ML21060B187

Enclosure 3 - 1-26-21 Diablo Canyon Renewal pre-app Meeting Slides

ML21060B187
Person / Time
Site:	Diablo Canyon
Issue date:	01/26/2020
From:	Pacific Gas & Electric Co
To:	Office of Nuclear Material Safety and Safeguards
Markley C
Shared Package
ML21060B179	List: ML21060B182 ML21060B184 ML21060B186 ML21060B187
References
EPID L-2021-LRM-0000
Download: ML21060B187 (32)

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

• Mark Mayer - Diablo Canyon (DC) Nuclear Fuel Manager

• 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

• Provide preliminary information to the NRC staff on the license renewal application (LRA)

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)

DCPP Fuel Within the Diablo Canyon Handling Building DC ISFSI Power Plant (DCPP) site boundary and owner-controlled area ISFSI is at 310 ft.

above sea level Marine environment Pacific Ocean 5

Overview of DC ISFSI and License

• Site-specific 10 CFR Part 72 license SNM-2511 issued in March 2004 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

• DC ISFSI consists of:

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 Embedment rings 1,856 fuel assemblies stored in 58 casks for overpack anchors N

• LRA submittal planned for Q4 2021 6

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

• PG&E has initiated consultation with the California Coastal Commission for DC ISFSI license renewal

• Expect to use the same process as used for the Humboldt Bay ISFSI license renewal 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-24EF

• MPC-24E

• MPC-32 Encased concrete Only the MPC-32 has been loaded to-date

• MPC 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 Anchor Pedestal exposed to outdoor air stud holes for MPC 10

Overview of DC ISFSI Pads ISFSI Pad Construction

• 7 storage pads

• Steel-reinforced concrete

• Provide the embedment for anchored overpacks Anchor

• Founded on bedrock with Embedment mudmat placement prior to concrete placement 11

Overview of Unique DC ISFSI Components

• Cask Transfer Facility Transporter Positioned at CTF 4

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 CTF During Construction Empty CTF steel shell HI-STORM Seismic Restraint Transporter in CTF Seismic 3

Restraints 1 2 (4 total)

Seismic Restraint Anchor 12

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

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:

• Humboldt Bay (PG&E)

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

• Chapter 2, Scoping Evaluation

• FSAR supplement with LRA summaries

• Chapter 3, Aging Management Review

• Periodic AMP effectiveness reviews and health reports

• Chapter 4, Time-Limited Aging Analyses

• Appendix A, Aging Management Programs

• Appendix B, Granted Exemptions

• Appendix C, Proposed License Changes

• Appendix D, Final Safety Analysis Report (FSAR)

Supplement

• Appendix E, Pre-Application Inspection Report

• Appendix F, Environmental Report

• Appendix G, Decommissioning Funding Plan 16

DC ISFSI Scoping Results Structures/Components Criterion 1 Criterion 2 In-Scope Important to Spent Fuel Assemblies Yes N/A Yes Safety (ITS) to MPC Yes N/A Yes ensure quality HI-TRAC 125D Transfer Cask Yes N/A Yes and purity; HI-STORM 100SA Overpack Yes N/A Yes credited for Cask Transportation System (including transporter) Yes N/A Yes long-term ISFSI Storage Pads Yes N/A Yes environment Cask Transfer Facility Yes N/A Yes used to Helium Fill Gas Yes N/A No determine aging Fuel Debris (within MPCs) No No No Security Systems No No No Fencing No No No FSAR specifically Lighting No No No discusses why Electrical Power No No No failure of these Communications Systems No No No does not impact Automated Welding System No No No ITS function 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 N

17 Supplemental Cooling System No No No

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

• Determines the site and MPC susceptibility to stress corrosion cracking

• 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 20 publishing operations and holds numerous technical conferences and hundreds of professional development courses each year.

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 21

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

• ACI 349.3R (concrete inspections)

• NUREG-1801, Rev. 2, Sections IX.D and IX.F (soil chemistry)

• Calculated dose rates in the DC ISFSI Updated Final Safety Analysis Report N 22

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 Cask restraint 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

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 24

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 Overpack vents Coating degradation / Anchor stud pitting / surface corrosion surface corrosion 25

Existing DC ISFSI Inspections

• Cask Transporter, CTF, and Transfer Cask prior-to-use inspections Transfer Cask 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 Transporter (non-structural) Coatings weld crack degradation 26

Existing DC ISFSI Inspections

• 2014 EPRI inspection of two MPCs (EPRI Report 3002002822) Top Volunteered for inspection surface of Temperature measurements, surface inspected MPC sampling, and remote visual examination Surface No stress corrosion cracking identified sampler

• Thermoluminescent dosimeter FSAR Model (TLD) dose monitoring compiled quarterly since initial loading No adverse dose trend observed compared Actual Doses to background Well below conservative model assumed in FSAR 27

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 Heat Load1 Years Since Material (kW) Loading 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 30

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