CEP Discussion: AREVA s SONGS-Specific Used Fuel Solution

Transcription

1 CEP Discussion: AREVA s SONGS-Specific Used Fuel Solution AREVA TN October, 14, 2014 Dr. Michael V. McMahon, Sr. VP AREVA TN Americas AREVA TN

2 AREVA s SONGS-Specific Solution Topical Outline 1. Overview of Cask/Canister System Design and Implementation 2. Defense in Depth, Maintenance & Surveillance Requirements 3. Anticipated Aging Management Plan 4. Mitigation of Degraded Canister Safe Used Fuel Solutions for SONGS October, 14, p.2

3 1. Overview of Cask & Storage System Design and Implementation Dry Shielded Canister The primary criticality control and storage container for the used fuel assemblies Shell designed for extremely long lifetime Ability to can assemblies in retrievable cans (NRC license submittal in progress) High Seismic Horizontal Storage Module Passively removes heat from canister Protects canister against external hazards Protects canister from the environment Provides heavy duty biological shielding Robust Design is Engineered for Long-Term Storage Safe Used Fuel Solutions for SONGS October, 14, p.3

4 1. Overview of Cask & Storage System Design and Implementation Transfer Cask Assures safe loading and transfer of the canister from the Spent Fuel Pool to the storage module Provides biological shielding during transfer Loaded canister is always in the transfer cask during handling Transportation Cask Transports fuel safely away from the site In fabrication now; ready to deploy in 2016 Only cask licensed to transport canisters loaded with high burn-up fuel in the U.S. NUHOMS Systems are Licensed Today to Transport SONGS Fuel Off-Site Safe Used Fuel Solutions for SONGS October, 14, p.4

5 1. Overview of Cask and Storage System Design and Implementation Requires expansion of existing ISFSI pad Horizontal storage requires shallow excavation Final appearance can be readily enhanced during final site grading Low schedule risk for meeting spent fuel pool offload dates Implements technology already in use at SONGS NUHOMS Implementation Assures Path of Greatest Certainty to Early Spent Fuel Pool Off-Load Safe Used Fuel Solutions for SONGS October, 14, p.5

6 2. Defense-in-Depth Layers of Protection Key Safety Functions Heat Removal Ensure fuel/cladding stays intact and in stable temperature range Confinement Protect public health and safety by keeping radioactive material out of the biosphere Defense in Depth Components Fuel Assemblies (pellets and cladding) Dry Shielded Canister Horizontal Storage Module Robust Learning Aging Management Program (LAMP) Inspection/Monitoring Mitigation/Repair Isolation/Replacement Protecting the Fuel is Our Number One Safety Priority Safe Used Fuel Solutions for SONGS October, 14, p.6

7 2. Defense in Depth: Fuel Assembly Integrity Fuel Pellets (UO 2 ) Hard ceramic matrix that locks in and immobilizes 99.9%+ of radioactive materials Keep temperature within stable limits to keep radioactive materials trapped inside the pellets Fuel Rod Cladding (Zirconium metal alloy) Added layer of protection for the fuel pellets Contain radioactive gases generated in the fuel Keep temperature within stable limits to keep cladding intact First Line of Defense to Contain the Radioactive Inventory Safe Used Fuel Solutions for SONGS October, 14, p.7

8 2. Defense in Depth Heat Removal: Canister and HSM Design Dry Shielded Canister Horizontal Storage Module Canister cools fuel passively through internal conduction to shell surface Helium leak would have minimal impact on heat removal capabilities Passive cooling maintained even if lower vents blocked by flood/debris Expedient debris and mud removal from airflow paths Easily accessible for visual inspection of airflow paths Above Ground System Provides Robust Heat Removal Capabilities Safe Used Fuel Solutions for SONGS October, 14, p.8

9 2. Defense in Depth Confinement: Canister Design Dry Shielded Canister Confinement barrier for radioactive gases escaping the fuel assemblies Corrosion-resistant stainless steel shell designed for 100 year + lifetime with LAMP Low helium back-fill pressure Loaded canister is always in the transfer cask during handling Double welded lid safeguards confinement integrity Inspections During Fabrication Every canister is tested under the most robust guidelines as dictated by Section III, Subsection NB of the ASME code and ANSI N 14.5 Mechanical testing for yield strength, ultimate strength and elongation of each component Completed welds are 100% visually, 100% radiography (RT) or liquid dye penetrant (PT) inspected Engineered and Fabricated with Highest Level of Standards Safe Used Fuel Solutions for SONGS October, 14, p.9

10 2. Defense in Depth Confinement: Horizontal Storage Module Design Horizontal Storage Module 4 foot thick steel reinforced concrete roof Dose reduced to levels indistinguishable from natural background radiation at ISFSI fence Licensed to withstand all of SONGS Site-Specific External Hazards Earthquake: 1.5g horizontal / 1.0g vertical / 2.35g combined acceleration specification makes NUHOMS the highest seismically qualified dry storage system in the world Tsunami/Flood: qualified for a flood height more than 40 higher than the SONGS site design basis flood height Tornado: can withstand impact of tornado accelerated objects (e.g. 4,000 lbs. automobile traveling more than 195 mph) Aircraft Impact: no release of radioactive material in case of aircraft impact and above ground system not susceptible to jet fuel fires Robust Storage Module Engineered to Perform Through Hazards Safe Used Fuel Solutions for SONGS October, 14, p.10

11 3. Learning Aging Management Program (LAMP) 3 Pillars Adaptive System 3 Pillars Inspection/Monitoring Mitigation/Repair Isolation/Replacement Periodic Inspections Data Collection Initiated at license renewal; timed to occur well before degradation can progress Subsequent 5 year inspection intervals are spaced to detect any degradation mechanism Potential additional inspection LAMP includes toll gate feature at five year intervals, which evaluates latest research and industry experience of dry storage aging mechanisms and inspection methods and results Correspondingly appropriate changes to LAMP will be implemented LAMP is a Further Line of Defense for Long Term Storage Safe Used Fuel Solutions for SONGS October, 14, p.11

12 3. Aging Management Plan: Inspection Capabilities Inspections Capability for inspection of 100% of canister surface Non-Destructive Examination (NDE) Tools Exam tools ready for field deployment in years ahead of need for SONGS license renewal Current standard is enhanced Visual Inspection (VT) using high resolution video cameras; can use other techniques if needed Above ground system allows for: Simple retrieval for inspection and shipment Accessibility in case of remediation (cleaning, repair) NUHOMS System Provides Easy Access for Inspection Safe Used Fuel Solutions for SONGS October, 14, p.12

13 3. Aging Management Plan: Research and Licensing The NRC issued the initial licenses for components for 20 years, and will reissue them in up to 40-year increments with toll gates AREVA TN currently submitting license renewals at other sites AREVA has 5 years of experience in research and development of LAMP SONGS NUHOMS system will have the benefit of standardized NUHOMS System LAMP experience (17 sites, 381 DSCs and canister years ) Long term NRC High Burn-up Fuel (HBF) licensing coordinated with DOE/EPRI Research AREVA (TN-32) plays a central role in the Department of Energy s HBF storage research and demonstration program AREVA TN plays critical role in study concerning licensing analysis AREVA s global research and engineering resources augments DOE/EPRI Research AREVA TN is at the Forefront of High Burn-up Fuel Research and LAMP Development Safe Used Fuel Solutions for SONGS October, 14, p.13

14 3. Aging Management Plan: Long-Term Solutions Used Fuel Waste MOX REPU AREVA TN has a fully-licensed solution for off-site transportation today Since 1966, AREVA TN has transported more than 75,000 spent nuclear fuel assemblies worldwide, including 15,000 high burn-up fuel assemblies No release of radioactive material ever No damage to fuel during transport AREVA TN has the Most Experience in Transporting Used Fuel including High Burn-up Fuel Safe Used Fuel Solutions for SONGS October, 14, p.14

15 4. Mitigation of Degraded Canister Repair/Replacement Canister Repair If crack is detected by LAMP on a canister it can be repaired by grinding to the root, if shallow, or weld-repaired, if larger Sufficient time exists for remediation action due to extremely slow progress of degradation mechanisms Through-wall crack poses no threat to health and safety of the public Canister Replacement Provide oversized storage module and canister for overpack in the event a canister requires replacement Overpack canister is bolted, sealed, and monitored Transportation cask is used to move canister off-site No Impact to Public Health and Safety Safe Used Fuel Solutions for SONGS October, 14, p.15

16 Conclusion Long-term public health and safety is assured through Defense in Depth protection: Fuel rod in the assembly captures 99.9%+ of radioactive material by design Canister is designed to remove heat and confine any radioactive gases Storage Module is designed to remove heat and protect canister from external hazards Adaptive and Conservative Learning Aging Management Program ensures long-term integrity of the system Inspection/Detection Mitigation/Repair Isolation/Replacement AREVA TN has more than 50 years of experience in safely managing used nuclear fuel SONGS Can Rely on AREVA TN as a Strong, Long-Term Partner Safe Used Fuel Solutions for SONGS October, 14, p.16

17 Safe Used Fuel Solutions for SONGS October, 14, p.17 Backup Material

18 Appendix A: Case Studies Maintenance and Inspection Case Studies Secondary seal leak: Peach Bottom (TN-68) and Surry (TN-32) Metal Casks AREVA has never experienced any failure of a system leading to radioactive material leakage Release of helium from the monitoring system due to water intrusion at outer aluminum seal; inner seal intact Pressure between inner and outer seals continuously monitored; reduction in pressure gave operators plenty of time to correct the problem NUHOMS canisters are sealed by welds, not by bolts and seals Idaho Nat l Lab NUHOMS storage of Three Mile Island core material Water collected in hole for roof attachment bolt, then froze, cracking the concrete; damage repaired and hole re-designed to prevent freeze damage Cracks in the concrete roof, no impact on the canister: no leakage, no reduction of physical protection or shielding; no generalized concrete deterioration Safe Used Fuel Solutions for SONGS October, 14, p.18

19 Safe Used Fuel Solutions for SONGS October, 14, p.19 Appendix A: Case Studies

20 Appendix B: Aging Management Program Aging Management Program (AMP) for DSCs: Visual inspections of the DSC external surfaces in accordance with ASME Section XI IWA ASME Section XI VT-1 visual examination is conducted to detect discontinuities and imperfections including cracks. Sampling of deposits on the DSC surface are also taken for chemical analyses to determine actual salt concentration. Inspection acceptance criteria: cracks are absent within the material and indications of crevice corrosion or heavy pitting corrosion are also absent. If acceptance criteria is not met, a Condition Report is initiated per the site s Corrective Action Program to drive further evaluation, characterization, and additional NDE inspections. Initial inspection: at or prior to 20 years of DSC in-service. Tests and other available information indicate that the earliest that cracking would initiate is at about 30 years. However, there is significant uncertainty about these estimates, and the NRC is not currently relying nor has sufficient confidence on them to make regulatory decisions. This may change in the future as licensees perform inspections in the next few years and atmospheric and salt concentration data are collected and correlations to crack initiation estimates are validated. Safe Used Fuel Solutions for SONGS October, 14, p.20

21 Appendix B: Aging Management Program Aging Management Program (AMP) for DSCs: Inspection Interval: Every five years. This inspection interval may be adjusted based on results and evaluation of prior SONGS DSC inspections and review of new research on minimum chloride concentrations required to initiate cracking. The visual inspection, surface deposit sampling, and other NDE can be conducted remotely by inserting the inspection devices through the vents or through the annular gap between the DSC and the HSM front door opening. The DSC may also be withdrawn into a Transfer Cask (TC) and inspected by inspection tools in the docking ring mounted between the TC and the HSM. The DSC top cover and weld can be inspected directly before returning the DSC to the HSM. The bottom cover can also be examined directly while the DSC is in the HSM with the door removed. Although not required, SONGS may consider implementation of an environment air monitoring program to monitor airborne salts concentration around the ISFSI site. Once sufficient environmental and sampling data are collected, it should be feasible to establish a correlation to adjust frequency of inspections. Safe Used Fuel Solutions for SONGS October, 14, p.21