This is an example of the answers to the 22nd-25th examination problems for certification of the chief technician of nuclear fuel. Short explanations or references are given for each answer. Those for laws and regulations are not contained. Ordinance for the enforcement of the law concerning prevention from radiation hazards due to radioisotopes etc. was amended and enforced in 1990. Therefore, some difference was seen before and after 1990 in the examination problems of `technologies concerning radiation and radioactivity measurement and radiation protection`. Thus the 22nd-25th examination problems were adopted in this report. (author).