Abstract
Abstract. The meteorological surveillance of the four nuclear power plants in Switzerland is of first importance in a densely populated area such as the Swiss Plateau. The project "Centrales Nucléaires et Météorologie" CN-MET aimed at providing a new security tool based on one hand on the development of a high resolution numerical weather prediction (NWP) model. The latter is providing essential nowcasting information in case of a radioactive release from a nuclear power plant in Switzerland. On the other hand, the model input over the Swiss Plateau is generated by a dedicated network of surface and upper air observations including remote sensing instruments (wind profilers and temperature/humidity passive microwave radiometers). This network is built upon three main sites ideally located for measuring the inflow/outflow and central conditions of the main wind field in the planetary boundary layer over the Swiss Plateau, as well as a number of surface automatic weather stations (AWS). The network data are assimilated in real-time into the fine grid NWP model using a rapid update cycle of eight runs per day (one forecast every three hours). This high resolution NWP model has replaced the former security tool based on in situ observations (in particular one meteorological mast at each of the power plants) and a local dispersion model. It is used to forecast the dynamics of the atmosphere in the planetary boundary layer (typically the first 4 km above ground layer) and over a time scale of 24 h. This tool provides at any time (e.g. starting at the initial time of a nuclear power plant release) the best picture of the 24-h evolution of the air mass over the Swiss Plateau and furthermore generates the input data (in the form of simulated values substituting in situ observations) required for the local dispersion model used at each of the nuclear power plants locations. This paper is presenting the concept and two validation studies as well as the results of an emergency response exercise performed in winter 2009.
Highlights
The main environmental concerns affecting the acceptance of nuclear power plants (NPP) by the public are the emission of radioactive materials, the potential for nuclear accidents, and the generation of radioactive waste
These data were used as input data either directly into a Gaussian-type model or, combined with a climatological wind pattern selected with additional wind data from neighbouring stations, into a Lagrangian model to forecast the shape of potential radioactive plumes and their dispersion at the local scale (Schorling, 2000). This former safety tool was developed over many years at each of the NPPs sites, and a number of field experiments were conducted using surface automatic weather stations (AWS) and remote sensing instruments, in particular wind measurements performed by Doppler Sodar and tethered balloon
The CN-MET tool is a combination of a dedicated measurement network including three ground-based remote sensing stations and the fine-scale NWP model COSMO-2
Summary
The main environmental concerns affecting the acceptance of nuclear power plants (NPP) by the public are the emission of radioactive materials, the potential for nuclear accidents, and the generation of radioactive waste. In Switzerland, the former safety tool was based on meteorological towers and in situ observations of wind and temperature measurements at different heights up to 120 m above ground level (a.g.l.) installed at the NPP sites measuring the meteorological conditions within the surface layer These data were used as input data either directly into a Gaussian-type model or, combined with a climatological wind pattern selected with additional wind data from neighbouring stations, into a Lagrangian model to forecast the shape of potential radioactive plumes and their dispersion at the local scale (Schorling, 2000). Vertical wind shear could only coarsely be captured and only if sufficiently represented in the selected wind class and was totally neglected for the Gaussian model
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