It is harmless. The International Atomic Energy Agency (IAEA) defines the annual level of 50 mSv as safe for health – this is roughly the equivalent of 50 X-ray examinations taken on the old equipment. Radiation exposure of personnel is controlled by modern personal dosimeters – special instruments that are given to every employee before he enters “non-occupied” zone and information from the dosimeter is displayed on a digital screen. The same dosimeters are given to tour visitors to the NPP.
It should be noted that the number of employees at the station is large and many departments and many areas of work, are for the most part not exposed to radiation. For example, staff working in the administrative building are not affected all. Workers carrying out repairs and maintenance on contaminated components are exposed to the largest doses of radiation and they account for over 70% of the collective exposure to radiation. But even they are exposed to less than the secure threshold limit of an annual 50 mSv.