No abstract available

[en] An actinide nitride-fueled nuclear reactor and a method of operation therefor, including continuous in situ removal of fission products and optional addition of fuel-forming actinide material as the reaction proceeds. The reactor employed has a fuel system comprising a critical mass of a nitride of an actinide metal in contact with a non-critical solution of the actinide metal in a molten metal solvent of low neutron adsorption cross section such as tin, the fuel system being maintained under a nitrogen atmosphere in an inert, refractory vessel such as graphite which is non-conducive to the formation of actinide oxides. Fission products formed are continuously exchanged with the actinide metal dissolved in the molten metal solvent as the nuclear reaction proceeds, with equivalent amounts of actinide nitride being formed and precipitated into the critical mass as fission products are dissolved in the molten metal solution

[en] In this report are established the optimum working conditions of a filter cleaning system by blow back. For this purpose it was determined in the first place the blow back air rate necessary to have a good cleaning. The reasons for which it was not possible until now to control the pressure in a fluidized bed calcination reactor are analyzed and a criteria is established to calculate the optimum floe necessary to clean efficiently a porous by this procedures. (Author)

[en] SHEBA (Solution High Energy Burst Assembly) was built at the Los Alamos National Laboratory, New Mexico, in the 1980s. Both SHEBA-I and -II used uranyl fluoride solution with 4.95% enriched ²³⁵U. The fluoride solution is being replaced by 20% enriched ²³⁵U in nitrate solution. Two concentrations have been considered: 150 and 180 g/ell uranium. Temperature feedback, volumetric feedback, and its internal neutron source are calculated using transport codes and other computer programs

[en] The Dual Fluid Reactor, DFR, is a novel concept of a fast heterogeneous nuclear reactor. Its key feature is the employment of two separate liquid cycles, one for fuel and one for the coolant. As opposed to other liquid-fuel concepts like the molten-salt fast reactor (MSFR), in the DFR both cycles can be separately optimized for their respective purpose, leading to advantageous consequences: A very high power density resulting in enormous cost savings, and a highly negative temperature feedback coefficient, enabling a self-regulation without any control rods or mechanical parts in the core. The fuel liquid, an undiluted actinide trichloride (consisting of isotope-purified ³⁷Cl) in the reference design, circulates at an operating temperature of 1300 K and can be processed on-line in a small internal processing unit utilizing fractionated distillation or electro refining. Medical radioisotopes like Mo-99/Tc-99m are by-products and can be provided right away. In a more advanced design, an actinide metal alloy melt with an appropriately low solidus temperature is well possible which further compactifies the core and allows to further increase the operating temperature due to its high heat conductivity. The best choice for the coolant is pure lead which yields a very hard neutron spectrum. (author)

No abstract available

[en] A review of the last 20 years of nuclear power development is presented in celebration of the 21st birthday of the British Nuclear Energy Society's journal. It examines the changes since the author's 1962 paper, 'The development of fluid-fuel reactors'. (U.K.)

[en] Hybrid systems studied for fissile material production, were reconsidered for minor actinide and long-lived fission product destruction as alternative to the traditional final disposal of nuclear waste. Now there are attempts to extend the use of the concepts developed for minor actinide incineration to plutonium burning. The most promising hybrid system concept considers fuel and target both as liquids. From the results obtained, the possibility to adopt composite targets seems the most promising solution, but still there remains the problem of Pu production, not acceptable in a burning system. This kind of targets can be mainly used for fissile material production, while for accelerator driven burners it is most convenient to use a liquid lead target. The most suitable solvent is heavy water for minor actinide annihilation in the blanket of a hybrid system. Due to the criticality conditions and the necessity of electric energy production, the blanket using plutonium dissolved in molten salts is the most convenient one. (author)

[en] Temperature in a nuclear system can affect the cross section of neutrons by raising the neutron spectrum in energy and changing the reactivity of the system. This feedback in nuclear system due to the change in thermal cross section is investigated by using transport codes. Temperature effects have been studied before both in fast and thermal regions. Cross sections that are involved in the thermal region are especially important for water solution because the cross section of fission and absorption in that region for fissile materials such as ²³⁵U and ²³⁹Pu are enormous. Previous study has shown that 69-group cross sections created by ENDF/B-VI and LEAPR, which create the S(α,β) scattering law for incoherent scatters, matched very well with other benchmark results. In this study, another approach to benchmarking temperature feedback coefficients is attempted by using a Monte Carlo transport code, MCNP

No abstract available