Characterization of 235U Targets for the Development of a Secondary Neutron Fluence Standard

Abstract The MetroFission project, a Joint Research Project within the European Metrology Research Program (EMRP), aims at addressing a number of metrological problems involved in the design of proposed Generation IV nuclear reactors. As part of this project a secondary neutron fluence standard is being developed and tested at the neutron time-of-flight facility GELINA of the JRC Institute for Reference Materials and Measurements (IRMM). This secondary standard will help to reach the neutron cross section measurement uncertainties required for the design of new generation power plants and fuel cycles. Such a neutron fluence device contains targets for which the neutron induced cross section is considered to be a standard. A careful preparation and characterization of these samples is an essential part of its development. In this framework a set of 235 U targets has been produced by vacuum deposition of UF4 on aluminum backings by the target preparation laboratory at IRMM. These targets have been characterized for both their total mass and mass distribution over the sample area.