NRC 2014-0007, Response to Request for Additional Information Regarding NRC Bulletin 2012-01, Design Vulnerability in Electric Power System

Response to Request for Additional Information Regarding NRC Bulletin 2012-01, Design Vulnerability in Electric Power System

ML14031A249
Person / Time
Site:	Point Beach
Issue date:	01/31/2014
From:	Mccartney E Point Beach
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BL-12-001, NRC 2014-0007
Download: ML14031A249 (5)

Text

NEXTera**

ENERGY~

POINT BEACH January 31, 2014 NRC 2014-0007 10 CFR 50.54(f)

BL 2012-01 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units 1 and 2 Docket 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 NextEra Energy Point Beach. LLC Response to Reguest for Additional Information Regarding NRC Bulletin 2012-01 Design Vulnerability in Electric Power System References : (1) U.S. Nuclear Regulatory Commission , "Design Vulnerability in Electric Power System, " NRC Bulletin 2012-01, July 27, 2012 (ML12074A115)

(2) NextEra Energy Point Beach, LLC letter to NRC, NextEra Energy Point Beach, LLC Response to NRC Bulletin 2012-01 Design Vulnerability in Electric Power System, dated October 24, 2012 (ML12298A515)

(3) NRC letter to NextEra Energy Point Beach, LLC, Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability in Electric Power System," dated December 20, 2013 (ML13351A314)

Via Reference (1 ), the Nuclear Regulatory Commission (NRC) issued Bulletin (BL) 2012-01, "Design Vulnerability in Electric Power System ." The BL requested NextEra Energy Point Beach, LLC (NextEra) provide information regarding the Point Beach Nuclear Plant (PBNP) electric power system design, in response to the recent operating experience that involved the loss of one of the three phases of the offsite power circuit at Byron Station, Unit 2, to determine if future regulatory action is warranted. NextEra responded to this bulletin in Reference (2).

The NRC requested additional information regarding Bulletin 2012-01 via Reference (3). The enclosure to this letter contains NextEra's response to Reference (3)

Regulatory Commitment:

NextEra will follow the generic schedule provided in the Nuclear Energy Institute letter to the NRC, Industry Initiative on Open Phase Condition, dated October 9, 2013.

This letter contains no revisions to existing Regulatory Commitments.

NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241

Document Control Desk Page 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on January 31, 2014.

Very truly yours, NextEra Energy Point Beach, LLC

• Eric McCartney Site Vice President Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC

ENCLOSURE NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 NEXTERA ENERGY POINT BEACH, LLC RESPONSE TO REQUEST FOR ADDITIONAL INFORMATIONREGARDING NRC BULLETIN 2012-01 DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM On July 27, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued Bulletin 2012-01, "Design Vulnerability in Electric Power System" (Agencywide Documents Access and Management System Accession No. ML12074A115), to all holders of operating licenses and combined licenses for nuclear power reactors. In addition, Watts Bar Nuclear Plant, Unit 2, is addressing the issues identified in the bulletin as part of the licensing process. Bulletin 2012-01 requested information about each facility's electric power system designs, in light of recent operating experience involving the loss of one of the three phases of the offsite power circuit (single-phase open circuit condition) at Byron Station, Unit 2.

In order for the NRC staff to complete its review of responses to the bulletin, the following additional information is requested:

1. Provide a summary of all interim corrective actions that have been taken since the January 30, 2012, event at Byron Station, Unit 2, to ensure that plant operators can promptly diagnose and respond to open phase conditions on the offsite power circuits for Class-1 E vital buses until permanent corrective actions are completed.

NextEra Response Lessons learned from the events at Byron station were reviewed and various interim corrective actions evaluated for safety and efficiency at the NextEra Energy Point Beach, LLC (NextEra).

Based on the plant's offsite power configuration , electrical design details, and lessons learned; the following actions were taken to ensure plant operators can promptly diagnose and respond to open phase conditions (OPC):

• Interim Corrective Actions o Switchyard rounds are performed twice per day and include general and detailed inspections of the transformers to ensure parameters are within expected limits.

o Bi-annual infrared inspections of switchyard equipment are being completed as part of routine inspections.

o Operators have reviewed the Byron loss of phase event during re-qualification training.

Page 1 of 3

2. Provide a status and schedule for completion of plant design changes and modifications to resolve issues with an open phase of electric power.

NextEra Response

• Status o Point Beach and Next Era's nuclear fleet, in cooperation with other holders of licenses for nuclear power reactors, are investigating options being researched by several vendors (PSC2000, EPRI, Schweitzer, etc.) to detect OPC faults .

There is currently no generic, off-the-shelf technology that has been proven to detect all the required open phase fault conditions for all plant and transformer designs.

o Point Beach and Next Era's nuclear fleet are engaged in the development of the NEI OPC Guidance Document, as well as development of enhancements to software tools being used to analyze OPC faults.

o With the goal of ensuring accurate detection without compromising nuclear safety or increasing plant risk, this new OPC technology is being thoroughly evaluated, will be tested, and will be fully analyzed before installation.

o Next Era has begun initial testing and development (T&D) by FPL Transmission of a potential hardware solution to determine viability for the open phase issue.

o NextEra's response (reference 1) to Bulletin 2012-01 stated on page 6 of Enclosure 1:

Consistent with the CLB, existing protective circuitry will separate the ESF buses from a connected failed offsite source due to a loss of voltage or a sustained, balanced degraded grid voltage concurrent with certain design basis accidents. The relay systems were not specifically designed to detect an open single phase of a three phase system. Detection of a single-open phase condition is beyond the approved design and licensing basis of the plant. However, due to the transformer configurations at PBNP, it is expected that either adequately balanced three phase conditions will exist or actuation of the degraded voltage relays will occur because two of the three line-to-line voltages will be below the degraded voltage relays setpoint. Therefore, if an open phase condition were to exist at PBNP, all ESF equipment would remain capable of performing its designated safety function by having adequate offsite power or be isolated from offsite power and loaded onto the EDGs However, NextEra is exploring design modifications in order to ensure an open phase condition would be promptly detected. NextEra has initiated a project and is in the process of pursuing project and budget approval.

Page 2 of 3

• Schedule o NextEra has committed to the generic schedule provided in the Industry NEI OPC Initiative, dated October 9, 2013 (Reference 2) .

o It is our intention to meet the milestones of this schedule; however, deviations may be required to accommodate outage schedules, software and hardware availability, manufacturer's delivery capabilities, licensing delays, etc.

o Any deviation from the Industry OPC Initiative schedule will be documented through the deviation/exemption process currently being developed by NEI.

References

1. NextEra Energy Point Beach, LLC letter to NRC, NextEra Energy Point Beach, LLC Response to NRC Bulletin 2012-01 Design Vulnerability in Electric Power System, dated October 24, 2012 (ML12298A515)

2. Nuclear Energy Institute letter to the NRC, Industry Initiative on Open Phase Condition, dated October 9, 2013 (ML13333A147)

Page 3 of 3

Text

NEXTera**

ENERGY~

POINT BEACH January 31, 2014 NRC 2014-0007 10 CFR 50.54(f)

BL 2012-01 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units 1 and 2 Docket 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 NextEra Energy Point Beach. LLC Response to Reguest for Additional Information Regarding NRC Bulletin 2012-01 Design Vulnerability in Electric Power System References : (1) U.S. Nuclear Regulatory Commission , "Design Vulnerability in Electric Power System, " NRC Bulletin 2012-01, July 27, 2012 (ML12074A115)

(2) NextEra Energy Point Beach, LLC letter to NRC, NextEra Energy Point Beach, LLC Response to NRC Bulletin 2012-01 Design Vulnerability in Electric Power System, dated October 24, 2012 (ML12298A515)

(3) NRC letter to NextEra Energy Point Beach, LLC, Request for Additional Information Regarding Response to Bulletin 2012-01, "Design Vulnerability in Electric Power System," dated December 20, 2013 (ML13351A314)

Via Reference (1 ), the Nuclear Regulatory Commission (NRC) issued Bulletin (BL) 2012-01, "Design Vulnerability in Electric Power System ." The BL requested NextEra Energy Point Beach, LLC (NextEra) provide information regarding the Point Beach Nuclear Plant (PBNP) electric power system design, in response to the recent operating experience that involved the loss of one of the three phases of the offsite power circuit at Byron Station, Unit 2, to determine if future regulatory action is warranted. NextEra responded to this bulletin in Reference (2).

The NRC requested additional information regarding Bulletin 2012-01 via Reference (3). The enclosure to this letter contains NextEra's response to Reference (3)

Regulatory Commitment:

NextEra will follow the generic schedule provided in the Nuclear Energy Institute letter to the NRC, Industry Initiative on Open Phase Condition, dated October 9, 2013.

This letter contains no revisions to existing Regulatory Commitments.

NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241

Document Control Desk Page 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on January 31, 2014.

Very truly yours, NextEra Energy Point Beach, LLC

• Eric McCartney Site Vice President Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC

ENCLOSURE NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 NEXTERA ENERGY POINT BEACH, LLC RESPONSE TO REQUEST FOR ADDITIONAL INFORMATIONREGARDING NRC BULLETIN 2012-01 DESIGN VULNERABILITY IN ELECTRIC POWER SYSTEM On July 27, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued Bulletin 2012-01, "Design Vulnerability in Electric Power System" (Agencywide Documents Access and Management System Accession No. ML12074A115), to all holders of operating licenses and combined licenses for nuclear power reactors. In addition, Watts Bar Nuclear Plant, Unit 2, is addressing the issues identified in the bulletin as part of the licensing process. Bulletin 2012-01 requested information about each facility's electric power system designs, in light of recent operating experience involving the loss of one of the three phases of the offsite power circuit (single-phase open circuit condition) at Byron Station, Unit 2.

In order for the NRC staff to complete its review of responses to the bulletin, the following additional information is requested:

1. Provide a summary of all interim corrective actions that have been taken since the January 30, 2012, event at Byron Station, Unit 2, to ensure that plant operators can promptly diagnose and respond to open phase conditions on the offsite power circuits for Class-1 E vital buses until permanent corrective actions are completed.

NextEra Response Lessons learned from the events at Byron station were reviewed and various interim corrective actions evaluated for safety and efficiency at the NextEra Energy Point Beach, LLC (NextEra).

Based on the plant's offsite power configuration , electrical design details, and lessons learned; the following actions were taken to ensure plant operators can promptly diagnose and respond to open phase conditions (OPC):

• Interim Corrective Actions o Switchyard rounds are performed twice per day and include general and detailed inspections of the transformers to ensure parameters are within expected limits.

o Bi-annual infrared inspections of switchyard equipment are being completed as part of routine inspections.

o Operators have reviewed the Byron loss of phase event during re-qualification training.

Page 1 of 3

2. Provide a status and schedule for completion of plant design changes and modifications to resolve issues with an open phase of electric power.

NextEra Response

• Status o Point Beach and Next Era's nuclear fleet, in cooperation with other holders of licenses for nuclear power reactors, are investigating options being researched by several vendors (PSC2000, EPRI, Schweitzer, etc.) to detect OPC faults .

There is currently no generic, off-the-shelf technology that has been proven to detect all the required open phase fault conditions for all plant and transformer designs.

o Point Beach and Next Era's nuclear fleet are engaged in the development of the NEI OPC Guidance Document, as well as development of enhancements to software tools being used to analyze OPC faults.

o With the goal of ensuring accurate detection without compromising nuclear safety or increasing plant risk, this new OPC technology is being thoroughly evaluated, will be tested, and will be fully analyzed before installation.

o Next Era has begun initial testing and development (T&D) by FPL Transmission of a potential hardware solution to determine viability for the open phase issue.

o NextEra's response (reference 1) to Bulletin 2012-01 stated on page 6 of Enclosure 1:

Consistent with the CLB, existing protective circuitry will separate the ESF buses from a connected failed offsite source due to a loss of voltage or a sustained, balanced degraded grid voltage concurrent with certain design basis accidents. The relay systems were not specifically designed to detect an open single phase of a three phase system. Detection of a single-open phase condition is beyond the approved design and licensing basis of the plant. However, due to the transformer configurations at PBNP, it is expected that either adequately balanced three phase conditions will exist or actuation of the degraded voltage relays will occur because two of the three line-to-line voltages will be below the degraded voltage relays setpoint. Therefore, if an open phase condition were to exist at PBNP, all ESF equipment would remain capable of performing its designated safety function by having adequate offsite power or be isolated from offsite power and loaded onto the EDGs However, NextEra is exploring design modifications in order to ensure an open phase condition would be promptly detected. NextEra has initiated a project and is in the process of pursuing project and budget approval.

Page 2 of 3

• Schedule o NextEra has committed to the generic schedule provided in the Industry NEI OPC Initiative, dated October 9, 2013 (Reference 2) .

o It is our intention to meet the milestones of this schedule; however, deviations may be required to accommodate outage schedules, software and hardware availability, manufacturer's delivery capabilities, licensing delays, etc.

o Any deviation from the Industry OPC Initiative schedule will be documented through the deviation/exemption process currently being developed by NEI.

References

1. NextEra Energy Point Beach, LLC letter to NRC, NextEra Energy Point Beach, LLC Response to NRC Bulletin 2012-01 Design Vulnerability in Electric Power System, dated October 24, 2012 (ML12298A515)

2. Nuclear Energy Institute letter to the NRC, Industry Initiative on Open Phase Condition, dated October 9, 2013 (ML13333A147)

Page 3 of 3