Measurement of concentrations of γ-ray emitters induced in the concrete shield of the JAERI electron linac facility

Measurement has been made to study distributions of γ-ray emitters induced in the concrete shield of the JAERI electron linac facility. Core boring was carried out at seven positions to take samples from the concrete shield, and γ-ray counting rates and γ-ray spectra of these samples were measured with a NaI(Tl) detector and a Ge semiconductor detector, respectively. The following radionuclides were detected in the concrete samples: 60Co, 134Cs, 152Eu and 154Eu generated through thermal neutron capture reaction, and 22Na and 54Mn generated through nuclear reactions by bremsstrahlung and fast neutrons. The relation between the distributions of γ-ray emitters, as a function of the depth of concrete, and the positions of core boring is discussed. (author)