Monitoring of radiation exposure

Monitoring of radiation exposure comprises monitoring of radiation exposure and individual monitoring. Monitoring of working conditions ensures that the work environment is safe. Individual monitoring refers to determining the dose of an individual worker.

Monitoring of working conditions

Monitoring of working conditions must be arranged at all workplaces where radiation work is conducted. The purpose of the monitoring of working conditions is to identify the changes in the work environment and to assess their impact on radiation exposure. Monitoring the working conditions enables detecting unforeseen abnormalities in factors affecting the radiation exposure of workers. Monitoring of working conditions includes, for example, dose rate measurement of external radiation and contamination measurements in the work environment as well as making observations on whether the safety equipment functions as intended.

The results of the monitoring of working conditions can be used for determining the need for individual monitoring. Monitoring of working conditions must enable verifying that the workers are appropriately classified to radiation work categories A and B. It must be possible to determine the workers’ radiation exposure based on the measurements of monitoring the working conditions, for example in the event of dosimeter failure or radiation exposure due to an abnormal incident or if incorrect dose determination is suspected.

Individual monitoring

Individual monitoring shall be arranged for category A workers. It is often reasonable to also arrange individual monitoring for category B workers. As a rule, the monitoring period of category A workers is one month at the most. The monitoring period of other workers can be up to three months. The classification to different radiation work categories is described in more detail in Guide ST 1.6.

The individual monitoring measurements must be conducted by an approved dosimetric service. Workers may not share dosimeters in individual monitoring. Use of a group dosimeter is not considered individual monitoring. The results of individual monitoring measurements are recorded in a dose register, which is maintained by the Radiation and Nuclear Safety Authority.

STUK has approved four dosimetric services: Doseco Oy and Landauer Nordic as well as the dosimetric services of TVO and Fortum nuclear power plants, which are located in Olkiluoto and Loviisa, respectively.