Original sentence: Operational since 1966, the HFIR is an 85 MW reactor designed for the production of special radioisotopes (it is the only US source of Californium-252) and high thermal neutron fluxes for research purposes
Edited sentence: In 1989 the power rating was lowered to 85 MW to improve the safety margins for the reactor vessel.It has a fuel load of 9.4 kg of highly enriched uranium as uranite / aluminum cermet.It produces radioisotopes including Californium-252 and neutrons for research purposes.Operational since 1966, the HFIR is an 85 MW reactor designed for the production of special radioisotopes.The fuel is in involute-shaped plates arranged in two concentric fuel elements, 60 cm high, with an outer diameter of 45cm.The reactor is moderated by a 30 cm-thick annular beryllium reflector and the light water coolant.The reactor produces superlative neutron fluxes of 1.8 1015neutrons cm-2 s-1 at target positions inside the core.The reactor started operations in 1965, and reached its design power of 100 MW the following year