Investigation of Ion-Irradiated Beryllium Carbide (Be₂C) for High-Temperature Nuclear Reactor Moderators

Beryllium carbide (Be₂C) is an attractive alternative to graphite as a moderator material because of its high melting point, moderating efficiency, and theoretical environmental compatibility in molten salt reactors. However, its behavior under neutron irradiation is not yet known. For this work, a novel experiment was designed to safely irradiate beryllium-containing samples at the Michigan Ion Beam Laboratory. Using this new capability, Be₂C samples were irradiated with 9-MeV C³⁺ ions from 2 to 30 displacements per atom (dpa) at temperatures up to 500°C. Samples were characterized to investigate radiation tolerance. No evidence of phase precipitation, dislocation loops, or amorphization was observed up to 30 dpa, suggesting good radiation tolerance. One sample left in air for ~3 months oxidized slowly and lost structural integrity, while a sample kept in argon did not, suggesting that Be₂C is not suitable for moist environments, but maintains its integrity in dry environments.