2001 Volume 50 Issue 5 Pages 155-162
It is important to determine internal exposure dose in the case of accident, and it is usually estimated from intake radioactivity measured by human counter. Its detection efficiency necessary for calculation is determined from the measurement using phantoms or Monte-Carlo calculation, but other important problem arises for difference to actual measuring condition. The γ-ray sum peak method is one of them to resolve this problem, but application in the existence of plural radionuclides is difficult. The γ-γ coincidence measurement using two Ge detectors is another answer, and measurements for 24Na, 60Co and 134Cs were carried out for the existence of single nuclide or plural nuclides. The results for single nuclide and for plural nuclides showed agreement with disintegration rates determined by 4πβ-γ coincidence within ±10% and ±15%, respectively.