German carbide irradiation test experience for fast reactors

Most of the open problems in carbide pin design and performance are of a very simple nature. As was the case with mixed oxide one or two decades ago, we must get experience in the parameter field of design and operation conditions. The main design parameters are carbide composition, density, internal geometry. The operation conditions in question are temperature and linear rod power and, of course, the achievable burnup. This field of experience should include steady-state as well as power-cycling and transient conditions. Finally the performance of representative carbide bundle structures are to be considered