L-MT-09-079, Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01

Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01

ML092290180
Person / Time
Site:	Monticello
Issue date:	08/14/2009
From:	O'Connor T Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-08-001, L-MT-09-079
Download: ML092290180 (8)

Text

August 14,2009 L-MT-09-079 10 CFR 50.540 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License No. DPR-22 Monticello Nuclear Generating Plant Nine-Month Supplemental (Post-Outage)

Response to NRC Generic Letter 2008-01 The U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01 (Reference Iof Enclosure I ) to request that each licensee evaluate the licensing basis, design, testing, and corrective actions for the emergency core cooling (ECCS), decay heat removal (DHR), and containment spray systems to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, and that appropriate action is taken when conditions adverse to quality are identified.

As requested by the NRC in Reference 2 of Enclosure 1, the Northern States Power Company, a Minnesota corporation (NSPM), is providing a supplemental response to the nine-month response (Reference 3 of Enclosure I ) submitted for the Monticello Nuclear Generating Plant (MNGP). This supplemental response is being provided within 90 days following return to full power from the spring 2009 Refueling Outage, i.e.,

the outage in which the deferred actions were completed.

In summary, with one exception discussed herein, the NSPM has concluded that the GL 2008-01 subject systems at the MNGP are operable and that the unit is in compliance with the plant licensing basis documentation and applicable regulations, including 10 CFR 50 Appendix B, Criteria Ill, V, XI, XVI, and XVII, with respect to the concerns outlined in GL 2008-01 regarding managing gas accumulation in these systems/functions.

2807 West County Road 75 e Monticello, Minnesota 55362-9637 Telephone: 763.295.5151 e Fax: 763.295.1 454

Document Control Desk L-MT-09-079 Page 2 of 2 Enclosure Iprovides the NSPM supplemental response to GL 2008-01 Summarv of Commitments The following commitments made in Reference 3 of Enclosure 1 have been completed:

1 Complete the detailed walkdowns of the applicable inaccessible sections of the Generic Letter 2008-01 subject systems (does not include piping downstream of the low pressure ECCS outboard injection valves) prior to startup from the 2009 Refueling Outage.

2. NSPM will complete the evaluations of the applicable inaccessible sections of the Generic Letter 2008-01 subject systems and provide a supplement to the October 2008 response to Generic Letter 2008-01 within 90 days following return to full power from the 2009 Refueling Outage.

The following new commitments are proposed:

I A vent valve assembly will be installed on the High Pressure Coolant Injection (HPCI) discharge line to restore full qualification of the HPCl System. Due to an unventable high point, HPCl is operable but not in conformance with the plant design basis. This corrective action will be completed by startup from the 2011 refueling outage (currently scheduled for June 2011).

2. Operating procedures will be revised to require dynamic venting via Core Spray injection if activities requiring system restoration occur on the unventable portion of the Core Spray System. This corrective action will be completed by November 30,2009.

Ity of perjury that the foregoing is true and correct.

e President, Monticello Nuclear Generating Plant ny - Minnesota Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce

ENCLOSURE 1 MQNTICELLO NUCLEAR GENERATING PLANT NINE-MONTH SUPPLEMENTAL RESPONSE TO GENERIC LETTER 2008-Q"1

L-MT-09-079 Page 1 of 5 Nine-Month Supplemental Response to Generic Letter 2008-01 This enclosure provides the Northern States Power Company (NSPM) nine-month supplemental (post-outage) response to U.S. Nuclear Regulatory Commission (NRC)

Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (Reference I ) for those actions deferred until the next refueling outage as requested by the NRC in response to the NSPM supplemental response to GL 2008-01 (Reference 2).

The following information is provided within this enclosure:

A description of the results of evaluations that were performed pursuant to GL 2008-01 on previously incomplete activities, such as system piping walkdowns, at the Monticello Nuclear Generating Plant (MNGP).

A description of any additional corrective actions determined necessary to assure system operability and compliance with the quality assurance criteria in Sections Ill, V, XI, XVI, and XVll of 10 CFR 50, Appendix B and the licensing basis and operating license with respect to the subject systems, and a summary of any changes or updates to previous corrective actions.

The original conclusions documented in the nine-month month response with respect to the licensing basis evaluation, design evaluations, testing evaluations, and corrective action evaluations are unchanged except as described herein. This supplement only discusses the results of the reviews, and associated design and operability evaluations, associated with the activities conducted during the 2009 Refueling Outage.

L-MT-09-079 Page 2 of 5 A. EVALUATION RESULTS

1. Design Basis Documents There have been no changes with respect to the MNGP design basis documentation related to gas accumulation since the submittal of the MNGP nine-month response to NRC GL 2008-01 (Reference 3).

2. Confirmatory Walkdowns As proposed in the MNGP three-month response to NRC GL 2008-01 (Reference 4), walkdowns of those portions of the Residual Heat Removal (RHR) Shutdown Cooling suction piping, and the High Pressure Coolant Injection (HPCI) discharge piping in inaccessible areas of the plant were completed during the spring 2009 refueling outage, i.e., RFO 24. No new locations susceptible to gas accumulation were identified. All piping system segments conformed to the design information, in particular the physical location of the high point vents.

Although not part of the required scope, as discussed in Reference 3, the RHR injection piping downstream of the injection valves and the Core Spray piping downstream of the injection valves were also walked down. No new locations susceptible to gas accumulation were identified. All piping system segments conformed to the design information, in particular the physical location of the high point vents.

In addition to the required walkdowns, ultrasonic examinations were used to evaluate the effectiveness of the restoration procedures as GL 2008-01 subject systems were returned to service during RFO 24. These ultrasonic examinations also confirmed that dynamic venting was a tool that could be successfully used to remove air from susceptible piping locations.

The Core Spray and HPCI Systems were each found to have an air pocket by ultrasonic examination following initial restoration (i.e., after refilling, venting and surveillance performance that provided dynamic venting) from maintenance during the refueling outage. Due to the air pocket locations neither was able to be dynamically vented with the normal venting process.

The following actions were taken:

a. Another procedure that injects the Core Spray System into the reactor vessel was performed to successfully dynamically vent the Core Spray discharge piping. This was verified by ultrasonic examination.

L-MT-09-079 Page 3 of 5

b. An air pocket less than 1 cubic-foot in volume in the HPCl discharge line was evaluated and the HPCl System was determined to be operable, but not in conformance with the plant design basis, with the air pocket present. Following RFO 24, the HPCl keep-fill system, although not required for HPCl operability, pressurized the line resulting in the air pocket being no longer of a measurable size.

3. Vent Valves A vent valve assembly will be installed in the HPCl discharge line to allow complete venting of the line, with a proposed completion date of startup from the 201 1 refueling outage.

4. Procedures As discussed in the nine-month response to GL 2008-01 (Reference 3), the MNGP has revised the order of operation of the Containment Spray Injection Valves in the Emergency Operating Procedures. This change has been implemented.

Enhancements to the existing procedures utilized for filling and venting the GL 2008-01 subject systems as part of the restoration process have been implemented.

Operating procedures are being revised to require dynamic venting via Core Spray injection if activities requiring system restoration occur on the unventable portion of the Core Spray System.

5. DESCRIPTION OF NECESSARY ADDlTllONAL CORRECTIVE ACTIONS I Additional Corrective Actions A vent valve assembly will be installed on the HPCl discharge line to restore full qualification of the HPCl System. Due to this unventable high point, HPCl is operable but not in conformance with the plant design basis. This corrective action will be completed by startup from the 201Irefueling outage (currently scheduled for June 2011).

Operating procedures will be revised to require dynamic venting via Core Spray injection if activities requiring system restoration occur on the unventable portion of the Core Spray System. This corrective action will be completed by November 30,2009.

L-MT-09-079 Enclosure I Page 4 of 5

2. Corrective Action Updates One corrective action, to resolve the appropriate air entrainment limit in the Emergency Operating Procedures, remains open in accordance with the schedule provided in the MNGP nine-month response to NRC GL 2008-01 (Reference 3). No changes to that schedule are proposed at this time.

One commitment remains open from the MNGP nine-month response to GL 2008-01 (Reference 3) which will be adjusted in the future as necessary to conform with the NRC and industry resolution with respect to the necessity to develop a Technical Specification Task Force (TSTF) Traveler related to gas accumulation within the ECCS. In the interim, the following commitment will remain in-force:

a. The NSPM will evaluate the Technical Specification changes in the Technical Specification Task Force (TSTF) Traveler related to gas accumulation within the ECCS for applicability to the MNGP and submit a license amendment request, adjusted, as needed, to account for the MNGP plant-specific design and licensing basis, within 180 days following NRC publication of the Notice of Availability in the Federal Register.

No changes in the schedule for closing this commitment have been made.

All other corrective actions associated with GL 2008-01 have been completed.

D. CONCLUSION The NSPM has completed the evaluation of the previously inaccessible portions of the applicable systems at MNGP that perform the functions described in GL 2008-01. The HPCl System, while operable as discussed previously, will have a vent assembly installed to enable elimination of air from the discharge line location. The NSPM has concluded that the GL 2008-01 subject systems at the MNGP are operable, as defined in the MNGP TS, and except as stated, are in conformance with the MNGP licensing and design basis and with applicable regulatory requirements.

L-MT-09-079 Enclosure I Page 5 of 5 REFERENCES I. U.S. NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated January 11, 2008. (ADAMS Accession Number MLO72910759)

2. Letter NRC to NSPM, "Monticello Nuclear Generating Plant (MNGP) - Re:

Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," Proposed Alternative Course of Action (TAC No. MD7847)," dated September 9, 2008.

3. Letter NSP to NRC, "Nine-Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (L-MT-08-026) dated October 14, 2008.

(ADAMS Accession Number ML082880662)

4. Letter NSP to NRC, "Three-Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated April 1I , 2008. (ADAMS Accession Number ML081020695)

Text

August 14,2009 L-MT-09-079 10 CFR 50.540 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License No. DPR-22 Monticello Nuclear Generating Plant Nine-Month Supplemental (Post-Outage)

Response to NRC Generic Letter 2008-01 The U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01 (Reference Iof Enclosure I ) to request that each licensee evaluate the licensing basis, design, testing, and corrective actions for the emergency core cooling (ECCS), decay heat removal (DHR), and containment spray systems to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, and that appropriate action is taken when conditions adverse to quality are identified.

As requested by the NRC in Reference 2 of Enclosure 1, the Northern States Power Company, a Minnesota corporation (NSPM), is providing a supplemental response to the nine-month response (Reference 3 of Enclosure I ) submitted for the Monticello Nuclear Generating Plant (MNGP). This supplemental response is being provided within 90 days following return to full power from the spring 2009 Refueling Outage, i.e.,

the outage in which the deferred actions were completed.

In summary, with one exception discussed herein, the NSPM has concluded that the GL 2008-01 subject systems at the MNGP are operable and that the unit is in compliance with the plant licensing basis documentation and applicable regulations, including 10 CFR 50 Appendix B, Criteria Ill, V, XI, XVI, and XVII, with respect to the concerns outlined in GL 2008-01 regarding managing gas accumulation in these systems/functions.

2807 West County Road 75 e Monticello, Minnesota 55362-9637 Telephone: 763.295.5151 e Fax: 763.295.1 454

Document Control Desk L-MT-09-079 Page 2 of 2 Enclosure Iprovides the NSPM supplemental response to GL 2008-01 Summarv of Commitments The following commitments made in Reference 3 of Enclosure 1 have been completed:

1 Complete the detailed walkdowns of the applicable inaccessible sections of the Generic Letter 2008-01 subject systems (does not include piping downstream of the low pressure ECCS outboard injection valves) prior to startup from the 2009 Refueling Outage.

2. NSPM will complete the evaluations of the applicable inaccessible sections of the Generic Letter 2008-01 subject systems and provide a supplement to the October 2008 response to Generic Letter 2008-01 within 90 days following return to full power from the 2009 Refueling Outage.

The following new commitments are proposed:

I A vent valve assembly will be installed on the High Pressure Coolant Injection (HPCI) discharge line to restore full qualification of the HPCl System. Due to an unventable high point, HPCl is operable but not in conformance with the plant design basis. This corrective action will be completed by startup from the 2011 refueling outage (currently scheduled for June 2011).

2. Operating procedures will be revised to require dynamic venting via Core Spray injection if activities requiring system restoration occur on the unventable portion of the Core Spray System. This corrective action will be completed by November 30,2009.

Ity of perjury that the foregoing is true and correct.

e President, Monticello Nuclear Generating Plant ny - Minnesota Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce

ENCLOSURE 1 MQNTICELLO NUCLEAR GENERATING PLANT NINE-MONTH SUPPLEMENTAL RESPONSE TO GENERIC LETTER 2008-Q"1

L-MT-09-079 Page 1 of 5 Nine-Month Supplemental Response to Generic Letter 2008-01 This enclosure provides the Northern States Power Company (NSPM) nine-month supplemental (post-outage) response to U.S. Nuclear Regulatory Commission (NRC)

Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (Reference I ) for those actions deferred until the next refueling outage as requested by the NRC in response to the NSPM supplemental response to GL 2008-01 (Reference 2).

The following information is provided within this enclosure:

A description of the results of evaluations that were performed pursuant to GL 2008-01 on previously incomplete activities, such as system piping walkdowns, at the Monticello Nuclear Generating Plant (MNGP).

A description of any additional corrective actions determined necessary to assure system operability and compliance with the quality assurance criteria in Sections Ill, V, XI, XVI, and XVll of 10 CFR 50, Appendix B and the licensing basis and operating license with respect to the subject systems, and a summary of any changes or updates to previous corrective actions.

The original conclusions documented in the nine-month month response with respect to the licensing basis evaluation, design evaluations, testing evaluations, and corrective action evaluations are unchanged except as described herein. This supplement only discusses the results of the reviews, and associated design and operability evaluations, associated with the activities conducted during the 2009 Refueling Outage.

L-MT-09-079 Page 2 of 5 A. EVALUATION RESULTS

1. Design Basis Documents There have been no changes with respect to the MNGP design basis documentation related to gas accumulation since the submittal of the MNGP nine-month response to NRC GL 2008-01 (Reference 3).

2. Confirmatory Walkdowns As proposed in the MNGP three-month response to NRC GL 2008-01 (Reference 4), walkdowns of those portions of the Residual Heat Removal (RHR) Shutdown Cooling suction piping, and the High Pressure Coolant Injection (HPCI) discharge piping in inaccessible areas of the plant were completed during the spring 2009 refueling outage, i.e., RFO 24. No new locations susceptible to gas accumulation were identified. All piping system segments conformed to the design information, in particular the physical location of the high point vents.

Although not part of the required scope, as discussed in Reference 3, the RHR injection piping downstream of the injection valves and the Core Spray piping downstream of the injection valves were also walked down. No new locations susceptible to gas accumulation were identified. All piping system segments conformed to the design information, in particular the physical location of the high point vents.

In addition to the required walkdowns, ultrasonic examinations were used to evaluate the effectiveness of the restoration procedures as GL 2008-01 subject systems were returned to service during RFO 24. These ultrasonic examinations also confirmed that dynamic venting was a tool that could be successfully used to remove air from susceptible piping locations.

The Core Spray and HPCI Systems were each found to have an air pocket by ultrasonic examination following initial restoration (i.e., after refilling, venting and surveillance performance that provided dynamic venting) from maintenance during the refueling outage. Due to the air pocket locations neither was able to be dynamically vented with the normal venting process.

The following actions were taken:

a. Another procedure that injects the Core Spray System into the reactor vessel was performed to successfully dynamically vent the Core Spray discharge piping. This was verified by ultrasonic examination.

L-MT-09-079 Page 3 of 5

b. An air pocket less than 1 cubic-foot in volume in the HPCl discharge line was evaluated and the HPCl System was determined to be operable, but not in conformance with the plant design basis, with the air pocket present. Following RFO 24, the HPCl keep-fill system, although not required for HPCl operability, pressurized the line resulting in the air pocket being no longer of a measurable size.

3. Vent Valves A vent valve assembly will be installed in the HPCl discharge line to allow complete venting of the line, with a proposed completion date of startup from the 201 1 refueling outage.

4. Procedures As discussed in the nine-month response to GL 2008-01 (Reference 3), the MNGP has revised the order of operation of the Containment Spray Injection Valves in the Emergency Operating Procedures. This change has been implemented.

Enhancements to the existing procedures utilized for filling and venting the GL 2008-01 subject systems as part of the restoration process have been implemented.

Operating procedures are being revised to require dynamic venting via Core Spray injection if activities requiring system restoration occur on the unventable portion of the Core Spray System.

5. DESCRIPTION OF NECESSARY ADDlTllONAL CORRECTIVE ACTIONS I Additional Corrective Actions A vent valve assembly will be installed on the HPCl discharge line to restore full qualification of the HPCl System. Due to this unventable high point, HPCl is operable but not in conformance with the plant design basis. This corrective action will be completed by startup from the 201Irefueling outage (currently scheduled for June 2011).

Operating procedures will be revised to require dynamic venting via Core Spray injection if activities requiring system restoration occur on the unventable portion of the Core Spray System. This corrective action will be completed by November 30,2009.

L-MT-09-079 Enclosure I Page 4 of 5

2. Corrective Action Updates One corrective action, to resolve the appropriate air entrainment limit in the Emergency Operating Procedures, remains open in accordance with the schedule provided in the MNGP nine-month response to NRC GL 2008-01 (Reference 3). No changes to that schedule are proposed at this time.

One commitment remains open from the MNGP nine-month response to GL 2008-01 (Reference 3) which will be adjusted in the future as necessary to conform with the NRC and industry resolution with respect to the necessity to develop a Technical Specification Task Force (TSTF) Traveler related to gas accumulation within the ECCS. In the interim, the following commitment will remain in-force:

a. The NSPM will evaluate the Technical Specification changes in the Technical Specification Task Force (TSTF) Traveler related to gas accumulation within the ECCS for applicability to the MNGP and submit a license amendment request, adjusted, as needed, to account for the MNGP plant-specific design and licensing basis, within 180 days following NRC publication of the Notice of Availability in the Federal Register.

No changes in the schedule for closing this commitment have been made.

All other corrective actions associated with GL 2008-01 have been completed.

D. CONCLUSION The NSPM has completed the evaluation of the previously inaccessible portions of the applicable systems at MNGP that perform the functions described in GL 2008-01. The HPCl System, while operable as discussed previously, will have a vent assembly installed to enable elimination of air from the discharge line location. The NSPM has concluded that the GL 2008-01 subject systems at the MNGP are operable, as defined in the MNGP TS, and except as stated, are in conformance with the MNGP licensing and design basis and with applicable regulatory requirements.

L-MT-09-079 Enclosure I Page 5 of 5 REFERENCES I. U.S. NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated January 11, 2008. (ADAMS Accession Number MLO72910759)

2. Letter NRC to NSPM, "Monticello Nuclear Generating Plant (MNGP) - Re:

Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," Proposed Alternative Course of Action (TAC No. MD7847)," dated September 9, 2008.

3. Letter NSP to NRC, "Nine-Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (L-MT-08-026) dated October 14, 2008.

(ADAMS Accession Number ML082880662)

4. Letter NSP to NRC, "Three-Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated April 1I , 2008. (ADAMS Accession Number ML081020695)