Canadian Nuclear Safety Commission canadienne de sûreté nucléaire

Canadian Nuclear Safety Commission canadienne de sûreté nucléaire Human Intrusion scenarios for Radioactive Waste Management Facilities – Regulatory Guide and Practices in Canada Julie Mecke – Senior Project Officer Shizhong Lei – Geoscience Technical Specialist Presentation to IAEA Technical Meeting on Human Intrusion and future Human Actions in relation to Disposal of Radioactive Waste Vienna, Austria 24 -28 September 2012 1

Overview 1. 2. Existing Regulatory Guidance on Human Intrusion: Regulatory Guide G-320 (2006) “Assessing the Long-Term Safety of Radioactive Waste Management” Examples of proposed Human Intrusion (HI) scenarios for; • • • 3. Port Hope Long-term Waste Management Facility - Surface facility for low-level radioactive waste – licensed, but not constructed Deep Geological Repository for low & intermediate-level radioactive waste – undergoing regulatory reviews Conceptual Deep Geological Repository for Used Nuclear Fuel (Spent Fuel) – no licence application, looking for site Conclusions 2

Canadian Nuclear Safety Commission (CNSC) Regulates… • • • Uranium mines and mills Uranium fuel fabricators and processing Nuclear power plants Waste management facilities Nuclear substance processing Industrial and medical applications Nuclear research and educational Export/import control Radioactive waste management facilities …From Cradle To Grave 3

Regulatory Guide G-320: Assessing the Long-Term Safety of Radioactive Waste Management • • Published in December 2006 Scope: - Long term care and maintenance considerations; - Setting post-decommissioning objectives; - Establishing assessment criteria; - Assessment strategies and level of detail; - Selecting time frames and defining assessment scenarios; - Identifying receptors and critical groups; and - Interpretation of assessment results. 4

Regulatory Guide G-320 on Human Intrusion 1. Scenarios of inadvertent intrusion should estimate the exposure of the intruder not aware 2. Risk Scenarios should be case-specific 3. Doses should be predicted • Both the likelihood and the risk from the intrusion should therefore be reported 4. Reasonable efforts to limit dose from a highconsequence intrusion scenario, and to reduce the probability of intrusion occurring 5

Example 1 – Port Hope Area Initiative (PHAI) Port Hope Long Term Waste Management Facility (LTWMF) • Cleanup and safe long-term management of approximately 2 million cubic metres of historic lowlevel radioactive waste. • LTWMF Construction expected 2014 -2015 Source: AECL, www. phai. ca 6

PHAI – Port Hope Long-term Waste Management Facility (LTWMF) –Engineered Mound 7

Port Hope LTWMF – Human Intrusion (HI) Scenario 1 Construction and occupation of residence on Longterm Waste Management Facility (LTWMF) • Excavate through cover layers to build house foundation on top of MCS; • Occupant spends 75% of the time indoors in the home, with 60% of that time on the main floor and 40% in the basement. • Pathways: Gamma radiation and radon from radionuclides in MCS or LLRW 8

Port Hope LTWMF – HI Scenario 1 Construction and occupation of residence on LTWMF 9

Port Hope LTWMF – HI Scenario 2 Exposure to Marginally Contaminated Soil (MCS) /Low Level Radioactive Waste (LLRW) during excavation • Cut 4 m x 4 m square area through the cover to the MCS or LLRW • One person on a backhoe and one person watching; • MCS (or LLRW) exposed for 3 hrs; • Backfilled the hole with 1 m of clean soil; • remain for 1 more hour after backfilling. 10

Port Hope LTWMF – HI Scenario 2 Exposure to MCS/LLRW during excavation 11

Port Hope LTWMF – HI Scenario 3 Exposure to LLRW removed from LTWMF - Excavate a bulk sample of LLRW rectangular cube 2. 5 x 1. 6 m; - Intruders: a backhoe driver and a spotter (on foot), no shielding, 1 m away from waste for 4 hrs and 2 m away for 4 hrs. Principal exposure pathways: External exposure to gamma radiation, and Inhalation of radon gas released to air from the waste deposit. 12

Port Hope LTWMF – HI Scenario 3 Exposure to LLRW removed from LTWMF 13

Deep Geological Repository - Ontario Power Generation for its L&ILW (OPG DGR) • Deep geological repository for OPG’s operating Low- and intermediatelevel radioactive waste 14

OPG DGR 15

OPG DGR Source: OPG www. opg. com 16

OPG DGR – HI Scenario Source: OPG 17

OPG DGR – HI Scenario Source: OPG 18

OPG DGR – HI Scenario Source: OPG 19

OPG DGR – HI Scenario Source: OPG 20

OPG DGR – HI Scenario Source: OPG 21

Conceptual DGR for Canada’s Used Nuclear Fuel – NWMO APM Project Nuclear Waste Management Organization (NWMO) Established in 2002 in accordance with the Nuclear Fuel Waste Act (NFWA) to assume responsibility for the long-term management of Canada’s used nuclear fuel. Adaptive Phased Management (APM) • Currently in site selection process • No licence application • Early regulatory involvement • Review of conceptual design and post-closure safety assessment reports for two hypothetical but realistic sites (crystalline or sedimentary rock) • Presentations to communities, media, municipal forum groups on CNSC’s early role in the APM Project 22

Example of future HI review – NWMO APM Project • Site unknown so conducting pre-project conceptual design for sedimentary and crystalline • Final Crystalline conceptual design to be submitted December 2012 and Sedimentary in April 2013 • CNSC to review for regulatory issues of concern and issue high-level statement • Any statements do not fetter future licensing decisions • Requirement for HI scenarios to be included in future licence application • “Living” Safety Case - HI - If willing and informed site found in suitable rock, the idea would be for the NWMO to use similar methodologies as in pre -project and look at international best practices/ documents 23

Example of future HI review – NWMO APM Project Preliminary review of conceptual design - Crystalline Preliminary review of draft 2011 “NWMO Interim Pre-Project Report Used Fuel Repository Conceptual Design and Post-closure Safety Assessment in Crystalline Rock” Proposed Human Intrusion Scenario • An exploratory borehole is drilled through the geosphere and into the repository. The drill bit is assumed to intersect a used fuel container. • The drill crew, exposed to contaminated drill slurry spread on the surface around the drill rig and to a core section containing used fuel; and • A resident at the site, exposed by living nearby and growing food on soil contaminated by drill slurry. 24

Concluding Comments • Human Intrusion is likely one of the scenarios to cause the highest dose to the critical group • Important topic for stakeholders – asked at outreach meetings • Current CNSC regulatory guide (G-320, 2006) is high-level • Development of future regulatory guidance • International co-operation to develop a guide on developing credible and conservative human intrusion scenarios is very important for the CNSC. • Support international workshop - long time scales of projects – important to keep knowledge management of this topic and to learn from other countries Saskatoon, January 2011 25 25

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