MEASURING RESULTS OF AN EMERGENCY SURVEY AND COMPARISON OF ACTIVITY IN WATCHBAND CONTAMINATED BY ~(60)Co
Xiao Xuefu 1) Chao Zhexiong 2) Gan Lin 1) Huang Naiming 3) Ji Changyu 4) Xie Zhiquan 3) Diao Lijun 5) Tian Gang 6) 1) Health Physics Division of China Institute of Atomic Energy,Beijing,102413 2) The National Nuclear Emergency Administration Agency,Beijing,100037 3) The Environmental Radiation Research & monitoring Center in Guangdong Province,Guangzhou,510330 4) Health Physics Division of Daya Bay Nuclear Power Station,Shenzheng,518100 5) Primary Radiometrology Laboratory of the Commission of Science, Technology and Industry for National Defense,Beijing,102413 6) The Nuclear Emergency & Radiation Administration Agency of Environmental Protection in Guangdong Province,Guangzhou,510095
The sampling program and measuring methods for activity concentration in spindles of watchband contaminated by cobalt 60, which were sold in some countries, are described. 619 samples of the spindle were randomly sampled from some 32100 spare spindles,of which 141 spindle samples contain cobalt 60. The distribution of activity concentration of cobalt 60 measured by 3 laboratories well known in China is given respectively. The range of activity concentration of cobalt 60 in samples is 37.9～285.7 Bq/g, which obviously present 2 groups of distribution, the average activity concentration of cobalt 60 for higher level samples is 224.8± 11.9 Bq/g ( 1σ,n =103),and for lower level samples is 72.4±11.5 Bq/g,( 1σ,n =38). The maximum activity concentration of cobalt 60 in samples given by these laboratories is 285.7 Bq/g, which is 17 times as low as 1000 Bq/0.2 g given by the Office for Protection against Ionization Radiation (OPIR) of a certain country.