Liquid metals & molten salts for Gen IV 

• Generation IV reactors (Gen IV) are nuclear reactors that are considered successors of the latest available reactors (= generation III reactors).

• Some Gen IV reactors use liquid metals and molten salts as coolants.

  • Sodium-cooled fast reactor (SFR) using liquid Na

  • Lead-cooled fast reactor (LFR) using liquid Pb or Pb-Bi.

  • Molten-salt reactor (MSR) using molten salts

Challenges regarding chemical reactivity

• Liquid metals and molten salts have several properties suitable for the use as coolant more than water, such as high heat capacity, high boiling point, neutron cross sections that can realize fast reactors, etc. 

• However, the following two chemical characteristics bring significant engineering challenges, and any of the current candidate materials suffer from either:

  • For liquid Na, the high reactivity with oxygen and water may cause a fire if an accident occurs.

  • For liquid Pb and molten salts, the corrosion of structural materials is severe. 

Calculation of impurity solution enthalpy

• The impurity property primarily related to the corrosion is the solution enthalpy of impurity. Due to its importance, many experimental studies were performed. However, the deviation in measured values is often substantial due to the difficulty of purity control.

• We have been developing computational methods to accurately calculate the solution enthalpy of impurity based on first-principles calculations. 

  • The accuracy comparable with accurate experiments can be realized by careful calculation and appropriate correction.