On the accuracy of computing the effective delayed neutron fraction in fast and thermal zero-power assemblies using uranium fuel

Knowing the effective delayed neutron fraction is important for some reactor-physics studies. This fraction essentially defines kinetic behaviour of the reactor in accidental transients when reactivity disturbances have been occurred. Knowing this fraction also is of importance in order to compare measured reactivity effects on material samples with appropriate calculations using selected nuclear data. The accuracy of effective delayed neutron fraction is due to the accuracy of both the calculation methods and the nuclear data used. In this paper their influence on determining the delayed neutron fraction in a fast and a thermal zero-power assembly using uranium fuel is investigated. (author)