A thermal column has been designed and set up in the fast research reactor TAPIRO, in Casaccia ENEA Centre, near Rome, Italy. The TAPIRO reactor is a highly enriched (93.5%) Uranium-235 fast neutron facility. The power is 5 kW and the maximum neutron flux is 4(1012 cm-2(s-1. The reactor has a cylindrical core (12.58 diameter and 10.87 cm height) totally reflected by copper. A section of the copper reflector can be taken away and replaced by a convenient material. Weakly moderating materials can replace the graphite blocks of the thermal column; an epithermal column can be in such a way obtained. The epithermal column will be set on a trolley, which can be driven into the cave of the borate concrete shielding.In the present experiment, some preliminary measurements and simulations have been made in order to characterise the moderated neutron flux in the thermal column. The moderating structure, designed by means of MCNP simulations, is composed of 40 cm thick graphite blocks. The neutron flux in proximity of the copper reflector has been measured, with energy resolution, by means of Bonner spheres. The experimental results have been compared with simulation results obtained by means of MCNP-4B code using the Direct Statistical Approach for variance reduction.

Neutron Flux Characterisation in the Thermal Column of a Fast Research Reactor

Nava, E.
1999-09-12

Abstract

A thermal column has been designed and set up in the fast research reactor TAPIRO, in Casaccia ENEA Centre, near Rome, Italy. The TAPIRO reactor is a highly enriched (93.5%) Uranium-235 fast neutron facility. The power is 5 kW and the maximum neutron flux is 4(1012 cm-2(s-1. The reactor has a cylindrical core (12.58 diameter and 10.87 cm height) totally reflected by copper. A section of the copper reflector can be taken away and replaced by a convenient material. Weakly moderating materials can replace the graphite blocks of the thermal column; an epithermal column can be in such a way obtained. The epithermal column will be set on a trolley, which can be driven into the cave of the borate concrete shielding.In the present experiment, some preliminary measurements and simulations have been made in order to characterise the moderated neutron flux in the thermal column. The moderating structure, designed by means of MCNP simulations, is composed of 40 cm thick graphite blocks. The neutron flux in proximity of the copper reflector has been measured, with energy resolution, by means of Bonner spheres. The experimental results have been compared with simulation results obtained by means of MCNP-4B code using the Direct Statistical Approach for variance reduction.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12079/5874
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