The reduced enrichment uranium(LEU)conversion for prototype MNSR is to replace high-enriched uranium(~(235)U enrichment ratio was 90%)fuel assembly with low-enriched one(~(235)U enrichment ratio was less than 20%).Before unloading the high-enriched uranium fuel assembly,we need to remove the central control The reduced enrichment uranium (LEU) conversion for prototype MNSR is to replace high-enriched uranium (~ (235) U enrichment ratio was 90%) fuel assembly with low-enriched one (~ (235) U enrichment ratio was less than 20% Before unloading the high-enriched uranium fuel assembly, we need to remove the central control