A Comparison of Techniques for Radiation Induced Displacement Damage Predictions
Open Access
- Author:
- Gallagher, Joshua
- Graduate Program:
- Nuclear Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 29, 2021
- Committee Members:
- Arthur Motta, Professor in Charge/Director of Graduate Studies
Azaree Lintereur, Thesis Advisor/Co-Advisor
Xing Wang, Committee Member - Keywords:
- Radiation damage
Displacement damage
MCNP
SRIM/TRIM - Abstract:
- When material is exposed to radiation, atoms can be displaced from their lattice sites by the incident radiation, otherwise known as displacement damage. Atoms displaced from their lattice sites affects the microstructure of the material, affecting certain properties and performance, such as structural and electrical. Atoms can be displaced directly by the radiation, known as primary knock on atoms (PKA), or by already displaced atoms. Displacements are quantified by the number of PKAs produced as well as by the displacements per atom (DPA), or the average number of displacements an atom undergoes. Quantifying displacement damage can be a challenging task. Experimentally, material characterization techniques exist, however, it is impossible to determine which atoms were displaced directly by the radiation and if the atoms were displaced more than once. Radiation transport simulation programs are primarily used as particles can be tracked and counted. Monte Carlo N-Particle (MCNP) and TRansport of Ions in Matter (TRIM) are common Monte Carlo radiation transport programs used to quantify the number of PKAs and DPA, respectively. Moreover, both programs have limitations. This work applies analytical expressions to the results from MCNP and TRIM in order to correct for limitations, including accounting for energy transfer based on scattering angle and build-up of displaced atoms, respectively. Comparisons are made between traditional methods of obtaining the number of displaced atoms to those with the added analytical expressions. It was found that with MCNP, both output options, tally results and particle tracking (PTRAC) output, are both acceptable to predict the number of PKAs. Accounting for the distribution of energy transfer based on scattering angle provides the average number of PKAs produced. With TRIM, it was also found that both methods were acceptable to use to determine the resulting DPA as both methods provide values within uncertainty of each other. Accounting for a build-up of displaced atoms does not make a difference unless the rate at which atoms are being displaced is more than 1% of the atom density.