Fuel irradiation devices Test of sealed passages with optical fibres in support of the development of innovative instrumentation

International audienceWithin the scope of developing the experimental reactor means for the Jules Horowitz reactor (JHR) in France, certain R&D actions are currently focusing on technological building bricks. The action covered in this paper concerns fuel irradiation devices, in particular the fabrication and testing of leak tight feedthroughs equipped with optical fibres under thermal hydraulic conditions (155 bar and 100°C) that are representative of those in certain irradiation devices heads operating under pressurised water reactor (PWR) conditions. The test performed with these leak tight feedthroughs lasted five days and was representative of certain experimental power ramp-up scenarios on a fuel rod (conditioning, ramp-up, high power plateau for 24 hours, and cooling). The results of this test make it possible to validate the recommended technology. It therefore seems feasible to implement innovative instrumentation equipped with optical fibres in irradiation devices operating under similar experimental conditions. Following a general description of the project and the JHR facility currently under construction at the CEA Cadarache centre in France, this paper describes the relevant fuel irradiation devices. We have focused on the leak tight feedthroughs going through the device head, in particular those containing the optical fibres. We discuss the tests performed, their results and several future prospects with respect to the utilisation of optical fibres as a means to support the development of innovative instrumentation. IGORR-RRFM conference 24-28 th March 2019, Jordan 2-1