Only one radiological situation report (sitrep) will be relevant for assessment of the radiological situation. This will be drawn up by the government’s radiological situation centre for supraregional emergencies. In the case of regional emergencies drafting the report will generally be a task for the federal state in question. The situation is assessed and a sitrep produced using the available information about the plant’s current status, prevailing weather conditions, emissions and pollution. The sitrep is based initially on forecasts and then, increasingly, on measurements taken in the surrounding area.

Situation assessment phases

In the pre-release phase, an assessment is made of the expected radiological situation not only in the vicinity of the facility, but also nationwide and, if necessary, beyond. The Federal Office for Radiation Protection (BfS) uses the Real-time Online Decision Support System (RODOS) for this purpose, in combination, where appropriate, with the Länder authorities’ remote monitoring system for nuclear power plants (KFÜ). As an alternative, specific systems are applied by the individual Länder. RODOS calculates local, regional and wide-range effects of releases, in the latter case using long-range dispersion forecasts from the German Meteorological Service (Deutscher Wetterdienst – DWD), and predicts the expected impacts of initial protective measures.

These calculations provide an overview of the situation and an impact assessment which the authorities can use as decision support when planning and implementing appropriate measures. Data on the source term (i.e. the type and amount of radioactive material released to the environment and the temporal development of the release) are supplied by the operator based on his assessment of the situation. The required meteorological data are obtained from measurements taken at the site by the KFÜ, as well as from the German Meteorological Service’s weather forecasts.

In the release phase, the plant operator determines the source term, i.e. the type and amount of the radionuclides released to the environment. In this phase, data for assessment of the radiological situation in the vicinity of the plant continue to be available from the KFÜ’s permanent local dose rate probes and the Integrated Measuring and Information System for the Surveillance of Environmental Radioactivity (IMIS) operated by the Federal Office for Radiation Protection (BfS). Initial data from the measuring teams deployed by the Länder and the BfS are available in the post-release phase, i.e. after the passage of the radioactive cloud.

Further afield, the federal authorities’ measuring networks within IMIS feed monitoring data on environmental contamination, particularly the local dose, from around 1,800 measuring probe locations across Germany (BfS); air activity concentration is notified from around 50 stations (DWD). Measurements are taken on a continuous basis, enabling projections to be reviewed and updated.

In the post-release phase, the measurement and sampling services of the plant operator and of the Länder authorities (which employ independent measurement organisations) provide data to determine the local radiological situation, in accordance with the Directive for Emission and Immission Monitoring of Nuclear Facilities (REI), supplemented by simple follow-up measurements carried out by radiation detection teams. Further away from the plant, the Länder carry out sampling within the IMIS framework. The federal authorities’ measuring networks also continue to monitor the situation.