Calculation of the irradiation parameters for fuel rods in the RA-10 LOOP device. Control of power by liquid poisons. Estimated burn of bars

This paper presents the results of the neutronic calculations of a device placed in the Reflector of the RA-10 reactor. This device is a pressurized Loop, capable of containing an array of power station type-fuel rods, at pressure and temperature conditions similar to those in the power plant. An external, low pressure device provides attached to the LOOP controls the entrant neutron current, allowing the control of the power produced in fuel bars. Two LOOP models were developed, one for Base irradiations -long lasting irradiations for burn up accumulation, another for Ramp irradiations -in which the bars are exposed to cycles of controlled increase in produced power. The calculation code used is MCNP5 with ENDF-B VII libraries, as to achieve detailed transport of neutrons and photons. Both LOOP models were included in the comprehensive model of the nuclear island of RA-10; core, reflector and all facilities planned for the reactor and reflector, obtaining realistic spectra and intensities distributions for both radiation fields, as well as related factors, such as deposited energies and reaction rates. The burn up of the fuel bars is performed with COUPLE + ORIGEN-S, with input data from transport calculation. Between the parameters obtained for the both configurations are: power distribution and peak factors in irradiated fuel bars, with and without power control. Also, the burn prate, and cumulative burn pup to 36 power cycles of the reactor, the reactivity introduced for the power control device, and deposited power in components, coolant and other materials. (author)