Estimated uncertainties in nuclear data: an approach

The need to communicate estimated uncertainties in evaluated nuclear data to be used in the assessment of their adequacy in applications has been recognized in the ENDF/B system.Starting with ENDF/B-IV.the data files contain formatted data describing the estimated covariances of some of the microscopic cross sections in such a form that they can be processed by computer ;odes to generate covariance matrices of quantities used in solving neutron transport problems such as group cross sections.The basic concepts behind the representation of such quantities will be described and the work done so far in the representation and manipulation of such quantities will be discussed.Problem areas not yet addressed in ENDF/B-IV but under study will be discussed.(Evaluations, estimated uncertainties, correlations, covariances, data adequacy, neutron transport)