The neutron leakage from medical and industrial electron accelerators has become an important problem and its detection and shielding is being performed in their facilities. This study provides a new simple method of design calculation for neutron shielding of those electron accelerator facilities by dividing into the following five categories; 1) neutron dose distribution in the accelerator room, 2) neutron attenuation through the wall and the door in the accelerator room, 3) neutron and secondary photon dose distributions in the maze, 4) neutron and secondary photon attenuation through the door at the end of the maze, 5) neutron leakage outside the facility-skyshine.
The accuracy of new simple method of design calculation for neutron shielding in medical and industrial electron accelerator facilities, described in the preceding paper, is investigated in this work by comparing with the measured data in the actual facilities. For this comparison, several published data which have been measured in medical electron accelerator facilities were used, and in industrial facilities the measurement was performed in this work with a neutron dose equivalent meter. From the comparison of measured and calculated neutron dose equivalents, it was confirmed that this simple design method has sufficiently good accuracy.
Instrumental neutron activation analysis was carried out to obtain the normal concentration of trace elements in bovine tissues (heart, liver, kidney, spleen, lymph nodes) and serum. Concentrations of 17 elements were determined. In this paper, concentrations of Al, Br, Cs, In and Rb are given and correlations of concentrations are discussed between Cl and Br and between K and Cs or Rb. Significant positive correlations have been found between Cl and Br concentrations in all tissues, between K and Cs concentrations in tissues excluding kidney, and between K and Rb concentrations in tissues excluding liver.
In order to clarify the behavior of radionuclides (60Co, 85Sr and137Cs) in an aerated sand layer, the column experiments were carried out under co-existent ion (Ca2+, HCO3-) and different silt contents (0-15%) condition. It was noted that60Co migrated into deeper layer when Ca2+or silt was contained. However, the migration of60Co was not affected by HCO3-. In the presence of Ca2+or silt, the migration of85Sr was also observed. But, in the presence of HCO3-, 85Sr was retained at the upper layer because of the formation of insoluble85SrCO3. A large portion of137Cs was adsorbed on the surface of sand layer, and the influences of Ca2+, HCO3-and silt contents on the migration of137Cs were not found.