Theoretical-experimental investigations into the behaviour of catalyst, silica gel and activated carbon in the GWTS system for Flamanville 3 EPR

The EPR Gaseous Waste Treatment System (GWTS) has as specific roles the management of the hydrogen risk and the radiochemical gas discharges. In order to accomplish these missions, the TEG system is composed of three main types of equipment: A recombiner filled with a catalyst which removes hydrogen and oxygen from the nitrogen flushing gas stream which is used to sweep the biphasic gas tanks in order to avoid hazard mixtures and ensure the safety conditions. Three delay beds filled with activated carbon used to retain for a set period of time radioactive noble gases (krypton and xenon) in order to limit the discharges to the environment. A gel drier filled with silica gel which reduces the humidity of the gas stream entering the delay beds in order to guarantee the optimal performance of activated carbon. This paper initially describes the functional operation of these items of equipment and the theoretical assumptions taken into account in their design. The paper will go on to discuss the qualification tests that have been carried out by EDF in collaboration with the University of Pisa (DIMNP/CPTM). The tests were carried out on several samples of each material (catalyst, silica gel, activated carbon) on a test rig in order to select the best performing product in the EPR normal operating conditions. In overall, the qualification tests performed for EPR GWTS equipments constitute a complete matrix of parametrical tests which can be useful for different scientific and industrial applications. In particular, these tests have also notably enabled EDF, as the designer and future operator, to fully understand the physical behaviour of the materials in various operating conditions (pressure, temperature, humidity, flow rate) so that system design and operating procedures can be optimised. (author)