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Canadian NuclearSafety Commission

Commission canadiennede sûreté nucléaire

Julie Mecke – Senior Project OfficerShizhong Lei – Geoscience Technical Specialist

Presentation to IAEA Technical Meeting on Human Intrusion and future Human Actions in relation to Disposal of Radioactive WasteVienna, Austria24 -28 September 2012

Human Intrusion scenarios for Human Intrusion scenarios for Radioactive Waste Management Radioactive Waste Management Facilities – Regulatory Guide and Facilities – Regulatory Guide and Practices in CanadaPractices in Canada

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Overview

1. Existing Regulatory Guidance on Human Intrusion:Regulatory Guide G-320 (2006) “Assessing the Long-Term Safety of Radioactive Waste Management”

2. Examples of proposed Human Intrusion (HI) scenarios for;• 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

3. Conclusions

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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

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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.

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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-specific3. 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 high-consequence intrusion scenario, and to reduce the probability of intrusion occurring

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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 low-level radioactive waste.

• LTWMF Construction expected 2014-2015

Source: AECL, www.phai.ca

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

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Port Hope LTWMF – Human Intrusion (HI) Scenario 1

Construction and occupation of residence on Long-term 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

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Port Hope LTWMF – HI Scenario 1

Construction and occupation of residence on LTWMF

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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.

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Port Hope LTWMF – HI Scenario 2

Exposure to MCS/LLRW during excavation

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Port Hope LTWMF – HI Scenario 3

Exposure to LLRW removed from LTWMF

- Excavate a bulk sample of LLRW rectangular cube 2.5x2.5x1.6m;- Intruders: a backhoe driver and a spotter (on foot), no shielding, 1m away from waste for 4 hrs and 2m away for 4 hrs.

Principal exposure pathways:External exposure to gamma radiation, and Inhalation of radon gas released to air from the waste deposit.

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Port Hope LTWMF – HI Scenario 3

Exposure to LLRW removed from LTWMF

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Deep Geological Repository - Ontario Power Generation for its L&ILW (OPG DGR)

• Deep geological repository for OPG’s operating Low- and intermediate-level radioactive waste

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OPG DGR

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OPG DGR

Source: OPGwww.opg.com

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OPG DGR – HI Scenario

Source: OPG

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OPG DGR – HI Scenario

Source: OPG

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OPG DGR – HI Scenario

Source: OPG

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OPG DGR – HI Scenario

Source: OPG

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OPG DGR – HI Scenario

Source: OPG

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

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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

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Example of future HI review – NWMO APM ProjectPreliminary 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.

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• 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

Concluding Comments

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