Levelized Cost of Fuel (LCOF) studies for microreactors using TRISO fuel in hydride and beryllium-based composite moderators in open and closed fuel cycles

Abstract

This study provides a comprehensive techno-economic evaluation of a specific class of nuclear batteries—high-temperature gas-cooled 10 MW_th microreactors (HTGRs) with TRISO fuel in prismatic- and pebble-bed cores—using four composite moderator concepts (MgO–Be, MgO–BeO, MgO–YH, MgO–ZrH). These options are compared against a prismatic graphite benchmark, under both once-through and continuous-recycle fuel cycles.

In once-through prismatic systems, hydride-based moderators can reduce overall fuel-cycle costs by up to about 20% relative to graphite, whereas beryllium-based moderators may remain 40–50% costlier due to higher raw material expenses. Shifting from prismatic blocks to pebble beds decreases moderator usage and increases burnup, thus making advanced moderator options more competitive.

Adopting a continuous-recycle strategy replaces enrichment with reprocessing and can further lower fuel-cycle costs by roughly 30%. Coupling a sodium-cooled fast reactor (SFR) to supply transuranic’s further reduces the cost: SFR driver fabrication and reprocessing can account for the bulk of total costs, rendering microreactor-level variations comparatively minor. Meanwhile, pebble-bed designs propose ultra-high burnups and extended residence times, which could yield significant economic gains, contingent on demonstrated long-term TRISO fuel integrity.

Waste handling also factors into the analysis. Deconsolidation—removing the inert moderator before disposal—can shrink spent-fuel volumes by more than 90%, easing repository demands. Continued R&D into advanced additive manufacturing, high-burnup TRISO performance, and streamlined waste management will be crucial for capitalizing on these potential cost advantages.