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 react ion rate sensitivity to different ranges of neutron energy in heavy wa ter solutions of thorium nitrate are reported. The experiments were ca rried out at the MAKET critical plant at the institute for Theoretical and Experimental Physics. The reactivity effects were measured by a c ritical experimental method using the experimental dependence of latti ce reactivity variations as a function of heavy water levels in the co re tank. The reaction Fates and the functionals were measured in the e xperimental samples of Al-27, Cu-natur, and Th-232 and of a many-compo site Al + Mn-55 + Cu-natur + Au-197 + Lu-natur 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 expe rimental run yielded macrodistribution of reaction rates R-(n,R- gamma )(63Cu) in the lattice, the reactivity effects induced by different th orium nitrate concentrations in the heavy water solution within the vo lume of the experimental setup, the reactivity effects induced by diff erent heights of filling the experimental tank with the thorium nitrat e solution, distribution of reaction rates R-(n,R- gamma)(63Cu), R-(n, R- gamma)(55Mn), R-(n,R- gamma)(197Au), R-(n,R- gamma)(176Lu), R-(n,R- alpha)(27Al), and R-(n,R- gamma)(232Th) within the experimental volum e, and distributions of the functional sigma((n, alpha))(27Al)/sigma(( n, gamma))(232Th) within the experimental volume. All of the experimen tal data were simulated by the MCU code and partly by the TRIFON-TREC code. Therefore, it is possible to validate the applicability of the c odes for simulating blankets of subcritical accelerator-driven facilit ies with independent circulation of a heavy water solution of thorium such that U-233 buildup to replace the transmuted Pu-239 can be studie d. The results of the experiments and simulation are tabulated and dis played as plots.