this valve is closed after after transferring to cold leg recirculation, the only reason for opening the valve is to align the ND System for hot leg recirculation in order to prevent boron precipitation in the core. When the valve is closed, ND pump discharge pressure is 210 pisg (maximum),

and_the water temperature is 190 degrees F (maximum). When the. valve is opened for hot leg recirculation 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> into an accident,,there would be pump discharge pressure on the upstream side of the valve, which would help the valve to open. Therefore, hydraulically-induced pressure locking is 2 Revision 1

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not probable. If the piping between the valve and the pump were to rupture, pressure could be trapped in the valve's bonnet. However, in that scenario, there would be no need to open the valve since either NI pump is capable of providing enough recirculation flow. Additionally, at hot  !

leg recirculation, the ND System temperature would not '

exceed the maximum of 190 degrees F. Therefore, thermally-induced pressure locking is not probable.

According to the thermal binding screening criteria, systems at temperatures less than 200 degrees F are not  !

susceptible to this phenomenon. Since the highest temperature these valves would see is 190 degrees F, thermal binding of these valves is not probable.

Conclusion:

These valves are not susceptible to pressure locking or thermal binding.

Corrective Actions: None

3. Valves 1(2)NS12B, 1(2)NS15B, 1(2)NS29A, and 1(2)NS32A -

Containment Spray Headers Isolation The NS System Operating Procedures, OP/2/A/6200/07, were I revised in April, 1997 to include steps to cycle these valves after any evolution that could potentially pressurize the valves' bonnets.

4. Valves 1(2) NV252A - 'A' Train Charging Pump Suction Valves The motor operators for these valves will be replaced. The actuator for 1NV252A will be replaced during refueling outage 1EOC12 and the actuator for 2NV252A will be replaced  !

during refueling outage 2EOC10. '

5. Valves 1NS38B, 2ND28A, 1(2)NS43A, and 1(2)NV253B A re-evaluation of these valves has determined that there is adequate thrust margin with the current valve actuators to preclude the possibility of pressure locking or thermal binding for potential conditions to which these valves may be exposed. Therefore, no modifications are planned for these valves.

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