Delayed Neutron Data for Actinides Obtained from Global Level Measurements

Abstract

If weapons-grade plutonium is burned as fuel in LWRs, it may be necessary, for licensing purposes, to predict the behavior of full core loadings of such fuel during postulated accident transients. Operation with full core loadings of plutonium fuel will put increased emphasis on accurate knowledge of the “six group” delayed neutron parameters for plutonium and actinide isotopes. Comparisons of the six group delayed neutron data sets available in the literature for thermal neutron induced fission of Pu-239 indicate differences in the predicted reactor period for positive reactivity insertions of from 5 to 15 percent. It is desirable for reactor design and licensing analyses to decrease the range of uncertainty in the predicted reactor period. Therefore, improvements in the delayed neutron emission data for actinide isotopes is being sought. This paper summarizes some results based on recent measurements of delayed neutron emission from actinide isotopes conducted at Texas A&M University (TAMU).