Iodine induced stress corrosion cracking and axial creep: 2 new cladding testing facilities at Leci laboratory

Extension and refurbishment of the CEA Saclay Leci hot laboratory initiated 10 years ago is now considered as completed. The present paper describes two new cladding testing facilities available at Leci. Iodine induced stress corrosion cracking of zirconium alloys fuel claddings may develop during power transient due to pellet-cladding interaction (PCI). This phenomenon was studied in the previous CEA installation using iodine atmosphere internal pressure creep tests on defuelled samples. The new facility allows tests to be performed in two modes: i) driving on the pressure with the ability to do complex loading creep tests, ii) driving on the hoop strain thanks to the diameter laser measurement, which allows relaxation tests to be achieved and consequently to be more representative of the loading imposed by the pellet on the cladding during PCI. Inert atmosphere can also be used in order to determine mechanical properties of irradiated claddings or hydrides reorientation conditions. For investigating the axial creep two electro-mechanical tensile machines have been set up to test several geometries of irradiated materials i.e. tubular and flat specimens or bars. Variable gauge length extensometers with ceramic rods have been adapted for handling with remote manipulators and are used for both creep and relaxation tests up to 800 deg. C