ML16357A687

One-Time License Amendment Request Unit 3 Train B Diesel Generator

ML16357A687
Person / Time
Site:	Palo Verde
Issue date:	12/20/2016
From:	Siva Lingam Plant Licensing Branch IV
To:	Edington R Arizona Public Service Co
Lingam S
References
Download: ML16357A687 (25)

Text

One-Time License Amendment Request Unit 3 Train B Diesel Generator Palo Verde Nuclear Generating Station December 20, 2016

Agenda

• Event Description

• Palo Verde AC Power System

• Operating Experience

• Event Investigation

• Response Plan

• Risk Assessment

• License Amendment Request

• Regulatory Options 2

Event Description

• On 12/15/16 at 03:02, Unit 3 Train B (3B)

Diesel Generator (DG) was started for routine surveillance testing

• At 03:56, 3B DG was operating at 2.5 MW and a loud bang was heard and the 3B DG tripped on low lube oil pressure

• At 04:10, Alert classification (EAL HA2.1) was declared (explosion with visible damage to 3B DG, ENS 52435)

• At 06:36, the Alert was terminated 3

Palo Verde AC Power System

• Seven, independent offsite power transmission lines

• Two, redundant, class 1E emergency diesel generators per unit

• Two station blackout generators (SBOGs)

• Two 4160V portable diesel generators 4

Palo Verde AC Power System 5

Palo Verde AC Power System

• Diesel Generator Design

- Cooper-Bessemer Model KSV-20

- 20 cylinder engine with vee configuration

- 5.5 MW continuous output

- 6.05 MW output for 2 hours0.0833 days <br />0.0119 weeks <br />0.00274 months <br /> out of 24 hours1 days <br />0.143 weeks <br />0.0329 months <br /> 6

Operating Experience (OE)

• Cooper-Bessemer KSV-20 OE

- 1986 - Palo Verde 3B DG connecting rod (9R) failure during unit startup testing program

- 1989 - South Texas Project DG 22 connecting rod failure during a surveillance test

- 2003 - South Texas Project DG 22 connecting rod failure during a surveillance test (one-time LAR using a two-phased approach to extend allowable outage time to 113 days)

- 2016 - Palo Verde 3B DG connecting rod (9R) failure during a surveillance test 7

Event Investigation 8

Event Investigation

• Identified damage

- Power cylinders 9-Right, 9-Left, 8-Right, and 8-Left

- Crankshaft and connecting rods

- Left and right cylinder blocks

- Centerframe

- Crankcase floor and lube oil headers 9

Event Investigation Master Rod Fracture Surface 10

Event Investigation

• Evidence of high cycle fatigue on master connecting rod

• Second major failure of DG 3B (9R)

• Additional evidence needed to fully evaluate cause and potential for common mode failure

- Analysis of parts as engine is dismantled

- Forensics plan established

- Strong focus on 1986 repairs

• Partnerships established with MPR, Goltens, Structural Integrity, EPRI, and the Cooper-Bessemer Owners Group 11

Assessment of DG 3A

• 3A DG test run following 3B DG failure

• Comparative analysis of 3A/3B DGs performed

- Lubrication history

- Vibration history

- System parameter reviews (temperatures, pressures)

- Maintenance history

- Run times 12

Response Plan

• South Texas Project and vendor expert involvement

• Outage Control Center activated and staffed 24/7

• Current repair plan includes:

- Visual inspection, damage assessment and parts recovery

- Crankshaft and internal parts removal dimensional laser scan of DG internals

- Engine block repair

- Install new and refurbished components including crankshaft

- Engine assembly and alignment

- Retest and restoration of Operability

• Response plan shows additional time (beyond 10-day completion time) will be required to perform repairs and testing

• Parts are available to perform repairs 13

Risk Assessment

• PRA models for

- Internal Events

- Internal Flood

- Internal Fire

- Seismic

• Other hazards screened out 14

PRA Model and Risk-Informed Application Model History Internal Events CEOG peer review & numerous risk-informed Technical Specification changes Internal Flood peer review Risk-informed 7-day inverter Technical Specification approved Internal Events self-assessment per RG 1.200 App B TSTF-425 Surveillance Frequency Control Program approved External Hazards Screening peer review 1st fire PRA peer review Seismic PRA peer review 2nd fire PRA peer review TSTF-505 submitted All Unit 3 Mods Comp

& all ASME PRA Std SRs Met to CC II Pre-2010 2010 2011 2012 2013 2014 2015 2016 15

Palo Verde is Special and Unique

• Six 100% capacity SG makeup pumps all supplied by onsite power sources

- Only one of these powered by DG B if loss of offsite power

• RCP seal LOCAs negligible - ECCS significance minimal in loss of offsite power events

• No Pressurizer power-operated relief valves

• Very low internal events CDF and LERF - consistent with STP and Millstone 3

• Only shared systems in PRA are SBOGs and firewater

• Dedicated fire department staff and equipment

• Risk significant FLEX connections outside of unit

• Did not need to implement NFPA-805 to address multiple spurious operations 16

Risk Assessment

• Defense-in-Depth Evaluation

- Unavailability does not reduce the amount of available equipment to a level below that necessary to mitigate a design basis accident

• Safety Margin Evaluation

- No significant reduction in margin of safety

• Regulatory Guide 1.200, Revision 2 compliant

• Regulatory Guide 1.177, Revision 1 compliant

• Regulatory Guide 1.174, Revision 2 compliant 17

Risk Assessment Unit 3 Baseline Average Annual CDF/LERF CDF LERF Hazard (per year) (per year)

Internal events 1.3E-6 4.3E-8 Internal flooding 4.1E-7 1.9E-8 Seismic 2.8E-5 5.3E-6 Internal Fire 2.1E-5 2.1E-6 Total 5.1E-51 7.5E-62 Notes:

1. Meets Regulatory Guide 1.174 acceptance criteria of < 1E-4/yr

2. Meets Regulatory Guide 1.174 acceptance criteria of < 1E-5/yr 18

Risk Assessment ICCDP and ICLERP for One-Time Technical Specification Change ICCDF ICCDP ICLERF ICLERP Hazard (11 days) (11 days)

(per year) (per year)

Internal 1.2E-6 3.6E-8 5.5E-8 1.7E-9 events Internal 2.2E-8 6.6E-10 5.0E-10 1.5E-11 flooding Seismic 3.0E-5 9.0E-7 7.3E-7 2.2E-8 Internal 2.8E-4 8.4E-6 4.5E-6 1.4E-7 Fire Total 3.1E-4 9.3E-61 4.9E-6 1.56E-72 Notes:

1. Meets Regulatory Guide 1.177 acceptance criteria of < 1E-5

2. Meets Regulatory Guide 1.177 acceptance criteria of < 1E-6 19

Compensatory Measures

• 15 compensatory measures will be established during extended completion time, including:

- Two, 2 MW portable DGs staged, test run and hooked-up to Unit 3 FLEX 4.16KV connections

- Diesel driven FLEX Steam Generator make-up pump staged in Unit 3

- Suspension of discretionary maintenance on SBOGs, Switchyard, Safety Systems

- Establish protected equipment controls for Train A equipment, SBOGs, portable equipment

• Additional measures to reduce fire risk will stringently control transient combustibles and limit performance of hot work 20

Risk Profile During Repairs 21

License Amendment Request

• Request one-time extension of Technical Specification 3.8.1 Condition B.4 Completion Time from current 10 days to 21 days

• Request on Emergency Basis

• Risk-Informed Submittal

• To be submitted Wednesday, December 21

• Requesting approval by Sunday, December 25, prior to 3:56 am

• A two-phased approach will be used with a second LAR to request additional extension to completion time 22

Conclusion

• Palo Verde continues to have diverse and redundant sources of AC power and steam generator makeup

• PRA risk acceptable in accordance with Regulatory Guides 1.174 and 1.177

• No significant hazards consideration criteria satisfied

• Second submittal expected upon further completion of the causal evaluation 23

Regulatory Options Current AOT is 10 days, extended AOT times to be determined

• LAR 1 (risk - 11 days)---------------LAR 2 (risk total)

• LAR 1 (deterministic)------LAR 2 (risk total)

• NOED--------------------LAR 1 (risk total)

• NOED---LAR 1 (risk)---LAR 2 (risk total) 24

Questions?