Aside from the challenges discussed above, there are several other po­tential challenges that MITR will face during the transition to an LEU-fueled core. First, MITR is likely to be the first reactor to convert using UMo monolithic LEU fuel. MITR staff is presently working to better understand how best to introduce this first-of-a-kind fuel into the reactor. The current plan is to gradually introduce LEU fuel into the HEU core. To evaluate this plan, a mixed-core analysis will be carried out prior to conversion. Two challenges are foreseen in the mixed-core transition: Power peaking is gener­ally higher in new LEU elements, and steady-state HEU and LEU margins to ONB decrease with an increasing number of LEU fuel elements in the mixed core. MITR staff project that partially burned HEU elements may need to be kept in reserve as the reactor is transitioned to the full LEU core.

Second, the heating from gamma ray absorption outside the fuel is significantly less for LEU than for HEU, resulting in a lower heat load on the deuterium reflector and shield system. However, some in-core materials experiments rely on gamma heat for temperature control and may need to be redesigned.

Finally, it is also possible that mechanical stresses from the heavier loading of the denser LEU fuel will necessitate some redesigning of the fa­cility. However, current analyses indicate that heavier loading is not likely to pose a problem.