A family of ternary carbides and nitrides, known as MAX phases, combine attractive properties of both ceramics and metals, and has been suggested for potential nuclear reactor applications. The unirradiated materials properties of importance for in-core structural materials and as fuel pellet coatings for several leading MAX phase materials have been summarized from literature. The materials show high mechanical damage tolerance in terms of creep, thermal/mechanical fatigue and fracture resistance, and very good chemical compatibility with select coolants such as molten lead and sodium. Neutron activation has been calculated for commercial purity materials exposed to both idealized fast and thermal reactor neutron spectra for 10, 30, and 60 years of exposure. The specific activities of Ti 3 SiC 2 , Ti 3 AlC 2 , and Ti 2 AlC were compared to those of SiC and Alloy 617, two leading candidate materials for next generation reactor components. The specific activities of MAX phases were similar to SiC and three orders of magnitude less than Alloy 617 after 10-60 years decay for all three activation times in both the fast and thermal spectra. As with SiC, the main radioisotopes after a decay period of 10 years for all three activation times in the MAX phases are tritium and C 14. Neutron irradiation results of Ti 3 SiC 2 , Ti 3 AlC 2 , and Ti 2 AlC experimentally confirmed the neutron transmutation analysis.

Research reactors use a number of different fuel designs. These designs can be organized into three broad types: (1) materials and test reactor (MTR)-type design, which includes plate-type designs and concentric tube-type designs, (2) pin-type design, and (3) involute-type design. The following summarizes specific characteristics of the different types of fuel named above.

Following discharge from research reactors, spent nuclear fuel may be stored "wet" in water pools or basins, or it may be stored "dry" in various configurations including non-sealed or sealed containers until retrieved for ultimate disposition. Interim safe storage practices are based on avoiding degradation to the fuel that would impact functions related to safety. Recommended practices including environmental controls with technical bases, are outlined for wet storage and dry storage of aluminum-clad, aluminum-based research reactor fuel.For wet storage, water quality must be maintained to minimize corrosion degradation of aluminum fuel. For dry storage, vented canister storage of aluminum fuel readily provides a safe storage configuration. For sealed dry storage, drying must be performed so as to minimize water that would cause additional corrosion and hydrogen generation. Consideration must also be given to the potential for radiolytically-generated hydrogen from the bound water in the attendant oxyhydroxides on aluminum fuel from reactor operation for dry storage systems.

An analytic model and calculational methodology have been established previously to quantify the radioisotopes present in the Savannah River Site (SRS) P-reactor and R-reactor tanks and in the structural materials surrounding those tanks. These radioisotopes are the result of neutron activation of the materials during reactor operation. The analysis results were based upon a specific set of input assumptions for the elemental composition of the materials of construction. Based upon the results of that analysis, efforts to more accurately quantify the silver content in the stainless steel used in the fabrication of the reactor vessel have been completed. Laboratory testing of vintage stainless steel from stainless piping extracted from R-reactor indicates a maximum silver content that is nearly an order of magnitude lower than that assumed in the previous calculation. Based on the new silver content information simulations were completed to evaluate the impact of the reduced silver content.

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