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 27Al, naturCu, and 232Th and of a many-composite Al + 55Mn + naturCu + 197Au + naturLu 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(n,)63Cu 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 of reaction rates R(n,)63Cu, R(n,)55Mn, R(n,)197Au, R(n,)176Lu, R(n,)27Al, and R(n,)232Th within the experimental volume, and distributions of the functional (n,)27Al/(n,)232Th 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 233U buildup to replace the transmuted 239Pu can be studied.

The results of the experiments and simulation are tabulated and displayed as plots.