The situation at the Bratrství repository is unique due to the fact that it is located in a former uranium mine. It is clear therefore that the water and surrounding areas contain and will always contain certain quantities of radionuclides produced by the natural conversion of uranium and thorium, regardless of the stored waste. This is reflected in the Bratrství repository monitoring programme as approved by the SÚJB.
The monitoring programme includes the periodic sampling of mine water, water flowing out of the mining areas and surface water in the surroundings of the facility, particularly from the Veseřice stream. Samples are analysed by an accredited laboratory for the presence (volume activity) of selected radionuclides. In 2016, values were determined which corresponded to those expected in the Jáchymov area, i.e. local background levels, and the values determined did not exceed the limits set out in the monitoring programme, thus proving that there is no leakage of radionuclides from the stored waste.
The volume activity of radon and the radionuclides which cause its transformation are monitored in the atmosphere of the underground areas of the repository by the State Institute for Nuclear, Chemical and Biological Protection. The entry of persons into the repository’s underground areas is possible only following mine ventilation and when the measured values do not exceed set limits. The dose received by workers from radon exposure is included in the total occupational dose received as a result of activities carried out in all the repositories administered by SÚRAO. Further, monitoring includes the monthly evaluation of personal film badge dosimeter recordings and an annual assessment employing a whole-body computer. In 2016, no readings exceeding the legal limits for the occupational exposure of workers were measured and, over the long term, the tendency is towards readings of mere tenths of these limits.
The assessment of dose received is conducted not only for the staff of the facility but for all persons who enter the repository. The dose is determined based on the duration of stay in the underground areas of the repository, the concentration of radon in the underground atmosphere, and an evaluation of measurements taken by the electronic dosimeter with which all visitors are provided with upon entering the facility. Records of the doses received by such individuals are archived; the doses themselves are well below the legal limits.