COQUI: A Single Purpose Reactor

Nowadays, Multi-Purpose reactors provide a good solution for a wide variety of activities including fundamental physics, material science and radioisotope production. Sometimes, using one of these capabilities, neutron beams for example, penalizes radioisotope production and vice-versa. COQUI is a project to design a reactor dedicated to produce Molybdenum (⁹⁹Mo) from ²³⁵U as a single purpose. The neutronic and thermal-hydraulic design of the COQUI reactor was optimized in order to achieve and guarantee a high production rate, an easy operation, and a maximum availability while ensuring a safe operation. This optimization resulted in a compact core, both, in number and dimensions of the fuel assemblies, surrounded by a "cloud" of Mo targets in the Beryllium (Be) reflectors grid ensuring a continuous production. The thermal-hydraulic design of the COQUI reactor has represented a real challenge as high heat fluxes need to be removed from both, the core and the structures surrounding them. The COQUI reactor has two separate cooling systems, one for the core, including fuel assemblies and reactivity control elements, and one for the reflector and the irradiation positions. Both cooling circuits guarantee an adequate heat removal during the normal operating conditions and in accidental scenarios. This paper presents an overview of the reactor together with a summary of the thermal-hydraulic design. Reference is made to the fulfillment of the design criteria and requirements, adopted safety and operational features and computational tools used, as well. (author)