ML21060B187

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Enclosure 3 - 1-26-21 Diablo Canyon Renewal pre-app Meeting Slides
ML21060B187
Person / Time
Site: Diablo Canyon  Pacific Gas & Electric icon.png
Issue date: 01/26/2020
From:
Pacific Gas & Electric Co
To:
Office of Nuclear Material Safety and Safeguards
Markley C
Shared Package
ML21060B179 List:
References
EPID L-2021-LRM-0000
Download: ML21060B187 (32)
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Text

Diablo Canyon Independent Spent Fuel Storage Installation License Renewal Pre-Application Meeting January 26, 2020

Meeting Attendees

  • Tom Jones - Pacific Gas and Electric (PG&E) Director, Strategic Initiatives
  • Rich Hagler - PG&E Dry Cask Storage Supervisor
  • Philippe Soenen - PG&E Decommissioning Environmental and Licensing Manager
  • Michelle Olsofsky - Strategic Initiatives Licensing Engineer
  • Holtec Leadership, Licensing, Engineering, and Project Manager 2

Tom Jones: PG&E Director, Strategic Initiatives Slides 4 - 8 3

Meeting Purpose / Goals

  • Provide background information to the NRC staff on the DC Independent Spent Fuel Storage Installation (ISFSI) license renewal

Humboldt Bay ISFSI lessons learned incorporated

  • Obtain feedback from the NRC staff on the LRA:

Aging management program (AMP) scopes

Pre-application inspection scope 4

Overview of the DC ISFSI Site

  • Location:

6-7 miles northwest of Avila Beach, California (midway between San Francisco and Los Angeles)

Within the Diablo Canyon Power Plant (DCPP) site boundary and owner-controlled area

ISFSI is at 310 ft.

above sea level

Marine environment DC ISFSI Pacific Ocean 5

DCPP Fuel Handling Building

Overview of DC ISFSI and License

License expires in March 2024

Storage of spent fuel, including high-burnup fuel (no greater than Class C waste)

Accommodates all spent fuel generated through the end of the DCPP operating licenses

HI-STORM 100 System

Storage pads and anchorage

Cask Transfer Facility (CTF)

Cask Transporter, Transfer Cask, Low-Profile Transporter (LPT)

  • Current status:

7 completed loading campaigns

1,856 fuel assemblies stored in 58 casks

  • LRA submittal planned for Q4 2021 6

Embedment rings for overpack anchors N

Overview of DC ISFSI and License

  • DC ISFSI was fully permitted and mitigated in perpetuity with state and local agencies:

California Coastal Commission

San Luis Obispo County

  • Coastal Zone Management Act (CZMA):

Addressed during initial permitting through the environmental impact statement in accordance with the California Environmental Quality Act

Consulted the California Coastal Commission regarding CZMA for license renewal

  • Requested submission of a coastal consistency letter similar to Humboldt Bay process 7

California Coastal Commission CZMA Letter for Humboldt Bay ISFSI / Applicability to DC ISFSI 8

Mark Mayer: DC Nuclear Fuel Manager Slides 10 - 13 9

Overview of DC ISFSI Cask System

  • HI-STORM 100 System using the shortened, anchored (SA) overpack design

License allows use of four multi-purpose canisters (MPC) types

  • MPC-24
  • MPC-24E

Only the MPC-32 has been loaded to-date

Seal welded and helium-filled

Sheltered by the overpack

  • Overpack

Bolted lid; air vents to support heat transfer

Anchored to the ISFSI pad embedment rings

Internal space is sheltered; external surfaces are exposed to outdoor air 10 Encased concrete Pedestal for MPC Anchor stud holes

  • MPC-24EF
  • MPC-32

Overview of DC ISFSI Pads

  • 7 storage pads
  • Steel-reinforced concrete
  • Provide the embedment for anchored overpacks
  • Founded on bedrock with mudmat placement prior to concrete placement Anchor Embedment ISFSI Pad Construction 11

Overview of Unique DC ISFSI Components

  • Cask Transfer Facility

Comprised of reinforced concrete support structure (photo 1),

interlaying steel shell (photo 2), removable seismic restraints (photo 3), and transporter restraint anchors (photo 4)

Facilitates transfer of a loaded MPC to the HI-STORM overpack

Mating device is used to guide the MPC transfer 12 Empty CTF steel shell Seismic Restraint Anchor CTF During Construction HI-STORM Seismic Restraint in CTF 1

2 3

Transporter Positioned at CTF 4

Transporter Seismic Restraints (4 total)

Overview of Unique DC ISFSI Components

  • Cask Transporter

Self-propelled, open-front, tracked vehicle

Custom-designed for DCPP conditions

Shared with PG&Es Humboldt Bay ISFSI

  • Low-Profile Transporter

Dedicated-use multi-roller heavy haul device

Transports transfer cask outside of the power block to the Cask Transporter 13 Cask restraint LPT

Philippe Soenen: PG&E Decommissioning Environmental and Licensing Manager Slides 15 - 31 14

DC ISFSI License Renewal Application Preparation

  • Will use the following guidance:

NUREG-1927, the Standard Review Plan (SRP) for ISFSI renewal, Rev. 1 NUREG-2214, Managing Aging Processes in Storage (MAPS), Rev. 0 NEI 14-03, Guidance for Aging Management of Dry Cask Storage, Rev. 2 Recent ISFSI license renewal precedent:

  • Rancho Seco
  • Trojan
  • HI-STORM 100 Certificate of Compliance (NRC review in-progress)
  • HI-STAR 100 Certificate of Compliance (NRC review in-progress) 15

DC ISFSI License Renewal Application Overview

  • Chapter 1, General Information
  • Chapter 2, Scoping Evaluation
  • Chapter 4, Time-Limited Aging Analyses
  • Appendix B, Granted Exemptions
  • Appendix C, Proposed License Changes
  • Appendix D, Final Safety Analysis Report (FSAR)

Supplement

  • Appendix F, Environmental Report

Will have similar attributes as seen in PG&Es Humboldt Bay ISFSI LRA:

FSAR supplement with LRA summaries Periodic AMP effectiveness reviews and health reports

DC ISFSI Scoping Results 17 N

Structures/Components Criterion 1 Criterion 2 In-Scope Spent Fuel Assemblies Yes N/A Yes MPC Yes N/A Yes HI-TRAC 125D Transfer Cask Yes N/A Yes HI-STORM 100SA Overpack Yes N/A Yes Cask Transportation System (including transporter)

Yes N/A Yes ISFSI Storage Pads Yes N/A Yes Cask Transfer Facility Yes N/A Yes Helium Fill Gas Yes N/A No Fuel Debris (within MPCs)

No No No Security Systems No No No Fencing No No No Lighting No No No Electrical Power No No No Communications Systems No No No Automated Welding System No No No MPC Helium Backfill System No No No MPC Forced Helium Dehydration System No No No Rockfall Fence No No No Rock-Bolted Cut-slope No No No Supplemental Cooling System No No No FSAR specifically discusses why failure of these does not impact ITS function Important to Safety (ITS) to ensure quality and purity; credited for long-term environment used to determine aging

Scoping and Aging Management Review

  • Format and content will model PG&Es Humboldt Bay ISFSI LRA LRA will breakdown into sub-components per fabrication drawing bill of materials listings and provide the safety intended functions
  • Fabrication drawings will be made available to the NRC in an electronic reading room Aging Management Review (AMR) is only conducted on those sub-components that have a safety intended function or whose failure could prevent fulfillment of a safety function
  • Safety function based on confinement, sub-criticality control, heat transfer, structural integrity, shielding, and retrievability AMR tables in LRA Chapter 3 provide materials, internal and external environments, aging effects/mechanisms, and aging management
  • Each AMR line will address whether it is consistent with the MAPS Report N

18

Aging Management Programs PG&E is proposing six AMPs to manage all aging effects requiring management

1. High Burnup Fuel AMP Relies on the joint EPRI and Department of Energy High Burnup Dry Cask Storage Research and Development Project (HDRP).

Includes justification that the demonstration program applies to DCPP fuel 3 formal evaluations will occur as follows:

1. Prior to March 2024 (end of the initial license) 2.

March 2034 (10 years after first assessment) 3.

March 2044 (10 years after second assessment)

N 19

Aging Management Programs 2.

MPC AMP

Consistent with American Society of Mechanical Engineers (ASME*) Code Case N-860

  • Performs screening exam, assessment exam (if required), and supplemental exam or analysis (if required)
  • Sets scope and inspection frequency based on results and susceptibility 3.

Transfer Cask AMP

Prior to use; inspections are valid for five years

  • Visual Testing (VT)-3 100% of normally accessible surfaces (exterior, interior cavity, lid surfaces, bottom)
  • VT-2 of water jacket

Acceptance criteria is consistent with MAPS example AMP

  • ASME is a not-for-profit membership organization that is known for setting codes and standards for mechanical applications. ASME conducts one of the world's largest technical publishing operations and holds numerous technical conferences and hundreds of professional development courses each year.

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Aging Management Programs

4. Overpack AMP Every five years
  • VT-3 100% of normally accessible surfaces (outside of overpack, anchorages); applies to all loaded overpacks
  • VT-3 anchor stud sampling plan During remote inspections of MPCs
  • VT-3 100% of the metallic surfaces made accessible by the MPC inspections (i.e., inside of overpacks; number of overpacks inspected would be consistent with number of MPCs inspected)

Acceptance criteria is consistent with MAPS example metallic surfaces AMP N

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Aging Management Programs

5. Reinforced Concrete Structures AMP Every five years
  • American Concrete Institute (ACI) 349.3R inspection of 100% of above-grade storage pads and CTF structural concrete
  • Soil testing in vicinity of ISFSI to determine whether soil is aggressive
  • Shielding concrete (un-reinforced) effectiveness survey on those overpacks inspected by remote means Opportunistic
  • ACI 349.3R inspection of below-grade concrete exposed for any reason Acceptance criteria is consistent with
  • NUREG-1801, Rev. 2, Sections IX.D and IX.F (soil chemistry)

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Aging Management Programs

6. Cask Transportation AMP

Transporter: because it is shared with the Humboldt Bay ISFSI, the following proposed AMP inspections are the same as those approved by the NRC for Humboldt Bay

  • VT-3 100% of accessible portions of structural members, restraint system, MPC downloader, wedge lock assembly
  • Torque check for 100% accessible bolting
  • Visual and tactile inspection of 100% seismic restraint (sling)
  • Periodic replacement of polymer adjustable bumpers

Transfer Equipment: prior to use; inspections are valid for five years

  • VT-3 100% of the following accessible surfaces: lift links, lift cleats, lift brackets, connector pins, CTF liner and lateral restraints, mating device, LPT

Acceptance criteria are consistent with

  • Previously-approved acceptance criteria from the Humboldt Bay LRA
  • MAPS example metallic surfaces AMP N

23 Cask restraint

Time-Limited Aging Analyses

  • Developed a preliminary list of time-limited aging analyses (TLAAs) and technical evaluations based on:

Previous LRA reviews DC ISFSI design and licensing documentation reviews NRC guidance

  • One evaluation was identified as meeting all six TLAA criteria and was evaluated for the additional 40 years:

Neutron absorber and shielding performance

  • Although not a TLAA, one evaluation was reviewed to disposition aging on components within the scope of renewal:

Number of MPC lifts allowed over renewed license period N

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Existing DC ISFSI Inspections

  • Annual overpack / surrounding storage pad visual inspections

Coatings degradation - no impact to overpack intended function

Surface corrosion - no impact to overpack intended function

  • Minor anchor stud pitting and surface corrosion - no impact to intended function
  • Daily overpack vent inspections 25 Overpack vents Coating degradation /

surface corrosion Anchor stud pitting / surface corrosion

Existing DC ISFSI Inspections

  • Cask Transporter, CTF, and Transfer Cask prior-to-use inspections

Coatings degradation

  • Complete Transporter re-coat in 2020
  • Transfer cask completely re-coated prior to loading campaigns

Transporter loose bolting and weld cracking

  • Weld continues to be monitored to ensure no impact to intended function 26 Transporter (non-structural) weld crack Coatings degradation Transfer Cask

Existing DC ISFSI Inspections

Volunteered for inspection

Temperature measurements, surface sampling, and remote visual examination

No stress corrosion cracking identified

  • Thermoluminescent dosimeter (TLD) dose monitoring compiled quarterly since initial loading

No adverse dose trend observed compared to background

Well below conservative model assumed in FSAR 27 Top surface of inspected MPC Surface sampler FSAR Model Actual Doses

Proposed Pre-Application Inspection

  • Scope

7 MPC inspections (VT-3 100% accessible by remote means)

  • Includes each MPC build (i.e., vintage)

7 overpack inspections (VT-3 100% accessible, same as MPCs)

ISFSI storage pads and CTF structural concrete (ACI 349.3R 100% above grade, accessible)

Soil testing

  • Planning for inspection in March - May 2021
  • Relying on previous inspection results (2007-2020) for the Transfer Cask, CTF metallic components, and cask transportation components (transporter, LPT, lifting devices) 28

Proposed Pre-Application Inspection Proposed cask inspection considerations:

Material: DC ISFSI has 3 MPC material types in service; some more susceptible to chloride-induced stress corrosion cracking (CISCC)

Heat load: lower heat loads are more susceptible to CISCC Time since loading (age):

Components have more time to degrade (corrosion, etc.)

More time for fuel to cool (deliquescence)

Burnup: high burnup fuel is the subject of significant research for long-term storage Manufacturing deviations: may impact canister susceptibility Trending information for EPRI-inspected casks Proposed casks bound the above considerations 29

Pre-Application Inspection Locations 30 Heat Load1 (kW)

Years Since Loading Material Grade2 1

12 8

304 2

20 11 304 3

15 8

304 4

20 10 304 5

16 7

304/304L 6

24 2

316/316L 7

16 4

316/316L Insp. Avg.3 17.8 7.1 N/A Avg. All4 20.2 6.4 N/A Notes - 1) Heat load at loading

2) Material types in use at DC ISFSI are 304, 304/304L, and 316/316L stainless steels
3) Average of the 7 inspection locations
4) Average of all 58 loaded casks Selection accounts for all material types, all builds, range of cask ages, and range of heat loads

Next Steps Schedule Pre-Application Inspection: March - May 2021 Inviting NRC, California Energy Commission, and Diablo Canyon Independent Safety Committee to observe LRA submittal: Q4 2021 Required submittal: March 2022 Questions and Feedback?

31

Thank You 32

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