Application of neutron radiography for estimating concentration and distribution of hydrogen in Zircaloy cladding tubes

Practicability of neutron imaging plate (IP) and computed tomography (CT) for estimating the distribution of the hydrogen concentration in Zircaloy tubes was investigated. Zircaloy tubes with controlled amount of hydrogen which is segregated at the periphery were prepared. The width of the hydrogen region is small around 0.1 mm. In IP image the small segregated hydrogen region is recognized, and the distribution of the hydrogen in the Zircaloy tubes is displayed. The hydrogen region is also recognized in a CT image of the tube containing large amount of hydrogen. These results show that both neutron IP and CT methods are applicable tools to estimate hydrogen distribution. A quantitative evaluation of the hydrogen concentration by those images is also discussed.