Radiological consequence analysis
With some applications it is unavoidable that radioactive substances are released into the environment, e.g. in radiomedical applications. These are planned or scheduled discharges. However, unplanned releases into the environment can also occur, for example in the event of accidents, inadvertent improper handling, and through criminal acts or terrorist attacks.
A radiological consequence analysis deals with the consequences for man and the environment when radioactive substances are released into the biosphere as a result of human activities - in addition to radioactive substances already present naturally. On the basis of the investigations, it can be checked whether legally prescribed limit values are complied with for normal operation or for incidents and accidents. For this purpose, mainly simulation programs are used for the radiological consequence analysis. A main focus is on the dispersion of airborne radioactive substances in the atmosphere since these can be spread quickly and widely by the wind.
We carry out consequence analyses for discharges during normal operation, during events and accidents, and due to the influence of malicious acts. In addition to many expert and scientific studies (e.g. transport safety analyses) or in connection with emergency response planning - where the radiological consequence analysis makes an important contribution - we work on the following focal areas:
- Calculation of source terms: In order to consider radiological consequences, it must first be known how many radioactive substances enter the environment in the first place. Transport and storage casks for radioactive waste are designed in such a way that the waste is safely enclosed and does not enter the environment. However, it cannot be completely ruled out that containers are damaged in accidents and that some of the radioactive inventory is released. Depending on the severity of the accident (possibly involving fire), the container type, the type of conditioning and the radioactive nuclide, these so-called release fractions can vary. Based on theoretical principles and experimental data, the methodologies for deriving release fractions are further developed and applied at GRS.
- Atmospheric dispersion models: GRS is involved in the further development and validation of atmospheric dispersion models, in particular the Atmospheric Radionuclide Transport Model ARTM. The objectives here are to improve and validate the applicability of the models for licensing and supervision. In addition, these models are used in combination with dose models for the radiological consequence analysis in expert opinions. Both deterministic methods (conservative estimation from individual calculations for set weather situations) and probabilistic methods (frequency-weighted evaluation of individual calculations with complete weather statistics of the site under consideration) are applied.