Prompt and Delayed Neutron Emissions and Fission Product Yield Calculations with Hauser-Feshbach Statistical Decay Theory and Summation Calculation Method

Shin Okumura,Satoshi Chiba,Toshihiko Kawano

doi:10.1051/epjconf/201921104005

Abstract

We demonstrate the neutron emission and fission product yield calculations using the Hauser–Feshbach Fission Fragment Decay (HF3D) model and β decay. The HF3D model calculates the statistical decay of more than 500 primary fission fragment pairs formed by the neutron induced fission of 235U. In order to calculate the prompt neutron and photon emissions, the primary fission fragment distributions, i.e. mass, charge, excitation energy, spin and parity are deterministically generated and numerically integrated for all fission fragments. The calculated prompt neutron multiplicities, independent fission product yield are fully consistent each other. We combine the β-decay and the summation calculations with the HF3D model calculation to obtain the cumulative fission product yield, decay heat and delayed neutron yield. The calculated fission observables are compared with available experimental data.

Highlights

The nuclear data of fission yields are essential ingredients for numerous nuclear applications such as the conception of new generation of reactors and nuclear fuel cycle developments
We demonstrate the calculations of the fission observables such as independent/cumulative fission product yields (FPY), prompt/delayed neutron and photon emissions, and decay heats in a consistent manner starting from a unique fission fragment distribution until all fission fragment pairs de-excite and β decay until they reach to their stable isotopes
The decay heat and delayed neutron yield are calculated by the summation calculation method using a Oyak computer code [5] that incorporates ENDF/B-VII.1 decay data library

Summary

Introduction

The nuclear data of fission yields are essential ingredients for numerous nuclear applications such as the conception of new generation of reactors and nuclear fuel cycle developments. Numerous theoretical efforts have been made with both microscopic and macroscopic methods to understand the fission dynamics These approaches provide a quantum description of the fission dynamics and mass, kinetic energy distributions of excited fission fragments. Dynamical description of fission by Langevin equations is one of the examples, which can treat the deformation of each fragment independently and allows us to analyse key information about fission fragments such as mass distribution and total kinetic energy (TKE) [1]. These fission fragments formed just after fission will evaporate prompt neutrons and photons to reach their ground state or meta-stable state. One of the reliable approaches is the Hauser-Feshbach stastical decay of fission fragments

Methods

Results

Conclusion