ARTM – Atmospheric Radionuclide Transport Model
During operation of nuclear power plants, minimal quantities of radioactive substances are discharged with exhaust air through the stack into the biosphere. The contaminants disperse with the wind and may partly also deposit on the ground. According to § 47 of the Radiation Protection Ordinance, these discharges must be limited in a way that the maximum annual effective dose of 0.3 mSv for individuals is not exceeded.
Operators of nuclear power plants have to demonstrate at regular intervals that these limits are not exceeded and that even discharges that lie below these limits will be kept as low as reasonably practicable. The data provided by the plant operators are regularly checked by the supervisory authorities for compliance with the legal limits as part of the supervision procedure. To do so, the authorities use i.a. simulation tools, so-called dispersion programs.
What is ARTM?
ARTM is a program system developed by GRS and the engineering firm Janicke by order of the Federal Ministry for the Environment, Nature Conservation and Nuclear safety (BMU) and the Federal Office for Radiation Protection (BfS). It simulates the atmospheric dispersion of released airborne radioactive substances as well as subsequent deposition of the materials on the ground, taking into account their physical and chemical properties that govern their deposition behaviour. ARTM reflects the current state of the art in science and technology. For example, it complies with the current requirements of the administrative provision “Technical Guideline for Air Pollution Control (TA-Luft)” of the Federal Immission Control Act.
By means of the DARTM dose module developed by the Federal Office for Radiation Protection (BfS), it is possible to determine the maximum additional dose caused by the discharged radionuclides from the radionuclide concentration calculated by ARTM. The DARTM 1.5 dose module is included in the code package GO-ARTM 2.0.
Development: From AUSTAL2000 to GO-ARTM
ARTM is based on the AUSTAL2000 code package. AUSTAL2000 was designed for modelling the dispersion of so called conventional air pollutants, i.e. non-radioactive pollutants, and uses a Lagrangian particle dispersion model in combination of a diagnostic flow model.
ARTM was adapted and extended to consider airborne radioactive substances: For this purpose, algorithms for the consideration of gamma cloud radiation as well as the washout of radioactive particles by precipitation – the so-called wet deposition – were developed and implemented into the existing source code of the AUSTAL2000 version 2.2.11. Thus, ARTM features the flexible and realistic modelling of the spatial distribution of radionuclide concentrations and dry and wet radionuclide deposition. The extended ARTM code package contains the diagnostic flow model TALdia and the graphical user interface GO-ARTM developed by GRS. This user interface allows for a user-friendly control and evaluation of ARTM, TALdia and DARTM calculations. Further auxiliary programs facilitate this process and extend the analysis possibilities.