Results of development and field tests of a radar-tracer system providing meteorological support to modeling hazardous technological releases

Full text: Radar support to systems of automated radiation monitoring requires dealing with determination of geometric characteristics of air release of radionuclides. For doing this, an air release can be labeled by chaff propagating in the air similarly to particles of radioactive substance. Then, a chaff suspension can be treated as a spatially distributed radar target and thus be detected by a radar. For a number of years the Science and Production Association 'Typhoon' of Roshydromet, Obninsk has been developing a radar tracer system (RTS) for meteorological support of modeling hazardous technological releases. In September -December 2002 experiments were conducted to test the RTS in field. This presentation contains preliminary results of testing this system. A total of 9 experiments pursuing different goals were carried out. Of them 6 experiments were conducted approximately 6 km south-west of Obninsk in the vicinity of the village of Potresovo. The first three experiments were aimed at working out interaction between the MR and LDU and assessing the chaff cloud observation distance. In doing this, radar information was not transmitted from the MR to the CCS. In the last three experiments radar information was transmitted to the CCS by cell communication lines using telephones Siemens S35 with in-built modems. The CCS was deployed in building 4/25 of SPA 'Typhoon'. All information received in the CCS was put an a map. Three experiments were conducted in the area of the Kursk NPP as part of preparations for training exercises near the village of Makarovka about 7 km north-west of the city of Kurchatov. In the first two experiments radar information from the MR was passed by cell communication channels to the CCS deployed in the laboratory of external radiation monitoring of the Kursk nuclear power plant. Experiment 3 was a demonstration and arranged during the emergency response exercises at the Kursk NPP. The MR was based on the site of the external radiation monitoring laboratory and the LDU was on the bank of the cooling pond. The main characteristics of a cloud of substances are standard deviations in the spatial concentration distributions in the cloud along mutually perpendicular directions, which are representative spatial scales of the cloud in these directions. The squares of these values are relative variances of the cloud. These characteristics were the first to determine and are among the most important input parameters in different models assessing transport and dispersion of hazardous substances. Dispersion of a cloud of substances is influenced by turbulence and vertical shifts of the mean wind speed, with the patterns of dispersion being different depending an diffusion time (or distance to a source). The results of the conducted experiments have revealed an important advantage of the used radar complex in terms of support to predictions of possible contamination in case of release of hazardous materials. As the chaff cloud moves with the wind and is dispersed, it echoes the meteorological situation at a given time moment (vertical wind distribution and air temperature, turbulence level, boundary layer thickness, type of underlying surface) and any changes occurring in the conditions on its way. Based on obtained radar data, the radar complex is capable of assessing the dispersion parameters which can then be used in the mathematical transport and dispersion models. What's more, determination of these parameters does not require any meteorological measurements. In addition, using data about movement of the cloud centroid, the wind speed and direction is estimated at the release height by the radar complex itself. The conducted experiments have shown that the developed technology makes possible measuring key parameters of a cloud of substances at the height of dispersion and taking into account local features of the distribution of meteorological quantities occurring in the vicinity of a source. This enables a significant reduction in uncertainties associated with lack of detailed meteorological measurement data when modeling dispersion of radioactive materials in case of an accident at a nuclear power plant. (author)