Differential integral experiments for testing cross section evaluations for fusion reactors

The conceptual design of fusion reactors and fusion-fission hybrid reactors brings into focus a large number of problems dealing with the interaction of 14-MeV neutrons with materials to be used in the design of the different components of the reactor. These components include the first wall, the blanket, the magnets and the shielding system. The accuracy of the design calculations can be assured, providing the transport codes correctly describe the interaction of 14-MeV neutrons with these materials. As part of the Pulsed Sphere Program at Livermore, measurements of the neutron and gamma emission spectra from a large number of materials ranging from Li to Pu have been carried out using the sphere transmission and time-of-flight techniques. The comparison of these measurements with calculations has provided a powerful tool to test the accuracy of the cross sections used in the calculations, the mathematical assumptions and approximations introduced in solving the transport equations and to check for possible errors in the coding stage of the calculations. Some specific cases will be discussed to illustrate the value of the measurements