Physical calculations for the design of irradiation device and nuclear heating calculation in silicon ingots at Es Salam research reactor

To insure homogeneity of the neutron flux through Silicon irradiated at a Es-salam research reactor an irradiation device have to be conceived. The main criteria of its design are to fulfil all the necessary safety restrictions and recommendations while inserted into the core of the reactor. The excess of reactivity has to be also evaluated as well as nuclear heating in irradiated material. This work consist on the evaluation of excess reactivity misleads by the insertion of the device in the reactor core. To do so, the reactor core has been divided into several homogeneous regions and a cartesian three dimensional XYZ model of the reactor core was performed using the three dimension diffusion code CITATION. The fewgroup library was generated by WIMS/D4. The obtained excess reactivity of the irradiation device is negative, and with regards to neutronic consideration some positive reactivity is needed to make up for its insertion. This can be achieved through appropriate choice of the control rods insertions. s for nuclear heating in the Silicon both neutron and photons contribution have been considered. The 1D transport code ANISN was used to perform the heating calculations. We have choice Pl= 3 order of scattering, S8 quadratic order and a distributed source in 207 energy group, 171 neutron group and 36 photon group to perform the calculations. As it was expected photon heating is predominant on neutron part. This will allow us to neglect the neutron contribution to the heating and performing the design of the necessary cooling system. In this paper, the adopted methodology is specified and the obtained results will allow us to decide on the cooling system and the rate of coolant to be fulfilled, also the necessary actions to maintain the reactor critical can be drawn. (author)