Text

License Amendment, Issuance of Amendments Allowed Outage Time Extensions to Support Residual Heat Removal Service Water Maintenance (TAC Nos. ME3551 and ME3552)
	ML111960066
Person / Time
Site:	Limerick
Issue date:	07/29/2011
From:	Peter Bamford; Plant Licensing Branch 1
To:	Pacilio M; Exelon Nuclear
	Bamford, Peter J., NRR/DORL 415-2833
References
	TAC ME3551, TAC ME3552
	Download: ML111960066 (51)
	v • d • e

"-,,,II REGU~ UNITED STATES

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,fJ'" . °11. L NUCLEAR REGULATORY COMMISSION

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.fJ July 29, 2011

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Mr. Michael J. Pacilio President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LIMERICK GENERATING STATION, UNITS 1 AND 2 -ISSUANCE OF AMENDMENTS RE: ALLOWED OUTAGE TIME EXTENSIONS TO SUPPORT RESIDUAL HEAT REMOVAL SERVICE WATER MAINTENANCE (TAC NOS.

ME3551 AND ME3552)

Dear Mr. Pacilio:

The U.S. Nuclear Regulatory Commission (NRC or the Commission) has issued the enclosed Amendment No. 203 to Facility Operating License No. NPF-39 and Amendment No.165 to Facility Operating License No. NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, respectively. The amendments are in response to your application dated March 19, 2010,1 as supplemented by additionalletters.2 The amendments consist of changes to the Technical SpeCifications of each unit extending the allowed outage time for the Suppression Pool Cooling mode of the Residual Heat Removal system, the Residual Heat Removal Service Water (RHRSW) system, the Emergency Service Water system, and the [Alternating Current] A.C. Sources - Operating from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 7 days, under certain conditions, in order to allow for repairs of the RHRSW system piping.

A copy of the Safety Evaluation is also enclosed. The Notice of Issuance will be included in the Commission's biweekly Federal Register notice.

~'Ik~

Peter Bamford, Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-352 and 50-353

Enclosures:

1. Amendment No. 203 to License No. NPF-39

2. Amendment No. 165 to License No. NPF-85

3. Safety Evaluation cc w/enclosures: Distribution via Listserv

1. Agencywide Documents Access and Management System (ADAMS) Accession No. ML100810151.

2. June 16, 2010 (ADAMS Accession No. ML101670319); October 29, 2010 (ML103060379); December 3, 2010 (ML103370328); January 14, 2011 (ML110180009); and March 23, 2011 (ML110840186).

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 EXELON GENERATION COMPANY, LLC DOCKET NO. 50-352 LIMERICK GENERATING STATION, UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No.203 License No. NPF-39

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

A. The application for amendment by Exelon Generation Company, LLC (the licensee), dated March 19,2010,1 as supplemented byadditionalletters,2 complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's 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 Commission's 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 Commission's regulations and all applicable requirements have been satisfied.

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 Facility Operating License No. NPF-39 is hereby amended to read as follows:

1. Agencywide Documents Access and Management System (ADAMS) Accession No. ML100810151.

2. June 16, 2010 (ADAMS Accession No. ML101670319); October 29,2010 (ML103060379); December 3,2010 (ML103370328); January 14, 2011 (ML110180009); and March 23, 2011 (ML110840186).

-2 (2) Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 203 ,are hereby incorporated into this license.

Exelon Generation Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3. This license amendment is effective as of its date of issuance and shall be implemented within 60 days of the date of issuance. Implementation of the amendment shall include updating the UFSAR in accordance with 10 CFR 50.71 (e). This update shall include, but not be limited to, a description of the regulatory commitments made by letter dated October 29, 2010, Attachment 4, as updated by the supplements dated December 3, 2010, and March 23, 2011.

FOR THE NUCLEAR REGULATORY MMISSION pHarold Chernoff, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications and Facility Operating License Date of Issuance: Jul y 29, 2011

ATIACHMENT TO LICENSE AMENDMENT NO. 203 FACILITY OPERATING LICENSE NO. NPF-39 DOCKET NO. 50-352 Replace the following page of the Facility Operating License with the revised page. The revised page is identified by amendment number and contains marginal lines indicating the area of change.

Remove Page 3 Page 3 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 3/46-16 3/46-16 3/47-1 3/47-1 3/47-1a 3/4 7-3 3/4 7-3 3/48-1 3/48-1 3/4 8-2 3/4 8-2

-3 (3) Pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess and use at any time any byproduct, source and special nudear 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, 70, to receive, possess, and use in amounts as required any byproduct, source or special nudear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5) Pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nudear materials as may be produced by the operation of the facility, and to receive and possess, but not separate, such source, byproduct, and special nudear materials as contained in the fuel assemblies and fuel channels from the Shoreham Nuclear Power Station.

C. This license shall be deemed to contain and is subject to the conditions specified in the Commission's regulations set forth in 10 CFR Chapter I (except as exempted from compliance in Section 2.0. below) and 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 Exelon Generation Company is authorized to operate the facility at reactor core power levels not in excess of 3515 megawatts thermal (100% rated power) in accordance with the conditions specified herein and in Attachment 1 to this license. The items identified in Attachment 1 to this license shall be completed as specified. Attachment 1 is hereby incorporated into this license.

(2) Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 203 , are hereby incorporated into this license.

Exelon Generation Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

Amendment No. ~, 400, ~. 447,~, 203

CONTAINMENT SYSTEMS SUPP~ESSION POOL COOLING LIMITING CONDITION FOR OPERATION 3.6.2.3 The suppression pool cooling mode of the residual heat removal (RHR) system shall be OPERABLE with two independent loops, each loop consisting of:

a. One OPERABLE RHR pump, and

b. An OPERABLE flow path capable of recirculating water from the suppression chamber through an RHR heat exchanger.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, and 3.

ACTION:

a. With one suppression pool cooling loop inoperable, restore the inoperable loop to OPERABLE status within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s** or in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

b. With both suppression pool cooling loops inoperable, be in at least HOT SHUTDOWN within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN* within the next 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

4.6.2.3 The suppression pool cooling mode of the RHR system shall be demonstrated OPERABLE:

a. In accordance with the Surveillance Frequency Control Program by verifying that each valve (manual, power-operated, or automatic) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position.

b. By verifying that each of the required RHR pumps develops a flow of at least 10,000 gpm on recirculation flow through the flow path including the RHR heat exchanger and its associated closed bypass valve, the suppression pool and the full flow test line when tested pursuant to Specification 4.0.5.

Whenever both RHR subsystems are inoperable, if unable to attain COLD SHUTDOWN as required by this ACTION, maintain reactor coolant temperature as low as practical by use of alternate heat removal methods.

- During the extended 7 day Allowed Outage me (AOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the 72-hour AOT for one inoperable suppression pool cooling loop may also be extended to 7 days for the same 7-day riod.

LIMERICK - UNIT 1 3/4 6 16 Amendment No. ~ ,~,+/-J+/-,~,203

- COMMON SYSTEM 3.7.1.1 At least the following independent residual heat removal service water (RHRSW) system subsystems, with each subsystem comprised of:

a. Two OPERABLE RHRSW pumps, and

b. An OPERABLE flow path capable of taking suction from the RHR service water pumps wet pits which are supplied from the spray pond or the cooling tower basin and transferring the water through one Unit 1 RHR heat exchanger, shall be OPERABLE:

a. In OPERABLE CONDITIONS 1, 2, and 3, two subsystems.

b. In OPERABLE CONDITIONS 4 and 5, the subsystem(s) associated with systems and components required OPERABLE by Specification 3.4.9.2, 3.9.11.1, and 3.9.11.2.

APPLICABI LITY; OPERATIONAL CONDITIONS 1, 2, 3, 4, and 5.

ACTION:

a. In OPERATIONAL CONDITION 1, 2, or 3:

1. With one RHRSW pump inoperable, restore the inoperable pump to OPERABLE status within 30 days, or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

2. With one RHRSW pump in each subsystem inoperable, restore at least one of the inoperable RHRSW pumps to OPERABLE status within 7 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

3. With one RHRSW subsystem otherwise inoperable, restore the inoperable subsystem to OPERABLE status with at least one OPERABLE RHRSW pump within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , unless otherwise specified in a) or b) be1ow**, or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

a) When the 'A' RHRSW subsystem is inoperable to allow for repairs of the 'A' RHRSW subsystem piping, with Limerick Generating Station Unit 2 shutdown, reactor vessel head removed and reactor cavity flooded, the 72-hour Allowed Outage Time may be extended to 7 days once every other calendar year with the following compensatory measures established:

- Only one of these two Actions, either a.3.a) or a.3.b), may be entered on Unit 1 in a calendar year. However, if either Unit 2 TS LCD 3.7.1.1, Action a.3.a) or a.3.b) has previously been entered in the calendar year, then Unit 1 Action a.3.a) or a.3.b) may not be entered during that same calendar year.

LIMERICK - UNIT 1 3/4 7-1 Amendment No. %8,g& , 203

3/4.7 PLANT SYSTEMS ACTION: (Continued)

1) The following systems and subsystems will be protected in accordance with applicable station procedures:

'B' RHRSW subsystem

' B' ESW loop

'B' and 'D' RHR subsystems

012, D14. 022. and D24 4kV buses and emergency diesel generators

Division 2 and Division 4 Safeguard DC, and

2) The 'A' and 'B' loop of ESW return flow shall be aligned to the operable 'B' RHRSW return header only.

The ESW return valves to the 'B' RHRSW return header (i.e., HV-ll 015A and HV-11-015B) will be administratively controlled in the open position and de-energi prior to entering the extended AOT. The ESW return valves to the 'A' RHRSW return header (i .e., HV 11-011A and HV 11 011B) wi 11 be administratively controlled in the closed position and de energized as part of the work boundary.

b) When the 'B' RHRSW subsystem is inoperable to allow for repairs of the 'B' RHRSW subsystem piping, with Limerick Generating Station Unit 2 shutdown. reactor vessel head removed and reactor cavity flooded, the 72-hour Allowed Outage Time may be extended to 7 days once every other calendar year with the following compensatory measures established:

1) The following systems and subsystems will be protected in accordance with applicable station procedures:

'A' RHRSW subsystem

' A' ESW loop

'A' and 'C' RHR subsystems

011, D13, 021, and 023 4kV buses and emergency diesel generators

Division 1 and Division 3 Safeguard DC, and

2) The 'A' and 'B' loop of ESW return flow shall be aligned to the operable 'A' RHRSW return header only.

The ESW return valves to the 'A' RHRSW return header (i.e .* HV 11 OllA and HV-U-OllB) will be administratively controlled in the open position and de-energized prior to entering the extended AOT. The ESW return valves to the 'B' RHRSW return header (i .e., HV-ll-015A and HV 11-015B) will be administratively controlled in the closed position and de energized as part of the work boundary.

4. With both RHRSW subsystems otherwise inoperable, restore at least one subsystem to OPERABLE status within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN* within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

Whenever both RHRSW subsystems are inoperable, if unable to attain COLD SHUTDOWN as requi by the ACTION, maintain reactor coolant temperature as low as practical by use of alternate heat removal methods.

LIMERICK UNIT 1 3/4 7-1a Amendment No. ~,ge,~. 203 I

PLANT SYSTEMS EMERGENCY SERVICE WATER SYSTEM - COMMON SYSTEM 3.7.1.2 At least the following independent emergency service water system loops, with each loop comprised of:

a. Two OPERABLE emergency service water pumps, and

b. An OPERABLE flow path capable of taking suction from the emergency service water pumps wet pits which are supplied from the spray pond or the cooling tower basin and transferring the water to the associated Unit 1 and common safety related equipment, s hall be OPERABLE:

a. In OPERATIONAL CONDITIONS 1, 2, and 3, two loops.

b. In OPERATIONAL CONDITIONS 4, 5, and *, one loop.

APPLICABI LITY; OPERATIONAL CONDITIONS 1, 2, 3, 4, 5, and

ACTION:

a. In OPERATION CONDITION 1, 2, or 3:

1. With one emergency service water pump inoperable, restore the inoperable pump to OPERABLE status within 45 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

2. With one emergency service water pump in each loop inoperable.

restore at least one inoperable pump to OPERABLE status within 30 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

3. With one emergency service water system loop otherwise inoperable, declare all equipment aligned to the inoperable loop inoperab1e**. restore the inoperable loop to OPERABLE status with at least one OPERABLE pump within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s# or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

When handling irradiated fuel in the secondary containment.

- The diesel generators may be aligned to the OPERABLE emergency service water system loop provided confirmatory flow testing has been performed. Those diesel generators no aligned to the OPERABLE emergency service water system loop shall declared inoperable and the actions of 3.8.1.1 taken.

During the extended 7-day Allowed Outage Time (AOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT for one inoperable emergency service water system loop may also be extended to 7 days for the same 7-day period.

LIMERICK UNIT 1 3/4 7 3 Amendment No. ,4{,},~,-l-M, 203

3/4.8 ELECTRICAL POWER SYSTEMS 3/4.8.1 A.C. SOURCES A.C. SOURCES - OPERATING 3.8.1.1 As a minimum, the following A.C. electrical power sources shall be OPERABLE:

a. Two physically independent circuits between the offsite transmission network and the onsite Class IE distribution system, and

b. Four separate and independent diesel generators, each with:

1. A separate day tank containing a minimum of 250 gallons of fuel,

2. A separate fuel storage system containing a minimum of ,500 gallons of fuel, and

3. A separate fuel transfer pump.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, and 3.

ACTION:

a. With one diesel generator of the above required A.C. electrical power sources inoperable, demonstrate the OPERABILITY of the remaining A.C.

sources by performing Surveillance Requirement 4.8.1.1.1.a within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months and at least once per 7 days thereafter. If the diesel generator became inoperable due to any cause other than an inoperable support system, an independently testable component, or preplanned preventive maintenance or testing, demonstrate the OPERABILITY of the remaining operable diesel generators by performing Surveillance Requirement 4.8.1.1.2.a.4 for one diesel generator at a time, within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , unless the absence of any potential common-mode failure for the remaining diesel generators is determined. Restore the inoperable diesel generator to OPERABLE status within 30 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . See also ACTION e.

b. With two diesel generators of the above required A.C. electrical power sources inoperable, demonstrate the OPERABILITY of the remaining A.C.

sources by performing Surveillance Requirement 4.8.1.1.1.a within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months and at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter. If either of the diesel generators became inoperable due to any cause other than an inoperable support system, an independently testable component, or preplanned preventive maintenance or testing, demonstrate the OPERABILITY of the remaining di generators by performing Surveillance Requirement 4.8.1.1.2.a.4 for one diesel generator at a time, within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months , unless the absence of any potential common-mode failure for the remaining diesel generators is determined. Restore at least one of the inoperable diesel generators to OPERABLE status within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s* or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . See also ACTION e.

During the extended 7-day Allowed Outage Time CAOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the 72-hour AOT for two inoperable diesel generators may also be extended to 7 days for the same 7 day period.

LIMERICK - UNIT 1 3/4 8 1 Amendment No. ~.~,~,+9J,203

ELECTRICAL POWER SYSTEMS ACTION: (Continued)

e. In addition to the ACTIONS above:

1. For two train systems, with one or more diesel generators of the above required A.C. electrical power sources inoperable, verify within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereafter that at least one of the required two train system subsystem, train, components, and devices is OPERABLE and its associated diesel generator is OPERABLE. Otherwise, restore either the inoperable diesel generator or the inoperable system subsystem to an OPERABLE status within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s* or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

2. For the LPCI systems, with two or more diesel generators of the above required A.C. electrical power sources inoperable, verify within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereafter that at least two of the required LPCI system subsystems, trains, components, and devices are OPERABLE and its associated di generator is OPERABLE. Otherwise, be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

This ACTION does not apply for those systems covered in Specifications 3.7.1.1. and 3.7.1.2.

During the extended 7-day Allowed Outage me (AOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the 72-hour AOT may also be extended to 7 days for the same 7-day period.

LIMERICK UNIT 1 3/4 8 2 Amendment No. ~,4G, 203

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC DOCKET NO. 50-353 LIMERICK GENERATING STATION, UNIT 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 165 License No. NPF-85

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

A. The application for amendment by Exelon Generation Company, LLC (the licensee), dated March 19,2010,1 as supplemented byadditionalletters,2 complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's 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 Commission's 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 Commission's regulations and all applicable requirements have been satisfied.

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 Facility Operating License No. NPF-85 is hereby amended to read as follows:

1. Agencywide Documents Access and Management System (ADAMS) Accession No. ML100810151.

2. June 16. 2010 (ADAMS Accession No. ML101670319); October 29. 2010 (ML103060379): December 3.2010 (ML103370328): January 14. 2011 (ML110180009); and March 23, 2011 (ML110840186).

- 2 (2) Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 165, are hereby incorporated into this license.

Exelon Generation Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3. This license amendment is effective as of its date of issuance and shall be implemented within 60 days of the date of issuance. Implementation of the amendment shall include updating the UFSAR in accordance with 10 CFR 50.71 (e). This update shall include, but not be limited to, a description of the regulatory commitments made by letter dated October 29, 2010, Attachment 4, as updated by the supplements dated December 3, 2010, and March 23, 2011.

NUCLEAR REGULATORUOMMISSION

~

rold Chernoff, Chief Plant licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications and Facility Operating License Date of Issuance: Jul y 29, 2011

AITACHMENT TO LICENSE AMENDMENT NO. 165 FACILITY OPERATING LICENSE NO. NPF-85 DOCKET NO. 50-353 Replace the following page of the Facility Operating License with the revised page. The revised page is identified by amendment number and contains marginal lines indicating the area of change.

Remove Insert Page 3 Page 3 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 3/46-16 3/46-16 3/47-1 3/4 7-1 3/47-1a 3/4 7-3 3/4 7-3 3/48-1 3/48-1 3/4 8-2 3/4 8-2

-3 (4) Pursuant to the Act and 10 CFR Parts 30,40, 70, 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 calibration or associated with radioactive apparatus or components; and (5) Pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility, and to receive and possess, but not separate, such source, byproduct, and special nuclear materials as contained in the fuel assemblies and fuel channels from the Shoreham Nuclear Power Station.

C. This license shall be deemed to contain and is subject to the conditions specified in the Commission's regulations set forth in 10 CFR Chapter I (except as exempted from compliance in Section 2.0. below) and 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 specrfied or incorporated below:

(1) Maximum Power Level Exelon Generation Company is authorized to operate the facility at reactor core power levels of 3515 megawatts thermal (100 percent rated power) in accordance with the conditions specified herein.

(2) Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 165 , are hereby incorporated into this license. Exelon Generation Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

(3) Fire Protection (Section 9.5, SSER-2, -4)*

Exelon Generation Company shall implement and maintain in effect all provisions of the approved Fire Protection Program as described in the Updated Final Safety Analysis Report for the facility, and as approved in the NRC Safety Evaluation Report dated August 1983 through Supplement 9, dated August 1989, and Safety Evaluation dated November 20, 1995, subject to the follOWing provision:

The licensee may make changes to the approved fire protection program without prior approval of the Commission only if those changes would not adversely affect the ability to achieve and maintain safe shutdown in the event of a 'fire.

The parenthetical notation following the title of license conditions denotes the section of the Safety Evaluation Report and/or its supplements wherein the license condition is discussed.

Amendment No.4, 27, it, 00, ~,4Q8, 493 165

CONTAINMENT SYSTEMS SUPPRESSION POOL COOLING 3.6.2.3 The suppression pool cooling mode of the residual heat removal (RHR) system shall be OPERABLE with two independent loops, each loop consisting of:

a. One OPERABLE RHR pump, and

b. An OPERABLE flow path capable of recirculating water from the suppression chamber through an RHR heat exchanger.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, and 3.

ACTION:

a. With one suppression pool cooling loop inoperable, restore the inoperable loop to OPERABLE status within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s** or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

b. With both suppression pool cooling loops inoperable, be in at least HOT SHUTDOWN within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDDWN* within the next 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

4.6.2.3 The suppression pool cooling mode of the RHR system shall be demonstrated OPERABLE:

a. In accordance with the Surveillance Frequency Control Program by verifying that each valve (manual, power operated, or automatiC) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position.

b. By verifying that each of the required RHR pumps develops a flow of at least 10,000 gpm on recirculation flow through the flow path including the RHR heat exchanger and its associated closed bypass valve, the suppression pool and the full flow test line when tested pursuant to Specification 4.0.5.

Whenever both RHR subsystems are inoperable, if unable to attain COLD SHUTDOWN as required by this ACTION, maintain reactor coolant temperature as low as practical by use of alternate heat removal methods.

- During the extended 7 day Allowed Outage Time (AOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the 72-hour AOT for one inoperable suppression pool cooling loop may also be extended to 7 days for the same 7-day period.

LIMERICK - UNIT 2 3/4 6-16 Amendment No. ~,~,~,+47,165

3/4.7 PLANT SYSTEMS 3/4.7.1 SERVICE WATER SYSTEMS RESIDUAL HEAT REMOVAL SERVICE WATER SYSTEM - COMMON SYSTEM 3.7.1.1 At least the following independent residual heat removal service water (RHRSW) system subsystems, with each subsystem comprised of:

a. Two OPERABLE RHRSW pumps, and

b. An OPERABLE flow path capable of taking suction from the RHR service water pumps wet pits which are supplied from the spray pond or the cooling tower basin and transferring the water through one Unit 2 RHR heat exchanger, shall be OPERABLE:

a. In OPERATIONAL CONDITIONS 1, 2, and 3, two subsystems.

b. In OPERATIONAL CONDITIONS 4 and 5, the subsystem(s) associated with systems and components required OPERABLE by Specification 3.4.9.2, 3.9.11.1, and 3.9.11.2.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, 3, 4, and 5.

ACTION:

a. In OPERATIONAL CONDITION 1, 2, or 3:

1. With one RHRSW pump inoperable, restore the inoperable pump to OPERABLE status within 30 days, or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

2. With one RHRSW pump in each subsystem inoperable, restore at least one of the inoperable RHRSW pumps to OPERABLE status within 7 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

3. With one RHRSW subsystem otherwise inoperable, restore the inoperable subsystem to OPERABLE status with at least one OPERABLE RHRSW pump within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , unless otherwise specified in a) or b) below**, or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

a) When the 'A' RHRSW subsystem is inoperable to allow for repairs of the 'A' RHRSW subsystem piping, with Limerick Generating Station Unit 1 shutdown, reactor vessel head removed and reactor cavity flooded, the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Allowed Outage Time may be extended to 7 days once every other calendar year with the following compensatory measures established:

- Only one of these two Actions, either a.3.a) or a.3.b), may be entered on Unit 2 in a calendar year. However, if either Unit 1 TS LCO 3.7.1.1, Action a.3.a) or a.3.b) has previously been entered in the calendar year, then Unit 2 Action a.3.a) or a.3.b) may not be entered during that same calendar year.

LIMERICK UNIT 2 3/4 7-1 Amendment No. ~,+Q,~, 165

PLANT SYSTEMS (Continued)

1) The following systems and subsystems will be protected in accordance with applicable station procedures:

'B' RHRSW subsystem

'B' ESW loop

'B' and 'D' RHR subsystems

D12, D22, and 024 4kV buses and emergency di generators

Division 2 and Division 4 Safeguard ~C, and

2) The 'A' and 'B' loop of ESW return flow shall be aligned to the operable 'B' RHRSW return header only.

The ESW return valves to the 'B' RHRSW return header (i .e., HV-11-015A and HV-11-015B) will be administratively controlled in the open position and de-energi prior to entering the extended AOT. The ESW return valves to the 'A' RHRSW return header (i .e., HV-11-011A and HV 11-011B) will be administratively controlled in the closed position and de energized as part of the work boundary.

b) When the 'B' RHRSW subsystem is inoperable to allow for repairs of the 'B' RHRSW subsystem piping, with Limerick Generating Station Unit 1 shutdown, reactor vessel head removed and reactor cavity flooded, the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Allowed Outage Time may be extended to 7 days once every other calendar year with the following compensatory measures established:

1) The following systems and subsystems will be protected in accordance with applicable station procedures:

'A' RHRSW subsystem

' A' ESW loop

'A' and 'c' RHR subsystems

011, 021, and 023 4kV buses and emergency diesel generators

Division 1 and Division 3 Safeguard DC, and

2) The 'A' and 'B' loop of ESW return flow shall be aligned to the operable 'A' RHRSW return header only.

The ESW return valves to the 'A' RHRSW return header (i.e., HV-11-011A and HV-ll-011B) will be administratively controlled in the open position and de-energized prior to entering the extended AOT. The ESW return valves to the 'B' RHRSW return header (i.e., HV-11-015A and HV 11-015B) will be administratively controlled in the closed position and de energized as part of the work boundary.

4. With both RHRSW subsystems otherwise inoperable, restore at least one subsystem to OPERABLE status within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN* within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

Whenever both RHRSW subsystems are inoperable, if unable to attain COLD SHUTDOWN as required by this ACTION, maintain reactor coolant temperature as low as practical by use of alternate heat removal methods.

LIMERICK - UNIT 2 3/4 7-1a Amendment No. JQ,+G,~,

165

COMMON SYSTEM 3.7.1.2 At least the following independent emergency service water system loops, with each loop comprised of:

a. Two OPERABLE emergency service water pumps, and

b. An OPERABLE flow path capable of taking suction from the emergency service water pumps wet pits which are supplied from the spray pond or the cooling tower basin and transferring the water to the associated Unit 2 and common safety-related equipment, shall be OPERABLE:

a. In OPERATIONAL CONDITIONS I, 2, and 3, two loops.

b. In OPERATIONAL CONDITIONS 4, 5, and

one loop.

APPLICABILITY; OPERATIONAL CONDITIONS 1, 2, 3, 4, 5, and

ACTION:

a. In OPERATION CONDITION 1, 2, or 3;

1. With one emergency service water pump inoperable, restore the inoperable pump to OPERABLE status within 45 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

2. With one emergency service water pump in each loop inoperable, restore at least one inoperable pump to OPERABLE status within 30 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

3. With one emergency service water system loop otherwise inoperable, declare all equipment aligned to the inoperable loop inoperable**, restore the inoperable loop to OPERAB status with at least one OPERABLE pump within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s# or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

When handling irradiated fuel in the secondary containment.

- The diesel generators may be aligned to the OPERABLE emergency service water system loop provided confirmatory flow testing has been performed. Those diesel generators not aligned to the OPERABLE emergency service water system loop shall be declared inoperable and the actions of 3.8.1.1 taken.

During the extended 7-day Allowed Outage Time (AOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the 72-hour AOT for one inoperable emergency service water system loop may also be extended to 7 days for the same 7 day period.

LIMERICK - UNIT 2 3/4 7 3 Amendment No.

165

3/4.8 ELECTRICAL POWER SYSTEMS 3/4.8.1 A.C. SOURCES A.C. SOURCES - OPERATING 3.8.1.1 As a minimum, the following A.C. electrical power sources shall be OPERABLE:

a. Two physically independent circuits between the offsite transmission network and the onsite Class IE distribution system, and

b. Four separate and independent diesel generators, each with:

1. A separate day tank containing a minimum of 250 gallons of fuel,

2. A separate fuel storage system containing a minimum of 33,500 gall ons of fuel, and

3. A separate fuel transfer pump.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, and 3.

ACTION:

a. With one diesel generator of the above required A.C. electrical power sources inoperable, demonstrate the OPERABILITY of the remaining A.C.

sources by performing Surveillance Requirement 4.8.1.1.1.a within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months and at least once per 7 days thereafter. If the di generator became inoperable due to any cause other than an inoperable support system, an independently testable component, or preplanned preventive maintenance or testing, demonstrate the OPERABILITY of the remaining operable diesel generators by performing Surveillance Requirement 4.8.1.1.2.a.4 for one diesel generator at a time, within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , unless the absence of any potential common-mode failure for the remaining diesel generators is determined. Restore the inoperable diesel generator to OPERABLE status within 30 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . See also ACTION e.

b. With two diesel rators of the above required A.C. electrical power sources inopera e, demonstrate the OPERABILITY of the remaining A.C.

sources by performing Surveillance Requirement 4.8.1.1.1.a within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months and at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter. If either of the diesel generators became inoperable due to any cause other than an inoperable support system, an independently testable component, or preplanned preventive maintenance or testing, demonstrate the OPERABILITY of the remaining diesel generators by performing Surveillance Requirement 4.8.1.1.2.a.4 for one diesel generator at a time, within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months , unless the absence of any potential common-mode failure for the remaining diesel generators is determined. Restore at least one of the inoperable diesel generators to OPERABLE status within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s* or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . See also ACTION e.

During the extended 7 day Allowed Outage Time (AOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the hour AOT for two inoperable diesel generators may also be extended to 7 days for the same 7-day period.

LIMERICK - UNIT 2 3/4 8-1 Amendment No. ~. ~,165

ELECTRICAL POWER SYSTEMS ACTION: (Continued)

e. In addition to the ACTIONS above:

1. For two train systems, with one or more diesel generators of the above required A.C. electrical power sources inoperable, verify within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereafter that at least one of the required two train system subsystem, train, components, and devices is OPERABLE and its associated diesel generator is OPERABLE. Otherwise, restore either the inoperable diesel generator or the inoperable system subsystem to an OPERABLE status within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s* or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

2. For the LPCI systems, with two or more diesel generators of the above required A.C. electrical power sources inoperable, verify within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereafter that at least two of the required LPCI system subsystems, trains, components and devices are OPERABLE and its associated diesel generator is OPERABLE. Otherwise, be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

This ACTION does not apply for those systems covered in Specifications 3.7.1.1 and 3.7.1.2.

During the extended 7-day Allowed Outage Time (AOT) specified by TS LCO 3.7.1.1, Action a.3.a) or a.3.b) to allow for RHRSW subsystem piping repairs, the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT may also be extended to 7 days for the same 7-day period.

LIMERICK UNIT 2 3/4 8-2 Amendment No. 165

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 203 TO FACILITY OPERATING LICENSE NO. NPF-39 AND AMENDMENT NO. 165 TO FACILITY OPERATING LICENSE NO. NPF-85 EXELON GENERATION COMPANY, LLC LIMERICK GENERATING STATION, UNITS 1 AND 2 DOCKET NOS. 50-352 AND 50-353

1.0 INTRODUCTION

By application dated March 19, 2010,1 as supplemented by additional letters, 2 Exelon Generation Company, LLC (Exelon, the licensee) submitted a license amendment request (LAR) proposing to extend certain Limerick Generating Station (LGS) Units 1 and 2, Technical Specification (TS) allowed outage times (AOTs). The supplements provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the staff's original proposed no significant hazards consideration determination as published in the Federal Register on May 18, 2010 (75 FR 27828).

The proposed changes would extend the AOTs from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven (7) days for the Suppression Pool Cooling (SPC) mode of the Residual Heat Removal (RHR) system, the Residual Heat Removal Service Water (RHRSW) system, the Emergency Service Water (ESW) system, and the A.C. Sources - Operating (Emergency Diesel Generators or EDGs). This extension would only be applicable under certain plant conditions and is being proposed in order to allow for periodic repairs of the RHRSW system piping. The AOT extension would only be allowed once every other calendar year, for each unit, with the opposite unit shutdown, reactor vessel head removed, and reactor cavity flooded, and certain other compensatory measures, described later in this safety evaluation, in effect.

The licensee plans to replace large diameter piping in both the 'A' and 'B' RHRSW return headers, one at a time, and needs the longer AOTs in order to accomplish that work. Placing one RHRSW return header out of service makes one RHRSW subsystem inoperable, one ESW loop inoperable (but available), one loop of SPC mode of RHR inoperable and two EDGs per unit inoperable (but available). While the licensee has immediate plans to repair certain known areas of degraded RHRSW return piping utilizing the extended AOTs, these TS changes may be used for other future RHRSW piping maintenance activities, as long as the appropriate TS restrictions are observed.

1. Agencywide Documents Access and Management System (ADAMS) Accession No. ML100810151

2. June 16. 2010 (ADAMS AcceSsion No. ML101670319); October 29,2010 (ML103060379); December 3,2010 (ML103370328); January 14,2011 (ML110180009); and March 23, 2011 (ML110840186).

Enclosure

- 2

2.0 REGULATORY EVALUATION

The U.S. Nuclear Regulatory Commission (NRC, or Commission) staff evaluated the proposed changes in the areas of plant systems, risk assessment, electrical engineering, technical specifications, and human factors, utilizing the requirements and guidance documents described below.

Section 182a of the Atomic Energy Act of 1954, as amended, requires applicants for nuclear power plant operating licenses to include TSs as a part of the license. The Commission's regulatory requirements related to the content of TSs are set forth in Title 10 of the Code of Federal Regulations (10 CFR), Section 50.36, which requires that the TSs include items in eight specific categories: (1) safety limits, limiting safety system settings and limiting control settings; (2) limiting conditions for operation (LCOs); (3) surveillance requirements (SR); (4) design features; (5) administrative controls; (6) decommissioning; (7) initial notification; and (8) written reports. Further, 10 CFR 50.36(c)(2)(i) states that TSs will contain LCOs which "are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When a limiting condition for operation of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met." The proposed changes must meet the requirements of 10 CFR 50.36.

For this risk-informed LAR, the Regulatory Guides (RGs) on which the NRC staff based its acceptance are described as follows:

RG 1.174, "An Approach for USing Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," Revision 1, describes a risk-informed approach, acceptable to the NRC, for assessing the nature and impact of proposed permanent licensing basis changes by considering engineering issues and applying risk insights. This RG also provides risk acceptance guidelines for evaluating the results of such evaluations.

RG 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications," describes an acceptable risk-informed approach specifically for assessing proposed permanent TS changes in AOTs. This RG also provides risk acceptance guidelines for evaluating the results of such assessments. RG 1.177 identifies a three-tiered approach for the licensees evaluation of the risk associated with a proposed AOT TS change, as discussed below.

Tier 1 assesses the risk impact of the proposed change in accordance with acceptance guidelines consistent with the Commission's Safety Goal Policy Statement, as documented in RG 1.174 and RG 1.177. The first tier assesses the impact on operational plant risk based on the change in core damage frequency (.6CDF) and change in large early release frequency (.6LERF). It also evaluates plant risk while equipment covered by the proposed AOT is out of service, as represented by incremental conditional core damage probability (ICCDP) and incremental conditional large early release probability (ICLERP).

Tier 1 also addresses probabilistic risk assessment (PRA) quality, including the technical adequacy of the licensee's plant-specific PRA for the subject application. Cumulative risk of the present TS change in light of past related applications or additional applications under review are also considered along

- 3 with uncertainty/sensitivity analysis with respect to the assumptions related to the proposed TS change.

Tier 2 identifies and evaluates any potential risk-significant plant equipment outage configurations that could result if equipment, in addition to that associated with the proposed license amendment, is taken out of service simultaneously, or if other risk-significant operational factors, such as concurrent system or equipment testing, are also involved. The purpose of this evaluation is to ensure that there are appropriate restrictions in place such that risk-significant plant equipment outage configurations will not occur when equipment associated with the proposed AOT is implemented.

Tier 3 addresses the licensee's overall confjguration risk management program (CRMP) to ensure that adequate programs and procedures are in place for identifying risk-significant plant configurations resulting from maintenance or other operational activities and appropriate compensatory measures are taken to avoid risk-Significant configurations that may not have been considered when the Tier 2 evaluation was performed. Compared with Tier 2, Tier 3 provides additional coverage to ensure risk-significant plant equipment outage configurations are identified in a timely manner and that the risk impact of out-of service equipment is appropriately evaluated prior to performing any maintenance activity over extended periods of plant operation. Tier 3 guidance can be satisfied by the Maintenance Rule, 10 CFR 50.65(a)(4), which requires a licensee to assess and manage the increase in risk that may result from activities such as surveillance testing and corrective and preventive maintenance, supject to the guidance provided in RG 1.177, Section 2.3.7.1, and the adequacy of the licensee's program and PRA model for this application. The CRMP is to ensure that equipment removed from service prior to or during the proposed extended AOT will be appropriately assessed from a risk perspective.

RG 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," Revision 2, describes an acceptable approach for determining whether the quality of the PRA, in total or the parts that are used to support an application, is sufficient to provide confidence in the results, such that the PRA can be used in regulatory decision making for light water-reactors. This version of RG 1.200 was utilized in the NRC's review of this application. The NRC staff notes that the licensee's application refers to Revision 1 of this standard and the application also states that the document revision (RG 1.200 Revision 1 to Revision 2) does not materially affect the full power internal events portion of the analysis.

General guidance for evaluating the technical basis for proposed risk-informed changes is provided in Chapter 19.2, "Review of Risk Information Used to Support Permanent Plant Specific Changes to the Licensing Basis: General Guidance," of the NRC Standard Review Plan (SRP), NUREG-0800. Guidance on evaluating PRA technical adequacy is provided in Chapter 19.1, "Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities." More specific guidance related to risk-informed TS changes is provided in SRP Section 16.1, "Risk-Informed Decisionmaking: Technical Specifications," which includes AOT changes as part of risk-informed decision making. Chapter 19.2 of the SRP

-4 states that a risk-informed application should be evaluated to ensure that the proposed changes meet the following key principles:

The proposed change meets the current regulations, unless it explicitly relates to a requested exemption or rule change.

The proposed change is consistent with the defense-in-depth philosophy.

The proposed change maintains sufficient safety margins.

When proposed changes increase core damage frequency or risk, the increase{s) should be small and consistent with the intent of the Commission's Safety Goal Policy Statement.

The impact of the proposed change should be monitored using performance measurement strategies.

Specific to the area of Electrical Engineering, the regulatory requirements which the staff applied in the review of the application are as follows:

General Design Criteria {GDC)-17, "Electric power systems," contained in Appendix A to 10 CFR Part 50, "General Design Criteria for Nuclear Power Plants," states, in part, that nuclear power plants have onsite and offsite electric power systems to permit the functioning of structures, systems, and components that are important safety. The onsite system shall have sufficient independence, redundancy, and testability to perform its safety function, assuming a single failure. The onsite power system shall be supplied from the transmission network by two physically independent circuits that are designed and located so as to minimize, to the extent practical, the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. In addition, this criterion states that provisions shall be included to minimize the probability of losing electric power from the remaining electric power supplies as a result of, or coincident with, loss of power from the unit, the offsite transmission network, or the onsite power supplies. The LGS Updated Final Safety Analysis Report (UFSAR), Section 3.1. states that onsite and offsite power systems are provided in accordance with this GDC.

GDC-18, "Inspection and testing of electric power systems," states, in part, that electric power systems important to safety shall be designed to permit appropriate periodic inspection and testing. The LGS UFSAR, Section 3.1, states that the inspection and testing of electrical power systems at LGS, as described in UFSAR chapters 8 and 16, conforms with this GDC.

10 CFR 50.63, "Loss of all alternating current power," requires a nuclear power plant to be able to withstand for a specified duration and recover from a complete loss of offsite and onsite AC sources.

10 CFR 50.65, "Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," requires licensees to monitor the performance or condition of structures, systems, or components, against licensee-established goals, in a manner sufficient to provide reasonable assurance that these structures, systems, and components are capable of fulfilling their intended functions.

- 5 In the area of Human Factors, the NRC staff used the following guidance documents in performing its review:

NRC Information Notice (IN) 97-78, "Crediting Operator Actions in Place of Automatic Actions and Modifications of Operator Actions, Including Response Times."

ANSI/ANS-58.8 1994, "Time Response Design Criteria for Safety Related Operator Actions."

NUREG-1764, "Guidance for the Review of Changes to Human Actions."

NUREG-0711, "Human Factors Engineering Program Review Model," Revision 2.

NUREG-0800, "Standard Review Plan (SRP}," Sections 13.2.1, 13.2.2, 13.5.2.1, and 18.0.

3.0 TECHNICAL EVALUATION

3.1 Description of the Proposed Change The current LGS, Unit 1 and 2, TS LCOs require two operable and independent RHRSW subsystems, two operable and independent ESW loops, two operable and independent loops of SPC mode of RHR, and four separate and independent EDGs for a unit in Operational Condition (OPCON) 1, 2, or 3. Redundant subsystems or loops are required to perform the system's safety function and meet the single failure criteria of GDC-17, GDC-38, "Containment Heat Removal," and GDC-44, "Cooling Water." As previously discussed, the LGS UFSAR states that onsite and offsite power systems are provided in accordance with GDC-17 and the UFSAR, Section 3.1, further states that LGS meets the requirements of GDC-38 and GDC-44.

The TS allow a 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT for one of the redundant subsystems/loops described above. The purpose of the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT is to allow a temporary relaxation of the single failure criteria to perform surveillances or necessary maintenance before plant shutdown is required. Otherwise, the unit has to be in hot shutdown within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in cold shutdown within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

The proposed TS change extends the AOT for the following Unit 1 and Unit 2 Technical Specifications (TS): TS LCO 3.6.2.3 (SPC mode of RHR) Action a., TS LCO 3.7.1.1 (RHRSW)

Action a.3., TS LCO 3.7.1.2 (ESW) Action a.3, and TS LCO 3.8.1.1 (AC Sources) Actions band e.1 from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 7 days in order to allow for repairs of the RHRSW system piping.

The provisions of this TS change are applicable to each unit individually. Specifically, when in OPCON 1,2, or 3, TS LCO Action 3.7.1.1 a.3 is being revised to add the following two conditions for each Unit:

Addition to TS LCO 3.7.1.1 Action a.3 a) When the 'A' RHRSW subsystem is inoperable to allow for repairs of the 'A' RHRSW subsystem piping, with [the opposite uni~ shutdown, reactor vessel head removed and the reactor cavity flooded, the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Allowed Outage Time may be extended to 7 days once every other calendar year with the following compensatory measures established:

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1) The following systems and subsystems will be protected in accordance with applicable station procedures:

'8' RHRSW subsystem

'8' ESW loop

'8' and '0' RHR subsystems

012,014,022, and 0244 [kilovolt] kV buses and emergency diesel generators

Division 2 and Division 4 Safeguard [Direct Current] DC, and

2) The 'A' and '8' loop of ESW return flow shall be aligned to the operable '8" RHRSW return header only. The ESW return valves to the '8' RHRSW return header (i.e., .

HV-11-015A and HV-11-0158) will be administratively controlled in the open position and de-energized prior to entering the extended AOT. The ESW return valves to the

'A' RHRSW return header (Le., HV-11-011A and HV-11-011 8) will be administratively controlled in the closed position and de-energized as part of the work boundary.

b) When the '8' RHRSW subsystem is inoperable to allow for repairs of the '8' RHRSW subsystem piping with [the opposite unit] shutdown, reactor vessel head removed and the reactor cavity flooded, the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT for the applicable unit may be extended to 7 days once every other calendar year with the following compensatory measures established:

1) The following systems and subsystems will be protected in accordance with applicable station procedures:

'A' RHRSW subsystem

'A' ESW loop

'A' and 'C' RHR subsystems

011, 013, 021, and 023 4kV buses and emergency diesel generators

Division 1 and Division 3 Safeguard DC, and

2) The 'A' and '8' loop of ESW return flow shall be aligned to the operable 'A" RHRSW return header only. The ESW return valves to the 'A' RHRSW return header (i.e.,

HV-11-011A and HV-11-011 8) will be administratively controlled in the open position and de-energized prior to entering the extended AOT. The ESW return valves to the

'8' RHRSW return header (i.e., HV-11-015A and HV-11-0158) will be administratively controlled in the closed position and de-energized as part of the work boundary.

Only one of the above two Actions, either TS LCO 3.7.1.1, Action a.3.a or a.3.b, may be entered on the applicable unit in a calendar year. However, if either opposite unit TS LCD 3.7.1.1, Action a.3.a or a.3.b has previously been entered in the calendar year, then the applicable unit's Action a.3.a or a.3.b may not be entered during the same calendar year. The net effect of these usage restrictions is that the entry into an extended AOT for RHRSW piping work would be allowed a maximum of one time per calendar year for the site as a whole.

During the extended 7-day AOT specified by TS LCD 3.7.1.1 Action a.3.a or a.3.b, the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT may also be extended to 7 days for the same 7 day period for the following TS Actions:

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1) TS LCO 3.6.2.3 Action a - for one inoperable SPC loop

2) TS LCO 3.7.1.2 Action a.3 - for one inoperable ESW system loop

3) TS LCO 3.8.1.1 Action b - for two inoperable EDGs

4) TS LCO 3.8.1.1 Action e.1 - for one or more inoperable EDGs 3.2 Plant Systems and Probabilistic Risk Assessment Review An acceptable approach for making risk-informed decisions about proposed TS changes is to show that the proposed changes meet the five key principles stated in RG 1.177. The licensee endorsed this approach in their application, and the NRC staff utilized the RG 1.177 approach in its review. The five key principles are:

1. The proposed change meets the current regulations unless it is explicitly related to a requested exemption or rule change.

2. The proposed change is consistent with the defense-in-depth philosophy.

3. The proposed change maintains sufficient safety margins.

4. When the proposed changes result in an increase in core-damage frequency or risk, the increases should be small and consistent with the intent of the Commission's Safety Goal Policy Statement.

5. The impact of the proposed changes should be monitored using performance measurement strategies.

These key principles are evaluated below:

Key Principle 1 - Compliance with Current Regulations TS requirements for licensees are specified in 10 CFR 50.36(c). The licensee is not changing the LCO requirements or shutdown requirements of the current TSs or the requirements of 10 CFR 50.36(c). Therefore, the NRC staff concludes that the licensee's LAR does not deviate from existing regulations. A more detailed evaluation of 10 CFR 50.36 compliance may be found in Section 3.4 of this safety evaluation (SE).

Key Principle 2 - Defense-In-Depth Evaluation The elements of the defense-in-depth philosophy are described in RG 1.177 and RG 1.174.

Section 4.3 of the licensee's application dated March 19, 2010, provides a summary of the licensee's defense-in-depth assessment of the LAR.

Consistency with defense in depth philosophy is maintained if:

A reasonable balance among prevention of core damage, prevention of containment failure and consequence mitigation is preserved.

During the extended AOT for the unit in OPCON 1, 2, or 3:

1. One RHRSW subsystem will be inoperable, causing loss of redundancy of RHRSW.

However, the safety functions of the RHRSW system can still be performed by the remaining operable RHRSW subsystem assuming no single failure occurs during the

-8 extended AOT. The operable RHRSW subsystem will be protected in accordance with TS LCO 3.7.1.1 Action a.3.

2. One ESW loop will be inoperable because its discharge is not independent of the discharge of the other ESW loop, causing loss of redundancy of ESW. However, the safety functions of the ESW system can still be performed by the remaining operable ESW loop assuming no single failure occurs during the extended AOT. The operable ESW loop will be protected in accordance with TS LCO 3.7.1.1 Action a.3.

The staff also notes that the inoperable ESW loop is still available to perform all its functions and will be protected in accordance with a regulatory commitment controlled under the licensee's commitment management program.

3. One loop of the SPC mode of the RHR system will be inoperable because of the loss of an RHRSW heat exchanger, causing loss of redundancy of SPC. However, the safety functions of the SPC mode of the RHR system can still be performed by the remaining operable loop of the SPC mode of RHR assuming no single failure occurs during the extended AOT. The two operable RHR subsystems that are available for the operable SPC loop will be protected in accordance with TS LCO 3.7.1.1 Action a.3.

4. Two EDGs on the operating unit will be inoperable, but still available due to the normal cooling supply of ESW being inoperable, but available. The safety functions of the EDG system can still be performed assuming no single failure occurs during the extended AOT. The operable EDGs and 4 kV buses on the operating unit that power the operable RHRSW subsystem, operable ESW loop, operable RHR subsystems and the operable core spray subsystems (CSS) will be protected in accordance with TS LCO 3.7.1.1 Action a.3. The staff also notes that the EDGs and 4kV buses for the operating unit that power the inoperable but available ESW loop, RHR subsystems and CSS subsystems are still available to perform their functions and will be protected in accordance with a regulatory commitment controlled under the licensee's commitment management program.

5. The safeguard DC buses associated with the subsystems protected in TS 3.7.1.1.

Action a.3 will also be protected in TS 3.7.1.1 Action a.3. The staff also notes that the other safeguard DC buses will also be protected by a regulatory commitment controlled under the licensee's commitment management program. The licensee will also enact other compensatory measures by regulatory commitment controlled under the licensee's commitment management program during the extended outage, including precautions for adverse weather and limiting work in the switchyard.

6. The staff notes that by letter dated October 29,2010, the licensee has also made a regulatory commitment, controlled under the licensee's commitment management program, for proper standby alignment of RHRSW prior to entry into the AOT.

Additionally, flow balance verification testing will be performed in advance of the extended AOT, for each RHRSW subsystem, to demonstrate acceptable cooling flow rates are maintained for all ESW system cooled equipment when the flow from both ESW loops is returned through one RHRSW return header. This flow test is a one time test for each RHRSW subsystem, and will be performed initially, and once per 10 years thereafter, if required, to support future RHRSW piping repairs beyond the

-9 current plan of two refueling outages per unit. Completion of this testing will be a procedural pre-requisite of the special procedure controlling the RHRSW work. This testing provides an added measure of assurance that proper RHRSW/ESW system flows will be available during the maintenance window.

The emergency core cooling systems (ECCS) and the decay heat removal systems prevent core and containment damage during a design-basis accident. Although the CSS and low pressure coolant injection (LPCI) subsystems of the ECCS systems lose redundancy and require entry into TS Actions when an RHRSW return header is inoperable, the licensee did not propose any changes with their associated AOTs in this LAR because the applicable AOT is already 7 days. The high pressure coolant injection (HPCI) system of ECCS remains operable. Therefore, the ECCS safety functions are maintained.

Although the systems used for decay heat removal, (i.e. RHRSW, SPC Mode of RHR, ESW, and EDGs) lose redundancy and their AOTs are extended, the redundant subsystemslloops remain operable and protected during the extended AOT and are capable of performing the system's (RHRSW, RHR, ESW, and EDGs) safety functions.

The relaxation of redundancy as described above is currently allowed by the TS for 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . The TS change lengthens the AOT to 7 days once every other calendar year per unit, while adhering to the plant conditions and compensatory measures described previously.

This LAR does not affect liquid or gaseous radioactive effluents or filtration systems; therefore, radiological consequence mitigation is unaffected.

Based on the above described ECCS and decay heat removal systems capability and the absence of any affect on radiological mitigation factors, the staff considers that a reasonable balance among prevention of core damage, prevention of containment failure and consequence mitigation is preserved during the extended AOT.

Over-reliance on programmatic activities to compensate for weaknesses in plant design is avoided.

No additional programs or optimistic program assumptions are being relied upon to assure plant safety. NewTS action requirements (TS LCO 3.7.1.1 Action a.3) contain additional requirements that compensate for the extended AOT timeframe. The additional measures of system protection and administrative controls are concepts that the plant staff is familiar with, and trained upon. The frequency of the extended AOT is specifically limited by the TS to only be entered once per calendar year for the site.

Therefore, the staff finds that the proposed TS change would not involve an over reliance on programmatic activities.

System redundancy, independence, and diversity are maintained commensurate with the expected frequency, consequences of challenges to the system, and uncertainties (e.g., no risk outliers).

1. TS 3.7.1.1: The extension of the AOT for one inoperable RHRSW subsystem from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to up to 7 days results in a corresponding increase in the amount of time

-10 that redundancy of the RHRSW system is not available. The remaining operable RHRSW subsystem is protected as required by TS LCO 3.7.1.1.a.3.a and a.3.b. The extension of the AOT is allowed only once per year for the site. This limited frequency, short AOT extension, and protective compensatory measures provided by TS Actions are commensurate with the temporary relaxation of redundancy for RHRSW.

2. TS 3.7.1.2: The extension of the AOT for one inoperable ESW loop from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to up to 7 days results in a corresponding increase in the amount of time that redundancy of the ESW system is not available. The remaining operable ESW loop is protected as required by TS LCO 3.7.1.1.a.3.a and a.3.b. The inoperable ESW loop will be aligned to discharge to the operable RHRSW discharge header making the inoperable ESW loop available to perform its design function. The inoperable but available ESW loop and the associated inoperable but available cooling loads will remain aligned for automatic initiation and will be capable of performing their intended design function. The extension of the AOT is allowed only once per year for the site. This limited frequency and short AOT extension and protective compensatory measure provided by TS Action are commensurate with the temporary relaxation of redundancy for ESW. The NRC staff also notes that the inoperable but available ESW loop is protected by regulatory commitments under the control of the licensee's commitment management program.

3. TS 3.6.2.3: The extension of the AOT for one inoperable loop of SPC mode of RHR from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to up to 7 days results in a corresponding increase in the amount of time that redundancy of the SPC mode of RHR is not available. The remaining operable loop of the SPC mode of RHR is protected as required by TS LCO

3. 7.1.1.a.3.a and a.3.b. The extension of the AOT is allowed only once per year for the site. This limited frequency and short AOT extension and protective compensatory measures provided by TS Action are commensurate with temporary relaxation of redundancy for the SPC mode of RHR.

The LAR dated March 19, 2010, considered the loss of SPC in that it requested that the allowed AOT for TS LCO 3.6.2.3 for SPC also be extended to 7 days. Since the compensatory actions did not list the SPC and Suppression Pool Spray (SPS) loops as equipment to be protected, the NRC staff submitted a request for additional information (RAI), asking the licensee to explain why the proposed TS LCO 3.7.1.1 Actions a.3.a and a.3.b require protection of RHR subsystems and not the operable SPC and SPS loops. The staff also asked the licensee to explain the criteria used in identifying structures, systems, and components for inclusion in the list of protected equipment. In their reply dated March 23, 2011, the licensee stated that the primary focus in establishing the list of equipment and systems to protect was decay heat removal. They also stated that given the multiple functions of the RHR subsystems, the stated boundaries of the RHR subsystems, and the other equipment and subsystems listed as protected systems, the injection and spray capabilities of the RHR system are also protected. The licensee stated that this includes the SPS mode and the SPC mode of the RHR system.

The NRC staff evaluated this response as follows: First, the staff agrees that the licensee's characterization of the RHR subsystem including the SPS and SPC

- 11 modes of the RHR system, and also the injection and spray capabilities of the RHR system, is appropriate. However, the staff does not concur that the primary focus in establishing the list of equipment to protect is just decay heat removal. The staff considers that any safety-related function, where redundancy is lost as a result of the inoperable RHRSW subsystem, should be evaluated for additional protection. That evaluation would include the CSS, whose core spray pump room coolers are supplied by the inoperable ESW loop, and the control room emergency fresh air supply (CREFAS) system, whose control enclosure chillers are supplied by the inoperable ESW loop. However, the staff notes that the AOT for an inoperable CSS subsystem per TS 3.5.1 and the inoperable CREFAS subsystem per TS 3.7.2 are 7 days, which do not need to be extended to support the planned work. Therefore, additional protection for CSS and CREFAS are not warranted because the existing requirements for the licensee to assess and manage risk for the remaining operable CSS and CREFAS subsystem will be sufficient, in accordance with 10 CFR 50.65, "Requirements for monitoring the effectiveness of maintenance at nuclear power plants."

4. TS 3.8.1.1 Action b: The extension of the AOT for two inoperable EDGs from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to up to 7 days results is a corresponding increase in the amount of time that four separate and independent EDGs are not operable. But, the other EDGs that power the remaining operable RHR subsystems, RHRSW pumps, and ESW pumps are protected by TS LCO 3.7.1.1.a.3.a and a.3.b. Further, the staff notes that the EDGs that power the inoperable, but available RHR subsystems, and ESW pumps are protected by regulatory commitment under the control of the licensee's commitment management program. Similarly, to reduce risk of loss of offsite power, the switchyard will be protected in accordance with plant procedures per regulatory commitment under the control of the licensee's commitment management program.

The extension of the AOT has a limited frequency in that it is allowed only once per year for the site. The staff finds that the short AOT extension accompanied by the protective compensatory measures provided by the new TS Actions are commensurate with the limited frequency of the short AOT extension, which allows a temporary relaxation of redundancy for EDG systems. Further, the staff notes that regulatory commitments made under the control of the licensee's commitment management program provide an additional layer of assurance of safe plant operation.

During the extended AOT when Unit 2 is the operating unit, EDGs D13 and D14 are not protected by TS Action or regulatory commitment, according to the licensee's application. Per Table 8.3-3 of the UFSAR, D13 and D14 are the sole source of emergency power to some safety-related loads, Le. control room chiller and air conditioning unit, emergency switchgear and battery room air conditioner. The NRC staff notes that in this circumstance, the licensee has indicated by letter dated January 14, 2011, that one train of the CREFAS system will be inoperable due to the ESW inoperability. With one train of the CREFAS system inoperable, LGS Unit 2 TS 3.7.2, Action a.3 (not changed by this LAR), will require that a Unit 1 EDG supplying the other train of CREFAS system be restored within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months if the applicable ESW system is still inoperable at the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months point, otherwise Unit 2 will have to be in HOT SHUTDOWN within 12 additional hours and COLD SHUTDOWN within the following

- 12 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . Thus, for this specific circumstance, and regarding these particular EDGs, the current TS requirements provide appropriate actions to ensure that the safety related equipment powered by EDGs D13 and D14 are properly controlled.

5. TS 3.8.1.1 Action e.1: The extension of the AOT for one or more inoperable EDGs from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to up to 7 days results in a corresponding increase in the amount of time that two train safety-related systems are susceptible to a single failure upon a loss-of-offsite power. But, the risk of this occurring is minimized because the remaining two EDGs for the unit are operable and protected by TS LCO 3.7.1.1.a.3.a and a.3.b. Additionally, two RHR subsystems will be operable and protected by TS LCO 3.7 .1.1.a.3.a and a.3.b during this time. The extension of the AOT has a limited frequency in that it is allowed only once per year for the site. The NRC staff finds that the short AOT extension, accompanied by the protective compensatory measures provided by the new TS Actions, are commensurate with the limited frequency of the short AOT extension, and are acceptable. The staff notes that the potential for a loss of offsite power is reduced during this evolution because the switchyard will be protected in accordance with plant procedures, per regulatory commitment, under the control of the licensee's commitment management program.

Also, additional EDGs on the operating unit that are made inoperable during the extended AOT due to ESW inoperability are protected in accordance with plant procedures per regulatory commitment under the control of the licensee's commitment management program, so as to remain available to perform.

6. The 4 kV buses and division safeguard DC buses associated with the protected EDGs and the protected ESW loop, RHR, CSS and RHRSW subsystems are protected as required by TS LCO 3. 7.1.1.a.3.a and a.3.b.

The NRC staff finds that with the protection of systems described by this TS change that system redundancy, independence, and diversity are maintained commensurate with the expected frequency, consequences of challenges to the system, and uncertainties. A further discussion of electrical engineering related topics is contained in Section 3.3 of this SE.

Defenses against potential common cause failures are maintained and the potential for the introduction of new common cause failure mechanisms is assessed.

During the extended AOT when one RHRSW return header is inoperable, both ESW loops will be aligned to discharge to the operable RHRSW return header. The ESW loop that normally discharges to the operable RHRSW return header is operable. The ESW loop that normally discharges to the inoperable RHRSW return header, but is then aligned to the operable RHRSW return header is inoperable. Any active valves that could fail and disable the operable RHRSW return header will be administratively controlled in the safe position and de-energized.

A passive failure in the RHRSW return line of either valve 012-0120A or 012-0120B, such as disc separation, would be a common cause failure of both ESW loops and the only operable RHRSW subsystem. Although these valves are stainless steel construction and not likely to fail due to corrosion, the staff asked the licensee to provide additional justification that these valves will not fail closed during the extended AOT. By

- 13 letter dated March 23, 2011, the licensee stated that these valves are locked in the open position and that the only credible failure mechanism would be a separation of the valve stem from the disc. The stem and disc are connected by stainless steel keys and retaining ring, stainless steel cap screws and cover plate. Failure of the keys and cover plate and detachment of the stainless steel retaining ring would be required to detach the stem from the disc and this is not credible because corrosion would be the only failure mechanism and these parts are stainless steel. The licensee's review of their own operating experience and external operating experience for these valve types did not reveal any credible failures. Thus, the staff concludes that a failure of the operable RHRSW return header, which would cause a common failure of both ESW loops and its associated cooling loads during the extended AOT, has been assessed, and that staff agrees that such a failure is not credible during the extended AOT.

Independence of physical barriers is not degraded The physical barriers to radioactive release such as the fuel cladding, reactor coolant piping and the containment are not affected by this LAR

Defense against human errors are maintained The licensee will implement specific compensatory measures to reduce the risk of human errors. During the extended AOT, the opposite operable RHRSW subsystem and ESW loop and associated cooling loads necessary for ECCS will be protected and enforced by TS controls. The inoperable, but available ESW loop, and associated LPCI subsystems and the associated EDGs, 4kV buses and Safeguards buses will also be protected by regulatory commitment. Thus, no elective or discretionary maintenance or testing will be performed on these systems, reducing the possibility of human error causing the loss of a safety system. Other compensatory measures to reduce the possibility of human error include: suspension of activities in the switchyard of unit at power, suspension of activities in the outage unit switchyard supporting operability of its offsite source, specific shift briefs to reinforce operator performance during the extended AOT, suspension of hot work and unattended transient combustibles in key areas, and suspension of certain operational risk activities. The compensatory measures not covered by TS controls are not specifically credited in the licensee's risk analysis supporting this application, and therefore are controlled by a regulatory commitment under the licensee's commitment management program. Further discussion of the human factors associated with this application can be found in Section 3.5 of this SE. A discussion of TS versus non-TS compensatory action philosophy is contained in the Tier 2 evaluation of Key Principle 4, later in this section of the SE. The staff considers that the licensee has maintained defense against human errors in its proposed actions.

The intent of the GDC in Appendix A to Title 10 of the Code of Federal Regulations, Part 50, is maintained The design of the RHRSW and ESW systems are not changed. This change only impacts the amount of allowed out-of-service time for the subject systems, and therefore, the staff considers that the intent of the GDC is maintained with these changes.

- 14 Key Principle 3 - Evaluation of Safety Margins The proposed change does not modify or otherwise impact codes and standards that are applicable to the RHRSW system, RHR system, EDG AC systems, and ESW system. These systems are not being physically modified, and the proposed action AOT does not result in an unreasonable decrease in the availability of a redundant train of these systems.

The removal of the 'A' RHRSW subsystem from service will also temporarily eliminate the ability of the RHRSW system to support a non-TS operational mode of the RHR system. The 'A' RHRSW subsystem is designed to be able to provide water as a backup source for post accident containment spray and core flooding for Unit 2. Likewise, the removal of the '8' RHRSW subsystem from service will also temporarily eliminate the ability of the RHRSW system to support a non-TS operational mode of the RHR system. The '8' RHRSW subsystem is designed to be able to provide water for post-accident containment spray and core flooding for Unit 1. The RHRSW supply in these alignments is used for extreme emergency conditions when the RHR system cannot perform its cooling function. Since this is a non-TS function, and the probability of needing this function during the extended AOTs is judged to be low, the NRC staff considers the loss of this capability for the 7 day LCO Action time to be acceptable.

Therefore, an adequate margin of safety will be maintained.

Key Principle 4 - PRA Evaluation The evaluation presented below addresses the NRC staffs philosophy of risk-informed decision making, that when the proposed changes result in a change in CDF or risk, the increase should be small and consistent with the intent of the Commission's Safety Goal Policy Statement.

Tier 1: PRA Capability and Insights The first tier evaluates the impact of the proposed changes on plant operational risk. The Tier 1 staff review involves two aspects: (1) evaluation of the validity of the LGS PRA models and their application to the proposed changes, and (2) evaluation of the PRA results and insights based on the licensee's proposed application.

The objective of the PRA quality review is to determine whether the LGS PRA used in evaluating the proposed changes is of sufficient scope, level of detail, and technical adequacy for this application. The staff review evaluated the PRA quality information provided by the licensee in their submittal, including industry peer review results and self-assessments performed by the licensee.

PRA Quality - Internal Events Model The LGS PRA model, identified as revision LG108A (Unit 1) and LG208A (Unit 2), addresses both CDF and LERF for internal events at full power. The model includes the specific RHRSW and ESW components which are inoperable or in an abnormal alignment under the proposed TS changes, including the ESW return paths to RHRSW, the RHRSW loops and the RHRSW pump legs.

The licensee has processes for configuration control of the PRA model to reflect plant modifications and procedure changes, and identified eight outstanding plant changes as not yet

-15 incorporated into the LGS PRA model. One change involves an enhancement to the level of detail of the reactor protection system logic models which is unrelated to the RHRSW evaluations and would therefore be insignificant. For three changes, the current PRA model is conservative and so there would be no adverse impact on the risk calculations.

Four of the changes involve modifications not yet installed in the plant. By letter dated October 29, 2010, the licensee identified that three of the four modifications were either cancelled or were contingency changes which were either voided or otherwise completed without the change being installed as the contingencies were determined to not be needed. The fourth modification involved the "C" Standby Liquid Control system pump automatic start feature. The licensee conservatively evaluated the impact of this modification and demonstrated a negligible quantitative impact on this application. Therefore, the licensee has dispositioned all outstanding known plant changes for this application.

Appropriately low truncation levels of 1E-11 for CDF and 1E-12 for LERF were applied to generate the results for this application.

The LGS PRA model was subject to an industry peer review in November 1998, and the significant findings were resolved by a 2001 model update. A gap assessment was conducted in 2003 to assess the PRA model against the American Society of Mechanical Engineers (ASME) PRA Standard. Subsequent to this, in July 2004 LGS PRA model was assessed by the NRC staff as a pilot for RG 1.200, and another model update completed in 2005 to address identified gaps. In October 2005, the LGS PRA model was subject to a peer review using the ASME PRA Standard, Addendum B, and a focused scope peer review for an updated internal flooding analysis was completed in May 2008.

The NRC has previously reviewed the LGS PRA internal events model to support a license amendment for implementation of a Surveillance Frequency Control Program in September 2006.

The licensee submitted a list of all findings from its 2005 and 2008 peer reviews for which the supporting requirement from the standard was either not met or met at Capability Category I instead of II, and provided a disposition of each item for this application. Many of the findings have been previously addressed and closed out in the most recent update of the PRA models, and the staff review focused on the remaining open findings and the impact on this application, as discussed below:

Issue IE-A?: Plant-specific operating experience was not reviewed for initiating event precursors. The licensee stated that the scope of initiating events in its PRA models is thorough and consistent with other industry boiling water reactor (BWR) PRAs, and that a precursor review would have only a potentially minimal impact since the model already includes a full range of initiators.

Issue SY-A 12: Flow diversion pathways may not be thoroughly considered in the system success criteria. The licensee stated that the one flowpath identified by the peer review team was added to the system logiC model in the most recent model update, and that diversion paths were considered during the development of all system models. Flow diversion pathways are considered for ESW and RHRSW, and for many other systems, and small contributors to system unreliability. This is consistent with the fact that such failures involve spurious valve

- 16 operations or failure of one or more valves to isolate, and such failure modes are not typically significant to system unreliability.

Issue HR-A 1: A formal review of procedures and practices for testing and maintenance has not been done to identify pre-initiator alignment errors. The licensee stated that for the plant systems relevant to this application (RHRSW), pre-initiator events are included in the model, and that compensatory measures to confirm system alignment of RHRSW and ESW prior to entering the extended AOT will be in place per associated commitments.

Issues DA-C6, DA-C7: Plant-specific information is not used for component demands and unavailability, but is instead estimated from a plant database. The licensee identified a minimal impact based on its assessment that the deficiency associated with requirement DA-C6 still provides a reasonable estimate of the plant reliability response. The licensee also indicated that the deficiency associated with requirement DA-C7 is due to the specific approach taken for data collection, but is still an accurate assessment. The licensee believes the intent of these supporting requirements is achieved, and that the unavailability data used in the PRA model reasonably reflect the as-operated plant.

Issue IF-B3: The characterization of internal flooding sources did not include the capacity.

temperature and pressure of the source. The licensee identified a minimal impact on the application because internal flooding sources are low temperature, screening of scenarios did not consider capacity of the source, and internal flooding was not a significant contributor to the application risk.

Issue IF-C2b: Drains were not accounted for estimating flood impacts. The licensee identified a minimal impact on the application because internal flooding was not a significant contributor to the application risk.

Issue IF-E5a: Existing operator actions were not reassessed for internal flood scenarios. The licensee identified that this was done for major flood contributors, but other scenarios were left in the model as bounding scenarios. This deficiency has minimal impact on the application because internal flooding was not a significant contributor to the application risk.

In addition to the above issues, the licensee also identified peer review findings where the supporting requirement was still satisfactorily met at Capability Category II. The staff reviewed these items and found that they would not have any significant impact on the risk analyses supporting this application.

Based on consideration of the gaps to Capability Category II of the PRA standard and their disposition for this application, the NRC staff finds that the quality of the LGS internal events PRA is sufficient to support the risk evaluation provided by the licensee in support of the proposed license amendment.

PRA Quality - Internal Fires Model The licensee used a PRA analYSis to evaluate internal fires. The model is an update of the Individual Plant Examination of External Events (IPEEE). The first update was made in 2002 to develop an analysis with supporting documentation to facilitate updates and applications.

Further updates were made in 2007 to include specific area analyses, requanti'fication with the

- 17 existing internal events PRA model, and cable analyses for the control rod drive hydraulic system. The fire PRA includes both units, and the models reflect the as-built plant.

The fire PRA model includes a full scope representation of more than 100 fire compartments and the yard area. The selection of the global plant analysis boundary and the criteria for including or excluding plant areas are consistent with the current industry guidance (NUREG/CR-6850). No fire compartments were screened from final quantification, and therefore the scope of areas evaluated is sufficient for this application.

The submittal identified four areas where the fire PRA would require changes to address current technical issues. The licensee dispositioned these areas for this application as follows:

Multiple Spurious Operations (MSO): The licensee is addressing MSOs in accordance with current industry guidance, and has identified plant-specific applicable MSOs. These were entered into the corrective action program, and alternate compensatory measures are in place as per the guidance of Regulatory Issue Summary 2005-07, "Compensatory Measures to Satisfy the Fire Protection Program Requirements."

Instrumentation: The fire PRA does not explicitly account for the availability of plant instrumentation to assure that fire scenarios which rely upon an operator response do not also involve damage to the instrumentation needed to cue the response. The licensee identified that its safe shutdown program assures at least one unaffected instrument channel, and that plant procedures identify which instrument channels are not affected by a fire in a specific area.

Iterations: The LGS fire PRA has only undergone limited refinements of the fire scenarios, which retains conservatism in the PRA results. The licensee has performed a bounding analysis to demonstrate that such conservatisms would not significantly impact the results for change in risk.

Multi-compartment Analysis: The licensee identified the LGS plant layout and the reliability of the existing fire barriers (such as penetration seals and doors) ensure that the lack of a multi-compartment analysis would be a negligible impact on fire PRA results.

Based on the conservative assumptions applied to the analysis, and the licensee disposition of limitations in their existing fire PRA for this application, the NRC staff finds that the licensee's scope of analysis and methodology applied is acceptable for this application, and has satisfied the intent of RG 1.177 (Sections 2.3.1, 2.3.2, and 2.3.3), RG 1.174 (Section 2.2.3 and 2.5), and SRP Chapter 19.1, and that the quality of the fire risk analyses and methods applied is sufficient to support the risk evaluation provided by the licensee in support of the proposed license amendment.

PRA Quality - Seismic and Other External Hazards The licensee did not apply a seismic or other external hazards PRA to the evaluation of risk for this application, but instead provided a qualitative justification that the contribution of these hazard groups is not significant to the decision. The NRC staff evaluation of these justifications

-18 is provided below (Qualitative Evaluation of Seismic Risk and Qualitative Evaluation of Other External Events Risk).

PRA Risk Results and Insights The RHRSW and ESW systems are modeled in the PRA as impacting mitigation of initiating events, and therefore the RHRSW outage can be directly modeled in the PRA by assuming it is unavailable and unrecoverable. The ESW return alignment to the opposite train can also be modeled directly in the PRA. Unavailability of other plant equipment at their nominal average values is assumed, except for the specific equipment required to be available by TS during the period when the RHRSW train is inoperable.

The ICCDP and ICLERP are based on the entire 7-day duration of the proposed extended AOT.

The licensee's methodology is consistent with the guidance of RG 1.177, Section 2.3.4 and Section 2.4 and is, therefore, acceptable to the staff.

The licensee presented risk results for internal events and for internal fire events. The results are as follows:

Risk Measure Internal Events Internal Fires TOTAL ICCDP 7.61 E-S (Unit 1 - train A) 5.16E-7 (Unit 1 - train A) 5.92E-7 (Unit 1 - train A) 7.9SE-S (Unit 1 - train 8) 1.31 E-6 (Unit 1 - train 8) 1.39E-6 (Unit 1 - train 8) 7.71 E-S (Unit 2 - train A) 5.95E-7 (Unit 2 - train A) 6.72E-7 (Unit 2 - train A) 7.9SE-S (Unit 2 - train 8) 1.14E-6 (Unit 2 - train 8) 1.22E-6 (Unit 2 - train 8)

ICLERP 1.15E-10 (Unit 1 - train A). Not evaluated, determined Since fire contribution evaluated not significant. as not significant, total is the 6.81E-10 (Unit 1 -train 8) same as internal events results.

6.69E-10 (Unit 2 - train A) 1.2SE-10 (Unit 2 - train 8)

ACDF S.13E-S/year (Unit 1) 9.50E-7/year (Unit 1) 1.03E-6/year (Unit 1)

S.1SE-S/year (Unit 2) 9.06E-7/year (Unit 2) 9.8SE-7/year (Unit 2)

ALERF 4.15E-10/year (Unit 1) Not evaluated, determined Since fire contribution evaluated not significant. as not significant, total is the 4.16E-10/year (Unit 2) same as internal events resuHs.

The difference in fire ICCDP for trains A and 8 for each unit is due to the specific train dependency of the safety relief valve (SRV) DC power supplies, which results in fewer available success paths when RHRSW train '8' is out of service compared to train 'A'.

The licensee did not explicitly provide an estimate of the LERF metrics associated with fire initiating events. Due to the nature of the RHRSW function in mostly providing for long term containment heat removal, there is limited impact on LERF, as demonstrated by the internal events PRA calculations. The accident scenarios contributing to the change in CDF from fires are not expected to be substantially different than from internal events with respect to

- 19 containment performance, and so the increase in LERF due to fires is not expected to be significant.

The aCDF and aLERF are determined by assuming a frequency for entry into an extended AOT once per year, for each unit, according to the licensee's March 19, 2010, application. This adds a measure of conservatism to the analysis because the TSs will limit the use of the extended AOT to once every other calendar year per unit, or once per year for the site as a whole.

Per RG 1.174, the acceptance guidelines for aCDF and aLERF are 1E-6/year and 1E-7/year, respectively, for very small changes in risk. Changes greater than these values, but below 1E-5/year aCDF and 1E-6/year aLERF may be acceptable provided the total CDF and total LERF are below 1E-4/year and 1E-5/year, respectively.

The licensee's estimate of aCDF of 1.03E-6/year (Unit 1, most limiting) only slightly exceeds the criteria for a very small risk increase, but is well below the criteria for a small risk increase assuming the total CDF is below 1E-4/year. The licensee reported a baseline CDF of 3.2E-6/year for internal events and 1.43E-5/year for fires (Unit 2 limiting), for a total CDF from these hazard groups of approximately 1.BE-5/year, which is well below the criteria of 1E-4/year.

Based on the results of the licensee's IPEEE and the NRC staff review, high winds, floods, and other hazards were screened out as significant hazards based on design conformance to the Standard Review Plan. For seismic events, the licensee's IPEEE and staff review found no seismic vulnerabilities. Although the total risk contribution from these hazard groups is not quantified, there are no vulnerabilities from these hazard groups, and the total risk from the quantified hazards is well below the 1E-4/year criteria.

The internal events aLERF is a more than factor of 100 below the acceptance guidelines for very small changes. No unique fire impacts were identified which would impact the containment function, and so aLERF due to fire is not expected to be significant.

Per RG 1.177, the acceptance guidelines for ICCDP and ICLERP are 5E-7 and 5E-B, respectively, applicable to permanent changes to the TS. The licensee's estimate of total ICCDP of 1.39E-6 (Unit 1 - train B, most limiting) is not consistent with the guidance, while the internal events ICLERP of 6.B1 E-10 (Unit 1 - train B, most limiting) is more than a factor of 100 below the guidance. As noted above, LERF is not significant for this configuration. The purpose of the ICCDP and ICLERP guidelines is to assure that each individual entry into a TS action results in a very small risk increase, such that the use of the action over time does not result in significant increases in risk. This should be applied to proposed TS changes which do not explicitly restrict the frequency of entry into the action requirements. Since the licensee has proposed to specifically limit the frequency and conditions for which the extended AOT may be applied, there is not a staff concern, and therefore the ICCDP and ICLERP guidelines are not considered relevant to this change.

Qualitative Evaluation of Seismic Risk The licensee performed a bounding quantitative assessment of the impact of seismic events on CDF. The approach used was to partition the frequency of seismic events based on their plant impact, and evaluate the conditional core damage probability given the level of equipment damage. The plant impacts evaluated included a range of loss-of-coolant break sizes, a non recoverable loss of offsite power, and a loss of the condenser heat sink, based on the

- 20 magnitude of the postulated seismic event (loss of condenser heat sink was always assumed).

Bounding analyses were performed to evaluate the seismic contribution to the change in risk associated with the proposed TS configuration during the RHRSW outage. The analyses demonstrated that the impact was about 1 percent of the acceptance guidelines, and so seismic risk contributions were determined to be insignificant for this application.

Based on these considerations, the NRC staff concludes that seismic risk is not a significant contributor to the change in risk during the RHRSWoutage.

Qualitative Evaluation of Other External Events Risk The licensee qualitatively evaluated other external events, such as external floods and fires, high winds, and nearby facility accidents. The design of the LGS facility meets NRC's 1975 Standard Review Plan criteria for these types of events, so there are no unique plant-specific vulnerabilities. The licensee also provided its assessment of the role of RHRSW and supported systems in mitigation of these types of events. There is no unique important role of the RHRSW system, and given the robust design of the plant, the risk of these events are not significant to this application.

Shutdown Risk The licensee's submittal did not specifically address shutdown risk in the tier one risk evaluation, since the proposed change to TS is implemented for the unit operating at power.

The TSs applicable to the shutdown unit are unchanged. Avoided shutdown risk was conservatively not considered in the evaluation.

Uncertainty Analysis The licensee provided a detailed evaluation of uncertainties associated with the internal events CDF metrics. Uncertainties associated with LERF were not evaluated in detail due to the substantial margin between the calculated LERF associated with this application and the acceptance guidelines. Similarly, the licensee identified conservatisms in the fire PRA evaluation and did not perform a detailed uncertainty evaluation of the results.

The method employed first identified the significant contributors to risk for each planned configuration of the RHRSW and ESW systems. This involved evaluation of the significant accident classes, initiating events, and basic events corresponding to plant components and failure modes which dominate the configuration-specific risk profile. The inSights obtained from these reviews were used to identify compensatory measures to be implemented during the extended outages, as discussed in the Tier 2 evaluation, below.

An evaluation of parametric uncertainty was then performed using a Monte Carlo calculation to evaluate the mean value of CDF, compared to the point estimate of the mean used to assess the change in risk. The results showed a very small increase in the CDF value above the pOint estimate, and so demonstrated that the risk metrics are acceptable.

Model uncertainty was next evaluated using the guidance of Electric Power Research Institute Report 1016737, Treatment of Parameter and Model Uncertainty for Probabilistic Risk Assessments," dated December 2008, and NUREG-1885, "Guidance on the Treatment of

- 21 Uncertainties Associated with PRAs in Risk-Informed Decision Making." The method involves the identification of significant contributors to uncertainty for the application and evaluation of these uncertainties by sensitivity studies. Two sources of uncertainty, RHRSW alignment errors (pre-initiator) and EDG maintenance configurations, were identified as potential key sources of uncertainty, and were addressed by compensatory measures. Other sources of uncertainty were screened except for uncertainty associated with operator actions. These were evaluated in sensitivity analyses using the 95th percentile human error probabilities (typically a factor of 2 to 4 above the nominal value) and recalculating the risk metrics for CDF. The licensee identified an expected increase in the calculated CDF and ICCDP for the application, but that no new insights were identified.

Finally, completeness uncertainty was evaluated. The risk analyses addressed internal events and fires, while seismic and other external events were qualitatively evaluated and screened as inSignificant to this application. Therefore, there is no significant completeness uncertainty that would impact the results of this application.

Tier 2: Avoidance of Risk-Significant Plant Configuration The licensee identified certain compensatory measures to be implemented during any extended RHRSW outage. The following describes, in summary manner, the scope of these compensatory measures:

Verification of proper alignment of remaining operable RHRSW train

Prohibition of switchyard activities

Restriction of operational risk activities

Confirmation of favorable weather forecast

Shift briefings on important operator actions

Walkdowns for control of transient combustibles and prohibition of hot work in fire risk significant areas By letter dated October 29, 2010, the licensee identified these commitments as not being specifically credited in the risk evaluation. Hence the treatment of these actions as regulatory commitments, under the control of the licensee's commitment management program, is acceptable to the NRC staff. The NRC staff has reviewed the licensee's methodology for tier two and concluded that it is consistent with the guidance of RG 1.177, Section 2.3 and Section 2.4 and is, therefore, acceptable.

Tier 3: Risk-Informed Configuration Risk Management The licensee identified its Configuration Risk Management Program (CRMP) ensures that the risk impact of equipment out of service is appropriately evaluated prior to performing any maintenance activity. The program provides for proceduralized risk-informed assessment of equipment unavailability using a blended approach of defense-in-depth and PRA inSights, and requires assessment for both planned and unplanned activities, including emergent conditions resulting in configurations not previously assessed.

The licensee's methodology for tier three is consistent with the guidance of RG 1.177, Section 2.3.4 and Section 2.4 and is, therefore, acceptable to the NRC staff.

- 22 The risk impact of the proposed 7-day AOT for RHRSW piping repair outages, as reflected in t..CDF, t..LERF, ICCDP, and ICLERP, is reasonably consistent with the acceptance guidelines specified in RG 1.174, RG 1.177, and staff guidance outlined in Chapter 16.1, "Risk-Informed Decisionmaking: Technical Specifications," of NUREG-0800. The Tier 2 evaluation identified the applicable risk-significant plant equipment outage configurations needing compensatory measures that will be implemented by the licensee prior to and during the RHRSW outage. The licensee's CRMP satisfies the CRMP guidance of RG 1.177. Therefore, the NRC staff finds that the risk analysis methodology and approach used by the licensee to estimate the risk impacts and manage configuration risk during the extended RHRSW outage are reasonable and of sufficient quality.

Key Principle 5 - Performance Measurement Strategies RG 1.174 and RG 1.177 establish the need for an implementation and monitoring program to ensure that extensions to TS AOTs do not degrade operational safety over time and that no adverse degradation occurs due to unanticipated degradation or common cause mechanisms.

An implementation and monitoring program is intended to ensure that the impact of the proposed TS change continues to reflect the reliability and availability of systems, subsystems, and components impacted by the change. RG 1.174 states that monitoring performed in conformance with the Maintenance Rule, 10 CFR 50.65, can be used when the monitoring performed is sufficient for the SSCs affected by the risk-informed application. In this application, the NRC staff agrees with the licensee that monitoring under the maintenance rule fulfills this key principle.

3.3 Electrical Engineering Review 3.3.1 Background The two independent offsite electric power source connections to LGS are designed to provide reliable power sources for plant auxiliary loads and the engineered safeguard loads of both units. An alternate independent, but currently not connected, 13 kilo Volt (kV) offsite source, available as a potential source, can be connected to supply the engineered safeguard loads of both units in the event of the loss of one of the connected offsite power sources. Plant startup power, which is the preferred power for the engineered safeguard systems, is provided from two independent offsite power sources. The power for the engineered safeguard systems can also be provided from the alternate offsite source. The three sources are as follows:

a. 220-13 kV transformer connected to the 220 kV substation

b. A 13 kV tertiary winding on the 500-220 kV bus tie autotransformer

c. 66-13 kV transformer connected to the 66 kV Crornby-Moser Tie line Each of the three sources of offsite power, including transmission lines and transformers, have sufficient capacity to supply all connected loads including loads that may be automatically transferred to them when a LOCA in one unit coincides with a safe shutdown in the remaining unit. The design and configuration of the offsite power system with provisions for periodic testing are in full conformance with GDC-5, GDC-17 and GDC-18, and Regulatory Guide 1.32 (1977) and Regulatory Guide 1.93 (1974). In the event of a loss of offsite power (LOOP), eight

- 23 onsite independent EDGs (four EDGs per unit) provide the standby power for all engineered safeguard loads.

As described in the LGS UFSAR Section 8.3.1.1.3, the onsite Class 'I E power system includes a standby power supply for each division consisting of one EDG set complete with accessories and fuel storage and transfer systems. Each EDG is connected to one 4 kV Class 1E bus.

Each EDG set is operated independently (from the other sets) and is disconnected from the utility power system, except during tests. Each unit has four channels of standby power supply and four load divisions. The LGS UFSAR states that with the exception of the standby power supply requirements for the ESW system, the RHRSW system, the standby gas treatment system, the controlled structure chilled water system and the control room and control structure ventilation systems, which are common systems, that the operation of three out of four channels of the standby power supply in each unit is adequate to satisfy the minimum Class 1E load demand caused by a loss-of-coolant accident (LOCA) or LOOP sources. Common loads for the ESW and the RHRSW systems are split between Unit 1 and Unit 2 standby power supplies.

According to the LGS UFSAR Section 8.1.3, any combination of three-out-of-four divisions (EDGs) is acceptable, assuming a single failure. ECCS requirements are met assuming 2 out of 4 EDGs are operable.

The EDGs are capable of supplying power to the loads necessary to shut down and cool down the associated unit safely. Each EDG is rated at 2850 kilo Watts (kW) for continuous operation and at 3135 kW for 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of short-time operation in any 24-hour period. The EDGs are selected so that their ratings satisfy the requirements of Regulatory Guide 1.9, as discussed in Section 8.1.6.1.2 of the LGS UFSAR. In addition, the EDGs are capable of operating for extended periods of time at either low load or unloaded in the case of a LOCA occurring with the availability of offsite power.

3.3.2 Evaluation The NRC staff requested that the licensee explain how it will maintain defense-in-depth or any contingency backup provisions that can be staged for cooling of the EDGs by the ESW alignment for the purpose of maintaining the availability of emergency AC power by EDGs. In its response, the licensee stated that with one RHRSW retum header disabled for piping replacement, the associated ESW loop will be aligned to the operable RHRSW return header such that both ESW loops and one RHRSW loop would rely on the operable RHRSW return header for a flow path to the spray pond. The possibility of a single active failure rendering the ESW system inoperable will be eliminated by de-energizing the ESW loop return isolation motor operated valve in their safe position. Although the ESW system will meet single active failure criteria in this alternate alignment, the ESW system no longer meets the intent of GDC-44 for suitable redundancy and separation to prevent impairment of safety function assuming a passive failure. For this reason, the licensee stated that it would administratively declare the ESW loop that is not aligned to its normal RHRSW return header inoperable and enter the TS ACTION for a single ESW loop inoperable. The licensee also stated that associated components cooled by the inoperable ESW loop would be declared inoperable. The ESW loop and associated components cooled by the ESW loop would be considered inoperable but would remain aligned for automatic initiation (i.e., they would be expected to operate on demand and provide the required cooling and power).

- 24 With one train of ESW declared inoperable, two EDGs will remain operable on the operating unit to satisfy ECCS requirements. As previously described, while in the extended AOT, and with two EDGs declared inoperable, the single failure criteria will not be met. To compensate for the longer duration of the allowed AOT, the licensee will protect the two operable EDGs on the operating unit as well as the EDGs on either unit that supply the protected RHRSW train.

Protection means that all elective maintenance, discretionary maintenance, and testing will be suspended during the period of reliance on the extended AOTs. For the shutdown unit, with one train of ESW declared inoperable, two EDGs will remain operable and no changes are proposed to the TS applicable to OPCONs 4 and 5 (AC Sources, lCO 3.B.1.2) for this LAR.

Hence, the limitations specified in TS 3.B.1.2.a apply if less than two EDGs are operable on the shutdown unit.

In Attachment 4 of its letter dated October 29,2010, the licensee provided revised non-TS contingent compensatory measures as regulatory commitments. The licensee stated that these additional compensatory measures would be included in a special procedure specifically governing plant operation while in the extended AOTs. According to the licensee, the at-power unit switchyard will be protected in its entirety and the equipment in the outage unit switchyard supporting operability of its offsite source will be protected during RHRSW subsystem piping repairs. Also, certain electrical equipment will be protected and available during extended AOTs. These regulatory commitments also include provisions to examine the extended weather forecast to ensure that severe weather conditions that would threaten the loss-of-offsite power are not predicted prior to entry into the AOT and shift briefs to reinforce other potentially important operator actions associated with the performance of the extended AOT. The NRC staff reviewed these non-TS contingent compensatory measures and finds them to be appropriate, including their control under the licensee's commitment management program.

The NRC staff questioned the licensee regarding contact with the system load dispatcher prior to starting this maintenance to ensure no significant grid perturbations are expected during the extended AOT. In response, the licensee stated that contacting the system load dispatcher prior to starting the maintenance window, and during the early stages of the window, allows for the forecast of grid instability to be considered in the decision to either continue into the maintenance window or to halt the work prior to the start of pipe removal. Once the maintenance window extends beyond the start of pipe removal, maintaining contact with the system load dispatcher will serve to heighten the awareness of the operators to the potential of a loss of offsite power due to grid instability. The licensee stated that this will be controlled by the special procedure for the RHRSW repair. The NRC staff agrees that the procedural controls described over the contact with the load dispatcher are appropriate.

3.3.3 Electrical Engineering Conclusion Based on the above evaluation, the NRC staff finds the proposed changes to be reasonable and acceptable, and in compliance with the applicable regulations.

3.4 Technical Specification Review 3.4.1 Background During the review of the March 19, 2010, LAR, the NRC staff identified three concerns with the originally proposed extension of the AOT from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 7 days through an added footnote:

- 25

1. The footnotes extending the AOT were ambiguous in that each stated that the AOT "may be extended .. .for up to a period of 7 days .... " This could have been interpreted as a 7-day extension of the 72-hour AOT, for a 10-day total.

2. The footnotes in each LCO action requirement identify that the extended AOT may be applied once per calendar year "for one unit only," and also specify the status of the "opposite unit." Since the TSs are unit-specific, the references to the other unit are vague.

3. In the proposed TS changes, the reference to the compensatory measures referred to the NRC staffs safety evaluation authorizing this change. Since the compensatory measures are part of the operating restrictions for extending the AOT, it would be more appropriate to identify the compensatory measures in the TSs, and not in an external reference.

These concerns were communicated to the licensee in a request for additional information. On October 29, 2010, the licensee submitted a supplement to their license amendment request that revised the footnotes forTS 3.6.2.3, TS 3.7.1.1, TS 3.7.1.2, andTS 3.8.1.

The NRC staff has reviewed the revised and converted footnotes, and concluded that the wording "may be extended to 7 days" is more explicit and is no longer ambiguous. The new TS 3.7.1.1 sub-actions are no longer vague because they identify: (1) which RHRSW subsystem is being repaired; (2) which specific unit is shutdown; and (3) provide a clear requirement that the AOT can only be extended once every other calendar year. The revised TS 3.6.2.3, TS 3.7.1.2, and TS 3.8.1 footnotes are no longer vague because they refer to the requirements in TS 3.7.1.1 Actions a.3.a and a.3.b. The new TS 3.7.1.1 sub-actions require the compensatory measures to be established in order to extend the AOT and they appropriately state what compensatory measure actions are required.

3.4.2 Technical Specification Conclusion As indicated in the regulatory evaluation section of this SE, 10 CFR 50.36( c)(2)(i) states that TS will contain LCOs which "are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When a limiting condition for operation of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met." The current TS 3.6.2.3, TS 3.7.1.1, TS 3.7.1.2, and TS 3.8.1 LCOs meet the requirements of 10 CFR 50.36. The proposed changes add an extension of the affected AOTs from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 7 days through (1) a footnote in TS 3.6.2.3, TS 3.7.1.2, and TS 3.8.1, and (2) sub-actions in TS 3.7.1.1. The NRC staff has determined that the addition of a footnote and sub-actions to TS, 3.6.2.3, TS 3.7.1.2, TS 3.8.1, and TS 3.7.1.1 respectively, is consistent with, and meets the requirements of 10 CFR 50.36.

- 26 3.5 Human Factors Review 3.5.1 Staffing The licensee does not plan to augment its operating staff as a compensatory measure for the proposed amendment. In its letter dated October, 29, 2010, the licensee indicated that normal outage-level staffing would be in place via normal work control processes and that a commitment to provide additional staff was not needed. Based on the compensatory actions that the licensee proposes to reduce operator workload, simplify configuration control, and minimize potential sources of human error, the NRC staff agrees that normal outage staffing will be adequate during the proposed extended AOT.

3.5.2 Operator Actions The licensee provided a list of the tasks proposed to be performed by plant personnel. These tasks included:

1. Protection of various systems and operability confirmations;

2. Verification of the proper standby alignment of the RHRSW subsystem not impacted by the maintenance activities;

3. Verification of availability of specified plant equipment;

4. Shift briefings will be performed to reinforce other potentially important operator actions associated with the performance of the extended AOT;

5. Shift briefings and pre-job walkdowns to reduce and manage transient combustibles prior to entrance into the extended AOT; and

6. Flow alignment and administrative controls of key valve positions.

The NRC staff reviewed the proposed operator actions and concludes that they are not atypical of tasks that would be routinely performed by properly trained plant operators, and therefore are within the operators' capability to complete.

3.5.3 Time Available for Operator Action The extended AOT will provide additional time to implement RHRSW subsystem piping repairs.

This should reduce time pressure during the repairs, which should facilitate improved operator and maintenance personnel performance resulting in reduced errors. Compensatory actions are generally not time-constrained, consisting mainly of pre-job alignments, briefings, pre requisites, and other activities that are performed as entry conditions to the extended AOT.

Emergency actions, if needed, will be controlled by the site Emergency Operating Procedures (EOPs) which have been validated to be within the capability of operators to perform within the time constraints assumed in the design-basis analysis. Based on the fact that the compensatory actions are not time constrained and any necessary emergency actions have been validated as part of the EOP program, the NRC staff concludes that that the proposed

- 27 operator actions are within the operators' capability to complete within the time constraints used in the analysis.

3.5.4 Training and Procedures Required system alignments and alignment verifications and other actions credited to minimize the impact to plant safety during the extended AOTs will be contained in a special procedure.

The special procedure will include:

new proposed actions required by the revised TS LCO 3.7.1.1; identification of the equipment to be protected during the RHRSW piping repairs;

confirmation that the ESW flow balance verification testing has been performed prior to the work activity;

contacting the load dispatcher prior to and during early stages of the work activity to determine grid stability;

guidance to alert operators of the need to remotely, manually align the spray isolation valves from the winter bypass flow path to the spray networks; and

revised compensatory measures as described in Attachment 4 to the licensee's October 29,2010, letter.

This special procedure will be used in conjunction with existing plant procedures to provide control room operators with the necessary guidance to safely manage the units during the extended AOTs. Procedures are already in place that address safe plant shutdown and decay heat removal in situations like those in the proposed AOTs. During the 'A' RHRSW subsystem outage, since some of the normally operated equipment from the remote shutdown panel will not be available, alternate means of performing a remote plant shutdown will be available by operating equipment locally/remotely in accordance with a station procedure.

Operations personnel are qualified by normal periodic training to respond to and mitigate design-basis accidents, including the actions needed to ensure decay heat removal while the units are in the operational configurations like those described within the licensee's LAR submittal. Additionally, shift briefings will be provided to assure that the operating staff is fully aware of the plant configuration and actions that may be needed in order to respond to problems that could arise during the proposed AOT extensions for performing repairs of one RHRSW subsystem piping.

Based on the compensatory actions that will be taken, including development of a special procedure and shift briefings to remind operators of actions that may be necessary due to the unusual configuration of the plant, the NRC staff finds the licensee's proposed actions regarding procedures and training to be acceptable from a human factors perspective.

- 28 3.5.6 Equipment and Environmental Conditions The licensee indicated that no changes, additions, or deletions of control room displays and controls are needed. Regarding environmental concerns, the licensee stated that the general plant areas that must be accessed to remotely operate ESW, RHRSW, and RHR pumps and valves are not in areas in which environmental conditions will preclude access and will not have special access requirements. Based on this information, the NRC staff concludes that there are no equipment and environmental conditions that would prohibit proper performance of the compensatory actions proposed in support of this license amendment.

3.5.7 Human Factors Conclusion The NRC staff has reviewed the licensee's planned compensatory measures for the proposed AOT extension. The staff concludes that the licensee has adequately considered the impact of the proposed license amendment on operator staffing, procedures, equipment, and associated training. The information provided by the licensee establishes reasonable assurance for allowing credit for the proposed actions. Therefore, the NRC staff finds the operator performance aspects of the licensee's proposed LAR acceptable.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Pennsylvania State official was notified of the proposed issuance of the amendment. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendments change a requirement 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 May 18, 2010 (75 FR 27828). Accordingly, the amendment meets 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 amendment.

6.0 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) such activities will be conducted in compliance with the

- 29 Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: K. Bucholtz A. Howe G. Lapinsky G. Purciarello P. Sahay P. Bamford Date: July 29,2011

July 29, 2011 Mr. Michael J. Pacilio President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LIMERICK GENERATING STATION, UNITS 1 AND 2 -ISSUANCE OF AMENDMENTS RE: ALLOWED OUTAGE TIME EXTENSIONS TO SUPPORT RESIDUAL HEAT REMOVAL SERVICE WATER MAINTENANCE (TAC NOS.

ME3551 AND ME3552)

Dear Mr. Pacilio:

The U.S. Nuclear Regulatory Commission (NRC or the Commission) has issued the enclosed Amendment No. 203 to Facility Operating License No. NPF-39 and Amendment No. 165 to Facility Operating License No. NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, respectively. The amendments are in response to your application dated March 19,2010,1 as supplemented by additionalletters. 2 The amendments consist of changes to the Technical Specifications of each unit extending the allowed outage time for the Suppression Pool Cooling mode of the Residual Heat Removal system, the Residual Heat Removal Service Water (RHRSW) system, the Emergency Service Water system, and the [Alternating Current] AC. Sources - Operating from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 7 days, under certain conditions, in order to allow for repairs of the RHRSW system piping.

A copy of the Safety Evaluation is also enclosed. The Notice of Issuance will be included in the Commission's biweekly Federal Register notice.

Sincerely,

/raJ Peter Bamford, Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-352 and 50-353

Enclosures:

1. Amendment No. 203 to License No. NPF-39

2. Amendment No. 165 to License No. NPF-85

3. Safety Evaluation cc w/enclosures: Distribution via Listserv DISTRIBUTION:

PUBLIC RidsNrrDorlLpl1-2 Resource RidsNrrPMLimerick Resource RidsNrrLAABaxter Resource RidsNrrDorlDpr Resource LPL1-2 RtF RidsRgn1MailCenter Resource RidsAcrsAcnw_MailCTR Resource RidsNrrDraApla Resource RidsOgcRp Resource RidsNrrDeEeeb Resource RidsNrrDirslhpb Resource RidsNrrDssSbpb Resource RidsNrrDirsltsb Resource AHowe, NRRtAPLA PSahay, NRR GLapinsky. NRR KBucholtz, NRR GPurciarello, NRR Amendment* MI.111960066 " Concurrence via memo OFFICE LPLI-2/PM LPLI-2/LA DE/EEEB/BC DIRS/ITSB/BC DSS/SBPB/BC NAME PBamford ABaxter RMathew" RElliott* GCasto" DATE 7/15/11 7/20/11 01/0712011 01/13/2011 06/02/2011 DIRSIIHP RAlALPAlBC OGC LPLI-2/BC UShoop" DHarrison" DRoth HChernoff 12/08/2010 01/07/2011 7126111 7/29/11

..

OffiCial Record Copy

1. Agencywide Documents Access and Management System (ADAMS) Accession No. ML100810151.

2. June 16.2010 (ADAMS Accession No. ML101670319); October 29.2010 (ML103060379): December 3.2010 (ML103370328); January 14. 2011 (ML110180009); and March 23. 2011 (ML110840186).

v t e Letter Sequence Approval
TAC:ME3551, (Approved, Closed) TAC:ME3552, (Approved, Closed)
Initiation Request Acceptance Administration Questions 4 August 2010 28 September 2010 24 February 2011 21 September 2010 19 August 2010 24 September 2010 30 September 2010 14 December 2010 10 March 2011 Answers 29 October 2010 14 January 2011 23 March 2011 Results Approval Other:
MONTHYEAR2010-09-24 [Table View]

ML111960066

Text

SUBJECT:

Dear Mr. Pacilio:

Enclosures:

Attachment:

Attachment:

1.0 INTRODUCTION

2.0 REGULATORY EVALUATION

3.0 TECHNICAL EVALUATION

4.0 STATE CONSULTATION

5.0 ENVIRONMENTAL CONSIDERATION

6.0 CONCLUSION

SUBJECT:

Dear Mr. Pacilio:

Enclosures:

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