Power normalization requirements for reactor physics/engineering benchmark fields

Low power benchmark fields (BF) have been implemented in diverse reactor and critical assemblies throughout the world to test experimental and calculational methods in reactor physics and engineering, In order to compare experimental methods that possess different sensitivities, the BF must be operated at different power levels. Knowledge of the power-time history of the irradiations provides a power normalization factor that is essential in the comparison of different experimental methods used to characterize BF. Knowledge of the power normalization factor is also necessary for BF comparisons of experimental and calculational methods. Calculations are normally carried out on a per fission or a per fission neutron basis. Consequently for comparison with calculations, measurements must be scaled by the power-time history used in the reactor or critical assembly experiments. This scaling procedure provides experimental data in the same units. i.e., on a per fission or per fission neutron basis. On the basis of lessons learned in BF experiments in the United States and Europe, it is concluded that a power normalization uncertainty in the range of 1 to 2 per cent (1 sigma) is a necessary condition for a successful BF program.