A Physical Reason Why Molten Lead-bismuth Alloy has Advantage of Being Used as a Potential Coolant for Fast Nuclear Reactors Design

The development of new energy sources from nuclear energy is increasingly becoming the choice of many countries. One type of nuclear reactor that is promising to be developed in the future is a liquid lead-bismuth cooled fast nuclear reactor. The important use of this liquid bismuth eutectic (LBE) for coolant of fast nuclear reactor has long been a potential choice. The LBE with composition of Pb and Bi commonly used and about Pb 44.5wt% and Bi 55.5%wt. What is so special about this composition? This study seeks to see the physical reasons why the fast reactor nuclear design uses LBE with a composition of about Pb 44.5wt% and Bi 55.5%wt. From the result of the molecular dynamics simulation of iron in the LBE at a temperature of 1023K, it can be observed that the use of LBE liquid metal coolant with that composition caused the least damage effect (corrosion) to iron compared to using other compositions. It can be concluded from the calculation of the CNA values (Common Neighbour Analysis) of the iron structure in the LBE which shows that the crystal structure of iron in the LBE is the most stable for that composition. This simulation result is extraordinary because it explains the popular choice of the PbBi composition for the coolant candidate of fast nuclear reactors. Keywords: molecular dynamics, liquid metal corrosion, CNA, LBE, Pb - Bi coolant