Improved model for atomic displacement calculation

Shengli Chen,Cyrille De Saint Jean,David Bernard,Jean Tommasi,Z Ge,Y Chen,W Wang,N Shu,H Zhang

doi:10.1051/epjconf/202023908003

Abstract

Atomic displacement is one of the key factors that influence the behaviors of material properties during and after irradiation. Many models, including the international standard metric Norgett-Robinson-Torrens model (NRT), have been developed to calculate the number of Displacement per Atom (DPA) using the energy of Primary Knocked-on Atom (PKA) as a major parameter. However, extensive experiments and simulations indicate that the NRT-DPA model seriously overestimates (about 3 times) the actual DPA. Nordlund recently developed the Athermal Recombination-Corrected DPA (ARC-DPA) model, which shows that the Molecular Dynamics (MD) simulations can be directly used to compute DPA by fitting the simulated data for each isotope. The present work proposes a simpler expression for the efficiency function to calculate the DPA without requiring fitting parameters as needed in the ARC-DPA model. Our DPA calculation results utilizing the improved efficiency function are validated against the experimental data for the Fe, Ni, Cu, and Ag. The applications in fast breeder nuclear reactors show good agreement with the ARC-DPA metric for56Fe.

Highlights

In the nuclear industry, the operating lifetime of a LightWater Reactor (LWR) is determined by the life of Reactor Pressure Vessel (RPV), which contains the reactor core and is irradiated by neutrons and photons produced by nuclear reactions
The experimental data are extracted from the Nuclear Energy Agency (NEA) report [12], which accounts for the experimental measurements of Jung [13]
The Displacement per Atom (DPA) is proportional to the Resistivity of Frenkel pairs per unit concentration (RF)

Summary

Introduction

Water Reactor (LWR) is determined by the life of Reactor Pressure Vessel (RPV), which contains the reactor core and is irradiated by neutrons and photons (and other particles) produced by nuclear reactions. The accurate knowledge about the irradiation damage, which is conventional quantified by the number of Displacement per Atom (DPA), of RPV can help to decrease the safety margin for the life length of a LWR. In order to compute the DPA rate in materials, many methods and empirical formulae have been proposed by using the Primary Knock-on Atom (PKA) kinetic energy as a major parameter. Based on extensive Binary Collision Approximation (BCA) [1] simulations, Norgett, Robinson, and Torrens (NRT) proposed the modified Kinchin-Pease [2] formula in 1975 [3]. The NRT-DPA formula is nowadays used as the international standard of primary radiation damage

Methods

Results

Conclusion