This paper presents the results of calculating the distributions of neutron flux in an accelerator driven subcritical reactor (ADSR) with thorium fuel. The simulated ADSR consists of 90 fuel rods and 10 graphite reflector rods. All objects are placed in liquid lead. MCNP5 program is used to calculate energy distributions of the neutron flux, axial distributions and radial distributions inside the core of the ADSR. The results show that the neutron fluxes of 250, 450, 600 and 850 angles are similar; axial distributions of neutron flux decrease gradually; the neutron fluxes are the largest between 0.3 and 0.5 MeV. The radial distributions of neutron flux decrease gradually from center, and the largest value is between 30 and 40 cm. The results also show that the neutron fluxes are different with different radii. The results are important for the design and operation of the ADSR.

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In this paper, the Accelerator Driven Subcritical Reactor (ADSR) was simulated based on the structure of the TRIGA-Mark II reactor by the MCNPX program. The proton beam interacts on the Pb-Bi molten target with various energy levels from 0.5 GeV to 2.0 GeV. The important neutron parameters to evaluate the operability of ADSR were calculated as: the neutron yields according to various thicknesses of the target and according to the energy of the incident proton beam; the effective neutron multiplication factor for various fuel mixtures, along with its stability for some fuel mixtures; the axial and radial distributions of the neutron flux along with the height and radius of the core. The obtained results had shown a good agreement in using Pb-Bi molten as the interaction target and coolant for ADSR.

This paper presents results of calculating the neutron flux distribution in an accelerator driven subcritical reactor (ADSR) with (Th-233U)O2 and (Th-235U)O2mixed fuel. An ADSR consists of 90 fuel rods, and 10 graphite reflector rods. All objects are placed in liquid lead. Thorium is replaced by mixture of (Th-233U)O2 and (Th-235U)O2; MCNP5 program has been used to calculate radial distribution of the neutron flux, axial distribution and energy distribution from (p, n) reaction.The calculation results show that the axial distribution of the thermal and fast neutron flux reduce from the center of core but reduction rate is different.The thermal neutron flux decreases gradually from 0 to 2.5cm; decreases rapidly from 25cm to 5cm. In comparison, the thermal neutron flux is smaller than fast neutron flux from 0 to 4cm along the radius but the thermal neutron flux is larger than fast neutron flux at distances greater than 5cm along the radius of the reactor.

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