ML18102B037

Forwards Clarifying Info Re Mods Discussed in Util 970327 Submittal in Response to GL 96-06,as Requested in 970403 Telcon W/Nrc

ML18102B037
Person / Time
Site:	Salem
Issue date:	04/24/1997
From:	Eric Simpson Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-06, GL-96-6, LR-N97268, NUDOCS 9705050150
Download: ML18102B037 (10)

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' Company E. C. Simpson Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1700 Senior Vice President - Nuclear Engineering APR 241997 LR-N97268 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 SUPPLEMENTAL INFORMATION NRC GENERIC LETTER 96-06 SALEM GENERATING STATION UNIT NO. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 Gentlemen; Public Service Electric & Gas (PSE&G) has previously responded to this Generic Letter (GL) in correspondence dated January 28, 1997 and March 27, 1997 (LR-N97072 and LR-N97171, respectively). Attachment 1 to this transmittal provides clarifying information relative to the modifications discussed in PSE&G's March 27, 1997 submittal.

These clarifications were discussed in a conference call with Mr. L. Olshan and J. Tatum on April 3, 1997.

The information contained herein, as well as the information contained in the above referenced transmittals, also supplements information previously provided in support of PSE&G's request to amend the Salem Unit 1 and 2 Technical Specification requirements relating to the Containment Fan Coil Unit response time. That request was transmitted on October 25, 1996 (LR-N96278) as License Change Request (LCR) S96-13. It is PSE&G's understanding that, upon NRC receipt of the clarifications provided herein, all outstanding questions relating to LCR S96-13 have been addressed.

Should you have any questions regarding the enclosed information, please feel free to contact us.

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• APR 241997 LR-N97268 Attachments C Mr. H. Miller, Administrator - Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. L. N. Olshan, Licensing Project Manager - Salem U. S. Nuclear Regulatory Commission One White Flint North 115 55 Rockville Pike Mail Stop 14E21 Rockville, MD 20852 Mr. C. Marschall (X24)

USNRC Senior Resident Inspector Mr. K. Tosch, Manager, IV Bureau of Nuclear Engineering 33 Arctic Parkway CN415 Trenton, NJ 08625

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REF: LR-N97268 STATE OF NEW JERSEY )

) SS.

COUNTY OF SALEM )

E. C. Simpson, being duly sworn according to law deposes and says:

I am Senior Vice President - Nuclear Engineering of Public Service Electric and Gas Company - and as such, I find the matters set forth in the above referenced letter, concerning Salem Generating Station, Unit 1 and 2, is true to the best of my knowledge, information and belief Subscribed and~to _before me thisdl!J}!day o d.., , 1996 KIMBERLY JO BROWN NOTARY PUBLIC OF NEW JERSEY My Commission Expires April 21, 1998

• • ATTACHMENT 1 TO LR-N97268 NRC GENERIC LETTER 96-06 SUPPLEMENTAL INFORMATION

1. How will the reliability of the tank monitoring instrumentation be assured given its non-safety related designation?

Instrumentation provided to monitor storage tank operational parameters (i.e.,

level, temperature, pressure, etc.) is designated non-safety related. The non-safety classification was assigned on the basis that event mitigation actions and/or system safety functions are not initiated by this instrumentation. This instrumentation is provided solely for monitoring pre-event equipment/system status in order to assure that the system is available/capable of performing its design basis function.

Operational reliability of these instruments is assured through various means. This instrumentation is designed to meet seismic category 2 requirements. The associated sensors and indicating devices will be included in the Salem Station instrument calibration program. The tank instrumentation outputs will be processed by a programmable Logic Controller for the purpose of generating local and remote alarms and providing local indication. Redundant sensors, power supplies, and indicating channels will be provided. Separate from the indicating panel display, redundant indication is provided for level and pressure as an additional operator aid. Operational limits and alarm setpoints will be established in accordance with the appropriate Nuclear Business Unit (NBU) Technical Standard and will include consideration of instrument accuracy, setpoint drift, and measurement uncertainty as appropriate.

2. Clarify the interim administrative controls to be used to ensure that the critical elements of the new design satisfy the appropriate Technical Specification requirements.

As indicated in our March 27, 1997 submittal, additional requirements will be incorporated into the Salem Unit 1 and 2 Technical Specifications to assure (Containment Fan Coil Unit) CFCU operability and containment integrity requirements are satisfied during normal power operation. These additional requirements will consist of new surveillances to assure that critical design parameters are maintained during normal operation.

The additional Technical Specification surveillances that will be implemented are outlined as follows:

• Daily logs on Storage Tank temperature, pressure, and level

• 18 Month time response test of the Storage Tank discharge valves and the associated sensing and control circuitry 1 of7

• ATTACHMENT 1 TOLR-N97268 NRC GENERIC LETTER 96-06 SUPPLEMENTAL INFORMATION Operator Logs and surveillance procedures will be developed/revised as necessary to include the performance requirements discussed above. Guidance will also be incorporated in the applicable Alarm Response Procedures to direct plant operators to proceed to the appropriate Technical Specification section if a monitored parameter exceeds its acceptance value. If it is determined that a Service Water (SW) storage tank is inoperable, either through surveillances or alarm conditions, plant operators will be directed to comply with the ACTION statement requirements associated with Technical Specifications 3.6.1.1, "Primary CONTAINMENT INTEGRITY shall be maintained, " and 3.6.2.3, "Five containment cooling fans shall be operable."

Until such time as the administrative controls discussed above are incorporated into the Technical Specifications, PSE&G will notify the NRC in advance of any changes.

3. Provide a description of the programmatic controls that will be used to ensure that the Service Water System design will continue to satisfy the design basis over the life of the plant.

Each of the planned SW system modifications is being evaluated for inclusion in the appropriate design basis maintenance program. For example, Technical Specification surveillances will be utilized to monitor appropriate system performance requirements assumed in the design analysis. Valve performance will be monitored in accordance with the requirements of ASME Section XI and NRC GL 89-10, as appropriate. System integrity will be monitored through the periodic inspections required by ASME Section XI and the Salem Service Water Reliability Monitoring program which implements the requirements ofNRC GL 89-13.

Initial validation testing for the system will be performed as part of the post modification test plan. Subsequent testing will be performed under the above referenced programs at intervals specified either by regulation, performance trending, or recommended industry practice.

4. Clarify the basis for acceptability of a failed open SW Storage Tank discharge valve.

Two redundant, normally closed tank discharge valves are provided for each tank.

These valves are arranged in parallel in order to assure the tank discharges in the event that one valve fails to open on demand.

If a storage tank discharge valve were to fail open during normal operation, the tank contents would discharge until the pressure in the tank becomes equal to the pressure in the SW header (including any elevation head effects). Backflow to the 2 of7

• ATTACHMENT 1 TO LR-N97268 NRC GENERIC LETTER 96-06 SUPPLEMENTAL INFORMATION tank is prevented by installed check valves, as such, the tank will continue to "float" at the header pressure until restored. The total tank discharge would be less than that of the design basis tank discharge case. This condition is alarmed in the control room on the overhead annunciator panel. Operator response would" be in accordance with the Alarm Response Procedure which will direct entry into the appropriate Technical Specification, as previously discussed.

If a storage tank discharge valve were to fail to close following a valid discharge demand (i.e., Loss of Offsite Power condition), the affected tank would continue to discharge until the SW pumps were reenergized and header pressures equalized.

With the SW pumps again operating, the increase in system pressure and the subsequent closure of the SW Storage Tank discharge line check valves would prevent further draining of the storage tanks. The capacity of the tanks is sized sufficiently to provide a continues discharge until the SW pumps are restarted without injecting Nitrogen into the CFCU piping. This case is also less limiting than the design basis discharge case.

5. Provide a description of the bounding functional criteria for the new and modified SW system components.

The following are considered the bounding functional criteria for the planned modifications.

• SW Storage Tank:

• Each tank is sized to contain sufficient water and Nitrogen to maintain water filled, subcooled fluid conditions in 3 CFCU cooling loops in response to a Loss of Offsite Power, without injecting nitrogen into the CFCU cooling loops assuming the most limiting single active failure.

• SW Storage Tank Discharge Valves Response Time:

• The valve opening time, including associated sensor and signal processing time delays, must be short enough to allow the SW Storage Tank to discharge into its respective CFCU supply header prior to a water column separation condition developing in the CFCU discharge piping.

• The discharge valves must close after an appropriate time delay and remain closed during a Station Blackout (SBO) event until such time as control air header pressure is restored.

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• ATTACHMENT 1 TO LR-N97268 NRC GENERIC LETTER 96-06 SUPPLEMENTAL INFORMATION

• CFCU Flow Control Valves (SW223)

• Each valve (1/CFCU) must close as designed in order to limit the total SW Storage tank discharge to within the design assumptions.

• Each valve must reopen as designed, in sufficient time to assure that the CFCU response time assumed in the accident analysis is satisfied.

• Non-essential SW Header Isolation Valves (11, 13(21,23)SW20, 1(2)SW26)

• These valves must close in sufficient time to assure that design flow rates are achieved at the CFCU' s within the assumptions of the accident analyses.

• Component Cooling Heat Exchanger SW Flow Control Valves (SW122)

• These valves must close in sufficient time to assure that design flow rates are achieved at the CFCU' s within the assumptions of the accident analyses.

• Pressure Control Valves (SW57)

• Must open prior to CFCU fan restart in order to assure sufficient pressure exists at the CFCU cooling coil to prevent development of two phase fluid conditions.

• These valves must open in sufficient time to assure that design flow rates are achieved at the CFCU' s within the assumptions of the accident analyses.

6. Clarify the basis for concluding that there will be no boiling within the CFCU at the worst case CFCU outlet temperature.

The storage tank level and initial pressure and the opening stroke times for the storage tank discharge valves are set to preclude voiding in the CFCU piping. This is the fundamental acceptance basis for the modified CFCU cooling water piping system design. As long as pressure at all locations in the piping remains above the saturation pressure, the system will remain water solid and two phase flow will not occur.

The limiting conditions for evaluation of saturation margin (i.e. both pressure and temperature) in the CFCU' s occur in the period from event start until Turbine 4 of7

• ATTACHMENT 1 TOLR-N97268 NRC GENERIC LETTER 96-06 SUPPLEivIENTAL INFORMATION Generator Area (TGA) header isolation is complete. This period of time can be broken into two phases; 1) prior to SW pump restart when the SW storage tanks are maintaining system conditions, and 2) after pump start but prior to completion of the TGA isolation. The following is a summary of the limiting scenario for each condition and event phase, and the associated margin to saturation.

PRESSURE Prior to pump start: An SW223 valve fails wide open - If an SW223 valve fails wide open, the flow through the CFCU will be on the order of 5000 gpm. The minimum pressure for this failure occurs at the faulted CFCU and is approximately 16 psia. The post LOCA design basis CFCU exit temperature is 191 °F at the design flow rate of 2500 gpm. Use of this temperature in evaluating saturation margin is conservative in that a lower temperature would exist at the higher flow rate. The saturation pressure at 191 °F is on the order of 9. 5 psia. A positive margin to saturation exists and boiling will not occur.

After pump start: Failure of one of 3 SW pumps to start - The pressures in the system will be the lowest prior to TGA isolation. The 191 °F design basis outlet temperature is appropriate to use for this case as design flow would be achieved at each CFCU (i.e., no valve failures). Neglecting the effect of the pressurized storage tanks, the minimum pressure in the CFCU s is on the order of 18 psia, just prior to the closure of the TGA isolation valves. Following closure of the TGA isolation valves, pressure recovers to a significantly higher value. Again, a positive margin to saturation is achieved and no boiling occurs.

TEMPERATURE Failure of an SW223 valve in the low flow position: For this case the flow to the faulted CFCU is 700 gpm with a corresponding outlet temperature of 221°F.

The corresponding saturation pressure is 17. 5 psia. This failure is limiting during both phases of the CFCU response sequence as it results in the lowest flow through a CFCU at the post LOCA containment temperature. Prior to pump restart, the pressure is maintained by the SW storage tanks. By inspection, a significantly higher pressure is achieved at the faulted CFCU for this case compared to the pressure associated with a failed open SW223 valve. This is due to the significant difference in flow rates which are achieved for the different SW223 failure modes (i.e., 700 vs. 5000 gpm). Consequently, it can be concluded that a positive margin to saturation exists during this period. After pump restart, 3 pumps would be available to run (i.e., the SW223 valve is the single failure) and pressure would be greater than the 2 SW pump case described above. As such, a positive margin to saturation is achieved and boiling will not occur.

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• ATTACHMENT 1 TOLR-N97268 NRC GENERIC LETTER 96-06 SUPPLEMENTAL INFORMATION Initial discharge of stagnant volume: If the SW223 valves close as designed, pressure will initially be maintained at a high level (considerably in excess of saturation) by the pressurized SW storage tanks. During the period prior to pump restart, water in the CFCU will heat up to approximately 244 °F with a corresponding saturation pressure of 26.8 psia. The minimum CFCU pressure for this case is associated with the CFCU on the same header as a CFCU with a failed open SW223 valve. Prior to pump restart, the minimum pressure will be greater than 50 psia. Following pump restart, header pressure will continue to be maintained above saturation by a combination of the pumps and the tanks. At the design flow rate, the initial volume of hot fluid will clear the CFCU in less than 10 seconds and the outlet temperature will be reduced to approximately 191 °F (i.e.,

9.5 psia saturation pressure). SW storage tank isolation occurs after the initial volume of hot fluid has been cleared from the CFCU and coincides with the closure of the TGA isolation valves. The minimum pressure at the CFCU' s following pump restart and SW storage tank isolation will depend on the number of available SW pumps (e.g., dependent on the assumed single failure). The minimum pressure case would be the same as that associated with the previously described failure of a SW pump to start. For the case where the failure affects an SW223 valve, 3 SW pumps would be available and the minimum CFCU pressure would be in excess of 80 psia. In each case a positive margin to saturation is achieved and boiling does not occur.

Based on the above comparisons, it is concluded that two-phase flow conditions will not occur in the CFCU.

7. Provide the basis for the acceptability of local cavitation at the SW223 valve in support of the conclusion that two-phase flow has been eliminated.

Cavitation will occur at the SW223 valve as a result of the relatively hot fluid conditions exiting the CFCU and the pressure drop across the valve. The SW223 valves (8" Fisher "V' type ball control valves) are located outside containment on the 10" discharge piping from the CFCU. This piping connects to the 16" combined CFCU discharge header piping within several pipe diameters of the valve. The 16" pipe would remain flooded with a positive pressure since it is horizontal at the connection from the SW223 discharge and located below the main 24" return header. Any steam bubbles that develop at the valve discharge would be -swept into the 16" discharge piping as a result of the relatively high flowrate through the CFCU. Upon entering the 16" discharge piping, any steam bubbles would condense because the pressure in this recovery zone is greater than the bulk fluid saturation pressure (i.e., steam bubbles could not travel through the system past the 16" header connection).

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• ATTACHMENT 1 TO LR-N97268 NRC GENERIC LETTER 96-06 SUPPLEMENTAL INFORMATION Cavitation has been observed at these valves under conditions of normal operation and surveillance testing. The valves are rugged and have stainless steel bodies and balls with Stellite clad wear areas. The system piping is constructed of 6%

molybdenum stainless steel, which was selected on the basis of its resistance to erosion. Because the SW223 valves and associated piping are included in the Salem Service Water System Reliability Improvement Program (GL 89-13) scope, they have been routinely removed, disassembled, and inspected to meet program requirements. These inspections have shown seat degradation after long term operation, sometimes resulting in minor leakage through the valve while in the closed position. This condition would not affect the ability of the valve to function as designed during accident conditions.

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