Dry Cask Storage
Defense-in-Depth
Jerry Stephenson
Manager, ISFSI Engineering
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Dry Cask Storage Defense-in-Depth
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SCE’s Requirements for Dry
Cask Storage Systems
• SCE goal is to ensure fuel is prepared for both onsite and offsite storage
• Selection criteria
– Must be currently licensed for storage and transportation (at time of selection)
– Must meet SONGS seismic criteria
– Long enough to accommodate SONGS fuel assemblies
– Low Dose Rates
– Strong presence in the U.S. Nuclear industry
• Systems that did not meet criteria were disqualified
• Three vendors were identified that met the requirements
– AREVA (Now Orano,also called TN Nuhoms)
– Holtec
– NAC International
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Bolted-Lid Cask Limitations
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DOE Atlas Railcar
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Railcar can accommodate Orano and Holtec transportation casks
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• Design specifications– Licensed for storage and transportation
– Higher seismic design based on local seismic conditions
– Thicker shell at 5/8-inch vs standard 1/2-inch
– 316L low-carbon stainless steel for improved corrosion resistance
• Less susceptible to corrosion
• Holtec fabrication enhancements to address chloride-induced stress corrosion cracking– Laser peening to eliminate surface stresses
– Two-pass weld technique to minimize heat affected zone
– Shell over-rolling
Specifications
for Dry Cask Storage System
Safety and Technical FeaturesDry Cask Storage Systems at SONGS
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Chloride Induced Stress
Corrosion Cracking (CISCC)
• CISCC requires three conditions to start:– Salt and water environment
– Susceptible material
– Tensile stresses in steel to enable crack to grow
• No instances of CISCC have been identified on canisters during inspections conducted to date
• Several design & fabrication improvements minimize potential for development of canister flaws
• 316L is resistant to CISCC
• Peening results in compressive stresses versus tensile stresses
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Fabrication Improvement:
Peening Canister Welds
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Canister Inspection
• Loaded canisters have been inspected worldwide
– Both horizontal (TN NUHOMS) and vertical (Holtec) systems have
been robotically inspected
– 8 Holtec UMAX canisters inspected at SONGS in 2019
• Canister Inspections will continue at SONGS in 2021
– TN NUHOMS baseline inspection for aging management program
(AMP)
– Holtec UMAX as designated by inspection & maintenance (I&M)
plan in 2024
• Robotic systems are currently available for these inspections
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SCE Inspection Developments
• Holtec UMAX
– Implemented: SCE demonstrated that detailed visual inspections can be
performed at SONGS
– 8 canisters inspected in early 2019
– Available: Eddy current, ultrasonic inspection, and mitigation
technology available, if needed
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SCE Inspection Developments
• TN NUHOMS
– Implemented: Other utilities have performed detailed visual
inspections with robotic technology
– Available soon: Inspection Ring undergoing final testing, will be
available for SONGS use in 2020
• First TN NUHOMS Inspections planned for 4Q 2021
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Orano Inspection Ring
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Orano Inspection Ring
• Orano Inspection Ring developed for the SONGS TN
NUHOMS System
– Allows for more detailed inspections if degradation is discovered
during initial robotic inspection
• Can perform more detailed Visual, Eddy Current, and Ultrasonic
inspections as necessary
• Remediation will also be available before 2021 planned
inspections
– Status
• Final Performance Testing will occur 4th Quarter 2019
• Inspection Ring will be operational and ready for deployment by
end of 2019
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RemediationAddressing Potential Flaws
• SCE and nuclear industry are actively working to develop
remediation techniques to address a potentially degraded
canister
1. Robotic weld repair
• Mounted on inspection ring (Orano) or mobile robotics (Holtec)
2. Nesting or over-pack
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Canister Remediation
• Remediation capability will be available in time to support
planned Orano inspections and Holtec I&M Plan submittal
– Orano TN/NUHOMS
• Inspections planned for 4Q 2021
– Holtec/UMAX
• I&M Plan submittal to CCC planned for October 2020
• Inspections based on I&M Plan, likely next inspections in 2024
–5-year inspection interval
–Regulations require first inspections in 2035
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BREAKInformation Booths Available
For Internal Use Only
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CLOSING COMMENTSDAVID VICTOR AND DOUG BAUDER
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CEP Meetings
Topics Timing
Fuel Transfer Operations & Path Forward 6-5-19
Defense-In-Depth for Dry Cask Storage 8-22-19
SONGS Strategic Plan & the State of Private
Consolidated Interim Storage
11-21-19
Dry Fuel Storage Safety Workshop 1Q 2020
For Internal Use Only
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For Internal Use Only
Acronyms
For Internal Use Only
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APPENDIX
MCB Camp Pendleton22 Aug 2019
SONGS CEP Meeting
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MCB Camp Pendleton Population: 85,650
Marines 38,802 Navy 4,177 Civilian 6,350 Army/Air Force 21Family members 36,300
Daily population surges well above 86,000
Numbers as of Feb 2019
Local Communities Population Oceanside 178,240 San Clemente 66,245 Fallbrook 31,707
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For Internal Use Only
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FUEL TRANSFER OPERATIONS
Used Fuel
Readiness for Transportation
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• Some fuel qualified for transport now
• Remaining fuel qualifies over time
NOW ‘20 ‘21 ‘22 ‘23 ‘24 ‘25 ‘26 ‘27 ‘28 ‘29 ‘30 TOTAL
Units 2/3AREVA NUHOMS 24PT4
Unit 1AREVA NUHOMS 24PT1
Units 2/3HOLTEC MPC-37
6
1 95
1167 2 2
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17
73
33
2
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For Internal Use Only
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DRY CASK STORAGE
Dry Cask Storage
Holtec License Renewal Plan
• Holtec Inspection and Maintenance (I&M) Plan– Required for California Coastal Commission (CCC) coastal
development permit
• Must be submitted to CCC by 10/6/2020
• Four elements are required for I&M Plan
– Canister inspection, monitoring, and maintenance techniques
– Data that will be collected, and frequency of submission to CCC
– Available evidence related to the physical condition of the casks
– Remediation measures that will be implemented if canister condition is not sufficient to allow on-site and off-site transportation
– Will be implemented after CCC approval of plan• I&M Plan will be effective for initial license period (until 10/15/2035)
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Dry Cask Storage
Orano License Renewal Plan
• ORANO TN/NUHOMS/ License Renewal Application under review
by NRC
• Submitted by SCE to NRC May 2019
• 18-24 month review (normal NRC schedule)
• License expires 2/5/2023
– CA coastal development permit (CDP) renewal for NUHOMS system
• CDP application will be filed after NRC license renewal
• Submittal of CDP by SCE planned for 2/2022
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Sites Which Have Performed ISFSI
Canister Robotic Inspections
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Orano
Storage Module and Canister
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Outlet Vent
For Internal Use Only
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SONGS EMERGENCY SIRENS
This information is summarized in CEP Decommissioning Update handout
SONGS Emergency Sirens
• Fifty alert sirens depowered in local communities July 1, 2019
• NRC and Federal Emergency Management Agency (FEMA)
determined sirens were unnecessary
• Accident at defueled plant no longer exceed Environmental
Protection Agency (EPA) protective action guidelines (PAG) that
recommend evacuation or sheltering in place
• No credible radiological release beyond site boundary
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SONGS Emergency Sirens
• Sirens only were to be activated for two highest emergencies
– Site and general emergency
• Neither can occur at SONGS now that reactors are retired
– Sirens never activated due to an emergency in 39 years of service
• SONGS continues to maintain a robust emergency planning and
preparedness program
• More on emergency planning during decommissioning:
– https://www.songscommunity.com/safety/emergency-planning58
For Internal Use Only
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WHEELER NORTH REEF
EXPANSION PROJECT UPDATE
This information is summarized in CEP Decommissioning Update handout
Reef Expansion Project
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Reef Expansion Project
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Links to Important Topics on
SONGScommunity.com
• SCE White Paper on Incidental Canister Contact - June 3, 2019
– https://www.songscommunity.com/internal_redirect/cms.ipressroom.com.s3.amazonaws.co
m/339/files/20195/Effects%20of%20Incidental%20Contact%20White%20Paper%20FINAL
%20060319.pdf
• Drop Analysis of Fully Loaded Multi-Purpose Canister (Model MPC-37)
– https://www.songscommunity.com/internal_redirect/cms.ipressroom.com.s3.amazonaws.co
m/339/files/201810/Non-
proprietary%20SCE%20Summary%20of%20Hypothetical%20MPC-37%20Drop%2011-19-
18.pdf
• Frequently Asked Questions https://www.songscommunity.com/need-to-know/faq
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