While Russia has been working conversion of Soviet-built research reactors abroad to LEU fuel, no reactors in Russia have been converted so far. This may change soon - Russia agreed to begin feasibility studies of conversion of six of its research reactors
- IR-8, OR, and Argus at the Kurchatov Institute,
- IRT-2000 at MEPhI,
- MIR and SM-3 at the Research Institute of Atomic Reactors in Dimitrovgrad (there are also critical facilities FM MIR and FM S-3 associated with these reactors, which would probably be converted as well), and
- IRT-T in Tomsk.
Conversion of SM-3 would be an important development - the fuel that is used in this reactor is essentially the same as the one that would be used in the new PIK reactor that Russia is building in Gatchina. The elements are a bit different - the length of the active zone is 500 mm in PIK elements and 350 mm in SM-3 and the density of U-235 is a bit higher in PIK (0.54 vs. 0.49 g/cm3), but other than that these are the same elements. Both have X-shaped cross-section and contain 90% uranium oxide in copper-beryllium matrix in stainless steel cladding. If SM-3 is successfully converted, Russia could consider using LEU in the PIK reactor as well.
Then, two other reactors at Dimitrovgrad - RBT-10/2 and RBT-6 - use fuel discharged from SM-3 as their fresh fuel (initial enrichment is 63%). As I understand, there are plans to begin work on converting this reactors in a few years.