ML18092A487
| ML18092A487 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 02/07/1985 |
| From: | Liden E Public Service Enterprise Group |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| LCR-82-16, NUDOCS 8502190248 | |
| Download: ML18092A487 (4) | |
Text
Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Nuclear Department February 7, 1985 Ref:
LCR 82-16
- u. s. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Licensing Washington, D. c.
20555 Attention:
Mr. Steven A. Varga, Chief Operating Reactors Branch, No. 1
Dear Mr. Varga:
ECCS SEMI-AUTOMATIC SWITCHOVER TO RECIRCULATION SALEM GENERATING STATION UNIT NOS. 1 AND 2 License Change Request 82-16 was submitted in February 1983 to support the installation of an ECCS semi-automatic switchover-to-recirculation function as required in the Unit No. 2 license, and agreed to for Unit No. 1 as well.
The amendment requested was not issued due to several concerns of an NRC Reactor Systems Branch (RSB) staff reviewer.
A meeting to summarily resolve the open issues was held in Bethesda on November 29-30, 1984.
The majority of the concerns were closed out at this meeting; however, Reactor Systems Branch Chief, Mr. B. w. Sheron, requested a formal written response to a few of the items.
Provided below are the items requested and our responses.
0 Confirm that all safety equipment required to operate during a LOCA will not be adversely affected by a postulated backflow into the containment sump from the RWST during switchover-to-recirculation or due to a spurious signal during normal operations.
Except as noted below, all safety related components which could be adversely affected by flooding are located above the UFSAR documented maximum containment flood level.
Therefore, the faster flooding rate resulting from the simultaneous opening of valves SJ44 and RH4 does not have the potential to impact any safety related equipment.
The Energy People 8502190248 850207 PDR ADOCK 05000272 P
PDR 95-2168 (25M) 6-84
.. *~
Mr. Steven 2/7/85 0
0 Credit is taken for several containment isolation valves closing prior to being flooded, and remaining closed after flooding.
However, since these valves are shut within 10 seconds of the start of the ECCS injection, they will be closed long before the switchover to the recirculation phase is initiated.
Any increase in the flooding rate due to simultaneous opening of the RH4 and SJ44 valves during switchover will not affect the existing containment flooding analysis.
The flooding of containment during normal operation due to spurious opening of valve SJ44 would be detected before significant flooding could occur.
The operator would receive a "valve off normal" alarm as soon as the valve opened, followed by a "high sump level" alarm within seconds of the valve opening, alerting the operator to the problem.
Assuming the worst temperature/pressure conditions in containment, will the pressure drop across the SJ44 valve (at the point which they will provide the total flow required by each RHR pump, and the RWST check valve is forced closed) be large enough to result in voiding/water hammer, and possibly inadequate NPSH available to the RHR pump?
The RWST -
RHR pump suction check valve (i.e. RH77 or RH78) will not be forced closed until the SJ44 valve is open wide enough to deliver the total flow required by the RHR Pump plus a small margin of backf low which would result in check valve closure.
Check valve closure will occur when the SJ44 valve is approximately 40% open (i.e. t=7sec.).
At this time, the frictional loss of the piping between the sump and the valve is in the order of 0.3 feet, and across the valve it is 8.4 feet.
However, since the static head gain is approximately 29 feet, the frictional losses will not result in voiding and/or steam formation as the fluid passes through the valve.
Therefore, under the worst thermo-hydraulic circumstances, in which the water in the sump is assumed saturated, flashing would not occur in the RHR pump suction piping and the available NPSH would always be adequate.
Confirm that one Containment Spray (CS) pump will be secured when the RWST reaches its low level alarm.
Mr. Steven 2/7/85 0
0 The Emergency Instruction (EI) written to incorporate the Semi-Automatic Switchover modification was unclear as to whether one or two CS pumps would continue to operate until the RWST lo-lo level is readied.
The existing procedures will be modified to clearly state that one CS pump is to be secured at the low level setpoint.
In the event of failure of one RHR pump in the recirculation mode, confirm isolation of the RHR delivery directly to all cold legs to ensure sufficient head is available for CS operation.
In the event of a failure of one RHR pump, the other RHR pump will supply the suctions of the SI Pumps, Charging/SI Pumps, and the Containment Spray headers with no additional valve alignment except the closing of the appropriate SJ49 valve.
This action is necessary to ensure that the flow which would normally be delivered directly to the cold legs from the operating RHR pump is diverted to the Containment Spray header.
There is a "NOTE" early in the Cold Leg Recirculation section of the Emergency Instruction alerting the operator that this action (i.e. the closing of the appropriate SJ49 valve) is required if one RHR pump is unavailable at the commencement of switchover.
There is also a step provided within the body of the EI addressing the situation with one RHR Pump unavailable to ensure that the proper valve line-up is attained.
Confirm that the design changes incorporated as part of the Semi-Automatic Switchover modification will not violate single failure criteria.
As stated in Section V-A and V-D of our Functional Specification, the ECCS design in its present form meets all applicable single failure criteria.
The interface required by the new Semi-Automatic Switchover System shall not deviate from this design philosophy.
The system will be able to perform its function despite any single postulated instrumentation and control failure, or any postulated single failure of a fluid system.
No single failure shall:
Mr. Steven 2/7/85 0
0
- 1. Prevent semi-automatic transfer to the recirculation mode of operation, or
- 2. Cause inadvertent semi-automatic transfer to the recirculation mode of both trains of the ECCS.
Confirm that adequate NPSH is available to the RHR pumps during a small break LOCA (i.e. no accumulator injection) in which only 193,000 gallons from the RWST is available in the containment sump.
With only 193,000 gallons available from the injection phase, the containment sump will be flooded to approximately Elevation 81' 4" and the NPSH available will be approximately 2 feet greater than that required.
Confirm that procedures exist to ensure proper operation of the RHR Pump discharge orifice.
A full flow test procedure for the RHR pumps will be written.
This surveillance will be performed each refueling.
The above clarifications in combination with the information supplied during the November meetings should resolve all of the reviewer's concerns and facilitate a favorable SER for our requested Amendment.
If you have any further questions, we will be pleased to discuss them with you.
C Mr. Donald C. Fischer Licensing Project Manager Mr. James Linville Senior Resident Inspector Mr. B. W. Sheron, Chief Reactor Systems Branch Sincerely, E. A. Liden Manager - Nuclear Licensing and Regulation