Sai Prasad Balla and Jacopo Buongiorno
Report Date: March 2025
Program: NFC (Nuclear Fuel Cycle)
Type: TR
RPT. No.: 135
Nuclear batteries (NBs) are small, advanced microreactors with a thermal output of under 20 MWth. These compact reactors promise plug-and-play capability, ensuring reliable operation
with high capacity factors and reducing expensive transmission infrastructure requirements in remote areas. The bulk of these microreactors are based on graphite-moderated high-temperature gas-cooled reactor (HTGR) design. Graphite exhibits unfavorable properties under irradiation and tends to undergo non-uniform shrinkage followed by volumetric expansion and increased residual stress during irradiation, limiting its operational lifespan. Composite moderators, which combine a radiation- and chemically-stable magnesium oxide (MgO) host matrix with an entrained beryllium or hydride moderating phase, have shown potential as suitable alternatives for the graphite used in HTGRs.