Methodology And Software Development For Nuclear Material Characterization Using Weighing Scales

Weighing scales are the main measurement systems used in nuclear facilities for nuclear material first level controls. In addition, nuclear material characterization in processing facilities is usually performed combining weighing and analytical techniques on a sample taken from the product (UF6, uranium and/or plutonium oxides...). This paper describes the methodology and software implemented at IRSN for nuclear material physical inventory taking in its own facilities and in-field inspections using weighing scales. The modalities of calibration, control and use of each scale are defined according to the type of item to be measured, the application (gross mass, net mass, true mass and conventional mass) and the operating conditions (laboratory inventory taking, in-field inspection). Measurement uncertainties are estimated by considering the following influencing factors: the material itself, the measurement system, the applied method, the environmental conditions and the operator. Results obtained with different kinds of nuclear materials (noble material, technological wastes), scales and operating conditions (laboratory, in-field) are considered.