Speaker
Mr
Valery Borovikov
(USA)
Description
Radiation damage by fusion neutrons can significantly degrade material properties. In a fusion reactor, long-lasting radiation-induced defects such as vacancies, vacancy clusters, and voids introduce additional nuclear safety complication in terms of trap ites for excessive tritium retention. This is especially true in the divertor/first wall of a tokamak like ITER, where extreme thermal stress is also present. Here we use molecular dynamics simulations to elucidate a self-mitigating mechanism in which the large thermal stress can facilitate the recombination of the neutron-collision-cascade-induced vacancies and interstitials through coupled grain boundary (GB) motion in a bcc tungsten under fusion reactor conditions. Specifically, our simulations reveal that for a number of tungsten GBs, absorbing the fast-moving interstitials can help activate coupled GB motion at reduced mechanical stress; the migrating GB then sweeps up the less-mobile vacancies, facilitating vacancy-interstitial recombination inside the GB. We examine the stress-induced mobility characteristics of a number of GBs in W to investigate the likelihood of this cenario.
Country or International Organization of Primary Author
USA
Primary author
Mr
Valery Borovikov
(USA)
Co-authors
Dr
Arthur Voter
(Los Alamos National Laboratory)
Dr
Blas Uberuaga
(Los Alamos National Laboratory)
Dr
Danny Perez
(Los Alamos National Laboratory)
Dr
Xian-Ming Bai
(Los Alamos National Laboratory)
Dr
Xian-Zhu Tang
(Los Alamos National Laboratory)
