Research on the migration behavior of corrosion products of CLF-1 steel in magnetic fields

CLF-1 steel, a candidate material for cooling water pipes in fusion reactors, is not only corroded by cooling water producing corrosion products (CPs), but is also exposed to strong magnetic fields during service. Activated corrosion products (ACPs) are formed when CPs are irradiated by neutrons. ACPs are among the most serious sources of radiation risk. Strong magnetic fields in fusion reactors may affect the migration behavior of these ACPs, making the safety assessment of fusion reactors more challenging. The aim of this work is therefore to investigate the migration behavior of the corrosion products of CLF-1 steel in magnetic fields. To obtain the corrosion products, corrosion experiments were performed in a solution of 1 wt% H 2 O 2 and 0.1 wt% NaCl for 24 h. Migration experiments were performed on the corrosion products at different magnetic field strengths. The influence of magnetic fields on the migration behavior of corrosion products was experimentally observed for the first time. The XRD analysis reveals that the CPs are mixtures of multiple components. The same migration experiments were further performed for each of the main components of the corrosion products. The results indicate that, in the range of 200–1000 Gs, regarding quantity and migration distance of particles affected by the magnetic fields, Fe 3 O 4 is the largest; in the range of 3000–8000 Gs, the quantity and migration distance of the particles affected by the magnetic fields, from highest to lowest, is FeCr 2 O 4 > CPs > Fe 2 O 3 > Cr 2 O 3 , and the migration direction is mainly determined by the magnetic field gradient. In order to reveal the physical mechanism behind this phenomenon, the magnetic behaviors of corrosion products and the main components of the corrosion products were analyzed with a vibrating sample magnetometer. Analysis of the magnetization versus applied magnetic field curves indicates that the quantity and migration distance of the migrating particles affected by magnetic fields are positively correlated with their magnetization under the same magnetic field conditions. At 300 K, the magnetic response of the corrosion products exhibits weak ferromagnetism. The initial magnetic susceptibility of the corrosion products is higher than that of Fe 2 O 3 and FeCr 2 O 4 due to the presence of Fe 3 O 4 . In this study, the migration of reduced activation steel corrosion products affected by the magnetic fields was observed for the first time. Future work should further focus on the migration behavior of corrosion products in the actual magnetic fields of fusion reactors, which is important for the safety assessment of activated corrosion products in the fusion reactor environments.