RHF has a maximum power of 58 MW and a peak thermal neutron flux of about 1.5 x 1015 n/cm2-s. The core consists of a one-time-use as­sembly consisting of 280 curved plates arranged between two concentric cylindrical “sideplates.” The reactor is currently fueled with a 93 percent enriched UAlx-aluminum dispersion fuel with boron-10 burnable poisons at the tops and bottoms of the fuel plates.

This reactor is used as a neutron beam source, and a key requirement for conversion is the preservation of “brightness” (i. e., intensity) of these beams and the reactor cycle length. To meet these objectives, the fueled height of the reactor core will be increased by eliminating the burnable poi­son zones at the tops and bottoms of the fuel plates. (These poisons will be moved to another location in the reactor.) However, even with this change there will still be a 5-10 percent loss in brightness at key experimental positions. This loss of brightness can be compensated for by increasing the beam times for some experiments, but it will not affect overall throughput of experiments in the reactor.