| Popis: |
Methods are presented for reliably estimating the uncertainties in quantities of plutonium as measured using neutron coincidence counting for nuclear safeguards purposes. For the conventional two-parameter assay technique, semi-empirical equations are obtained that satisfactorily describe the observed measurement variances in the total and coincidence counts for multiplying plutonium oxide and metal. For the three-parameter assay method using neutron multiplicity analysis, covariance matrix methods are developed that describe, to an accuracy of approximately 10%, the uncertainty in the calculated plutonium mass, multiplication, and alpha-n reaction rate, for samples with small multiplication. |
