Critical review of an extremity monitoring program at the Instituto de Engenharia Nuclear in Brazil

摘要

Eventually the cyclotron of the Instituto de Engenharia Nuclear (IEN) will need maintenance. Its components are made of copper and they become highly activated after irradiations producing extensive Zn-65 sources. The individual monitoring of the maintenance workers is based on film badges and TLD rings. Both systems are calibrated in terms of 'Photon Dose Equivalent' and the extremity dosemeter is not able to discriminate the gamma and beta contributions to the total dose. Conservatively, it was possible to estimate, using another extremity dosemeter, that beta doses received by the workers' hands are three times higher than the gamma doses. Considering this result and the ring TL responses, it was possible to estimate Hp(0.07), in the case of the hands, for all the IEN cyclotron maintenance workers, since 1983. The results show that Hp(0.07) values are about 2.88 times higher than the previous reported extremity doses in mSv. 10 refs., 2 figs., 2 tabs.