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M. Budzanowski, P. Olko, E. Ryba, Large-area Field Test of a System for Rapid Assesment of Accidental Exposures, Based on Ultra-sensitive Thermoluminescent Detectors, Radiation Protection Dosimetry, Volume 92, Issue 1-3, 1 November 2000, Pages 127–130, https://doi.org/10.1093/oxfordjournals.rpd.a033256
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Abstract
Short-term measurements of kerma rate from external radiation in the environment have been performed simultaneously at 100 locations over an area of about 15,000 km2 using the Rapid Assessment of ACcidental Exposures (RACE) system which is based on LiF:Mg,Cu,P (MCP-N) ultra-sensitive thermoluminescent detectors. The short-term exposure lasted about 5 days, a total of about 128 h between pre-exposure annealing and readout, of which the exposure of the detector at the measurement site lasted about 96 h. To verify the short-term readouts, LiF:Mg,Cu,P (MCP-N) and conventional LiF:Mg,Ti (MTS-N) detectors were exposed at the same locations over a much longer period of 75 d. 100 field sites were selected over a large area in Southern Poland at distances of up to 150 km around Krakow. TL dosemeters, calibrated in terms of air kerma free-in-air using gamma rays from a 137Cs source, were field-exposed 1 m above ground. The average kerma rates over 75 d measured using MTS-N (LiF:Mg,Ti) detectors ranged between 47 and 87 nGy.h-1, using MCP-N between 60 and 107 nGy.h-1 while those measured over 4 days ranged between 56 and 100 nGy.h-1. Comparison of ratios of short-term/long-term readouts of MCP-N at rural locations (35 points) gave a mean ratio of 0.99 ± 0.09 (1 SD). Thus, using the RACE system based on MCP-N detectors, one is able simultaneously to monitor environmental radiation kerma rates at a large number of locations over a very large area, over periods of two days, or less. Provided natural background kerma rates at selected monitoring points are available prior to the accident, the RACE system can be applied to assess kerma rates in the environment rapidly, following a nuclear accident. Noting that kerma rates would then be considerably higher, only a few hours of evaluation time would be required. The system could also be useful in reclamation and restoration works in the environment.
