OSIRIS REACTOR - Centre de Cadarache - CEA

24EXPERIMENTAL DEVICESCEA••• NUCLEAR ENERGY AUTHORITYISABELLE loopsISABELLE loops are designed for the irradiation of fuel elements under thermohydraulic and chemical conditionsrepresentative of those of pressurized water reactors.Two devices exist: The ISABELLE 1 loop particularly well suited to the production of power ramps. The experimental load consists of a shortfuel rod, either new or re-manufactured in hot laboratories by the FABRICE process using a fuel element irradiatedin the power station. The power that can be evacuated by the loop is 60 kW and the maximum linear power on the fuelelement is 620 W cm -1 with a maximum ramp speed of 700 W.cm -1 min -1 . The ISABELLE 4 loop, which is more specifically dedicated to the production of qualification irradiations comprising powerscycles on two levels of power. The loop can house from 1 to 4 fuel elements as well as plate fuels or absorbent elements.The geometry of the fuel elements is similar to those accepted by ISABELLE 1. The power that can be evacuatedby the ISABELLE 4 loop is 90 kW and the maximum linear power on the fuel elements is 500 W.cm -1 .The design of these loops and their positioning on the periphery of the core enable irradiation and withdrawal with the reactorin operation. These devices are placed on mobile supports, the displacement of which in relation to the core of the reactoris used either to adjust the power of the fuel element, or to automatically control the power ramps or the cycles at variablespeeds, slaved to the neutron power.The fuel elements are cooled by forced convection produced by a flow of light water, demineralised, degassed andchemically processed, created by a nozzle injector system amplifying the flow generated by the pump unit of the loop feeding circuit.The hot caveof the installation.injectornozzleventurigas layerexternal pressure tubediffusedjointinternal pressure tubespacing gridinternal basketlockexternal basketThe ISABELLE 1 loopdisplacement system.The test channelof the ISABELLE 4loop.gas layer supply