Microbial studies in the Canadian nuclear fuel waste management program

Area of Science:

• Geological disposal of nuclear waste
• Microbial ecology in subsurface environments
• Materials science for containment

Background:

• Canada's concept for permanent geological disposal of used nuclear fuel involves a multi-barrier system.
• Disposal vaults are planned 500-1000 m deep in Canadian Shield granitic rock.
• Subsurface environments are not sterile, necessitating research into microbial effects.

Purpose of the Study:

• To address and quantify the potential effects of microbial action on the integrity of geological disposal vaults.
• To investigate microbial survival, mobility, and influence on container corrosion.
• To understand microbial gas production and nutrient introduction in disposal environments.

Main Methods:

• Experimental program initiated in 1991 by AECL.
• Assessing bacterial survival under radiation, temperature, and desiccation.
• Evaluating microbial mobility in compacted buffer materials.
• Investigating microbially influenced corrosion of titanium and copper containers.
• Monitoring microbial gas production and nutrient presence.
• Characterizing microbes in deep granitic groundwaters.
• Studying biofilm effects on radionuclide migration.

Main Results:

• Summarizes research activities and results to date from AECL's microbial program.
• Provides data on microbial survival, mobility, and potential impacts on disposal vault integrity.
• Quantifies microbial contributions to gas production and nutrient cycling.
• Assesses risks of microbially influenced corrosion.

Conclusions:

• Microbial activity is a significant factor to consider in the design and safety assessment of geological disposal vaults.
• Understanding microbial processes is crucial for ensuring the long-term integrity of nuclear waste repositories.
• AECL's research provides essential data for the Canadian concept for permanent disposal of used nuclear fuel.