Numerical simulation study on uranium mass estimation by time-correlation measurement

Systematical simulations and analysis on using time-correlation measurements to estimate the masses of uranium objects were carried out. In order to calculate the time distribution of correlated counts between neutron emissions and sources detectors, new functions are implemented to the JMCT Monte Carlo neutron-photon transport simulation code. Systematical simulations on time-correlation measurements have been carried out to study the methods used to estimate the masses of high-enriched uranium objects. Three possible methods, shape comparison method, empirical relations method and variable separation method, are introduced in the paper, together with examination by simulated blind samples. By the variable separation method, the inner and outer radius of uranium shell could be revealed, simultaneously. As shown by numerical simulation, the developed methods could be used to estimate the masses of uranium objects with various shapes. So it is possible to estimate the masses and some other features of uranium objects from time-correlation measurement.