Radioactivity, Radioactivity concentration, U-238series, Th-232series, K-40
¢£The values of radioactivity concentration of U-238 series, Th-232 series,
and K-40 are the mean values of the research results. Nuclides with no
value are under research. Individual values that are origins of the mean
value vary widely, with some more than 10 times the mean value. To check
the range values of radioactivity concentration of the U-238 series, Th-232
series, and K-40, see "Concentration range." To check the individual
values of the radioactivity concentration of the U-238 series, Th-232 series,
and K-40, see "Individual radioactivity data."
¢£According to the International Atomic Energy Agency (IAEA), a material
with a value below the IAEA critical value is exempt from regulation.
¢£In Japan, a material with a value below the quantity and concentration
determined by the Nuclear Reactor Regulation Law is exempt from regulation.
¢£If the value of a material exceeds the IAEA critical value, actual dose
measurement is recommended, even if the material is exempt from the Nuclear
Reactor Regulation Law.