Combined beta/gamma-radiation and bremsstrahlung monitor for measurements of incorporated radionuclides: the 90Sr in-vivo counter

A mobile in-vivo counter for β/γ-radiation and bremsstrahlung to detect and quantify incorporated radionuclides was demonstrated. β-particles of 90Sr daughter 90Y were measured with proportional counters in the area of the human head. Simultaneously the bremsstrahlung and other photons in this region were measured to check and to ensure the results from β-particle measurements and to correct for additional γ-ray emitting nuclides. Homogeneously distributed radionuclides in the body such as 40K or 137Cs were measured with germanium detectors in a standard chair geometry. First measurements of inhabitants in the region of Southern Urals affected by the early Soviet plutonium production around 1950 show a strong dependency of 90Sr body burdens on age and place of residence. In 1993, the maximum value was about 25 kBq 90Sr per body for persons born 20 years before the main releases of radioactive waste into the river Techa.