Intensified dissolution of uranium from graphite substrate using ultrasound

Area of Science:

• Nuclear Engineering
• Materials Science

Background:

• Graphite decontamination and uranium recovery are vital for nuclear fuel cycle sustainability.
• Minimizing waste and enabling fuel recycling necessitate efficient methods for processing spent graphite elements.

Purpose of the Study:

• To investigate the feasibility of intensified uranium dissolution from graphite using ultrasound.
• To determine the effect of operating parameters on sonocatalytic dissolution kinetics.
• To optimize conditions for efficient uranium recovery and graphite decontamination.

Main Methods:

• Studied sonocatalytic dissolution of uranium-impregnated graphite in nitric acid.
• Investigated effects of ultrasound frequency, acoustic intensity, acid concentration, and temperature.
• Analyzed dissolution rates, substrate erosion, and pitting under various conditions.

Main Results:

• Dissolution ratio increased with temperature, particularly at lower acid concentrations (6-8 M).
• Higher acid concentrations (>10 M) and 12 M HNO3 led to pitting and erosion.
• Optimal acoustic intensity (1.2 W/cm² at 33 kHz) maximized dissolution rate; higher frequencies reduced dissolution but increased erosion.

Conclusions:

• Ultrasound significantly intensifies uranium dissolution from graphite under optimized conditions.
• Parameter optimization (frequency, intensity, acid concentration, temperature) is critical for effective decontamination and recycling.
• Sonocatalysis offers a promising approach for nuclear waste management and fuel reprocessing.