A general framework for describing photofission observables of actinides at an average excitation energy below 30 MeV *

Abstract

A general framework is proposed for characterising photofission observables of actinides, including mass yield distributions (MYD) and isobaric charge distributions (ICD) of fission fragments, and multiplicity and energy distributions of prompt neutrons (np) and prompt γ rays (γp). The framework encompasses mainly various systematics neutron models and empirical models considering the Bohr hypothesis and does not rely on experimental data as input. These models are then validated separately against the experimental data at average excitation energy below 30 MeV. It is found that the Gorodisskiy model incorporating the Bohr hypothesis reproduces well the experimental data and hence is clearly a priority to characterize photofission MYD. The following benchmark results show that the LD model and the systematic model are suitable for describing the most probable charge of the light and heavy fragments of actinides, respectively. Furthermore, the np and γp predictions with the empirical models are in accordance with the experimental results, indicating the prediction capability of the general framework. It is suggested that the framework offers great potential to predict photofission observables for various scenarios such as short-lived isotope production, nuclear waste disposal and nuclear safeguards.

Parameterization of prompt neutron multiplicity for first-chance actinide photofission

“…Data about the yields of prompt neutrons is necessary to solve the current problems of atomic engineering, such as the methods of nuclear fuel burning and long-lived actinide decontamination, detecting and studying the characteristics of special nuclear materials, and others [5][6][7]. Especially this is true for photonuclear data [8,9]. To solve these problems, it was necessary to create methods for estimating (calculating) the dependence of the total average number of prompt neutrons (AF) and their dependence ν(A) on the mass of photofission fragments of a wide range of actinides at fixed excitation energies.…”

“…The important question is whether it is possible to describe (parameterize) some of the main patterns using the calculation results, that depend on such parameters of actinides photofission as charge, mass, photon energy, and shell characteristics [9,15]. According to the latest research [10,12], it is possible to parameterize total prompt neutron yields (AF), which depend on the fragment masses of actinide photofission and other parameters that would reproduce the complex structure of saw-tooth behavior and allow prediction of the ν(A) dependence for the photofission of a wide range of actinides for the first-chance photofission energy range (without pre-fission neutrons) [16,17].…”