Whole-body counter survey results 4 months after the Fukushima Daiichi NPP accident in Minamisoma City, Fukushima

摘要

Using the first WBC unit installed in Fukushima Prefecture after theaccident, the radiocesium body burdens of 566 high-risk residents of Minamisomacity were measured in July 2011 at the Minamisoma Municipal General Hospital.The analysis of the data was challenging because this chair-type WBC unit didnot have sufficient shielding against background gamma rays, and methods had tobe developed to reliably compensate for the body-attenuated backgroundradiation. Fortunately, data for repeated tests of hospital staff members usingboth the chair-type and well-shielded FASTSCAN WBC units, installed inSeptember 2011, were available, and could be used to check the validity of theanalysis. The CEDs of all subjects, estimated under the assumption of acuteinhalation in March 2011, were found to be less than 1 mSv.