ASK THE NWMO Week 4 – Assessing the Safety of a Site

Written by Nuclear Waste Management Organization on 27 March 2012

Canada’s plan for the long-term management of the country’s used nuclear fuel requires that used fuel be safely and securely contained and isolated in a deep geological repository in a suitable rock formation. The NWMO is committed to implement Canada’s plan in a manner that protects human health, safety, security and the environment.

Answering questions in this March 27^th edition of “Ask the NWMO” is Dr. Mahrez Ben Belfadhel the Director of Used Fuel Repository Geoscience at the Nuclear Waste Management Organization. His team is responsible for assessing the geoscientic suitability of potential host sites. Dr. Ben Belfadhel has more than 25 years of combined multidisciplinary experience in areas related to geotechnical and geoenvironmental engineering. With the Canadian Nuclear Safety Commission, he worked as a geoscience and safety assessment specialist for 11 years, during which he also assumed the responsibility of Acting Director of the Waste and Decommissioning Division. He has maintained an active involvement in the international nuclear waste community, mainly through his work with the International Atomic Energy Agency.

Dr. Ben Belfadhel has a bachelor’s degree in Civil Engineering from École Polytechnique of Algiers, and a master’s degree and Ph.D. inGeotechnical Engineering from Université de Sherbrooke in Quebec. He is also a registered Professional Engineer.

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QUESTION What studies will be conducted to assess the safety of a site?

ANSWER

The safety of any potential site will be assessed using a thorough site evaluation process and a comprehensive list of site evaluation criteria that are both technical and social in nature. It is expected that it will take between seven and 10 years to complete all the site evaluations and studies that are necessary to conrm the suitability of a site. The site will be assessed in a series of steps. Each step is designed to evaluate the site in greater detail than the step before. A site may be found to be unsuitable at any stage of evaluation, at which point work at that site would cease and the site would no longer be considered for a deep geological repository.

These studies will be conducted only in communities that have expressed an interest.

QUESTION What are the initial screening criteria?

ANSWER Any site will need to rst meet a minimum set of initial criteria in order to be considered.

The site must have available land of sufcient size to accommodate the surface and underground facilities.
This available land must be outside protected areas, heritage sites, provincial parks and national parks.
This available land must not contain known groundwater resources at the repository depth that could be used for drinking, agriculture or industrial uses.
This available land must not contain economically exploitable natural resources.
This available land must not be located in areas with known geological and hydrogeological characteristics that would prevent the site from being safe.

Potentially suitable sites that meet these initial criteria will be the subject of progressively more detailed studies in two primary areas:

First, ensuring safety – that is, the ability of the site to protect people and the environment, now and in the future.
Second, beyond safety – the effect of the project on the sustainability and well-being of the host community.

QUESTION What will detailed studies examine?

ANSWER Detailed studies will focus on the following questions:

Are the characteristics of the rock at the site appropriate to ensuring the long-term containment and isolation of used nuclear fuel from humans, the environment and surface disturbances caused by human activities and natural events?
Is the rock formation at the site geologically stable and likely to remain stable over the very long term considering geological and climate change processes such as earthquakes and glacial cycles?
Are conditions at the site suitable for the safe construction, operation and closure of the repository?
Is human intrusion at the site unlikely, for instance through future exploration or mining?
Can the geological conditions at the site be practically studied and described?
Can a transportation route be identied or developed by which used nuclear fuel can safely and securely be transported to the site from the locations at which it is stored?

A robust safety case will be developed. The preferred site will be in a rock formation with desirable characteristics (geological, hydrogeological, chemical and mechanical). The rock formation must support containment and repository performance that meet or exceed the regulatory expectations of the Canadian Nuclear Safety Commission, the guidance of the International Atomic Energy Agency and the experience in other countries with nuclear waste management programs.