Self-accelerated corrosion of nuclear waste forms at material interfaces

Area of Science:

• Materials Science
• Nuclear Engineering
• Geochemistry

Background:

• US high-level nuclear waste disposal involves immobilizing radionuclides in glass/ceramic within stainless-steel canisters for deep geological repositories.
• Current safety models do not account for accelerated corrosion at interfaces between dissimilar barrier materials.

Purpose of the Study:

• To investigate the impact of interfaces between stainless steel and nuclear waste forms (glass and ceramic) on corrosion under simulated repository conditions.
• To assess the implications of interface-accelerated corrosion on the long-term performance of nuclear waste packages.

Main Methods:

• Simulated repository conditions were used to examine corrosion at interfaces.
• Localized corrosion was analyzed at stainless steel-glass and stainless steel-ceramic interfaces.

Main Results:

• Severe localized corrosion was observed at the interfaces between stainless steel and both glass and ceramic waste forms.
• Accelerated corrosion is attributed to localized changes in solution chemistry, acidity/alkalinity within confined spaces.
• Interface interactions significantly alter the corrosion behavior of both waste forms and canisters.

Conclusions:

• Interface corrosion between dissimilar materials can significantly accelerate degradation, impacting nuclear waste package service life.
• Current safety and performance assessments may underestimate degradation due to unconsidered interface effects.
• Selecting compatible barrier materials is crucial for optimizing geological repository system performance.