ABSTRACT
Following the Fukushima nuclear power plant accident detections of (133)Xe have been made in various locations. Using results of these remote measurements the Fukushima (133)Xe source term has been reconstructed and compared with previously reconstructed (137)Cs and (131)I source terms. The reconstruction is accomplished by applying atmospheric transport modeling and an adapted least square error method. The obtained results are in agreement with previous estimations of the Fukushima radionuclide source, and also serve as a proof of principle for source term reconstruction based on atmospheric transport modeling.
Subject(s)
Air Movements , Air Pollution, Radioactive/statistics & numerical data , Fukushima Nuclear Accident , Radiation Monitoring/statistics & numerical data , Radioactive Fallout/statistics & numerical data , Radioisotopes/analysis , Air Pollution, Radioactive/analysis , Japan , Radiation Dosage , Radioactive Fallout/analysis , Risk Assessment/methodsABSTRACT
Measurements of environmental radioactivity by HPGe gamma-spectrometry were carried out with the aim of investigating the distribution of natural radionuclides in a volcanic area and to compare two different methodologies - an in situ gamma-survey of the area and high accuracy laboratory measurements of soil samples. Results demonstrate good performance of the in situ technique, also confirmed by a correlation analysis between the results obtained by the two methodologies. A volcanic gas discharge area was chosen as the test site for the presence of natural long-lived radionuclides such as (40)K and (238)U, (235)U and (232)Th, and their decay chain members. Clear evidence of (222)Rn degassing in the area was confirmed by (226)Ra values measured by the in situ technique. Higher (40)K values measured by the in situ technique may be attributed to the presence of vegetation in the study area.
Subject(s)
Air Pollutants, Radioactive/analysis , Radiation Monitoring/methods , Radioisotopes/analysis , Gamma Rays , Gases/analysis , Italy , Radiation Monitoring/instrumentation , Spectrometry, Gamma/instrumentation , Spectrometry, Gamma/methodsABSTRACT
Caesium-137 and Iodine-131 radionuclides released after the Fukushima Dai-ichi nuclear power plant accident in March 2011 were detected at monitoring stations throughout the world. Using the CTBT radionuclide data and the assumption that the Fukushima accident was the only source of these radionuclides, it was possible to estimate their time-dependent source-term fourteen days following the accident by using atmospheric transport modelling. A reasonable agreement was obtained between the modelling results and the estimated radionuclide release rates from the Fukushima accident.
