The Design of Novel Ramp Experiments in ATR Utilizing Pressurized He-3 for Evaluating Chrome Coated Cladding Behavior

Power ramp testing is an in-pile irradiation experiment that involves conditioning the nuclear fuel
test pin at a nominal, known power level for some time, usually several days but at least twelve
hours. Following the conditioning period, the specimen is ramped to a higher power level and held
at this ramp terminal power level for at least 12 hours. If cladding ruptures are not observed in 12
hours, it is generally assumed that the test pins survived the ramp. First the need for ramp testing of
chrome coated cladding concepts ins explored. Then a proposed experiment setup features two 17
cm long fuel rods irradiated in the center flux trap of ATR in the Loop 2A PWR environment is
described. The fuel rod heating rates are modeled using the Monte Carlo N-Particle (MCNP) code
to predict their behavior under varying operational conditions. Initially, a high-pressure He-3
environment will be maintained to suppress the LHGR. As the reactor power ramps up, the He-3
pressure will be reduced, inducing a sharp increase in the fuel's power output. This approach is
designed to simulate anomalous power increases that c