ML21312A021

Issuance of Amendment Nos. 237 and 225 Inoperable Cooling Water System Supply Header

ML21312A021
Person / Time
Site:	Prairie Island
Issue date:	11/23/2021
From:	Robert Kuntz Plant Licensing Branch III
To:	Domingos C Northern States Power Co
Kuntz R
References
EPID L-2021-LLA-0187
Download: ML21312A021 (19)

Text

November 23, 2021 Mr. Christopher P. Domingos Site Vice President Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota 1717 Wakonade Drive East Welch, MN 55089

SUBJECT:

PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 -

ISSUANCE OF AMENDMENT NOS. 237 AND 225 RE: INOPERABLE COOLING WATER SYSTEM SUPPLY HEADER (EPID L-2021-LLA-0187)

Dear Mr. Domingos:

The U.S. Nuclear Regulatory Commission (NRC, the Commission) has issued the enclosed Amendment No. 237 to Renewed Facility Operating License No. DPR-42 and Amendment No. 225 to Renewed Facility Operating License No. DPR-60 for the Prairie Island Nuclear Generating Plant, Units 1 and 2, respectively. The amendments consist of changes to the technical specifications (TSs) in response to your application dated October 7, 2021, as supplemented by letter dated November 4, 2021.

The amendments modify the TSs to include a note to TS 3.7.8 Cooling Water (CL) System, Condition B, one CL supply header inoperable, Required Action B.1, verify vertical motor-driven CL pump operable, with a completion time of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The note allows a completion time for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to support blind flange installation and for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to allow the removal of the blind flange during the time frame of November 28, 2021, to December 28, 2021.

C. Domingos A copy of our related safety evaluation is also enclosed. The Notice of Issuance will be included in the Commissions monthly Federal Register notice.

Sincerely,

/RA/

Robert F. Kuntz, Senior Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306

Enclosures:

1. Amendment No. 237 to DPR-42

2. Amendment No. 225 to DPR-60

3. Safety Evaluation cc: Listserv

NORTHERN STATES POWER COMPANY DOCKET NO. 50-282 PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 237 Renewed License No. DPR-42

1. The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by Northern States Power Company, a Minnesota Corporation (NSPM, the licensee), dated October 7, 2021, as supplemented by letter dated November 4, 2021, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.

Enclosure 1

2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. DPR-42 is hereby amended to read as follows:

(2) Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 237, are hereby incorporated in the renewed operating license. NSPM shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 5 days.

FOR THE NUCLEAR REGULATORY COMMISSION Digitally signed by Nancy Nancy L. L. Salgado Date: 2021.11.23 Salgado 08:55:48 -05'00' Nancy L. Salgado, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Renewed Facility Operating License and Technical Specifications Date of Issuance: November 23, 2021

NORTHERN STATES POWER COMPANY DOCKET NO. 50-306 PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 225 Renewed License No. DPR-60

1. The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by Northern States Power Company, a Minnesota Corporation (NSPM, the licensee), dated October 7, 2021, as supplemented by letter dated November 4, 2021, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.

Enclosure 2

2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. DPR-60 is hereby amended to read as follows:

(2) Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 225, are hereby incorporated in the renewed operating license. NSPM shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 5 days.

FOR THE NUCLEAR REGULATORY COMMISSION Digitally signed by Nancy L. Nancy L. Salgado Date: 2021.11.23 Salgado 08:56:37 -05'00' Nancy L. Salgado, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Renewed Facility Operating License and Technical Specifications Date of Issuance: November 23, 2021

ATTACHMENT TO LICENSE AMENDMENT NOS. 237 AND 225 PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 RENEWED FACILITY OPERATING LICENSE NOS. DPR-42 AND DPR-60 DOCKET NOS. 50-282 AND 50-306 Replace the following pages of the Renewed Facility Operating License Nos. DPR-42 and DPR-60 with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicate the areas of change.

Renewed Facility Operating License No. DPR-42 REMOVE INSERT Page 3 Page 3 Renewed Facility Operating License No. DPR-60 REMOVE INSERT Page 3 Page 3 Technical Specifications Replace the following pages of the Appendix A Technical Specifications with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.

REMOVE INSERT 3.7.8-2 3.7.8-2

(3) Pursuant to the Act and 10 CFR Parts 30, 40 and 70, NSPM to receive, possess, and use at any time any byproduct, source and special nuclear material as sealed neutron sources for reactor startup, sealed sources for reactor instrumentation and radiation monitoring equipment calibration, and as fission detectors in amounts as required; (4) Pursuant to the Act and 10 CFR Parts 30, 40, and 70, NSPM to receive, possess and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument and equipment calibration or associated with radioactive apparatus or components; (5) Pursuant to the Act and 10 CFR Parts 30 and 70, NSPM to possess but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility; (6) Pursuant to the Act and 10 CFR Parts 30 and 70, NSPM to transfer byproduct materials from other job sites owned by NSPM for the purpose of volume reduction and decontamination.

C. This renewed operating license shall be deemed to contain and is subject to the conditions specified in the following Commission regulations in 10 CFR Chapter l:

Part 20, Section 30.34 of Part 30, Sections 50.54 and 50.59 of Part 50, and Section 70.32 of Part 70; is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

(1) Maximum Power Level NSPM is authorized to operate the facility at steady state reactor core power levels not in excess of 1677 megawatts thermal.

(2) Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 237, are hereby incorporated in the renewed operating license.

NSPM shall operate the facility in accordance with the Technical Specifications.

(3) Physical Protection NSPM shall fully implement and maintain in effect all provisions of the Commission-approved physical security, guard training and qualification, and safeguards contingency plans including amendments made pursuant to provisions of the Miscellaneous Amendments and Search Requirements revisions to 10 CFR 73.55 (51 FR 27817 and 27822) and to the authority of 10 CFR 50.90 and 10 CFR 50.54(p). The combined set of plans, which contains Renewed Operating License No. DPR-42 Amendment No. 237

(3) Pursuant to the Act and 10 CFR Parts 30, 40 and 70, NSPM to receive, possess, and use at any time any byproduct, source and special nuclear material as sealed neutron sources for reactor startup, sealed sources for reactor instrumentation and radiation monitoring equipment calibration, and as fission detectors in amounts as required; (4) Pursuant to the Act and 10 CFR Parts 30, 40, and 70, NSPM to receive, possess and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument and equipment calibration or associated with radioactive apparatus or components; (5) Pursuant to the Act and 10 CFR Parts 30 and 70, NSPM to possess but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility; (6) Pursuant to the Act and 10 CFR Parts 30 and 70, NSPM to transfer byproduct materials from other job sites owned by NSPM for the purposes of volume reduction and decontamination.

C. This renewed operating license shall be deemed to contain and is subject to the conditions specified in the following Commission regulations in 10 CFR Chapter l:

Part 20, Section 30.34 of Part 30, Sections 50.54 and 50.59 of Part 50, and Section 70.32 of Part 70; is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

(1) Maximum Power Level NSPM is authorized to operate the facility at steady state reactor core power levels not in excess of 1677 megawatts thermal.

(2) Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 225, are hereby incorporated in the renewed operating license.

NSPM shall operate the facility in accordance with the Technical Specifications.

(3) Physical Protection NSPM shall fully implement and maintain in effect all provisions of the Commission-approved physical security, guard training and qualification, and safeguards contingency plans including amendments made pursuant to provisions of the Miscellaneous Amendments and Search Requirements revisions to 10 CFR 73.55 (51 FR 27817 and 27822) and to the authority of 10 CFR 50.90 and 10 CFR 50.54(p). The combined set of plans, which contains Renewed Operating License No. DPR-60 Amendment No. 225

CL System 3.7.8 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME A. (continued) A.1 Restore one safeguards CL 7 days pump to OPERABLE status. OR In accordance with the Risk Informed Completion Time Program B. One CL supply header ----------------NOTES---------------

inoperable. 1. Unit 1 enter applicable Conditions and Required Actions of LCO 3.8.1, AC Sources-MODES 1, 2, 3, and 4, for emergency diesel generator made inoperable by CL System.

2. Both units enter applicable Conditions and Required Actions of LCO 3.4.6, RCS Loops-MODE 4, for residual heat removal loops made inoperable by CL System.

B.1 Verify vertical motor driven 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />s*

CL pump OPERABLE.

AND

• As a contingency and if needed to support an adequate isolation boundary, the vertical motor driven CL pump is allowed to remain inoperable for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to support blind flange installation and for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to support the blind flange removal during the time frame of 11/28/2021 through 12/28/2021 to Support the A and B train CL Supply Header piping replacement project.

Prairie Island Unit 1 - Amendment No. 237 Units 1 and 2 3.7.8-2 Unit 2 - Amendment No. 225

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 237 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-42 AND AMENDMENT NO. 225 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-60 NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-282 AND 50-306

1.0 INTRODUCTION

By application dated October 7, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21281A017), as supplemented by letter dated November 4, 2021 (ADAMS Accession No. ML21308A566), Northern States Power Company, a Minnesota Corporation, doing business as Xcel Energy (NSPM, or the licensee), requested changes to the technical specifications (TSs) for Prairie Island Nuclear Generating Plant (Prairie Island), Units 1 and 2.

The proposed changes would modify the TS to include a note to TS 3.7.8 Cooling Water (CL)

System, Condition B, one CL supply header inoperable, Required Action B.1, verify vertical motor-driven CL pump operable with a Completion Time (CT) of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The proposed note would allow a CT for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to support blind flange installation and for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to allow the removal of the blind flange during the time frame of November 28, 2021, to December 28, 2021. The license amendment supports a contingency for the planned work to replace CL system supply header piping. NSPM is replacing sections of both trains of the Prairie Island, Units 1 and 2, CL system supply header because of suspected microbiologically induced corrosion (MIC).

The supplement dated November 4, 2021, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the Nuclear Regulatory Commission (NRC, or the Commission) staffs original proposed no significant hazards consideration determination as published in the Federal Register on October 21, 2021 (86 FR 58308).

Enclosure 3

2.0 REGULATORY EVALUATION

2.1 Cooling Water System Description and Operation The Prairie Island, Units 1 and 2, Updated Safety Analysis Report (USAR), Section 10.4.1 Cooling Water System, (ADAMS Accession No. ML20118D373) states that the CL system provides redundant cooling water supplies to auxiliary feedwater pumps, Prairie Island, Unit 1, diesel generators, air compressors, component cooling water heat exchangers, containment fan-coil units, and the Auxiliary Building unit coolers. The preferred source of water to the containment fan coil units and some Auxiliary Building unit coolers is provided by chilled water.

The CL system provides an alternate source of water to these components.

The license amendment request states that the CL system consists of a common CL pump discharge header for the five CL pumps: two horizontal pumps, two safeguards diesel driven vertical pumps, and one motor-driven vertical pump (MDCLP). The USAR states that a ring header, which is shared by Prairie Island, Units 1 and 2, can be isolated automatically to provide two redundant independent sources of cooling water for all essential services. One-half of essential services for each unit is supplied from each side of the isolable loop. Each side of the loop is designed to supply the needs for all essential services for both units. Thus, failure of one side of the loop still provides for the operation of all equipment required for the safe shutdown of both Prairie Island, Units 1 and 2.

The USAR describes normal operation of the CL system as using two non-safeguards horizontal pumps with a vertical motor-driven pump as a standby. The vertical motor-driven pump also functions as a replacement when a diesel driven pump is taken out of service.

2.1 Proposed Change The amendment requests to include the following note to Prairie Island TS 3.7.8, Condition B, Required Action B.1, CT:

As a contingency to support an adequate isolation boundary, the vertical motor-driven CL pump is allowed to remain inoperable for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to support blind flange installation and for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to support the blind flange removal during the time frame of 11/28/2021 through 12/28/2021 to Support the A and B train CL Supply Header piping replacement project.

The license amendment request states that sections of the Prairie Island, Units 1 and 2, CL system supply header piping will be replaced because of suspected MIC. These supply headers must be isolated to perform the replacement. The license amendment request states that if the planned isolation valve is found to leak excessively, a blind flange will be installed to provide isolation. Installation of the blind flange will require expanding the isolation boundary and result in an inoperable safeguard pump. The amendment request states that the contingency will require entry into LCO 3.7.8, Required Action B.1, which has a CT of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

The amendment request further states that installation of the blind flange would result in entry into Required Action B.1 for an estimated 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> for both installation and removal of the blind flange.

2.2 Regulatory Requirements The categories of items required to be in the TSs are provided in Title 10 of the Code of Federal Regulations (10 CFR) Section 50.36(c). As required by 10 CFR 50.36(c)(2)(i), the TSs include Limiting Conditions for Operations (LCOs), which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. Per 10 CFR 50.36(c)(2)(i), when an LCO of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the condition can be met.

The 10 CFR Part 50, Appendix A, General Design Criteria [GDC] for Nuclear Power Plants, specify minimum requirements for the principal design criteria that apply to water-cooled nuclear power plants. Prairie Island was not licensed to the 10 CFR Part 50, Appendix A, General Design Criteria (GDC). Prairie Island was designed and constructed to comply with NSPMs understanding of the intent of the Atomic Energy Commission (AEC) GDC for Nuclear Power Plant Construction Permits, as proposed on July 10, 1967. Since the construction of the plant was significantly completed prior to the issuance of the February 20, 1971, 10 CFR Part 50, Appendix A, GDC, the plant was not reanalyzed and the Updated Safety Analysis Report (USAR) was not revised to reflect these later criteria. However, the AEC Safety Evaluation Report (September 28, 1972) acknowledged that the principal design criteria (PDC) as described in the Prairie Island USAR conform to the intent of the 10 CFR Part 50, Appendix A, GDC.

The applicable PDC, as documented in Prairie Island USAR Section 1.5 General Design Criteria (ADAMS Accession No. ML20118D368), are:

PDC 4, Sharing of Systems states: reactor facilities shall not share systems or components unless it is shown safety is not impaired by the sharing.

PDC 37, Engineered Safety Features Basis for Design states:

Engineered safety features shall be provided in the facility to back up the safety provided by the core design, the reactor coolant pressure boundary, and their protection systems. As a minimum, such engineered safety features shall be designed to cope with any size reactor coolant pressure boundary break up to and including the circumferential rupture of any pipe in that boundary assuming unobstructed discharge from both ends.

PDC 41, Engineered Safety Features Performance Capability, states:

Engineered safety features such as emergency core cooling and containment heat removal systems shall provide sufficient performance capability to accommodate partial loss of installed capacity and still fulfill the required safety function. As a minimum, each engineered safety features shall provide this required safety function assuming a failure of a single active component.

PDC 55, Containment Heat Removal System states: where active heat removal systems are needed under accident conditions to prevent exceeding

containment design pressure, at least two systems, preferably of different principles, each with full capacity, shall be provided.

3.0 TECHNICAL EVALUATION

The Prairie Island, Units 1 and 2, shared CL system takes water inventory from the Mississippi River. The shared CL system is comprised of five pumps: two safeguard pumps (12, 22), two non-safeguard pumps (11, 21), and one motor-driven pump (MDCLP, Pump number 121) assigned to either a safeguard or non-safeguard pump operation. Both diesel driven safeguard vertical pumps (primary) and the one motor-driven vertical (standby) pump provide water to two independent supply headers (Trains A & B). The supply configuration for Train A includes one safeguard diesel pump (12), one non-safeguard pump (11), and the shared motor-driven safeguard pump (121) and Train B includes a separate safeguard diesel pump (22), one non-safeguard pump (12), and the shared motor-driven pump (121) connection to supply header.

Normal operation uses the two non-safeguard pumps with the vertical MDCLP as a standby pump. Two safeguard pumps are provided for emergency operation. The safeguard pumps are used whenever an engineered safety feature sequence is initiated, when discharge header pressure drops below its setpoint, or on a loss of offsite power (due to loss of motor-driven pumps and resultant low discharge header pressure). As described in USAR Section 10.4.1.2, the capacity of each safeguard pump and the MDCLP exceeds the maximum flow required for a single pump serving one unit in hot shutdown and a second unit in the long-term post-accident condition. The license amendment request (LAR) indicates a single safeguards CL pump can provide sufficient cooling water flow in one unit during the injection and recirculation phases of a postulated loss of coolant accident plus sufficient cooling to maintain the second unit in a safe shutdown condition. The performance analysis is further discussed in USAR Section 10.4.1.3.

During accident conditions, the single header is automatically split into two headers (or trains) by closure of redundant cross tie valves upon initiation of a safety signal. During the maintenance associated with the proposed amendment, NSPM plans to maintain the CL system header crossover valves in the open configuration (not split into trains), which maximizes the availability of components that are supported by the CL system. As such, the operable safeguard pump will also be capable of supporting components associated with the inoperable train. Each of the two supply headers are capable of supplying both units, and either can meet the cooling water requirements for long-term cooling of both units with an accident having occurred in one. Therefore, despite the inoperability of one train, the other train is available to supply sufficient cooling water for long-term cooling.

The LAR indicates the potential need to temporarily change isolation valve configuration to allow replacement of supply header piping on the CL system. This activity would impact both units because the CL system is a shared system and isolation valves are required to allow replacement of affected piping. If isolation valves do not seal adequately to allow removal of piping, a contingency plan is proposed to temporarily expand the isolation boundary. The expanded isolation boundary allows installation of a blind flange in place of the intended valve isolations. Temporary expansion of the isolation boundary results in the inoperability of the shared MDCLP and the plant will no longer meet TS 3.7.8, Required Action B.1, requiring verification of MDCLP operability.

Current TS 3.7.8, Condition B, is entered if one CL system supply header is inoperable.

Required Action B.1 is to verify that the vertical MDCLP is operable with a CT of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

Required Action B.2 is to verify the opposite train diesel driven cooling pump (safeguard pump)

is operable with a CT of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. Required Action B.3 is to restore supply header to operable status with a CT of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or in accordance with the Risk Informed Completion Time (RICT) program of TS 5.5.18. To meet Required Action B.3, one diesel pump and motor-driven pump must be operable for one operable train.

The LAR proposes a temporary extension of the CT for TS 3.7.8, Required Action B.1, of up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to allow blind flange installation in the event that isolation valves are found to leak excessively. After the flange is installed, the isolation boundary will be restored allowing the MDCLP to return to operable status and thereby meet Required Action B.1. The proposed temporary extension of the CT for TS 3.7.8, Required Action B.1 of up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> of MDCLP inoperability will be required to remove the blind flange following completion of header replacement. This operation could potentially be needed for both Trains A and B. The TS bases describe the CT as being related to redundant capabilities afforded by the operable train and pumps. The modification for both units could result in the plant being in the TS condition with lack of redundancy four times, each with an expanded CT of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The LAR described planned Risk Mitigation Actions (RMAs) to minimize risk and unavailability of redundant structures, systems and components (SSCs), and reduce demand on SSCs which call upon cooling water systems supports. These RMAs include:

Protecting equipment, such as opposite train residual heat removal, safety injection, and containment spray pumps, containment fan coils, auxiliary feedwater pumps, component cooling water pumps, Unit 1 diesel generators (note that Prairie Island, Unit 2 diesel generators do not rely on CL), the opposite train diesel driven CL pump, and instrument and air compressors.

Deferring maintenance and testing activities that could generate an initiating event that could challenge the operable SSCs.

Establishing compensatory actions, shift briefs, or a standing order that focuses on actions that the operators will take in response to an initiating event if an associated operable SSC fails.

Since the proposed LAR would result in isolated pumps while installing a blind flange, the required actions would no longer ensure the added capabilities of redundant pumps with only one safeguard pump required operable to supply cooling water to an operable train. Therefore, the NRC staff issued a request for additional information (RAI) (ADAMS Accession No. ML21305A010) that requested additional details of how the redundant capabilities relied upon for the existing CT requirements for Condition B would be satisfied with just the diesel-driven CL pump required to be operable.

The response to the RAI provided by letter dated November 4, 2021, described various system components and functions that could be impacted by the maintenance and loss of redundancy.

The RAI response described measures taken to minimize the risk or demand on the CL system in the event of an accident during the maintenance to account for the lack of redundancy. The RAI response provided a list of components that will remain available for non-safety injection initiating events during work on the header. Due to the significance of the planned maintenance, RMAs to protect SSCs listed in the RAI response will be implemented during the duration of an inoperable train.

In summary, the CL system normally provides redundancy and diversity with the diesel driven pumps and motor driven pump (MDCLP). Either safeguard pump is capable of maintaining both units in a safe shutdown condition (in the case one has a design basis event (DBE)) with the

capability of servicing either Unit 1 or Unit 2. While installing the isolation blind flange, one of the safeguard pumps will remain operable to perform its safety function. One safeguard pump will be inoperable and the MDCLP unavailable. While nonsafety-related, the non-safeguard pumps will continue operating to provide redundancy for events where offsite power is available.

Therefore, one train remains operable and capable of supporting the CL safety function as currently allowed in the existing TS 4-hour CT.

The NRC staff finds the operable train will remain capable of performing the CL system safety function of maintaining both units in a safe shutdown condition (in the event that one unit has DBE). The proposed RMAs and additional protective actions will further reduce risk during the maintenance activity. With the CL systems ability to perform its safety function and the short duration of an inoperable MDCLP, along with the planned risk reduction measures, the NRC staff finds the one-time extension of TS required action to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> for maintenance is acceptable.

3.1 Technical Evaluation Conclusion

Based on the above evaluation, the NRC staff finds that the proposed TS change will continue to meet the applicable PDC requirements. Further, the proposed addition of the note to limiting condition for operation (LCO) 3.7.8, Required Action B.1, Completion Time, does not affect the cooling systems current functional capability or performance levels of equipment required for safe operation of the facility. Therefore, the LCO meets the requirements of 10 CFR 50.36(c)(2)(i). The NRC staff, therefore, concludes that the TS change proposed by this LAR is acceptable.

4.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION

As stated above, the NRC staff made a proposed no significant hazards consideration determination as published in the Federal Register on October 21, 2021 (86 FR 58308).

Regulations in 10 CFR 50.92(c) state that the NRC may make a final determination, under the procedures in 10 CFR 50.91, that a license amendment involves no significant hazards consideration if operation of the facility, in accordance with the amendment, would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

An evaluation of the issue of no significant hazards consideration is presented below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The CL system is not an initiator of any accident previously evaluated. As a result, the probability of an accident previously evaluated is not increased by the allowance to extend the Completion Time of Required Action B.1 if needed for installation or removal of a blind flange. The consequences of an accident during the proposed extended Required Action B.1 Completion Time are no different than the consequences of an accident during the existing 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Completion Time. The MDCLP provides a source of cooling water to the operable CL header. However, the operable header is also served by the associated diesel

driven cooling water pump (DDCLP) and that CL header remains operable even if the MDCLP is inoperable, so the extended time will not significantly increase consequences of any of the accidents that CL mitigates.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed change will not permanently alter the design or function of the CL system. The proposed change provides an allowance for the MDCLP to be valved out of service and inoperable longer than the TS 3.7.8 Required Action B.1 Completion Time of four hours. Up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> will be required for the purpose of installing a blind flange if the leakage across the valve supporting the planned isolation is found to be too high. Similarly, up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> will be required for the purpose of removing the blind flange.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

The proposed change extends the Completion Time of Required Action B.1 of TS 3.7.8. Required Action B.1 verifies operability of the MDCLP. The MDCLP provides a source of cooling water to the operable header. However, the operable header is also served by the associated DDCLP and that CL header remains operable even if the MDCLP is inoperable.

Therefore, the proposed change does not result in a significant reduction in a margin of safety.

Based on the above evaluation, the NRC staff concludes that the three standards of 10 CFR 50.92(c) are satisfied. Therefore, the NRC staff has made a final determination that no significant hazards consideration is involved for the proposed amendment and that the amendment should be issued as allowed by the criteria contained in 10 CFR 50.91.

5.0 STATE CONSULTATION

In accordance with the Commissions regulations, the Minnesota State official was notified of the proposed issuance of the amendments on November 8, 2021. The State official had no comments.

6.0 ENVIRONMENTAL CONSIDERATION

The amendments change the requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.

The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public comment on such finding published in the Federal Register on October 21, 2021 (86 FR 58308). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

7.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: G. Curran, NRR Date of Issuance: November 23, 2021

ML21312A021 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DSS/SCPB/BC NRR/DSS/STSB/BC NAME RKuntz SRohrer BWittick NJordan MHamm for DATE 11/8/2021 11/8/2021 11/5/2021 11/8/2021 OFFICE OGC NLO NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME CKreuzberger NSalgado RKuntz DATE 11/18/2021 11/23/2021 11/23/2021