The relationship between structural changes of ceramic coatings and γ-ray irradiation effect on deuterium permeation

gamma-ray irradiation effect on deuterium permeation through three kinds of ceramic coatings with different crystal structures has been investigated. Deuterium permeation flux through the coatings increased during gamma-ray irradiation at 250-300 degrees C, but changes in the permeation flux were not detected at above 300 degrees C. The permeation flux through an erbium oxide coating increased due to crack formation during a permeation experiment at 500 degrees C. After deterioration of the coating, the gamma-ray irradiation effect on permeation through the coating was similar to that of reduced activation ferritic/martensitic steel F82H substrate. On the other hand, an yttrium oxide coating had an amorphous structure and started crystallization at 500 degrees C. Although the irradiation effect before the crystallization was derived from the F82H substrate, the effect derived from the coating was detected after crystallization because the rate-determining process of permeation shifted to the coating. Compared to the results at 300 degrees C before and after crystallization, the irradiation effect decreased, proving that the ceramic coatings reduced the deuterium permeation as well as the gamma-ray irradiation effect.