RBG-47100, Response to Request for Additional Information on Generic Letter 2008-01
| ML103550495 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 12/10/2010 |
| From: | Roberts J Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-08-001, RBG-47100 | |
| Download: ML103550495 (9) | |
Text
Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61 N
~ Entergy St. Francisville, LA 70775 Tel 225 381 4149 Fax 225 635 5068 jrober3@entergy.com Jerry C. Roberts Director, Nuclear Safety Assurance RBG-471 00 December 10, 2010 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555-0001
SUBJECT:
Response to Request for Additional Information on Generic Letter 2008-01 River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47
REFERENCES:
- 1. Email from Mr. Alan Wang, dated October 20, 2010, River Bend Station GL 2008-01 Request for Additional Information (TAC No. MD7870)
RBF1-10-0187 File Code No.: G9.5
Dear Sir or Madam:
By Reference 1, additional information regarding the response by River Bend Station to Generic Letter 2008-01 was requested. Attached to this letter is the response to that request.
If you have any questions on this matter, please contact David Lorfing, Manager -
Licensing, at 225-381-4157. This letter contains no commitments.
I declare under penalty of perjury that the foregoing is true and correct. Executed on December 10, 2010.
Sincerely,
-'tJJerry C. Roberts Director - Nuclear Safety Assurance
Response to Request for Additional Information RBG-471 00 December 10, 2010 Page 2 of 2 : Response to Request for Additional Information cc: Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector P. 0. Box 1050 St. Francisville, LA 70775 U. S. Nuclear Regulatory Commission Attn.: Mr. Alan B. Wang One White Flint, MS 0-8 B1 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Jeffrey P. Myers Louisiana Department of Environmental Quality Office of Environmental Compliance Attn.: OEC-ERSD P. 0. Box 4312 Baton Rouge, LA 70821-4312
Attachment 1 RBG-47100 Response to Request for Additional Information on Generic Letter 2008-01, Managing Gas Accumulation In Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems RBG-47100 Page 1 of 6
- 1. Discuss monitoring of pump operation in all modes and specialized monitoring of appropriate plant parameters during shutdown operations, including control of RV water level.
River Bend Station (RBS) Response:
Emergency Core Cooling Systems (ECCS) at RBS include Low Pressure Core Spray (LPCS), High Pressure Core Spray (HPCS), and Residual Heat Removal (RHR). (For the purposes of procedural references below, the RHR system is commonly referred to as Low Pressure Coolant Injection, or LPCI.) These systems are equipped with keep-fill pumps that maintain the systems filled and pressurized. ECCS operation at RBS is controlled by various operating, alarm / abnormal / emergency, and surveillance procedures., These procedures control aspects of ECCS pump operation during the various modes of plant operation at RBS, including shutdown operations.
System Operating Procedures (SOP) at RBS contain guidance on pump operating limits, expected operating indications, as well as guidance on the pump operation in various system modes. Detailed guidance is provided to ensure the system is properly filled and vented after maintenance. Guidance is provided for placing the system in standby line up to ensure the pump is aligned for automatic operation. Operating procedures provide guidance on how to operate the pump within various system operating modes, e.g., RHR system in its injection mode, test mode, shutdown cooling mode, etc.
The operating procedure for the shutdown cooling mode of the RHR system provides guidance on flushing the piping on both suction and discharge lines, as well as verifying the piping is filled to preclude a loss of reactor pressure vessel (RPV) inventory. The procedure for shutdown cooling cautions against opening the shutdown cooling isolation valves with portions of the RHR piping empty. Unless the RHR piping, including suction lines, is completely filled, reactor level could be significantly lowered upon pump start.
RPV water level, temperature, and system response are monitored as directed by procedures for proper operation.
Alarm emergency procedures provide guidance for system operation during events.
For example, alarm procedures provide guidance for a loss of the keep-fill subsystems.
Other procedures provide guidance for system operation when directed by the appropriate emergency operating procedure.
Surveillance Test Procedures (STPs) provide guidance to routinely test ECCS pumps to ensure they can meet their design requirements. Some STPs ensure the pump is in a standby line up by checking valve position. Other STPs ensure the pump / system is properly filled. Other STPs test the pump under simulated accident conditions (without actual injection to the RPV). Similar to operating procedures, STPs also contain guidance on pump operating limits, expected operating indications, as well as acceptance criteria that must be met. The acceptance criteria are primarily based on design requirements, Inservice Testing (IST) program guidelines, and Technical Specification (TS) requirements. Meeting acceptance criteria ensures the pump/
RBG-471 00 Page 2 of 6 system can perform its safety function. Pump and system performance that does not meet the established acceptance criteria is identified in a condition report which is assessed for operability and processed through the Corrective Action Program.
The following is a list of procedures that govern the various aspects of operation of ECCS Systems at RBS:
Monthly venting and verification of valve alignment of the HPCS, RHR, and LPCS systems are controlled by STPs:
- STP-203-0201, HPCS Piping Water Fill And Valve Position Verification
- STP-204-0201, LPCI A Discharge Piping Fill And Valve Lineup Verification
- STP-204-0202, LPCI B Discharge Piping Fill And Valve Lineup Verification
- STP-204-0203, LPCI C Discharge Piping Fill And Valve Lineup Verification
- STP-205-0201, LPCS Piping Water Fill And Valve Position Verification System fill and vent, restoration from maintenance activities, and normal, abnormal, and emergency operations for HPCS, RHR, and LPCS are controlled by procedures:
- SOP-0030, High Pressure Core Spray
- SOP-0031, Residual Heat Removal
- SOP-0032, Low Pressure Core Spray The following procedures provide steps to vent the associated systems:
- STP-203-6501, HPCS Pump and Valve Operability Test
- STP-203-6305, HPCS Quarterly Pump and Valve Operability Test
- STP-205-6301, LPCS Pump and Valve Operability Test The ECCS keep-fill subsystems are instrumented to monitor their proper operation. The following Alarm Response Procedures (ARP) provide steps to vent their associated systems and assure availability of the keep-fill systems:
- ARP-601-17, P601-17 Alarm Response
- ARP-601-20, P601-20 Alarm Response
- ARP-601-16, P601-16 Alarm Response
- ARP-601-21, P601-21 Alarm Response These procedures are approved and current.
- 2. In several instances in the submittal, the license states as a corrective action, "write Condition Report if significant air is vented." Please discuss what is meant by "significant air."
RBG-47100 Page 3 of 6 RBS Response:
Engineering Calculation G13.18.2.0-082, GAS VENT TIME, determined the vent time when the quantity of vented gas could become a concern and trending and/or investigation is merited. It is applicable to the venting of HPCS, LPCS, and RHR systems in any plant mode, after they have been established to be full. This calculation determined a conservative gas venting time to trigger trending before a void volume of 5 cubic feet (cf) of air is reached.
The quantity of vented gas could indicate a concern when the venting time exceeds 3 seconds. (The vent valve is assumed to be opened approximately one full turn.) At 3 seconds of vent time, the gas volume vented would be less than or equal to 3.9 cf and trending should be performed. At 4 seconds of vent time, the gas volume vented could exceed 5.0 cf, the gas void general limit. To enable trending before the general limit is reached, a 3 second vent time limit is recommended.
The STPs for monthly system fill/vent listed in Response No. 1 above contain the requirements for initiating a Condition Report if the 3-second criterion described here is exceeded.
- 3. Discuss re-performance of ultrasonic testing (UT) or venting at locations where gas may accumulate during venting at other locations to (1) verify gas was removed after venting and (2) to ensure gas was not transported into a high point that was previously found to be gas-free.
RBS Response:
STPs for ECCS systems provide guidance as to initiating a condition report when excessive quantity of air is encountered (see response 2 above). The corrective action process will be utilized to address the operability of the system and resolve the issues including quantifying the accumulated gas and the corrective actions to be taken. This corrective action drives the response and resolution to gas intrusion.
Fleet procedure EN-DC-219 Gas Accumulation Management provides the following guidance:
"A controlled vent and fill is performed by throttling the vent valve to a prescribed position and estimating the time necessary to vent the pipe or component.
Combined with other system information such as tank level trending or other parameters, engineering can make an estimate of the gas volume vented and potential gas remaining. The actions taken and degree of accuracy required at the given location should be evaluated and documented.
Gas identified should be quantified and compared to acceptance requirements for that specific location to determine operability. The accuracy of the method used for quantification should be sufficient to verify operability during the next monitoring interval and to evaluate past operability."
RBG-471 00 Page 4 of 6 As noted in the RBS response to the Generic Letter, field walkdowns of the applicable systems did not identify any new highpoints in piping runs, nor were any new vent locations found to be needed.
- 4. Discuss measures to guard against gas intrusion because of system realignments, incorrect maintenance procedures, or other evolutions.
RBS Response:
Operating procedures at RBS contain guidance on system operating limits, expected operating indications, as well as guidance on the pump operation in various system modes. Detailed guidance is provided to ensure the system is properly filled and vented after maintenance. The fill and vent surveillance procedure for the ECCS provides adequate guidance for actions to be taken if air is found during performance of system fill and vent surveillances, as described in Response No. 1 above. The system filling and venting is the responsibility of the Operations department. When system maintenance is performed the isolation, draining, and restoration of the system is performed by Operations personnel through established procedures. Additional Operator training has been performed to raise the awareness of GL 2008-01 and concerns about air accumulation and venting practices.
Operating procedure contain details for placing the system in standby line up to ensure the system is aligned for automatic operation. Procedural guidance is provided on how to operate the pump within various system operating modes (e.g., RHR system in its injection mode, test mode, shutdown cooling mode, etc).
System operations are performed at RBS using approved procedures for realignment of the systems or restoration from maintenance procedures or other evolutions. Prior to realignment of the systems, precautions and limitations for the systems are reviewed.
The procedures contain appropriate precautions regarding possibility of gas intrusion or inadvertent draining of a system if certain system alignment occurs, and specify the actions to take if the condition occurs, such as racking out pump breakers. RPV water level, temperature, and system response are monitored as directed by RBS procedures for proper operation.
- 5. Discuss the control and revision of work packages due to change in maintenance work scope, including review and reauthorization of the package and any new temporary procedures.
RBS Response:
Work packages are prepared by the Planning department in accordance with administrative work control procedures that consider the plant operating mode, TS requirements, and overall risk. The work packages are reviewed and approved by appropriate groups such as operations, engineering, and maintenance.
RBG-471 00 Page 5 of 6 Work packages are revised whenever changes in work scope are identified. Work package revisions follow the same review and approval processes as stated previously.
This would include changes to system boundaries controlled by the Operations department.
Temporary Modifications to the plant are controlled by a specific process procedure, and are reviewed by appropriate departments, including Operations, before implementation.
Temporary Modifications are tracked by Operations in a Temporary Modification log.
Inadvertent draining of a system is minimized by the use of approved work instructions and procedures, and by qualified plant personnel trained and authorized to operate plant equipment. System boundaries are protected by clearance orders controlled by Operations and established based on Maintenance and Operations review.
As part of system restoration, the work package identifies steps for Operations to remove the clearance order, and steps to restore the system, using the system procedure to fill and vent an applicable section or the whole system as appropriate. Any air, or other gas introduced into the system as a result of maintenance would occur within the controlled tagged boundary and would be vented out as part of the restoration by Operations. In some cases, depending on the maintenance activity boundaries and relative location, fill and venting may include additional system piping.
The ECCS pumps are subject to static head on the suction piping from suppression pool level being maintained at TS required limits. Once the suction pipe and pump are filled and vented, and the pump/ST test is finished, it is not likely a void will exist-or later form. The ECCS discharge piping is maintained at positive pressure by the keep-fill system. System piping is maintained at a positive pressure and any system boundary leaks would be noticeable. Keep-fill subsystems are instrumented to monitor for proper operation. This reduces the likelihood of pulling air into the system due to a reduced pressure in the system.
The following procedures contain the above guidance:
- EN-OP-102- Protective and Caution Tagging
- EN-WM-1 02 -Work Implementation and Closeout
- EN-WM-1 07 - Post Maintenance Testing
- EN-DC-1 36- Temporary Modifications
- Individual System Operating Procedures
- 6. Training was not identified in the GL but is considered to be a necessary part of applying procedures and other activities when addressing the issues identified in the GL as the licensee has recognized. Provide a brief description of training.
RBG-471 00 Page 6 of 6 RBS Response:
River Bend provides training on gas intrusion to personnel responsible for the design, performance monitoring, and operation of systems susceptible to gas intrusion or systems and components that may cause gas intrusion in safety systems.
Operations Personnel:
RBS provides both initial and requalification training to operators who perform monitoring and operation on systems that are susceptible to gas intrusion and components that could allow gas intrusion into safety systems. RBS Operations personnel are trained on the fundamental aspects of filling and venting systems and the procedures that are implemented to accomplish the filling and venting.
Engineering Personnel:
Training material has been developed and provided to Engineering personnel in the continuing training program on gas accumulation in ECCS systems.
Text
Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61 N
~ Entergy St. Francisville, LA 70775 Tel 225 381 4149 Fax 225 635 5068 jrober3@entergy.com Jerry C. Roberts Director, Nuclear Safety Assurance RBG-471 00 December 10, 2010 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555-0001
SUBJECT:
Response to Request for Additional Information on Generic Letter 2008-01 River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47
REFERENCES:
- 1. Email from Mr. Alan Wang, dated October 20, 2010, River Bend Station GL 2008-01 Request for Additional Information (TAC No. MD7870)
RBF1-10-0187 File Code No.: G9.5
Dear Sir or Madam:
By Reference 1, additional information regarding the response by River Bend Station to Generic Letter 2008-01 was requested. Attached to this letter is the response to that request.
If you have any questions on this matter, please contact David Lorfing, Manager -
Licensing, at 225-381-4157. This letter contains no commitments.
I declare under penalty of perjury that the foregoing is true and correct. Executed on December 10, 2010.
Sincerely,
-'tJJerry C. Roberts Director - Nuclear Safety Assurance
Response to Request for Additional Information RBG-471 00 December 10, 2010 Page 2 of 2 : Response to Request for Additional Information cc: Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector P. 0. Box 1050 St. Francisville, LA 70775 U. S. Nuclear Regulatory Commission Attn.: Mr. Alan B. Wang One White Flint, MS 0-8 B1 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Jeffrey P. Myers Louisiana Department of Environmental Quality Office of Environmental Compliance Attn.: OEC-ERSD P. 0. Box 4312 Baton Rouge, LA 70821-4312
Attachment 1 RBG-47100 Response to Request for Additional Information on Generic Letter 2008-01, Managing Gas Accumulation In Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems RBG-47100 Page 1 of 6
- 1. Discuss monitoring of pump operation in all modes and specialized monitoring of appropriate plant parameters during shutdown operations, including control of RV water level.
River Bend Station (RBS) Response:
Emergency Core Cooling Systems (ECCS) at RBS include Low Pressure Core Spray (LPCS), High Pressure Core Spray (HPCS), and Residual Heat Removal (RHR). (For the purposes of procedural references below, the RHR system is commonly referred to as Low Pressure Coolant Injection, or LPCI.) These systems are equipped with keep-fill pumps that maintain the systems filled and pressurized. ECCS operation at RBS is controlled by various operating, alarm / abnormal / emergency, and surveillance procedures., These procedures control aspects of ECCS pump operation during the various modes of plant operation at RBS, including shutdown operations.
System Operating Procedures (SOP) at RBS contain guidance on pump operating limits, expected operating indications, as well as guidance on the pump operation in various system modes. Detailed guidance is provided to ensure the system is properly filled and vented after maintenance. Guidance is provided for placing the system in standby line up to ensure the pump is aligned for automatic operation. Operating procedures provide guidance on how to operate the pump within various system operating modes, e.g., RHR system in its injection mode, test mode, shutdown cooling mode, etc.
The operating procedure for the shutdown cooling mode of the RHR system provides guidance on flushing the piping on both suction and discharge lines, as well as verifying the piping is filled to preclude a loss of reactor pressure vessel (RPV) inventory. The procedure for shutdown cooling cautions against opening the shutdown cooling isolation valves with portions of the RHR piping empty. Unless the RHR piping, including suction lines, is completely filled, reactor level could be significantly lowered upon pump start.
RPV water level, temperature, and system response are monitored as directed by procedures for proper operation.
Alarm emergency procedures provide guidance for system operation during events.
For example, alarm procedures provide guidance for a loss of the keep-fill subsystems.
Other procedures provide guidance for system operation when directed by the appropriate emergency operating procedure.
Surveillance Test Procedures (STPs) provide guidance to routinely test ECCS pumps to ensure they can meet their design requirements. Some STPs ensure the pump is in a standby line up by checking valve position. Other STPs ensure the pump / system is properly filled. Other STPs test the pump under simulated accident conditions (without actual injection to the RPV). Similar to operating procedures, STPs also contain guidance on pump operating limits, expected operating indications, as well as acceptance criteria that must be met. The acceptance criteria are primarily based on design requirements, Inservice Testing (IST) program guidelines, and Technical Specification (TS) requirements. Meeting acceptance criteria ensures the pump/
RBG-471 00 Page 2 of 6 system can perform its safety function. Pump and system performance that does not meet the established acceptance criteria is identified in a condition report which is assessed for operability and processed through the Corrective Action Program.
The following is a list of procedures that govern the various aspects of operation of ECCS Systems at RBS:
Monthly venting and verification of valve alignment of the HPCS, RHR, and LPCS systems are controlled by STPs:
- STP-203-0201, HPCS Piping Water Fill And Valve Position Verification
- STP-204-0201, LPCI A Discharge Piping Fill And Valve Lineup Verification
- STP-204-0202, LPCI B Discharge Piping Fill And Valve Lineup Verification
- STP-204-0203, LPCI C Discharge Piping Fill And Valve Lineup Verification
- STP-205-0201, LPCS Piping Water Fill And Valve Position Verification System fill and vent, restoration from maintenance activities, and normal, abnormal, and emergency operations for HPCS, RHR, and LPCS are controlled by procedures:
- SOP-0030, High Pressure Core Spray
- SOP-0031, Residual Heat Removal
- SOP-0032, Low Pressure Core Spray The following procedures provide steps to vent the associated systems:
- STP-203-6501, HPCS Pump and Valve Operability Test
- STP-203-6305, HPCS Quarterly Pump and Valve Operability Test
- STP-205-6301, LPCS Pump and Valve Operability Test The ECCS keep-fill subsystems are instrumented to monitor their proper operation. The following Alarm Response Procedures (ARP) provide steps to vent their associated systems and assure availability of the keep-fill systems:
- ARP-601-17, P601-17 Alarm Response
- ARP-601-20, P601-20 Alarm Response
- ARP-601-16, P601-16 Alarm Response
- ARP-601-21, P601-21 Alarm Response These procedures are approved and current.
- 2. In several instances in the submittal, the license states as a corrective action, "write Condition Report if significant air is vented." Please discuss what is meant by "significant air."
RBG-47100 Page 3 of 6 RBS Response:
Engineering Calculation G13.18.2.0-082, GAS VENT TIME, determined the vent time when the quantity of vented gas could become a concern and trending and/or investigation is merited. It is applicable to the venting of HPCS, LPCS, and RHR systems in any plant mode, after they have been established to be full. This calculation determined a conservative gas venting time to trigger trending before a void volume of 5 cubic feet (cf) of air is reached.
The quantity of vented gas could indicate a concern when the venting time exceeds 3 seconds. (The vent valve is assumed to be opened approximately one full turn.) At 3 seconds of vent time, the gas volume vented would be less than or equal to 3.9 cf and trending should be performed. At 4 seconds of vent time, the gas volume vented could exceed 5.0 cf, the gas void general limit. To enable trending before the general limit is reached, a 3 second vent time limit is recommended.
The STPs for monthly system fill/vent listed in Response No. 1 above contain the requirements for initiating a Condition Report if the 3-second criterion described here is exceeded.
- 3. Discuss re-performance of ultrasonic testing (UT) or venting at locations where gas may accumulate during venting at other locations to (1) verify gas was removed after venting and (2) to ensure gas was not transported into a high point that was previously found to be gas-free.
RBS Response:
STPs for ECCS systems provide guidance as to initiating a condition report when excessive quantity of air is encountered (see response 2 above). The corrective action process will be utilized to address the operability of the system and resolve the issues including quantifying the accumulated gas and the corrective actions to be taken. This corrective action drives the response and resolution to gas intrusion.
Fleet procedure EN-DC-219 Gas Accumulation Management provides the following guidance:
"A controlled vent and fill is performed by throttling the vent valve to a prescribed position and estimating the time necessary to vent the pipe or component.
Combined with other system information such as tank level trending or other parameters, engineering can make an estimate of the gas volume vented and potential gas remaining. The actions taken and degree of accuracy required at the given location should be evaluated and documented.
Gas identified should be quantified and compared to acceptance requirements for that specific location to determine operability. The accuracy of the method used for quantification should be sufficient to verify operability during the next monitoring interval and to evaluate past operability."
RBG-471 00 Page 4 of 6 As noted in the RBS response to the Generic Letter, field walkdowns of the applicable systems did not identify any new highpoints in piping runs, nor were any new vent locations found to be needed.
- 4. Discuss measures to guard against gas intrusion because of system realignments, incorrect maintenance procedures, or other evolutions.
RBS Response:
Operating procedures at RBS contain guidance on system operating limits, expected operating indications, as well as guidance on the pump operation in various system modes. Detailed guidance is provided to ensure the system is properly filled and vented after maintenance. The fill and vent surveillance procedure for the ECCS provides adequate guidance for actions to be taken if air is found during performance of system fill and vent surveillances, as described in Response No. 1 above. The system filling and venting is the responsibility of the Operations department. When system maintenance is performed the isolation, draining, and restoration of the system is performed by Operations personnel through established procedures. Additional Operator training has been performed to raise the awareness of GL 2008-01 and concerns about air accumulation and venting practices.
Operating procedure contain details for placing the system in standby line up to ensure the system is aligned for automatic operation. Procedural guidance is provided on how to operate the pump within various system operating modes (e.g., RHR system in its injection mode, test mode, shutdown cooling mode, etc).
System operations are performed at RBS using approved procedures for realignment of the systems or restoration from maintenance procedures or other evolutions. Prior to realignment of the systems, precautions and limitations for the systems are reviewed.
The procedures contain appropriate precautions regarding possibility of gas intrusion or inadvertent draining of a system if certain system alignment occurs, and specify the actions to take if the condition occurs, such as racking out pump breakers. RPV water level, temperature, and system response are monitored as directed by RBS procedures for proper operation.
- 5. Discuss the control and revision of work packages due to change in maintenance work scope, including review and reauthorization of the package and any new temporary procedures.
RBS Response:
Work packages are prepared by the Planning department in accordance with administrative work control procedures that consider the plant operating mode, TS requirements, and overall risk. The work packages are reviewed and approved by appropriate groups such as operations, engineering, and maintenance.
RBG-471 00 Page 5 of 6 Work packages are revised whenever changes in work scope are identified. Work package revisions follow the same review and approval processes as stated previously.
This would include changes to system boundaries controlled by the Operations department.
Temporary Modifications to the plant are controlled by a specific process procedure, and are reviewed by appropriate departments, including Operations, before implementation.
Temporary Modifications are tracked by Operations in a Temporary Modification log.
Inadvertent draining of a system is minimized by the use of approved work instructions and procedures, and by qualified plant personnel trained and authorized to operate plant equipment. System boundaries are protected by clearance orders controlled by Operations and established based on Maintenance and Operations review.
As part of system restoration, the work package identifies steps for Operations to remove the clearance order, and steps to restore the system, using the system procedure to fill and vent an applicable section or the whole system as appropriate. Any air, or other gas introduced into the system as a result of maintenance would occur within the controlled tagged boundary and would be vented out as part of the restoration by Operations. In some cases, depending on the maintenance activity boundaries and relative location, fill and venting may include additional system piping.
The ECCS pumps are subject to static head on the suction piping from suppression pool level being maintained at TS required limits. Once the suction pipe and pump are filled and vented, and the pump/ST test is finished, it is not likely a void will exist-or later form. The ECCS discharge piping is maintained at positive pressure by the keep-fill system. System piping is maintained at a positive pressure and any system boundary leaks would be noticeable. Keep-fill subsystems are instrumented to monitor for proper operation. This reduces the likelihood of pulling air into the system due to a reduced pressure in the system.
The following procedures contain the above guidance:
- EN-OP-102- Protective and Caution Tagging
- EN-WM-1 02 -Work Implementation and Closeout
- EN-WM-1 07 - Post Maintenance Testing
- EN-DC-1 36- Temporary Modifications
- Individual System Operating Procedures
- 6. Training was not identified in the GL but is considered to be a necessary part of applying procedures and other activities when addressing the issues identified in the GL as the licensee has recognized. Provide a brief description of training.
RBG-471 00 Page 6 of 6 RBS Response:
River Bend provides training on gas intrusion to personnel responsible for the design, performance monitoring, and operation of systems susceptible to gas intrusion or systems and components that may cause gas intrusion in safety systems.
Operations Personnel:
RBS provides both initial and requalification training to operators who perform monitoring and operation on systems that are susceptible to gas intrusion and components that could allow gas intrusion into safety systems. RBS Operations personnel are trained on the fundamental aspects of filling and venting systems and the procedures that are implemented to accomplish the filling and venting.
Engineering Personnel:
Training material has been developed and provided to Engineering personnel in the continuing training program on gas accumulation in ECCS systems.