Po-Containing Molecules in Fusion and Fission Reactors.

Area of Science:

• Nuclear Engineering
• Computational Chemistry
• Radiochemistry

Background:

• Inherent safety is crucial for future fission and fusion reactors.
• Undesired production of radiotoxic polonium (Po) is a challenge for some reactor designs.
• Filtering volatile Po species requires knowledge of their molecular forms.

Purpose of the Study:

• To predict the temperature-dependent stability of diatomic polonium-containing molecules.
• To determine the molecular composition of polonium in reactor cover gases.
• To assess polonium speciation in MYRRHA and DEMO reactor environments.

Main Methods:

• Utilized a quantum chemistry approach to model Po-molecule stability.
• Validated methodology using experimental data from lighter analogue molecules.
• Estimated relative occurrence of Po species in cover gas simulations.

Main Results:

• Predicted temperature-dependent stability of relevant diatomic Po molecules.
• Identified PbPo molecules and atomic Po as the dominant polonium species.
• Quantified polonium speciation in lead-bismuth and Pb-Li eutectic systems.

Conclusions:

• The study provides crucial molecular data for polonium removal strategies.
• PbPo and atomic Po are the primary forms in MYRRHA and DEMO reactor cover gases.
• Computational chemistry offers a viable alternative to experimental characterization for radioactive species.