ML18102A639
| ML18102A639 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 12/02/1996 |
| From: | Eric Simpson Public Service Enterprise Group |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LR-N96374, NUDOCS 9612090233 | |
| Download: ML18102A639 (11) | |
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Public Service Electric and Gas Company E. C. Simpson Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 Senior Vice President - Nuclear Engineering DEC 0 2 1996 LR-N96374 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION POST-FIRE SAFE SHUTDOWN CAPABILITY SALEM UNIT NOS. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 Public Service Electric and Gas (PSE&G) is providing the attached information in response to the Nuclear Regulatory Commission's Request for Additional Information dated October 30, 1996.
If you have any questions regarding this submittal, please contact us.
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Recycled Paper Sincerely,
{<3 609-339-1700
Document Control Desk 2
LR-N96374 C
Mr. Hubert J. Miller, Administrator -
Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 DEC 0 2 7996 Mr. L. N. Olshan, Licensing Project Manager -
Salem U. S. Nuclear Regulatory Commission One White Flint North 11555 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 CN 415 Trenton, NJ 08625
ATTACHMENT 1 LR-N96374 The following is Public Service Electric and Gas' (PSE&G) response to the additional information requested by the NRC.
The NRC's request for information is indicated in bold typeface followed by PSE&G's response.
2.1 Alternative Shutdown System Design Reliance on the Use of Repairs to Achieve and Maintain Hot Shutdown
- a.
... Confirm that repairs outside the fire area of concern are not necessary to achieve and maintain post-fire hot shutdown conditions using either the normal shutdown systems controlled from the control room or the alternative shutdown capability controlled from the emergency control stations outside the control room...
RESPONSE
Salem's Safe Shutdown Analysis for normal shutdown from within the control room (where the fire analysis is governed by the requirements of Appendix R,Section III.G.2) does not employ any repair activities to achieve and maintain post-fire hot standby.
For Salem's alternate shutdown capability (governed by the requirements of Appendix R,Section III.G.3 and Section III.L),
the issue of using repairs to achieve and maintain post-fire hot standby conditions was discussed in the February 7, 1996 meeting held between the NRC and PSE&G.
At that time, PSE&G identified that design changes were being implemented at Salem as an enhancement for overall safety and to eliminate "operator workarounds to achieve post-fire hot-standby.
These design changes will install isolation/transfer switches which eliminate the use of electrical jumpers, lifting leads, and replacing fuses, as a method for achieving post-fire hot standby.
PSE&G does not require the use of pneumatic jumpers to achieve post-fire hot standby.
The modifications (design change 2EC-3396-1) for the Salem Unit 2 motor operated valves and room coolers, etc., to achieve post-fire hot-standby have been installed.
The design change (lEC-3486) for Salem Unit 1, will be installed prior to restart of Unit 1.
During the February 1996 meeting, an issue was raised associated with interpretation of Section 5.3 of Generic Letter 86-10 for fire-induced spurious operation as it applies to alternate safe shutdown fire areas.
The NRC indicated that the scope of the installation of transfer switches should have considered the effects of multiple spurious actuations in alternate shutdown fire areas.
The NRC also stated that the licensee's assumption of one spurious operation per fire event is not consistent with the Staff guidance and does not appear to satisfy the regulatory requirements.
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PSE&G stated that the assumption of any one spurious actuation per fire event is consistent with the guidance of Generic Letter 86-10; nonetheless, a review would be completed of systems necessary to achieve and maintain hot standby conditions to determine if fire-induced multiple spurious operation of redundant components was a concern.
The results of this review are discussed in letter LR-N96215 from PSE&G to the NRC dated June 19, 1996.
As stated in the letter, PSE&G has developed a conceptual modification to install isolation/transfer switches on valves which may be affected by multiple spurious actuations impacting the alternate shutdown capability.
Although PSE&G still believes that the assumption of taking one spurious actuation is consistent with the guidance of Generic Letter 86-10, PSE&G has initiated design modifications to address the NRC's interpretation of multiple spurious actuations as presented at the February 7, 1996 meeting.
These design changes were initiated following the February 7, 1996 meeting and were discussed in letter LR-N96215 and acknowledged in the NRC's Request for Additional Information.
The Salem Unit 2 design change (2EC-3546-1) implementing the isolation/transfer switches for valves potentially impacted by assuming multiple spurious actuations will be completed by the end of the next refueling outage (Salem Unit 2 refueling outage 10) as discussed in the February 7, 1996 meeting and letter LR-N96215.
For Salem Unit 1, installation of the isolation/transfer switch modifications (design change lEC-3486) will be completed prior to restart of Unit 1.
Installation of these design changes will address the outstanding issues required to confirm that no repairs outside the fire area of concern are required to achieve and maintain post-fire hot-standby conditions.
This applies to using either the normal shutdown systems controlled from the control room or the alternative shutdown capability controlled from the emergency control stations outside the control room.
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2.1 Alternative Shutdown System Design Reliance on the Use of Repairs to Achieve and Maintain Hot Shutdown
- a.
... Provide a list of the post-fire alternative shutdown functions which will be isolated from the control room by the proposed isolation transfer.
RESPONSE
The following is a list of post-fire alternative shutdown functions that will be isolated from the control room by the installation of isolation/transfer switches:
POST FIRE SHUTDOWN FUNCTION Charging Chilled Water Component Cooling Containment Ventilation HVAC-Auxiliary Feedwater HVAC-Charging Reactor Depressurization Residual Heat Removal Safety Injection Service Water Service Water Ventilation To satisfy the above listed shutdown functions, the following valves and equipment have been or will be modified.
Some valves support more than one shutdown function.
SALEM UNIT 1 EQUIPMENT DESCRIPTION 1 AFW ROOM COOLER AUX FEEDWATER ROOM COOLER 11 CHG AUX LO PUMP 11 CHARGING PUMP AUX LUBE OIL PUMP 11 CHARGING RM COOLER 11 CHARGING PUMP ROOM COOLER 11 CHILLER 11 CHILLER 11 CHILLED WATER PUMP 11 CHILLED WATER PUMP 11 SW VENT FAN 11 SERVICE WATER INTAKE VENT FAN 11 CC ROOM COOLER 11 COMPONENT COOLING ROOM COOLER 12 CHG AUX LO PUMP 12 CHARGING PUMP AUX LUBE OIL PUMP 12 CHG ROOM COOLER 12 CHARGING PUMP ROOM COOLER 12 CHILLER 12 CHILLER 12 CHILLED WATER PUMP lL CHILLED WATER PUMP 12 SW VENT FAN 12 SERVICE WATER INTAKE VENT FAN 12 CC ROOM COOLER 12 COMPONENT COOLING ROOM COOLER 13 CHARGING ROOM COOLER 13 CHARGING ROOM COOLER 13 SW VENT FAN lJ SERVICE WATER INTAKE VENT FAN lJ CHILLER 13 CHILLER 14 SW VENT FAN 14 SERVICE WATER INTAKE VENT FAN 1CV139 11 & 12 CHG PMP MINI FLOW ISOL VLV 1CV140 11 & lL CHG PMP MINI FLOW ISOL VLV 1C:V4U CHG PUMP SUCTION FROM VCT ISOL VLV 1CV41 CHG PUMP SUCTION FROM VCT ISOL VLV 3
SALEM UNIT 1 (cont'd)
EQUIPMENT DESCRIPTION 1CV68 CHG PMP DISCH TO REGEN HX ISOL VLV 1CV69 CHG PMP DISCH TO REGEN HX ISOL VLV lPRb PRESSURIZER RELIEF STOP VALVE 1PR7 PRESSURIZER RELIEF STOP VALVE lSJl CHG PMP SUCTION FROM RWST ISOL VLV lSJlL'.
BIT ISOLATION VALVE 1SJ13 BIT ISOLATION VALVE 1SJ2 CHG PMP SUCTION FROM RWST ISOL VLV 1SW26 NON-NUCLEAR SERVICE WATER ISOL VLV llCClb 11 RHR HX CCW RETURN ISOLATION VLV 12CC16 12 RHR HX CCW RETURN ISOLATION VLV SALEM UNIT 2 EQUIPMENT DESCRIPTION 2 AFW ROOM COOLER AUX FEEDWATER ROOM COOLER 21 CHG AUX LO PUMP 21 CHARGING PUMP AUX LUBE OIL PUMP 21 CHARGING RM COOLER
- n CHARGING PUMP ROOM COOLER 21 CHILLER 21 CHI ILER 21 CHILLED WATER PUMP 21 CHIILED WATER PUMP 21 SW VENT FAN 21 SERVICE WATER INTAKE VENT FAN 21 CC ROOM COOLER 21 COMPONENT COOLING ROOM COOLER 22 CHG AUX LO PUMP 22 CHARGING PUMP AUX LUBE OIL PUMP 22 CHG ROOM COOLER 22 CHARGING PUMP ROOM COOLER 22 CHILLER 22 CHILLER 22 CHILLED WATER PUMP 22 CHILLED WATER PUMP 22 SW VENT FAN 22 SERVICE WATER INTAKE VENT FAN 22 CC ROOM COOLER 22 COMPONENT COOLING ROOM COOLER 23 CHARGING ROOM COOLER 23 CHARGING ROOM COOLER 23 SW VENT FAN 23 SERVICE WATER INTAKE VENT FAN 23 CHILLER 23 CHILLER 24 SW VENT FAN 24 SERVICE WATER INTAKE VENT FAN 2CV139 21 & 22 CHG PMP MINI FLOW ISOL VLV 2CV140 21 & 22 CHG PMP MINI FLOW ISOL VLV 2CV40 CHG PUMP SUCTION FROM VCT ISOL VLV 2CV41 CHG PUMP SUCTION FROM VCT ISOL VLV 2CV68 CHG PMP DISCH TO REGEN HX ISOL VLV 2CV69 CHG PMP DISCH TO REGEN HX ISOL VLV 2PR6 PRESSURIZER RELIEF STOP VALVE 2PR7 PRESSURIZER RELIEF STOP VALVE 2SJ1 CHG PMP SUCTION FROM RWST ISOL VLV 2SJ12 BIT ISOLATION VALVE 2SJ13 BIT ISOLATION VALVE 2SJ2 CHG PMP SUCTION FROM RWST ISOL VLV 2SW26 NON-NUCLEAR SERVICE WATER ISOL VLV 21SJ44 L'.l SI CONTMT SUMP ISOL VALVE 22SJ44 22 SI CONTMT SUMP ISOL VALVE 21CC16 21 RHR HX CCW RETURN ISOLATION VLV 22CC16 22 RHR HX CCW RETURN ISOLATION VLV 4
2.1 Alternative Shutdown System Design Reliance on the Use of Repairs to Achieve and Maintain Hot Shutdown
- b.
... Confirm that the proposed modifications will eliminate the need for electrical jumpers, pneumatic jumpers, fuse replacement, cutting or lifting leads and any other repair actions for achieving and maintaining post-fire safe hot shutdown conditions.
The scope of the proposed modifications discussed in the June 19, 1996 response include various 230V AC motor operated valves and 230V AC motors required to achieve and maintain hot standby.
No pneumatic valves are included in the scope of the proposed modification.
PSE&G does not require the use of pneumatic jumpers to achieve post-fire hot standby.
The Salem design for motor operated valves (MOV's) utilizes 230V AC motor control centers (MCC's).
Each MCC contains pans which hold the control circuitry for an MOV.
Within each pan are such items as the main contactors, thermal overload (TOL) relay, auxiliary relay, control fuses and field wiring terminal block.
The typical MOV transfer circuit scheme utilizes two switches and two valve position indicating lights mounted within the pan.
The first switch isolates wiring routed from the motor control center to the fire area of concern, inserts new fuses into the control circuit, inserts the valve position indicating lights into the circuit, and provides permissives to operate the MOV via the second switch.
The second switch serves as an operate switch to open or close the valve.
For motors such as room coolers, one switch and one indicating light is used.
The switch performs the function of isolating wiring routed from the MCC to the fire area of concern, inserting new fuses into the control circuit, inserting an indicating light into the control circuit (to identify operation in the remote shutdown mode) and operating the motor.
Therefore, the proposed design change will eliminate the need for electrical jumpers, fuse replacement, cutting or lifting leads and any other repair actions associated with operating the subject components.
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2.2 Analysis Assumptions Pertaining to the Plant's Ability to Cope with Fire-induced Spurious Signals
... the license has re-revaluated the alternative shutdown systems needed to achieve and maintain hot standby conditions.
As a result of this review, the licensee has found that certain redundant components of the service water system are vulnerable to fire-induced spurious operation.
In its June 19, 1996 response, the licensee stated that it had developed a "conceptual modification" similar to its design change to install isolation/transfer switches.
The licensee further stated that it planned to implement this design change by the end of the next refueling outage for Salem Unit 2.
- However, the date for Unit 1 is not known at this time.
Provide the schedule for Unit 1 for implementing these planned modifications.
RESPONSE
The planned isolation/transfer switch modifications (design change lEC-3486) for Salem Unit 1 will be completed prior to restart of Unit 1.
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2.3 Evaluation and Disposition of NRC Concerns Regarding the Potential for Loss of Remote Shutdown Capability Following a Control Room Fire (Information Notice 92-18)
... Describe the methodology and criteria that were used to assure that the thermal overload protection is sized properly and that it will adequately protect the subject MOVs from mechanical damage (e.g., deep seating and binding of the valve.)
RESPONSE
Methodology and Criteria:
All safety related motor operated valves (MOV) at Salem have thermal overload relays in their circuitry designed to protect the power feed to the MOV while providing maximum protection of the valve operator motor.
The thermal overload is sized to comply with Regulatory Guide 1.106 in accordance with the methodology provided in Appendix B of IEEE Standard 741.
This methodology takes into account the voltage and ambient temperature variations when plotting protection points for current at twice nominal torque and locked rotor withstand characteristics.
The thermal overloads are sized to ensure that the MOVs will not spuriously trip while providing the maximum amount of motor protection as documented in PSE&G calculation ES-
- 18. 006.
The thermal overload (TOL) issue and Engineering Evaluation S-C-ZZ-NEE-0838-0 (submitted October 26, 1993 by letter NLR-N93144) were discussed during the February 7, 1996 meeting between PSE&G and the NRC.
The engineering evaluation documented that for any valve potentially damaged by an Information Notice (IN) 92-18 hot short, a redundant valve or system was available to provide a safe shutdown path.
PSE&G also discussed the design change for re-installing the thermal overloads (TOL) and the design change for installing isolation/transfer switches on valves required to achieve hot-standby.
At the meeting, PSE&G indicated that these modifications should eliminate the issues discussed in IN 92-18 for Salem.
Upon further review of the TOL design change for mechanical valve damage, PSE&G noted that the TOLs for several valves have marginal values for motor torque capability at full voltage versus the valve assembly torque limit.
The valves identified by this review which are required to achieve hot-standby are as follows:
CV40, CV41, CV68, CV69, CV139, CV140, PR6, PR7, SJl, SJ2, SJ12, SJ13, and SW26.
Also identified by this review were several valves whose TOL do not fully provide valve motor protection.
These valves, which can be affected by multiple spurious actuations, are as follows:
CC30, CC31, SW21's, SW22'S, SW23's, 12/22SW20, and 14/24SW20.
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As discussed during the February 7, 1996 meeting, Engineering Evaluation S-C-ZZ-NEE-0838-0 verifies that a redundant valve or system is available to provide safe shutdown capability for any valve that may be potentially damaged by the IN 92-18 hot short, thereby providing assurance of design function for systems with valves potentially impacted by IN 92-18.
This conclusion is based on the assumption of one spurious actuation.
Although PSE&G believes that the assumption of taking one spurious actuation is consistent with the guidance of Generic Letter 86-10, PSE&G has initiated design change packages to modify the circuits of these valves to address the NRC's interpretation for multiple spurious actuations presented to PSE&G at the February 7, 1996 meeting.
The control circuits for these valves will be modified to prevent hot shorts from bypassing the torque and limit switches by electrically relocating the switches between the control room and the motor control center as recommended by IN 92-18.
These circuit modifications will resolve the NRC's IN 92-18 related concerns.
The design modifications will be installed for both Salem units.
For Salem Unit 2 valves required for hot-standby, the already installed isolation/transfer switches (design change 2EC-3396-1),
previously described in Section 2.1 of this response, provide the ability to isolate circuits to mitigate the potential for additional spurious actuations.
The proposed valve circuit modifications (design changes 2EC-3546-1 and 2EC-3546-2) to eliminate the NRC's IN 92-18 concerns for hot-standby and multiple spurious actuation valves, will be completed before the end of the next refueling outage (Refueling Outage 10 for Salem Unit 2).
PSE&G concludes that the schedule for implementation of these modifications for Salem Unit 2 is acceptable based on Engineering Evaluation S-C-ZZ-NEE-0838-0, discussion between the NRC and PSE&G during the February 7, 1996 meeting at which time PSE&G stated a review of multiple spurious actuations would be performed, and plans as identified in PSE&G's June 19, 1996 letter to resolve multiple spurious actuation concerns.
For Salem Unit 1, the proposed circuit modifications (design changes lEC-3486-1 and lEC-3486-2) to eliminate the NRC's IN 92-18 concerns will be completed prior to restart of Unit 1.
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2.3 Evaluation and Disposition of NRC Concerns Regarding the Potential for Loss of Remote Shutdown Capability Following a Control Room Fire (Information Notice 92-18)
Describe the typical isolation transfer circuit scheme for these MOVs and confirm that the tripping of the thermal overload protection devices would not render the subject MOVs inoperable and that once electrically isolated from the fire area of concern they can be operated remotely from the emergency control stations outside the control room.
Response
The Salem design for motor operated valves (MOV's) uses 230V AC motor control centers (MCC's).
Each MCC contains pans which hold the control circuitry for an MOV.
Within each pan are such items as the main contactors, thermal overload (TOL) relay, auxiliary relay, control fuses and field wiring terminal block.
The typical MOV transfer circuit scheme uses two switches and two valve position indicating lights mounted within the pan.
The first switch isolates wiring routed from the motor control center to the fire area of concern, inserts new fuses into the control circuit, inserts the valve position indicating lights into the circuit, and provides permissives to operate the MOV via the second switch.
The second switch serves as an operate switch to open or close the valve.
The TOL relay is also contained within the MOV pan.
Tripping of the thermal overload relay will de-energize the main contactor coil causing the main contactor to drop out.
The TOL relay can be reset at the MOV pan thus restoring valve operability.
Operation of a MOV via the transfer switches is in the process of being proceduralized as part of the design change that installed the switches.
The MOV is operated at the MCC pan.
Reset of the TOL relay is included in the procedure.
Therefore, potential tripping of the TOL relay will not render the MOV inoperable from the remote location.
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