A. L. Petelin

The Russian presentation focused on current characteristics and mis­sions of the research reactors at RIAR in Dimitrovgrad. RIAR is Russia’s largest complex for examinations of full-scale components of nuclear reac­tors and irradiated materials. It also has equipment and facilities for fuel cycle research and a radiochemical complex for investigation and produc­tion of transuranic elements and radioisotopes.

RIAR currently operates five research reactors. A sixth reactor is being decommissioned. The characteristics and missions of the operating reactors are described briefly in the following sections.

SM-3

SM-3 is a 100 MW pressurized water flux trap-type reactor contain­ing 32 fuel elements enriched in uranium-235 to 90 percent. The reactor has a compact square core (420 mm in plan dimension and 350 mm in height) with a central trap. Up to 41 positions are available for irradiation experiments in the central trap, core, and reflector. The maximum thermal neutron flux density in the central trap is 5 x 1015 n/cm2-s. Thermal neu­tron flux densities of 1.5 x 1013 to 1.5 x 1014 n/cm2-s can be obtained in the reflector.

The reactor has two low-temperature coolant water loops and a high — temperature loop that can be used for fuel testing, examination of fission — product releases from leaky fuel rods and their removal from primary cooling circuits, and the irradiation of structural and absorbing materi­als. The spectral characteristics and neutron-flux-density variability in this reactor also make it useful for producing a range of isotopes, including transplutonium elements and industrial isotopes such as cobalt-60.

This reactor is potentially useful for other high-dose irradiation ap­plications, for example, testing of fuel and structural materials for high- temperature reactors, fast-boiling reactors, and supercritical reactors, as well as new designs for research reactors. In particular, new LEU fuel compositions can be examined for applications in high-flux reactors. The reactor can also be used for training.

MIR. M1[38] [39]

MIR. M1 is a 100 MW loop-type reactor that uses 48-58 fuel elements enriched in uranium-235 to 90 percent (see Figure 3-8 in Chapter 3). It has seven loop facilities: Two with water coolant (PV-1, PV-2), two with water/ boiling-water coolant (PVK-1, PVK-2), two with water/boiling water and steam coolant (PVP-1, PVP-2), and one with nitrogen and helium coolant (PG). The facility also contains hot cells and cooling pools. The maximum thermal neutron flux in the loop channel is 5-7 x 1014 n/cm2-s.

A variety of experimental activities are currently performed in this reac­tor. These include the examination of advanced VVER-1000 fuel, testing of VVER-1000 fuel with high burnup (greater than or equal to 60 megawatt days per kilogram of uranium [MWd/KgU]), testing of new VVER cladding materials, and examination of fission-product releases from VVER-1000 fuel rods containing artificial defects. The reactor is also used to test LEU fuel and produce the industrial isotope iridium-192.

This reactor is potentially useful for other types of experimental ap­plications, including high-temperature and high-pressure testing of reactor materials, simulation of severe reactor accidents, testing of innovative fuel and cladding materials, and expanded production of isotopes. Realizing some of these activities would require upgrades to some of the reactor loops.