Radionuclides in the water of the primary circuit of the LVR-15 research reactor

The main reason for measuring the water activity of the primary circuit of nuclear reactors is the early detection of a fuel cell failure in the active zone of the reactor. This measurement also provides information on the radiation conditions near the primary circuit and on the radionuclide contamination of objects that have been in contact with the water of the primary circuit. A significant increase in the volumetric activity of water leads to a deterioration of radiation protection conditions, especially for maintenance workers on the reactor site, and in the case of a research reactor, also for workers preparing experiments near the primary circuit. Also, at the LVR-15 research reactor, regular water measurements of the primary circuit have been carried out since 1996. The reactor has a nominal thermal output of 10 MW and is in operation an average of 200 days a year, therefore the volume activity of the water is not negligible. Water activity is determined at least once a week. The article presents the time courses of volume activities of selected radionuclides for the entire measured period. (authors)