Helium high pressure irradiation facility for breeder fuel pins in the FR2 reactor

A helium test loop with 30 kp/cm2 coolant pressure has been operating in the Karlsruhe research reactor FR2 since 1966 for irradiation of fuel pin specimens. This loop is to be extended by a high pressure irradiation facility. On the one hand, this supplies the high heat transfer numbers which are necessary for testing high power fuel pins for sodium cooled breeders. On the other hand, it permits irradiation tests to be carried out with respect to gas cooled breeders under highly realistic conditions. The expansion covers in particular the construction of a special irradiation rig with an independent high pressure helium cooling circuit of a maximum operating pressure of 150 kp/cm2. The compressor for circulating the coolant is flanged right onto the irradiation rig. With a gas flow of about 250 kg/h the maximum thermal power of the fuel test pins is about 40 kW. The existing cooling system of 30 kp/cm2 is used as a secondary circuit for heat removal. The components of that cooling system, especially the purification system and the safety system, retain their previous functions almost unchanged. The high pressure irradiation facility has been set up for out-of-pile testing at the Institute of Reactor Development. The first irradiation in the FR2 will be carried out probably by late 1970.