FACILITY FOR IN-PILE CREEP EXPERIMENTS ON CLADDING TUBES UNDER THERMAL AND STRESS CYCLING.

The irradiation facility described for the BR2 reactor at Mol will be used for testing breeder fuel cladding tubes for their in-pile creep behavior under thermal and stress cycling. These stresses occur during startup, shutdown and load changes of the reactor. The facility is designed initially for tests of cladding tube specimens for the sodium cooled fast breeder. However, by different arrangement of the specimens it is possible also to simulate the operating conditions of the gas and steam cooled breeders, respectively. The report outlines the different requirements and the details of design, construction and operation of the irradiation facility. The test specimens can be loaded with gas pressures up to 500 kp/cm2 at electrically controlled temperatures of up to 900°C. The development of the facility has been based on all the experiences gathered from a similar test device which has been run for some years. The very important axial temperature distribution in the test specimens was greatly improved. The facility is presently under construction. The in-pile tests are scheduled to be started in the fall of 1971.