A Monte Carlo Model of Irradiation-Induced Recrystallization in Polycrystalline UMo Fuels

Journal Article · Tue Oct 01 04:00:00 EDT 2019 · Journal of Nuclear Materials

DOI:https://doi.org/10.1016/j.jnucmat.2019.07.004· OSTI ID:1568062

Frazier, William E. ^[1]; Hu, Shenyang ^[1]; Burkes, Douglas ^[1]; Beeler, Benjamin ^[2]

---

1. BATTELLE (PACIFIC NW LAB)
2. Idaho national laboratory

Experiments show that irradiation-induced recrystallization speeds up the swelling kinetics in U10wt%Mo fuels. However, recrystallization mechanisms and the effect of initial grain microstructures on recrystallization kinetics are still unclear. In this work a Monte Carlo model coupling the rate theory of defect evolution has been developed to study the irradiation-induced recrystallization. The rate theory is used to describe the spatial evolution of gas bubbles, interstitials and interstitial loops; First-Passage Kinetic Monte Carlo (FPKMC) approach is used to describe the fast and strongly anisotropic migration of interstitials, and a Cellular Automata method is used to model the formation of recrystallized grains. With the assumption that recrystallization may occur when the local interstitial loop density is larger than a given critical value, simulation results reveal that 1) recrystallized grains first nucleate on grain boundaries and the recrystallization zone front moves to the center of original coarse grains in the UMo matrix, and 2) recrystallization starts earlier in coarse polycrystalline structures, while the overall recrystallization kinetics decreases with increasing grain size. These results agree with experimental observations. The comparison of recrystallization kinetics obtained from experiments and modeling suggests that the interstitial loop accumulation leads to the recrystallization and the interstitial loop growth is suppressed inside coarse grains due to the over-pressured intra-granular gas bubbles.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1568062
• Report Number(s): PNNL-SA-142549
• Journal Information: Journal of Nuclear Materials, Journal Name: Journal of Nuclear Materials Vol. 524
• Country of Publication: United States
• Language: English