Experimental determination and simulation of the reactivity effects and reaction rate sensitivity to different ranges of neutron energy in homogeneous heavy water solutions of thorium

The experimental and simulated results of reactivity effects and reaction rate sensitivity to different ranges of neutron energy in heavy water solutions of thorium nitrate are reported. The experiments were carried out at the MAKET critical plant at the Institute for Theoretical and Experimental Physics. The reactivity effects were measured by a critical experimental method using the experimental dependence of lattice reactivity variations as a function of heavy water levels in the core tank. The reaction rates and the functionals were measured in the experimental samples of {sup 27}Al, {sup natur}Cu, and {sup 232}Th and of a many-composite Al + {sup 55}Mn + {sup natur}Cu + {sup 197}Au + {sup natur}Lu alloy. The experimental samples were measured using a Canberra comanufactured spectrometer (a GC-2518 Ge detector, a 1510 module, and a 1510 plate with software to emulate a multichannel analyzer on an IBM personal computer). The experimental run yielded macrodistribution of reaction rates R{sub (n,{gamma})}{sup {sup 63}Cu} in the lattice, the reactivity effects induced by different thorium nitrate concentrations in the heavy water solution within the volume of the experimental setup, the reactivity effects induced by different heights of filling the experimental tank with the thorium nitrate solution, distribution ofmore » reaction rates R({sub n,{gamma}}){sup {sup 63}Cu}, R{sub (n,{gamma})}{sup {sup 55}Mn}, R{sub (n,{gamma})}{sup {sup 197}Au}, R{sub (n,{gamma})}{sup {sup 176}Lu}, R{sub (n,{alpha})}{sup {sup 27}Al}, and R{sub (n,{gamma})}{sup {sup 232}Th} within the experimental volume, and distributions of the functional {sigma}{sub (n,{alpha})}{sup {sup 27}Al}/{sigma}{sub (n,{gamma})}{sup {sup 232}Th} within the experimental volume. All of the experimental data were simulated by the MCU code and partly by the TRIFON-TREC code. Therefore, it is possible to validate the applicability of the codes for simulating blankets of subcritical accelerator-driven facilities with independent circulation of a heavy water solution of thorium such that {sup 233}U buildup to replace the transmuted {sup 239}Pu can be studied. The results of the experiments and simulation are tabulated and displayed as plots.« less