Benchtop Zone Refinement of Simulated Future Spent Nuclear Fuel Pyroprocessing Waste.

Area of Science:

• Nuclear Engineering
• Materials Science
• Chemical Engineering

Background:

• The UK is exploring pyroprocessing for spent nuclear fuel, necessitating effective waste management strategies.
• Contaminated salt from electroreducing and electrorefining processes requires robust clean-up methods.
• Zone refining offers a potential solution by exploiting phase changes to separate contaminants.

Purpose of the Study:

• To investigate the feasibility of zone refining for cleaning waste salts from nuclear fuel pyroprocessing.
• To assess the effectiveness of zone refining in separating contaminants from electrorefining and electroreducing simulants.
• To determine segregation coefficients for contaminants in simulated waste salts.

Main Methods:

• Experiments were conducted using laboratory equipment to simulate zone refining processes.
• Off-the-shelf laboratory apparatus was utilized for waste simulant treatment.
• Segregation coefficients (k) were calculated to quantify separation efficiency.

Main Results:

• Zone refining successfully demonstrated contaminant separation in electrorefining simulant samples.
• Effective segregation coefficients (k) between 0 and 1 were achieved, with values as low as 0.542.
• A reduction in RECl3 content from 10.0 wt.% to 8.4 wt.% was observed for electrorefining simulants, enabling 80% salt reuse.

Conclusions:

• Zone refining is a feasible method for cleaning electrorefining waste simulants in nuclear fuel reprocessing.
• Challenges in preparing homogeneous electroreducing simulant waste hindered feasibility demonstration for this stream.
• Further research is required to optimize simulant preparation for electroreducing waste treatment via zone refining.