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| issue date = 10/23/2008 | | issue date = 10/23/2008 | ||
| title = Request for Additional Information, Topical Report WCAP-16294-NP, Revision 0, Risk-Informed Evaluation of Changes to Technical Specification Required Endstates for Westinghouse NSSS PWRs | | title = Request for Additional Information, Topical Report WCAP-16294-NP, Revision 0, Risk-Informed Evaluation of Changes to Technical Specification Required Endstates for Westinghouse NSSS PWRs | ||
| author name = Mensah T | | author name = Mensah T | ||
| author affiliation = NRC/NRR/DPR/PSPB | | author affiliation = NRC/NRR/DPR/PSPB | ||
| addressee name = Bradley B | | addressee name = Bradley B | ||
| Line 44: | Line 44: | ||
PROJECT NO. 689 By letter dated September 9, 2005, the NEI submitted TR WCAP-16294, Revision 0, "Risk-Informed Evaluation of Changes to Technical Specification Required Action Endstates for Westinghouse NSSS PWRs," for U.S. Nuclear Regulatory Commission (NRC) staff review and approval. The TR includes revising the improved standard technical specification (ISTS) endpoints from cold shutdown (Mode 5) to hot shutdown (Mode 4). The NRC staff requires additional information to complete the review of the proposed changes. All section, paragraph, page, table, or figure numbers in the questions below refer to items in TR WCAP-16294-NP, unless specified otherwise. | PROJECT NO. 689 By letter dated September 9, 2005, the NEI submitted TR WCAP-16294, Revision 0, "Risk-Informed Evaluation of Changes to Technical Specification Required Action Endstates for Westinghouse NSSS PWRs," for U.S. Nuclear Regulatory Commission (NRC) staff review and approval. The TR includes revising the improved standard technical specification (ISTS) endpoints from cold shutdown (Mode 5) to hot shutdown (Mode 4). The NRC staff requires additional information to complete the review of the proposed changes. All section, paragraph, page, table, or figure numbers in the questions below refer to items in TR WCAP-16294-NP, unless specified otherwise. | ||
Containment and Ventilation Branch Questions | Containment and Ventilation Branch Questions | ||
: 1. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The basis for the proposed changes for the containment pressure TS use vague language such as "variations in containment pressure are expected to be small, therefore, any increase above the Technical Specification limit is expected to be small-". No discussion is provided for the basis of the statement. There is no indication of the processes that can cause containment pressure to be greater than or lower than the specified range or if (and why) changes from these processes will be rapid or slow. There is no discussion of any automatic system actuations that will occur if the containment pressure is too high or too low. Please provide a more comprehensive basis for the statement "variations in containment pressure are expected to be small, therefore, any increase above the Technical Specification limit is expected to be small-" | : 1. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The basis for the proposed changes for the containment pressure TS use vague language such as "variations in containment pressure are expected to be small, therefore, any increase above the Technical Specification limit is expected to be small-". No discussion is provided for the basis of the statement. There is no indication of the processes that can cause containment pressure to be greater than or lower than the specified range or if (and why) changes from these processes will be rapid or slow. There is no discussion of any automatic system actuations that will occur if the containment pressure is too high or too low. Please provide a more comprehensive basis for the statement "variations in containment pressure are expected to be small, therefore, any increase above the Technical Specification limit is expected to be small-" | ||
: 2. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The basis provided for the proposed change discussed states that the "minimum technical specification containment pressure is established such that if there was an inadvertent actuation of the containment spray system, the minimum (negative) containment design pressure would not be exceeded. Inadvertent actuation of the containment spray system does not lead to core damage and LERF by itself." Please provide additional information that justifies that inadvertent actuation of containment heat removal systems, with containment pressure less than the minimum TS limit, the containment minimum (negative) design pressure would not be exceeded. Include in the discussion atmospheric containment designs that are not provided with vacuum relief systems. | : 2. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The basis provided for the proposed change discussed states that the "minimum technical specification containment pressure is established such that if there was an inadvertent actuation of the containment spray system, the minimum (negative) containment design pressure would not be exceeded. Inadvertent actuation of the containment spray system does not lead to core damage and LERF by itself." Please provide additional information that justifies that inadvertent actuation of containment heat removal systems, with containment pressure less than the minimum TS limit, the containment minimum (negative) design pressure would not be exceeded. Include in the discussion atmospheric containment designs that are not provided with vacuum relief systems. | ||
: 3. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The minimum TS containment pressure is used as input to determining the performance of the emergency core cooling system (ECCS) pumps. Provide a discussion in the basis for the change that there will be sufficient containment pressure for ECCS operation and that the criteria of 10 CFR 50.46 will be satisfied following a loss-of-coolant (LOCA) in Mode 4 with the containment below the minimum pressure limiting condition for operation (LCO). Include core reflood and ECCS pump net positive suction head available (NPSHa) in the discussion. | : 3. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The minimum TS containment pressure is used as input to determining the performance of the emergency core cooling system (ECCS) pumps. Provide a discussion in the basis for the change that there will be sufficient containment pressure for ECCS operation and that the criteria of 10 CFR 50.46 will be satisfied following a loss-of-coolant (LOCA) in Mode 4 with the containment below the minimum pressure limiting condition for operation (LCO). Include core reflood and ECCS pump net positive suction head available (NPSHa) in the discussion. | ||
: 4. TS 3.6.15, Ice Bed (Ice Condenser): Please provide a discussion in the basis for the change or the reference to a previously submitted evaluation that provides justification that with Ice Bed inoperable there will be a sufficient source of borated water (via the containment sump) for long-term ECCS operation and that the criteria of 10 CFR 50.46 will be satisfied following a LOCA in Mode 4. Include containment spray operation, ECCS pump vortex, and ECCS pump net positive suction head available (NPSHa) in the discussion. | : 4. TS 3.6.15, Ice Bed (Ice Condenser): Please provide a discussion in the basis for the change or the reference to a previously submitted evaluation that provides justification that with Ice Bed inoperable there will be a sufficient source of borated water (via the containment sump) for long-term ECCS operation and that the criteria of 10 CFR 50.46 will be satisfied following a LOCA in Mode 4. Include containment spray operation, ECCS pump vortex, and ECCS pump net positive suction head available (NPSHa) in the discussion. | ||
: 5. TS 3.6.16, Ice Condenser Doors (Ice Condenser): Please provide a discussion or the reference to a previously submitted evaluation that documents that when the Ice Condenser doors are inoperable-open, there will not be excessive sublimation nor obstruction of flow passages that will render the ice bed inoperable based on TS 3.6.15. | : 5. TS 3.6.16, Ice Condenser Doors (Ice Condenser): Please provide a discussion or the reference to a previously submitted evaluation that documents that when the Ice Condenser doors are inoperable-open, there will not be excessive sublimation nor obstruction of flow passages that will render the ice bed inoperable based on TS 3.6.15. | ||
: 6. TS 3.6.16, Ice Condenser Doors (Ice Condenser): Please provide a discussion that documents that when the Ice Condenser doors are determined to be inoperable in the closed position, for a LOCA while in Mode 4, there will be an adequate source of borated water available to the containment sump for long-term ECCS and containment spray heat removal functions in the recirculation mode. The evaluation should include ECCS pump NPSHa and ECCS pump vortex. | : 6. TS 3.6.16, Ice Condenser Doors (Ice Condenser): Please provide a discussion that documents that when the Ice Condenser doors are determined to be inoperable in the closed position, for a LOCA while in Mode 4, there will be an adequate source of borated water available to the containment sump for long-term ECCS and containment spray heat removal functions in the recirculation mode. The evaluation should include ECCS pump NPSHa and ECCS pump vortex. | ||
: 7. TS 3.6.17, Divided Barrier Integrity (Ice Condenser): Please provide a discussion of the basis for the change, or reference to a previously submitted evaluation, which provides justification that with the divided barrier inoperable, in the event of a LOCA while in Mode 4, the pressure in the containment lower compartment will be great enough to open the ice condenser doors permitting the steam air mixture to enter and flow through the ice condenser. If the ice condenser doors will not open, two trains of containment spray will be available for control of containment peak temperature and pressure control. Discuss, or reference, previously submitted documentation that show that containment spray alone without the benefit of the ice condenser is sufficient to control peak containment temperature and pressure. Also discuss, or reference previously submitted documentation that demonstrates that without the melt from the ice condenser, there will be an adequate source of borated water available to the containment sump for long-term ECCS and containment spray heat removal functions in the recirculation mode. The evaluation should include ECCS pump NPSHa and ECCS pump vortex. | : 7. TS 3.6.17, Divided Barrier Integrity (Ice Condenser): Please provide a discussion of the basis for the change, or reference to a previously submitted evaluation, which provides justification that with the divided barrier inoperable, in the event of a LOCA while in Mode 4, the pressure in the containment lower compartment will be great enough to open the ice condenser doors permitting the steam air mixture to enter and flow through the ice condenser. If the ice condenser doors will not open, two trains of containment spray will be available for control of containment peak temperature and pressure control. Discuss, or reference, previously submitted documentation that show that containment spray alone without the benefit of the ice condenser is sufficient to control peak containment temperature and pressure. Also discuss, or reference previously submitted documentation that demonstrates that without the melt from the ice condenser, there will be an adequate source of borated water available to the containment sump for long-term ECCS and containment spray heat removal functions in the recirculation mode. The evaluation should include ECCS pump NPSHa and ECCS pump vortex. | ||
: 8. TS 3.6.5B, Containment Air Temperature (Ice Condenser) and TS 3.6.5C, Containment Air Temperature (Subatmospheric): The bases for proposed changes address temperatures above the maximum temperature LCO. Please provide basis that discusses why it is acceptable to be in Mode 4 with the containment below the minimum temperature LCO. | : 8. TS 3.6.5B, Containment Air Temperature (Ice Condenser) and TS 3.6.5C, Containment Air Temperature (Subatmospheric): The bases for proposed changes address temperatures above the maximum temperature LCO. Please provide basis that discusses why it is acceptable to be in Mode 4 with the containment below the minimum temperature LCO. | ||
: 9. TS 3.6.8, Shield Building (Dual and Ice Condenser): Please provide a discussion or the reference to a previously submitted evaluation which documents, with the Shield Building inoperable, both trains Shield Building Air Cleanup System (Dual and Ice Condenser) remains operable. | : 9. TS 3.6.8, Shield Building (Dual and Ice Condenser): Please provide a discussion or the reference to a previously submitted evaluation which documents, with the Shield Building inoperable, both trains Shield Building Air Cleanup System (Dual and Ice Condenser) remains operable. | ||
: 10. TS 3.6.8, Shield Building (Dual and Ice Condenser): It is not clear if containment vacuum relief systems installed in Westinghouse Dual Containment design plants rely on the shield building for proper operation. If the containment vacuum relief draws air from the annulus between the shield building and the containment the system design may be based on a maximum shield building leakage. Please provide a discussion of any role the shield building may perform in the operation of containment vacuum relief systems in Mode 4. | : 10. TS 3.6.8, Shield Building (Dual and Ice Condenser): It is not clear if containment vacuum relief systems installed in Westinghouse Dual Containment design plants rely on the shield building for proper operation. If the containment vacuum relief draws air from the annulus between the shield building and the containment the system design may be based on a maximum shield building leakage. Please provide a discussion of any role the shield building may perform in the operation of containment vacuum relief systems in Mode 4. | ||
: 11. TS 3.6.8, Shield Building (Dual and Ice Condenser): The NEI response to NRC Request for Additional Information Regarding PWROG TR WCAP-16294-NP, Revision 0, dated December 12, 2007, revised the Defense-in-Depth Considerations for TS 3.6.8 (TR page 6-81). The change does not appear to be related to any specific RAI. Provide an explanation for the revision and why the change is acceptable. | : 11. TS 3.6.8, Shield Building (Dual and Ice Condenser): The NEI response to NRC Request for Additional Information Regarding PWROG TR WCAP-16294-NP, Revision 0, dated December 12, 2007, revised the Defense-in-Depth Considerations for TS 3.6.8 (TR page 6-81). The change does not appear to be related to any specific RAI. Provide an explanation for the revision and why the change is acceptable. | ||
: 12. TR WCAP-16294-NP, Revision 0, states that when in Mode 4 the secondary side steam pressure will be at normal operating pressure. Please verify that when the reactor coolant system (RCS) average temperature is decreased from approximately 560°F in Mode 1 to less than 350°F in Mode 4 the pressure in the secondary side remains at normal operating pressure. If secondary side pressure is not at normal operating pressure in Mode 4 please provide verification that there will be sufficient pressure to operate the turbine driven auxiliary feedwater pump. If secondary side steam pressure in Mode 4 will be less than normal operating pressure in Mode 1 please update all references in TR WCAP-16294-NP, Revision 0, and in the RAI responses.}} | : 12. TR WCAP-16294-NP, Revision 0, states that when in Mode 4 the secondary side steam pressure will be at normal operating pressure. Please verify that when the reactor coolant system (RCS) average temperature is decreased from approximately 560°F in Mode 1 to less than 350°F in Mode 4 the pressure in the secondary side remains at normal operating pressure. If secondary side pressure is not at normal operating pressure in Mode 4 please provide verification that there will be sufficient pressure to operate the turbine driven auxiliary feedwater pump. If secondary side steam pressure in Mode 4 will be less than normal operating pressure in Mode 1 please update all references in TR WCAP-16294-NP, Revision 0, and in the RAI responses.}} | ||
Revision as of 06:24, 12 July 2019
| ML082740382 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 10/23/2008 |
| From: | Tanya Mensah NRC/NRR/DPR/PSPB |
| To: | Bradley B Nuclear Energy Institute |
| Tanya Mensah, 415-3610 | |
| References | |
| TAC MD5134, WCAP-16294-NP | |
| Download: ML082740382 (6) | |
Text
October 23, 2008
Mr. Biff Bradley Risk Assessment Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RE: NUCLEAR ENERGY INSTITUTE (NEI) TOPICAL REPORT (TR) WCAP-16294-NP, REVISION 0, "RISK-INFORMED EVALUATION OF CHANGES TO TECHNICAL SPECIFICATION REQUIRED ENDSTATES FOR WESTINGHOUSE NSSS [NUCLEAR STEAM SUPPLY SYSTEM] PWRs [PRESSURIZED WATER REACTORS]"(TAC MD5134)
Dear Mr. Bradley:
By letter dated September 9, 2005 (Agencywide Documents Access and Management System Accession No. ML052620374), the NEI submitted for U.S. Nuclear Regulatory Commission (NRC) staff review TR WCAP-16294-NP, Revision 0 "Risk-Informed Evaluation of Changes to Technical Specification Required Endstates for Westinghouse NSSS PWRs." Upon review of the information provided, the NRC staff has determined that additional information is needed to complete the review. On October 23, 2008, Biff Bradley, Director, Risk Assessment, and I agreed that the NRC staff will receive your response to the enclosed Request for Additional Information (RAI) questions by November 28, 2008.
If you have any questions regarding the enclosed RAI questions, please contact me at 301-415-3610. Sincerely, /RA/ Tanya M. Mensah, Senior Project Manager Special Projects Branch Division of Policy and Rulemaking Office of Nuclear Reactor Regulation Project No. 689
Enclosure:
RAI questions cc w/encl: See next page
- no major changes from input. NRR-106 OFFICE PSPB/PM PSPB/LA SCVB/BC* PSPB/BC NAME TMensah DBaxley BDenning SRosenberg DATE 10/23/08 10/6/08 10/20/08 10/23/08 Nuclear Energy Institute Project No. 689 cc: Mr. Anthony Pietrangelo, Vice President Regulatory Affairs Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 arp@nei.org
Mr. Jack Roe, Director Operations Support Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 jwr@nei.org
Mr. Charles B. Brinkman Washington Operations ABB-Combustion Engineering, Inc. 12300 Twinbrook Parkway, Suite 330 Rockville, MD 20852 brinkmcb@westinghouse.com Mr. James Gresham, Manager Regulatory Compliance and Plant Licensing Westinghouse Electric Company P.O. Box 355 Pittsburgh, PA 15230-0355 greshaja@westinghouse.com Ms. Barbara Lewis Assistant Editor Platts, Principal Editorial Office 1200 G St., N.W., Suite 1100 Washington, DC 20005 Barbara_lewis@platts.com Mr. Alexander Marion, Executive Director Nuclear Operations & Engineering Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 am@nei.org Mr. John Butler, Director Safety-Focused Regulation Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 jcb@nei.org Mike Melton, Senior Project Manager 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 man@nei.org Dennis Buschbaum PWROG Chairman Comanche Peak Steam Electric Station 6322 North Farm to Marked Rd 56 Mail Code E15 Glen Rose, TX 76043 Dennis.Buschbaum@luminant.com Mr. James H. Riley, Director Engineering Nuclear Energy Institute 1776 I Street, NW Washington, DC 20006-3708 jhr@nei.org
ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION TOPICAL REPORT (TR) WCAP-16294-NP, REVISION 0, "RISK-INFORMED EVALUATION OF CHANGES TO TECHNICAL SPECIFICATION [(TS)] REQUIRED ENDSTATES FOR WESTINGHOUSE NSSS [NUCLEAR STEAM SUPPLY SYSTEM] PWRs [PRESSURIZED WATER REACTORS]" (TAC. NO. MD5134)
NUCLEAR ENERGY INSTITUTE (NEI)
PROJECT NO. 689 By letter dated September 9, 2005, the NEI submitted TR WCAP-16294, Revision 0, "Risk-Informed Evaluation of Changes to Technical Specification Required Action Endstates for Westinghouse NSSS PWRs," for U.S. Nuclear Regulatory Commission (NRC) staff review and approval. The TR includes revising the improved standard technical specification (ISTS) endpoints from cold shutdown (Mode 5) to hot shutdown (Mode 4). The NRC staff requires additional information to complete the review of the proposed changes. All section, paragraph, page, table, or figure numbers in the questions below refer to items in TR WCAP-16294-NP, unless specified otherwise.
Containment and Ventilation Branch Questions
- 1. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The basis for the proposed changes for the containment pressure TS use vague language such as "variations in containment pressure are expected to be small, therefore, any increase above the Technical Specification limit is expected to be small-". No discussion is provided for the basis of the statement. There is no indication of the processes that can cause containment pressure to be greater than or lower than the specified range or if (and why) changes from these processes will be rapid or slow. There is no discussion of any automatic system actuations that will occur if the containment pressure is too high or too low. Please provide a more comprehensive basis for the statement "variations in containment pressure are expected to be small, therefore, any increase above the Technical Specification limit is expected to be small-"
- 2. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The basis provided for the proposed change discussed states that the "minimum technical specification containment pressure is established such that if there was an inadvertent actuation of the containment spray system, the minimum (negative) containment design pressure would not be exceeded. Inadvertent actuation of the containment spray system does not lead to core damage and LERF by itself." Please provide additional information that justifies that inadvertent actuation of containment heat removal systems, with containment pressure less than the minimum TS limit, the containment minimum (negative) design pressure would not be exceeded. Include in the discussion atmospheric containment designs that are not provided with vacuum relief systems.
- 3. TS 3.6.4A, Containment Pressure (Atmospheric, Dual, and Ice Condenser) and TS 3.6.4B-B, Containment Pressure (Subatmospheric): The minimum TS containment pressure is used as input to determining the performance of the emergency core cooling system (ECCS) pumps. Provide a discussion in the basis for the change that there will be sufficient containment pressure for ECCS operation and that the criteria of 10 CFR 50.46 will be satisfied following a loss-of-coolant (LOCA) in Mode 4 with the containment below the minimum pressure limiting condition for operation (LCO). Include core reflood and ECCS pump net positive suction head available (NPSHa) in the discussion.
- 4. TS 3.6.15, Ice Bed (Ice Condenser): Please provide a discussion in the basis for the change or the reference to a previously submitted evaluation that provides justification that with Ice Bed inoperable there will be a sufficient source of borated water (via the containment sump) for long-term ECCS operation and that the criteria of 10 CFR 50.46 will be satisfied following a LOCA in Mode 4. Include containment spray operation, ECCS pump vortex, and ECCS pump net positive suction head available (NPSHa) in the discussion.
- 5. TS 3.6.16, Ice Condenser Doors (Ice Condenser): Please provide a discussion or the reference to a previously submitted evaluation that documents that when the Ice Condenser doors are inoperable-open, there will not be excessive sublimation nor obstruction of flow passages that will render the ice bed inoperable based on TS 3.6.15.
- 6. TS 3.6.16, Ice Condenser Doors (Ice Condenser): Please provide a discussion that documents that when the Ice Condenser doors are determined to be inoperable in the closed position, for a LOCA while in Mode 4, there will be an adequate source of borated water available to the containment sump for long-term ECCS and containment spray heat removal functions in the recirculation mode. The evaluation should include ECCS pump NPSHa and ECCS pump vortex.
- 7. TS 3.6.17, Divided Barrier Integrity (Ice Condenser): Please provide a discussion of the basis for the change, or reference to a previously submitted evaluation, which provides justification that with the divided barrier inoperable, in the event of a LOCA while in Mode 4, the pressure in the containment lower compartment will be great enough to open the ice condenser doors permitting the steam air mixture to enter and flow through the ice condenser. If the ice condenser doors will not open, two trains of containment spray will be available for control of containment peak temperature and pressure control. Discuss, or reference, previously submitted documentation that show that containment spray alone without the benefit of the ice condenser is sufficient to control peak containment temperature and pressure. Also discuss, or reference previously submitted documentation that demonstrates that without the melt from the ice condenser, there will be an adequate source of borated water available to the containment sump for long-term ECCS and containment spray heat removal functions in the recirculation mode. The evaluation should include ECCS pump NPSHa and ECCS pump vortex.
- 8. TS 3.6.5B, Containment Air Temperature (Ice Condenser) and TS 3.6.5C, Containment Air Temperature (Subatmospheric): The bases for proposed changes address temperatures above the maximum temperature LCO. Please provide basis that discusses why it is acceptable to be in Mode 4 with the containment below the minimum temperature LCO.
- 9. TS 3.6.8, Shield Building (Dual and Ice Condenser): Please provide a discussion or the reference to a previously submitted evaluation which documents, with the Shield Building inoperable, both trains Shield Building Air Cleanup System (Dual and Ice Condenser) remains operable.
- 10. TS 3.6.8, Shield Building (Dual and Ice Condenser): It is not clear if containment vacuum relief systems installed in Westinghouse Dual Containment design plants rely on the shield building for proper operation. If the containment vacuum relief draws air from the annulus between the shield building and the containment the system design may be based on a maximum shield building leakage. Please provide a discussion of any role the shield building may perform in the operation of containment vacuum relief systems in Mode 4.
- 11. TS 3.6.8, Shield Building (Dual and Ice Condenser): The NEI response to NRC Request for Additional Information Regarding PWROG TR WCAP-16294-NP, Revision 0, dated December 12, 2007, revised the Defense-in-Depth Considerations for TS 3.6.8 (TR page 6-81). The change does not appear to be related to any specific RAI. Provide an explanation for the revision and why the change is acceptable.
- 12. TR WCAP-16294-NP, Revision 0, states that when in Mode 4 the secondary side steam pressure will be at normal operating pressure. Please verify that when the reactor coolant system (RCS) average temperature is decreased from approximately 560°F in Mode 1 to less than 350°F in Mode 4 the pressure in the secondary side remains at normal operating pressure. If secondary side pressure is not at normal operating pressure in Mode 4 please provide verification that there will be sufficient pressure to operate the turbine driven auxiliary feedwater pump. If secondary side steam pressure in Mode 4 will be less than normal operating pressure in Mode 1 please update all references in TR WCAP-16294-NP, Revision 0, and in the RAI responses.