Head for gas control and instrumentation plugging of a test device for the Jules Horowitz Reactor

Experimental irradiations carried out in Material Testing Reactors are most of the time highly instrumented. The numbers of detectors as well as the sophistication of test devices have been increasing for years, in order to collect the maximum of information from an irradiation. Various needs have to be satisfied especially when it deals with the development of the new generation of research reactor such as the Jules Horowitz Reactor (JHR). A test device is composed of two main parts: the containment rig and the sample-holder. The containment rig is the outer shell of the test device that houses fluids. The sample-holder is plugged into the containment rig through the circular opening situated in the upper part. It holds the material samples to be irradiated and the specific experimental instrumentation such as thermocouples, radiations sensors, pressure sensors, strain gauges, displacement transducers, etc. In the case of the JHR, in-core test devices are located inside the reactor core which is under a few meters of water. To transfer signals from sensors to the out-of pile I&C system and to power electrical heaters and actuators, interconnection cables carrying electrical wires are routed to the so-called head of the test device. It is an underwater sealed junction box situated at the top of the test device above the reactor vessel cover. The specificities of the JHR lead to develop an advanced integrated head embedding many components such as hermetic electrical interfaces and pressure sensors for monitoring the gas of the test device. Keeping the size smaller enough, push-pull multipole connectors are implemented to allow fast disconnection during monthly handling phase between two reactor cycles. To check the easiness of changing sensors, plugging/unplugging actions, tightness of circuits, a specific hard mockup was manufactured and tested.