ML16358A676

Issuance of Amendment No. 199, Request for One-Time Extension of the Diesel Generator Completion Time (Emergency Circumstances)

ML16358A676
Person / Time
Site:	Palo Verde
Issue date:	12/23/2016
From:	Siva Lingam Plant Licensing Branch IV
To:	Bement R Arizona Public Service Co
Lingam S, NRR/DORL/LPLIV, 415-1564
References
CAC MF8961
Download: ML16358A676 (24)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Robert S. Bement Executive Vice President Nuclear/

Chief Nuclear Officer Mail Station 7602 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034 December 23, 2016

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 - ISSUANCE OF AMENDMENTS RE: REVISION TO TECHNICAL SPECIFICATION 3.8.1, "AC [ALTERNATING CURRENT] SOURCES-OPERATING" (EMERGENCY CIRCUMSTANCES) (CAC NO. MF8961)

Dear Mr. Bement:

The U.S. Nuclear Regulatory Commission has issued the enclosed Amendment No. 199 to Renewed Facility Operating License No. NPF-74 for the Palo Verde Nuclear Generating Station, Unit 3. The amendment consists of changes to the Technical Specifications (TSs) in response to Arizona Public Service Company's (the licensee's) application dated December 21, 2016, as supplemented by letter dated December 23, 2016.

The amendment revises TSs for a one-time extension of the emergency diesel generator (DG) completion time described in TS 3.8.1.B.4. Specifically, the emergency amendment extended the TS required action 3.8.1.B.4 completion time from 1 O days to 21 days for the purpose of collecting and analyzing data associated with the failure of train B DG and continue with the repair of the DG. During surveillance testing on December 15, 2016, the DG suffered a failure of the number nine right cylinder connecting rod and piston. Current plans to collect and analyze data associated with the engine failure and continue with the repair will exceed the TS required action completion time of 1 O days. As a result, the licensee evaluated the defense-in-depth and compensatory measures and is requesting a one-time deterministic license amendment to extend the completion time based upon the guidance of NUREG-0800, Standard Review Plan, Branch Technical Position 8-8, "Onsite (Emergency Diesel Generators) and Offsite Power Sources Allowed Outage Time Extensions."

The license amendment is issued under emergency circumstances as provided in the provisions of paragraph 50.91 {a){5) of Title 1 O of the Code of Federal Regulations due to the time critical nature of the amendment. In this instance, an emergency situation exists in that the proposed amendment is needed to allow the licensee to preclude a plant shutdown.

A copy of the related Safety Evaluation is also enclosed. The safety evaluation describes the emergency circumstances under which the amendment was issued and the final no significant hazards determination. A Notice of Issuance addressing the final no significant hazards determination and opportunity for a hearing associated with the emergency circumstances will be included in the Commission's next biweekly Federal Register notice.

Docket No. STN 50-530

Enclosures:

1. Amendment No. 199 to NPF-74

2. Safety Evaluation cc w/encls: Distribution via Listserv Sincerely,

~(f*~

Siva P. Lingam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 ARIZONA PUBLIC SERVICE COMPANY, ET AL.

DOCKET NO. STN 50-530 PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 199 License No. NPF-74

1.

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

A The application for amendment by the Arizona Public Service Company (APS or the licensee) on behalf of itself and the Salt River Project Agricultural Improvement and Power District, El Paso Electric Company, Southern California Edison Company, Public Service Company of New Mexico, Los Angeles Department of Water and Power, and Southern California Public Power Authority dated December 21, 2016, as supplemented by letter dated December 23, 2016, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act) and the Commission's 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 Renewed Facility Operating License No. NPF-74 is hereby amended to read as follows:

(2)

Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 199, and the Environmental Protection Plan contained in Appendix B, are hereby incorporated into this license. APS shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan, except where otherwise stated in specific license conditions.

3.

This license amendment is effective as of the date of issuance and shall be implemented prior to the expiration of the 10-days Technical Specification Completion Time, or December 25, 2016, at 3:56 AM Pacific1tandard Time.

FOR T~ ~ UCLEAR REGULATORY COMMISSION

Attachment:

Changes to the Renewed Facility Operating License No. NPF-74 and Technical Specifications Robert J. Pascarelli, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance: December 23, 2016

ATTACHMENT TO LICENSE AMENDMENT NO. 199 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-74 PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 DOCKET NO. STN 50-530 Replace the following pages of the Renewed Facility Operating Licenses No. NPF-74 and 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.

Renewed Facility Operating License No. NPF-74 REMOVE INSERT 4

4 Technical Specifications REMOVE INSERT 3.8.1-3 3.8.1-3 (4)

Pursuant to the Act and 10 CFR Part 30, 40, and 70, APS to receive, possess, and use in amounts 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 1 O CFR Parts 30, 40, and 70, APS to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

C.

This renewed operating 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 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 Arizona Public Service Company (APS) is authorized to operate the facility at reactor core power levels not in excess of 3990 megawatts thermal (100% power), in accordance with the conditions specified herein.

(2)

Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 199, and the Environmental Protection Plan contained in Appendix B, are hereby incorporated into this renewed operating license.

APS shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan, except where otherwise stated in specific license conditions.

(3)

Antitrust Conditions This renewed operating license is subject to the antitrust conditions delineated in Appendix C to this renewed operating license.

(4)

Initial Test Program (Section 14, SER and SSER 2)

Deleted (5)

Additional Conditions The Additional Conditions contained in Appendix D, as revised through Amendment No. 171, are hereby incorporated into this renewed operating license. The licensee shall operate the facility in accordance with the Additional Conditions.

Renewed Facility Operating License No. NPF-74 Amendment No. 199

ACTIONS CONDITION REQUIRED ACTION B.

(continued)

B.4 Restore DG to OPERABLE status.

C.

Two required offsite c.1 Declare required circuits inoperable.

feature(s) inoperable when its redundant required feature(s) is inoperable.

AND C.2 Restore one required offsite circuit to OPERABLE status.

PALO VERDE UNITS 1.2.3 3.8.1-3 AC Sources - Operating 3.8.1 COMPLETION TIME

- -- --NOTE-----

For the Unit 3 Train B DG failure on December 15.

2016. restore the inoperable DG to OPERABLE status within 21 days.

10 days 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> from discovery of Condition C concurrent with i noperabi l ity of redundant required feature(s) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (continued)

AMENDMENT NO. +/-9-7. 199

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 199 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-74 ARIZONA PUBLIC SERVICE COMPANY, ET AL.

PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 DOCKET NO. STN 50-530

1.0 INTRODUCTION

By application dated December 21, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16356A689), as supplemented by letter dated December 23, 2016,

• Arizona Public Service Company (APS, the licensee) submitted an emergency license amendment request (LAR) requesting changes to the Technical Specifications (TSs) for Palo Verde Nuclear Generating Station (PVNGS), Unit 3.

The amendment revises TSs for a one-time extension of the emergency diesel generator (DG) completion time (CT) described in TS 3.8.1.B.4. Specifically, the emergency amendment extended the TS required action 3.8.1.B.4 CT from 1 O days to 21 days for the purpose of collecting and analyzing data associated with the failure of train B DG and continue with the repair of the DG. During surveillance testing on December 15, 2016, the DG suffered a failure of the number nine right cylinder connecting rod and piston. Current plans to collect and analyze data associated with the engine failure and continue with the repair will exceed the TS required action CT of 10 days. As a result, the licensee evaluated the defense-in-depth and compensatory measures and is requesting a one-time deterministic license amendment to extend the CT based upon the guidance of NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition," Branch Technical Position (BTP) 8-8, "Onsite (Emergency Diesel Generators) [EDGs] and Offsite Power Sources Allowed Outage Time Extensions," dated February 2012 (ADAMS Accession No. MU 13640138).

• As of the date of issuance of this document, the letter had not been placed into ADAMS.

2.0 REGULATORY EVALUATION

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the LAA based on the following regulatory requirements:

General Design Criterion (GDC) 17, "Electric power systems," of Appendix A to Part 50 of Title 1 O of the Code of Federal Regulations (1 O CFR) requires, 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 to safety. The onsite system is required to have sufficient independence, redundancy, and testability to perform its safety function, assuming a single failure. The offsite power system is required to be supplied 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.

GDC 18, "Inspection and testing of electric power systems," of Appendix A to 1 O CFR Part 50, requires, in part, that electric power systems that are important to safety must be designed to permit appropriate periodic inspection and testing of important areas and features, such as wiring, insulation, connections, and switchboards to assess the continuity of the systems and the condition of their components.

1 O CFR 50.36, "Technical specifications," requires, in part, that the TSs shall be included by applicants for a license authorizing operation of a production or utilization facility.

Paragraph 1 O CFR 50.36(c) requires that TSs include items in five specific categories related to station operation. These categories are (1) safety limits, limiting safety system settings, and limiting control settings, (2) limiting conditions for operation (LCOs),

(3) SRs, (4) design features, and (5) administrative controls. The proposed change to the PVNGS TS relates to the LCO category.

10 CFR 50.63, "Loss of all alternating current power," requires, in part, that a nuclear power plant shall be able to withstand for a specified duration, and recover from a complete loss of offsite and onsite alternating current (AC) sources (i.e., a station blackout (SBO)).

1 O CFR 50.65, "Requirements for monitoring the effectiveness of maintenance at nuclear power plants," requires, in part, that performing maintenance activities shall not reduce the overall availability of the systems, structures, and components, which are important to safety of the plant.

The NRC staff also reviewed the LAA based on the following regulatory guidance documents:

Regulatory Guide (RG) 1.93, "Availability of Electric Power Sources," dated March 2012 (ADAMS Accession No. ML090550693), provides guidance with respect to operating restrictions or CT if the number of available AC sources is less than that required by the TS LCO. In particular, this guide recommends a maximum CT of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for an inoperable onsite or offsite AC source.

RG 1.155, "Station Blackout," dated August 1988 (ADAMS Accession No. ML003740034), provides guidance for complying with the 10 CFR 50.63 that requires nuclear power plants to be capable of coping with an SBO event for a specified duration.

RG 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications," dated May 2011 (ADAMS Accession No. ML100910008), describes an acceptable risk-informed approach for assessing proposed changes to TS allowed outage times (AOTs), or termed henceforth as CT.

NUREG-0800, BTP 8-8 provides guidance to the NRC staff in reviewing LARs for licensees proposing a one-time or permanent TS change to extend an EOG AOT beyond 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The BTP 8-8 emphasizes that more defense-in-depth is needed for SBO scenarios which are more likely to occur as compared to the likely occurrence of the large and medium size loss-of-coolant accident scenarios (which requires a fast start EOG).

3.0 TECHNICAL EVALUATION

3.1.

Description of the PVNGS, AC Power System In the LAA, the licensee explained that seven physically independent 525 kilovolt (kV) transmission lines of the Western Interconnection are connected to the PVNGS 525 kV switchyard. Three 525 kV tie lines supply power from the switchyard to three startup transformers, which supply power to six 13.8 kV intermediate buses (two per unit). Two physically independent circuits supply offsite (preferred) power to the onsite power system of each PVNGS unit.

The three startup transformers connect to the PVNGS 525 kV switchyard, and feed six 13.8 kV intermediate buses (two per unit). These buses are arranged in three pairs, each pair feeding only one unit. The intermediate buses for PVNGS Units 1, 2, and 3 are interconnected to the startup transformers so that each unit's buses can access a primary and backup startup transformer winding when all startup transformers are connected to the switchyard. The intermediate buses are connected to the onsite power system by one 13.8 kV transmission line per bus (two per unit).

The Class 1 E AC power system distributes power at 4.16 kV, 480 Volt (V), and 120 V to all Class 1 E loads. Also, the Class 1 E AC power system supplies power to certain selected loads that are not directly safety-related but are important to the plant. The Class 1 E AC power system contains standby power sources (EDGs) that automatically provide the power required for cold shutdown in the event of loss of the offsite source providing 4.16 kV Class 1 E bus voltage. The safety-related equipment is divided into two load groups per unit. For each unit, either of the associated load groups is capable of providing power for safely shutting down the unit.

The standby power supply for each safety-related load group consists of one EOG complete with its accessories, fuel storage and transfer systems. The standby power supply functions as a source of AC power for safe plant shutdown in the event of loss of preferred power and for post-accident operation of engineered safety feature (ESF) loads. Each EOG is rated at 5500 kilowatts (kW) for continuous operation and 6050 kW for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> out of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Each generator is driven by a turbo-charged, four-cycle, 20-cylinder diesel engine.

Each EOG is normally connected to a single 4.16 kV safety features bus of a load group.

However, there are provisions for connecting both ESF buses to a single diesel generator during emergency conditions. Each load group is independently capable of safely shutting down the unit or mitigating the consequences of a design basis accident. The components of the standby power supply system, including related controls, required to supply power to ESF and cold shutdown loads conform to the requirements of GDC 17.

3.2 Station Blackout In the LAR, the licensee explained that to meet 1 O CFR Part 50.63 requirements, the PVNGS has analyzed an SBO coping duration of 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. The analysis was submitted to the NRC on October 28, 2005, and approved by the NRC in a Safety Evaluation dated October 31, 2006 (ADAMS Accession No. ML062910280).

The 16-hour coping strategy analysis assumes that one of the two station blackout generators (SBOG), which serves as the alternate AC (AAC) for PVNGS, is started and connected to the AC distribution system to supply loads in the respective unit during the first hour to allow the analyzed SBO loads to be powered in accordance with administrative or emergency procedures. Should an SBO occur in any one unit (i.e., a loss of offsite power (LOOP) coincident with the unavailability of both EDGs in that unit), an AAC power source is available to provide the power necessary to cope with an SBO for a minimum of 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />.

The non-safety related AAC power source consists of two 100-percent capacity SBOGs that can be connected to each unit via the primary winding of the ESF transformer that is normally aligned to the train A 4.16 kV bus. One SBOG is analyzed to supply all required SBO loads, which are located on the A train. Each SBOG has a minimum continuous output rating of 3400 kW at 13.8 kV under worst case anticipated site environmental conditions. This rating is sufficient to provide power to the loads identified as being important for coping with the SBO.

Starting and loading of the AAC power system is performed manually; no autostart or automatic loading capability is provided.

Although the SBOGs are able to be aligned to Unit 3 train B from a defense-in-depth perspective, for this emergency LAR, the PVNGS SBOGs are not credited to provide power to Unit 3 in response to a LOOP event based on the guidance of BTP 8-8. The licensee has deployed three portable DGs at Unit 3 connected to the 4.16 kV AC FLEX connection box that can supply the train B 4.16 kV AC class bus to maintain the same level of defense-in-depth as of SBOGs for safe shutdown of the plant.

3.3 Proposed TS Changes

The licensee proposed the following specific changes to TS 3.8.1, "AC Sources - Operating," to extend the CT on a one-time basis for the PVNGS Unit 3 train B DG.

Add a new NOTE in the Completion Time column, associated with Required Action B.4 of the TS 3.8.1 Action Table, that reads as follows:

NOTE For the Unit 3 Train B DG failure on December 15, 2016, restore the inoperable DG to OPERABLE status within 21 days.

In the LAR, the licensee provided the following basis for the proposed change and duration of the CT extension request:

Need for Proposed Change During routine scheduled surveillance testing on December 15, 2016, the PVNGS [Unit 3] B train DG was operating partially loaded when the load suddenly decreased and a low lube oil pressure trip occurred. The physical damage was readily apparent to plant operators when responding to the event.

Oil and metal debris were observed on the engine room floor and the number 9 right cylinder (9R) crankcase cover was deformed. Physical damage was extensive, including but not limited to the number 9 master and articulating rod separating and impacting internal areas of the engine base and block. Both the 9R and 9L pistons, sleeves and associated components were damaged and will require replacement. The counterbalance was also fractured and the crankshaft damaged at this number 9 location. There was damage to the number 8 master and articulating rod, including the physical fracture of two studs on the rod cap.

A counterbalance at the number 8 location was also fractured and damaged.

Current plans to repair the DG and collect and analyze the engine failure data will exceed the TS required completion time of 1 o days. As a result, APS has evaluated the defense-in-depth and compensatory measures and is submitting an emergency LAR to extend the completion time to conduct repairs and allow the engineering team to perform the root cause investigation, understand the cause of the failure and evaluate the extent of condition. Following this analysis, a determination on the potential existence of a common mode failure of the train A DG will be made.

Basis for Duration of Completion Time Extension The completion time extension will allow for continued repairs and for the engineering team to perform the root cause investigation, understand the cause of the failure and evaluate the extent of condition. Following this analysis, a determination on the potential existence of a common mode failure will be made.

The duration to collect and analyze data is not expected to exceed a total of 21 days. Completed activities include initial visual inspection, damage assessment and parts recovery. Preparation for crankshaft and internal parts replacement is underway. Crankshaft removal and engine block repair require the following supporting activities: precision alignment checks of the DG internals, removal of pistons, liners and connecting rods, and removal of right and left bank intercoolers from turbo chargers. A new crankshaft will be installed, followed by engine assembly and retest.

The NRC staff finds the need for the proposed TS change and the duration of CT extension as reasonable, and therefore, acceptable.

3.4 Deterministic Evaluation 3.4.1 Defense-in-depth for Onsite and Off site Power Sources In the LAR, the licensee provided following the details of defense-in-depth for onsite and offsite power sources:

PVNGS is connected to the Western Interconnection, one of the two major power grids in North America. Seven physically independent transmission lines supply the PVNGS 525 kV switchyard that supplies offsite power to all three units.

These seven transmission lines are designed and located to minimize the likelihood of simultaneous failure. Each unit is provided with two offsite supplies from two of the three startup transformers. For onsite power, each PVNGS unit has two DGs and shares two SBOGs between the three units. The system design configuration ensures that each of the DGs is electrically and physically isolated. In addition, during the requested extended completion time, APS has deployed three portable diesel generators at Unit 3 connected to the 4.16 kV AC FLEX connection box that can supply the B train 4.16 kV AC class bus, and has deployed a diesel-driven FLEX steam generator (SG} makeup pump to Unit 3.

In the event of a loss of the preferred offsite power sources, the SBOGs can be aligned to either of the 4.16 kV AC class busses per design. During the period of this extended completion time for the train B DG, the associated train B 4.16 kV AC class bus will be powered from offsite power, and if offsite power is lost, would be powered by portable diesel generators, if necessary.

The train A DG is provided with adequate independence to mitigate all postulated accidents. The train A DG, SBOGs, and the portable diesel generators are all of diverse design, thus reducing the potential for common mode failures. The SBOGs are gas turbine generators. The three portable AC diesel generators are self-contained, enclosed tractor trailer mounted Cummins diesel generators.

Two are 4.16 kV generators and the third is a 480 V generator with a step-up transformer to convert the output voltage to 4.16 kV. The control systems for the three portable diesel generators have a common design which supports parallel operations. The portable DGs will be verified available and functional by the completion of a test run prior to the period of extended allowable outage time.

The three portable DGs in parallel provides a combined output of approximately 4800 kW. Attachment 4 of the LAA identifies the electrical load summary for the train B bus required for response to a LOOP event including placing the plant in cold shutdown. The load summary is conservatively determined to be approximately 4540 kW including losses for cables and transformers based upon the most heavily loaded of the six PVNGS DGs, which is the Unit 1 train B DG.

The result is that the three temporary portable DGs are sufficient to enable a cold shutdown of Unit 3 in the event of a LOOP with a single failure (e.g. DG A) during the extended time period while the B train DG is inoperable.

The station provides fuel delivery trucks and fuel trailers to perform refueling of the portable DGs and the FLEX steam generator make-up pump diesel engine.

On-site fuel oil tanks provide the ability to replenish fuel delivery trucks/trailers to support extended operation of the portable DGs. Designated personnel are available on all shifts to perform necessary refueling operations. Local commercial fuel delivery provides ready replenishment of onsite inventories. The portable DGs each have a lubrication oil sump with a specified minimum capacity of approximately 40 gallons of 15W-40 lubrication oil. Lubrication oil consumption by each engine is not specified by the manufacturer's maintenance manual but is expected to be approximately 0.5 gallons per 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br /> of operation per the vendor's operating experience. PVNGS maintains sufficient quantities on site of 15W-40 oil to meet the needs of extended operation of the portable DGs. During the extended AOT, routine inspections of the portable DGs will be performed by operations personnel to ensure normal standby conditions are maintained including lubrication and fuel levels, standby temperatures, and general equipment condition. The routine inspections will identify oil leakage conditions which could challenge availability of the engines.

In the event of a loss of offsite power and the limiting single failure of the train A DG, both the SBOGs and the portable DGs have the capability to establish power to the train B 4.16 kV class bus within one hour using existing procedural guidance.

The NAC staff evaluated the defense-in-depth aspects for onsite and offsite power sources.

Based on the information above, the staff has determined that there are multiple diverse means of supplying electrical power to the safety buses to safely shutdown Unit 3 and maintain the plant in a cold shutdown condition. In addition, the portable DGs have the capacity and capability to support the loads necessary to mitigate a LOOP event and bring the unit to cold shutdown in case of an extended LOOP concurrent with a single failure of the train A DG during plant operation, and meet the intent of BTP 8-8.

3.4.2 Safety Margin In the LAA, the licensee stated, in part, that The proposed one-time extension of the Unit 3 train B DG CT remains consistent with the codes and standards applicable to the PVNGS onsite AC sources and electrical distribution system. A loss of all AC power event would require a loss of all offsite power sources, failure of the train A DG, failure of both SBOGs, and failure of the portable DGs. In addition, with deployment of the diesel-driven FLEX SG Makeup Pump at Unit 3, another backup supply of SG makeup independent of offsite power or the 4.16 kV AC buses is provided to mitigate the most likely scenarios associated with a loss of offsite power event. Also, PVNGS has installed a cross-connection which allows make-up to SGs from the station fire protection system which provides additional defense-in-depth for the heat removal safety function.

The NRG staff reviewed whether the proposed TS changes will have any impact on the licensee's compliance with GDC 17, GDC 18, 10 CFR 50.36, 10 CFR 50.65, and 10 CFR 50.63.

The staff did not find any adverse impact on continued compliance with these regulatory requirements. Therefore, the staff finds that reduction in margin of safety will be minimal.

3.4.3. Risk Management and Compensatory Measures The licensee stated that risk will be managed during the extended CT via the Maintenance Rule 10 CFR 50.65(a)(4) Configuration Risk Management Program, which has been reviewed by NRG in prior risk-informed TS change requests.

In the Attachment 3 of the LAA, the licensee stated that the following list of compensatory measures will be implemented in accordance with PVNGS Configuration Risk Management Program:

1.

The redundant train A DG (along with all of its required systems, subsystems, trains, components, and devices) will be verified OPERABLE (as required by Technical Specification) and no discretionary maintenance activities will be scheduled on the redundant (OPERABLE)

DG.

2.

No discretionary maintenance activities will be scheduled on the SBOGs.

3.

No discretionary maintenance activities will be scheduled on the startup transformers.

4.

No discretionary maintenance activities will be scheduled in the Salt River Project (SAP) switchyard or the unit's 13.8 kV power supply lines and transformers which could cause a line outage or challenge off site power availability to the unit utilizing the extended DG completion time.

5.

All activity, including access, in the SAP switchyard shall be closely monitored and controlled.

6.

The SBOGs will not be used for non-safety functions (i.e., power peaking to the grid).

7.

All maintenance activities associated with Unit 3 will be assessed and managed per 10 CFR 50.65(a)(4) (Maintenance Rule). Planned work will be controlled during the extended completion time so that Unit 3 does not voluntarily enter a YELLOW Risk Management Action Level.

8.

The OPERABILITY of the steam driven auxiliary feedwater pump will be verified before entering the extended DG completion time.

9.

The system dispatcher will be contacted once per day and informed of the DG status, along with the power needs of the facility.

10.

Should a severe weather warning be issued for the local area that could affect the SRP switchyard or the offsite power supply during the extended DG completion time, an operator will be available locally at the SBOG should local operation of the SBOG be required as a result of on-site weather related damage.

11.

No discretionary maintenance will be allowed on the main and unit auxiliary transformers associated with the unit.

12.

APS has provided three portable diesel generators to ensure the ability to bring Unit 3 to cold shutdown in the event of a LOOP during the extended time period that the Unit 3 train B DG is inoperable. The three portable diesel generators operate in parallel as a set. The result is that the three portable diesel generators are sufficient to enable a cold shutdown of Unit 3 in the event of a LOOP with a single failure during the extended time period while the Unit 3 train B DG is inoperable. The three portable diesel generators are deployed and physically connected to the Unit 3 train B 4.16 kV AC FLEX connection box for the duration of the extended DG completion time.

13.

The portable DGs will be verified available and functional by the completion of a test run prior to the period of extended allowable outage time.

14.

A diesel-driven FLEX SG Makeup Pump is deployed to its FLEX pad at Unit 3 for the duration of the extended DG completion time.

15.

The following equipment will be protected by signage/chains for the duration of the extended completion time to prevent inadvertent impact from walkdowns, inspections, maintenance and potential for transient combustible fires:

a.

Both SBOGs

b.

Unit 3 train A DG

c.

Unit 3 train A Engineered Safety Features (ESF) Switchgear, DC equipment and DC Battery Rooms

d.

Three AC portable diesel generators deployed at Unit 3 and their connections to the train B FLEX 4.16 kV AC connection box

e.

Diesel-driven FLEX SG Makeup Pump deployed at Unit 3

f.

Turbine driven auxiliary feedwater pump The NRC staff finds that the above compensatory measures provide adequate risk management for the safety of plant.

3.4.4 Control Station Activities In Attachment 5 of the LAA, the licensee provided following list of commitments relating to Control Station Activities:

1.

The system load dispatcher will be contacted once per day to ensure no significant grid perturbations (high grid loading unable to withstand a single contingency of line or generation outage) are expected during the extended allowed outage time.

2.

Component testing or maintenance of safety systems and important non-saf ety equipment in the off site power systems that can increase the likelihood of a plant transient (unit trip) or LOOP will be avoided.

3.

Discretionary work will be prohibited in the SAP switchyard during the extended Unit 3 train B DG TS 3.8.1 Condition B required action completion time.

4.

TS required systems, subsystems, trains, components, and devices that depend on the remaining power sources will be verified to be operable and positive measures will be provided to preclude subsequent testing or maintenance activities on these systems, subsystems, trains, components, and devices.

5.

Steam-driven emergency feed water pump will be controlled as protected equipment.

6.

Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following unavailability of a portable DG, Unit 3 will enter TS condition 3.8.1.H to place the unit in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

7.

Availability of the portable DGs will be verified once per shift.

8.

Approval of transient combustibles and hot work in Unit 3 will be controlled by the outage control center (OCC).

9.

There will be an OCC position responsible for oversight and monitoring of the compensatory measures of Attachment 3 and the actions described in this attachment.

In addition, by letter dated December 23, 2016, the licensee provided the following information:

Compensatory measures described in Attachment 3 of the LAA are now formal regulatory commitments.

In case the licensee determines prior to expiration of the extended completion time, a common failure mode does exist, the licensee will shut down the plant.

An auxiliary operator (AO) on each shift will be dedicated to perform pre-start checks of the portable generators each shift. This dedicated AO will perform the emergency start of the portable generators when directed and monitor their operation. The dedicated AO will have no other assigned duties during the extended completion time.

In the event of a reactor trip with a loss of off-site power, the Area 4 (Control Building) AO, will perform the required electrical system alignments, as directed by the control room, to restore power to the B train Class 1 E 4.16 kv bus using the portable generators, in accordance with station procedures.

In the event of a reactor trip with a loss of off-site power, one of the on-shift reactor operators will be assigned to perform and direct actions to restore power to the B train Class 1 E 4.16 kv bus using the portable generators. During the event, this reactor operator will not be assigned other duties until completion of power restoration.

The NRC staff finds the above control station activities will enhance the defense-in-depth aspects of the plant.

3.4.5. Operator Training In the LAR, the licensee stated, in part, that Operators are trained on the strategies and hierarchy of procedures for LOOP that specify use of alternate power sources, including the portable DGs.

Training, briefings, and walkdowns are provided to the Operators responsible for operating the portable DGs as part of the preparation for use of the generators.

Operations crews are briefed on the implementing procedure. Designated operators will be familiar with instructions for starting and operating the portable DGs. Operations staff has received classroom training for FLEX strategies, which included the use of the portable DGs.

The NRC staff finds that the licensee has taken adequate steps to train operators as part of FLEX strategies for which the NRC staff issued a safety evaluation on July 20, 2016 (ADAMS Accession No. ML16088A261 ).

3.4.6 Human Factors The operator actions used to align an AAC power source are the same as those that operators currently train to implement FLEX strategies. These procedures were described in the response to EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML15364A034, non-public).

Furthermore, scenarios during which the licensee may have to rely on these operator manual actions are similar to the scenarios considered to support FLEX strategies developed in response to EA-12-049. The NRC has previously conducted an audit at PVNGS including a walkdown of the necessary equipment to demonstrate the feasibility of these actions and a review of the associated procedures as described in the Safety Evaluation regarding implementation of mitigating strategies to EA-12-049 (ADAMS Accession No. ML16088A261 ). There are no changes to human-systems interfaces, nor are there other changes affecting operator manual actions as a result of this amendment. Therefore, the operator manual actions under consideration require no additional review.

3.4.7 Probabilistic Risk Assessment In its LAA, the licensee stated that the basis for the proposed TS CT change is "a one-time deterministic license amendment to extend the completion time based upon the guidance of BTP 8-8, Onsite (Emergency Diesel Generators) and Offsite Power Sources Allowed Outage Time Extensions." Therefore, it is not a risk-informed LAR and a risk evaluation was not needed. However, to provide additional information, the licensee chose to provide risk insights related to the proposed TS CT change in Enclosure 2 of its LAR. In that enclosure, the licensee calculated the incremental conditional core damage probability (ICCDP) and incremental conditional large early release probability (ICLERP) for the plant-specific configuration that includes the proposed CT extension for Emergency Diesel Generator 3B inoperability. Based on the licensee's risk evaluation, the ICCDP and ICLERP are 7.9E-6 and 2.6E-7, respectively. These risk values are below the risk acceptance guidelines in RG 1.177, Revision 1. Based on the information provided by the licensee and the evaluation above, the NRC staff concludes that the licensee's risk evaluation for the plant configuration, which includes the proposed CT extension for Emergency Diesel Generator 38, is acceptable for the purposes of supporting the deterministic evaluation.

3.4.8 Summary The NRC staff concludes that the LAA meets the defense-in-depth guidance of BTP 8-8, and RG 1.177, Section 2.2.1, as discussed in Section 3.4 of this safety evaluation. The staff concludes that the licensee's request to revise TS 3.8.1 to extend the CT of an inoperable EOG to operable status from the current 1 O days to 21 days is acceptable from a deterministic perspective. The staff finds the proposed TS change will have no or minimal adverse impact on the licensee's compliance with 10 CFR 50, Appendix A, GDC 17 and GDC 18, 10 CFR 50.36, 10 CFR 50.65, and 10 CFR 50.63.

4.0 EMERGENCY CIRCUMSTANCES In its letter dated December 21, 2016, the licensee requests that the amendment be treated as an emergency amendment.

The proposed change is required due to an emergent equipment failure and is necessary to prevent shutdown of PVNGS Unit 3. The change is needed sooner than can be issued under exigent circumstances and this license amendment request is timely considering the unplanned nature of the DG failure.

The completion time extension will allow for continued repairs and for the engineering team to perform the root cause investigation, understand the cause of the failure and evaluate the extent of condition. Following this analysis, a determination on the potential existence of a common mode failure will be made. The duration to collect and analyze data is not expected to exceed a total of 21 days. Completed activities include initial visual inspection, damage assessment and parts recovery. Preparation for crankshaft and internal parts replacement is underway.

Crankshaft removal and engine block repair require the following supporting activities: precision alignment checks of the DG internals, removal of pistons, liners and connecting rods, and removal of right and left bank intercoolers from turbo chargers. A new crankshaft will be installed, followed by engine assembly and retest.

The NRC staff reviewed the licensee's explanation and found it acceptable because the condition was due to the recent unexpected failure of Unit 3 EOG B while performing the surveillance test, and therefore, the emergency situation could not have been avoided.

5.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION

The Commission may issue a license amendment before the expiration of the 60-day period provided that its final determination is that the amendment involves no significant hazards consideration. This amendment is being issued prior to the expiration of the 60-day period.

Therefore, a final finding of no significant hazards consideration follows.

The Commission has made a final determination that the amendment request involves no significant hazards consideration. Under the Commissions regulations in 1 O CFR 50.92, this means that operation of the facility in accordance with the proposed amendment does not

( 1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

As required by 10 CFR 50.91(a), in its letter dated December 21, 2016, the licensee has provided its analysis of the issue of no significant hazards consideration, which is presented below:

1.

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

Response: No.

The proposed change is a deterministic one-time extension of the Unit 3 B train Diesel Generator TS completion time from 10 days to 21 days.

The PVNGS Unit 3 8 train emergency diesel generator (DG) provides onsite electrical power to vital systems should offsite electrical power be interrupted. It is not an initiator to any accident previously evaluated.

Therefore, this extended period of operation with the B train DG out-of-service will not increase the probability of an accident previously evaluated.

The DGs act to mitigate the consequences of design basis accidents that assume a loss of offsite power. For that purpose, redundant DGs are provided to protect against a single-failure and the consequences of a loss of offsite power have already been evaluated. During the current Technical Specification (TS) 10-day required action completion time, an operating unit is allowed by the TS to remove one of the DGs from service, thereby losing this single-failure protection. This operating condition is considered acceptable. The consequences of a design basis accident coincident with a failure of the redundant DG during the proposed extended completion time are the same as those during the existing 10-day TS completion time. Therefore, during the period of the proposed extended required action completion time, there is no significant increase in the consequences of an accident previously evaluated.

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

2.

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

Response: No.

The proposed change is a deterministic one-time extension of the Unit 3 B train DG TS completion time from 10 days to 21 days. The PVNGS Unit 3 B train emergency DG provides onsite electrical power to vital systems should offsite electrical power be interrupted. There are no new failure modes or mechanisms created due to plant operation for the extended period to collect and analyze data of the PVNGS Unit 3 B train DG. Extended operation with an inoperable DG does not involve any modification in the operational limits or physical design of existing plant systems. There are no new accident precursors generated due to the extended required action completion time.

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

3.

Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No.

The proposed change is a deterministic one-time extension of the Unit 3 B Diesel Generator TS completion time from 1 O days to 21 days. The PVNGS Unit 3 B train emergency diesel generator (DG) provides onsite electrical power to vital systems should offsite electrical power be interrupted. During the extended completion time, sufficient compensatory measures including supplemental power sources have been established to maintain the defense-in-depth design philosophy to ensure the electrical power system meets its design safety function. The supplemental source has the capacity to bring the unit to cold shutdown in case of a loss of offsite power concurrent with a single failure during plant operation.

Therefore, the proposed change does not involve a significant reduction in a margin of safety as defined in the basis for any TS.

Based on its review of the licensee's no significant hazards consideration analysis quoted above, the NRG staff has determined that the proposed amendment involves no significant hazards consideration.

Accordingly, the Commission has determined that this amendment involves no significant hazards information.

6.0 STATE CONSULTATION

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

7.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 1 O CFR Part 20. The NRG staff has determined that the amendment involves 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. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 1 O CFR 51.22(c)(9). Pursuant to 1 O CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

8.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) the amendment does not (a) involve a significant increase in the probability or consequences of an accident previously evaluated; or (b) create the possibility of a new or different kind of accident from any accident previously evaluated; or (c) involve a significant reduction in a margin of safety; (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (3) there is reasonable assurance that such activities will be conducted in compliance with the Commission's regulations, and (4) 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: V. Goel, NRR/DE/EEEB T. Hilsmeier, NRR/DRA/APLA S. Weerakkody, NRR/DRA/APHB Date: December 23, 2016

A copy of the related Safety Evaluation is also enclosed. The safety evaluation describes the emergency circumstances under which the amendment was issued and the final no significant hazards determination. A Notice of Issuance addressing the final no significant hazards determination and opportunity for a hearing associated with the emergency circumstances will be included in the Commission's next biweekly Federal Register notice.

Docket No. STN 50-530

Enclosures:

Sincerely, IRA/

Siva P. Lingam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

1. Amendment No. 199to NPF-74

2. Safety Evaluation cc w/encls: Distribution via Listserv DISTRIBUTION:

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