Design of Containment for the Long-Term Isolation of Irradiated Fuel During Underground Disposal

Abstract

As part of the Canadian Nuclear Fuel Waste Management Program, work is underway to design high-integrity, corrosion-resistant containers for the direct disposal of unreprocessed, irradiated fuel in a geologic vault. The role of such containers is to provide isolation of the fuel for at least 300 years, thus ensuring that most fission products are contained for their hazardous lives.

Several container concepts are under investigation. The simplest container, called the "stressed-shell" design, has sufficient strength and shell thickness to withstand the hydrostatic pressures which could be experienced in a flooded disposal vault. Other designs provide internal support for a thinner shell, using a cast-in-place metal matrix, packed-particulate material or structural bracing.

Atomic Energy of Canada Limited (AECL) is investigating the stressed-shell and metal-matrix concepts and coordinating the overall development effort. Ontario Hydro is studying the packed particulate design, and Bristol Aerospace, the structurally supported design. The principal objectives of the program are to assess the feasibility of each concept in terms of ease of fabrication and inspection, cost and performance in the vault environment. On the basis of this assessment, one or more concepts will be recommended for more detailed evaluation.