The Nuclear Waste Management Organization (NWMO) is responsible for implementing Adaptive Phased Management (APM); the approach selected by the Government of Canada for long-term management of Canada’s used nuclear fuel.

The Canadian program is in the conceptual stages and layouts have been advanced to facilitate communication about the disposal concept, but without the benefit of having a specific site identified as the host for the repository. The Canadian layouts to date have assumed that a large enough homogeneous and isotropic domain of rock will be available to host the repository; therefore the layouts tend to be of very regular geometries and compact. Other countries, such as Finland and Sweden, have identified their hosting locations which exhibit crystalline geosphere conditions. They started the development of adaptive (flexible) site-specific underground layouts capable of adjusting to encountered structural anisotropy. When viewed from this angle, it is possible that a number of Canadian candidate sites in crystalline geosphere would exhibit similar features. With this recognition, NWMO has started the development of adaptive layouts.

This paper presents the results of the first comparative study between the base case (regular and compact) and more adaptive layouts applied to a hypothetical Canadian crystalline geosphere. The Pugh Matrix (opportunity analysis) suitable for early design stages is used for comparative studies taking into consideration various factors including cost, schedule, site characterization requirements, constructability, operational flexibility, maintainability, operational safety and long-term safety, etc. It was concluded that the concepts represented in the adaptive layout offer advantages in relation to flexibility, schedule, post closure safety and thermal performance that may justify a deviation from the base case once a site has been selected.