Radiation monitoring using imaging plate technology: A case study of leaves affected by the Chernobyl nuclear power plant and JCO criticality accidents

This paper describes the use of a photostimulable phosphor screen imaging technique to detect radioactive contamination in the leaves of wormwood (Artemisia vulgaris L) and fern (Dryopteris filix-max CL. Schoff) plants affected by the Chernobyl nuclear power plant accident. The imaging plate technology is well known for many striking performances in two-dimensional radiation detection. Since imaging plate comprises an integrated detection system, it has been extensively applied to surface contamination distribution studies. In this study, plant samples were collected from high- and low-contaminated areas of Ukraine and Belarus, which were affected due to the Chernobyl accident and exposed to imaging technique. Samples from the highly contaminated areas revealed the highest photo-stimulated luminescence on the imaging plate. Moreover, the radio nuclides detected in the leaves by gamma and beta ray spectroscopy were 137Cs and 90Sr, respectively. Additionally, in order to assess contamination, a comparison was also made with leaves of plants affected during the JCO criticality accident in Japan. Based on the results obtained, the importance of imaging plate technology in environmental radiation monitoring has been suggested

THE SCREENING INDOOR RADON AND PRELIMINARY STUDY OF INDOOR THORON CONCENTRATION LEVELS IN KUWAIT

Indoor measurements of radon and thoron in Kuwait were conducted during the years 2015 and 2016. In this study, 65 dwellings were selected for the long-term radon–thoron survey using passive nuclear track monitors. The monitors (at least one) were used at various locations in the dwellings for 83–306 days. Some measurements were also repeated at the same locations in different seasons. This current study is a preliminary thoron survey with relatively small sample size. The results showed that the range of thoron concentration was from below the lower limit of detection to 35 Bq m−3, whereas the range of radon concentration was within 10–202 Bq m−3. Furthermore, 22% of the radon results exceeded the WHO radon reference level of 100 Bq m−3. The analysis of variance showed a correlation between indoor radon concentration and the season. However, the thoron measurements were rather limited and the values were low. In addition, the relationship was investigated between radon and thoron concentrations involving the floor levels and the type of ventilation systems used

Challenge of 90Sr separation in environmental samples collected from the Fukushima exclusion zone

Fukushima Daiichi nuclear power plant (FDNPP) accident caused radioactive contamination with fission products (I, Te, Be, Cs, Sr isotopes, etc.). The fission products are neutron rich isotopes therefore beta particles will be released from the nucleus to reach stable isotope configuration. Since decay process is accomplished with gamma ray emission, gamma-ray spectroscopy is applied mainly for fission products determination in samples affected by nuclear accident. However, some fission products such as 90Sr, 89Sr are pure beta emitters. Since the energy distribution of the emitted electrons in the beta decay is continuous, element specific separation from the interfering beta emitters is essential for qualitative radioisotopes identification and subsequent measurement.The most important step for reliable 90Sr determination is the highly effective radionuclide separation. Even after five years of the Fukushima accident, there is radioactive contamination in environmental samples caused by radiocaesium isotopes (134Cs and 137Cs) around the Fukushima exclusion zone. The contamination of 90Sr is significantly lower, by four or five magnitudes than radiocaesium isotopes. Under this condition, the decontamination factor of caesium should be higher around six figures in order to eliminate interfering beta particles from radiocaesium isotopes during 90Sr analysis.In recent publication for chemical separation of 90Sr, extraction chromatography is preferred using Sr specific resin (crown ether). Therefore, caesium decontamination factor (DF) was determined in Sr resin using soil samples from the Fukushima exclusion zone with elevated 137Cs contamination (over 3,000 Bq g-1). The caesium separation was not adequate in every case (DF = 104 105), presence of radiocaesium affected the results of 90Sr measurement. Consequently, additional separation steps were required. Caesium purification, with classical selective oxalic acid precipitation method , was achieved with DF range from 50 to 100. However, applying oxalic precipitation combining with Eichrom Sr resin separation, interfering radiocaesium isotopes can be removed with high efficiency (DF>106). The details of this procedure will be discussed during the presentation.International Nuclear Chemistry Congress(INCC 2017

Measurement and validation of uranium isotope ratio in uranium ore for isotopic fingerprinting

Accurate determination of uranium isotope ratio can act as an efficient fingerprint in the nuclear forensics to identify source and intended use of illicit trafficking of uranium material. In this context, a rapid chemical separation technique to isolate uranium from uranium ore sample was developed using commercial extraction chromatographic resin. Uranium isotope ratio was measured using thermal ionization mass spectrometry (TIMS). Standard reference material (NBS U010) was used for validating the accuracy and precision of isotope ratio measurement by TIMS. The method is successfully applied to a natural ore (uraninite ore) for the determination of naturally occurring uranium isotope ratio

Radiological risk assessment of 238U, 232Th and 40K in Thailand coastal sediments at selected areas proposed for nuclear power plant sites

This paper reports on the distribution of three natural radionuclides 238U, 232Th and 40K in marine sediments long the Gulf of Thailand to establish baseline data for future environmental monitoring. Sediments were collected from five potential sites selected for nuclear and thermal power plants commission as well as heavy industry development. Concentration of uranium and thorium were determined using inductively coupled plasma mass spectrometry (ICP-MS) as well as activity of 238U series (226Ra), 232Th series (228Ac) and 40K by γ-spectroscopy. The radiation hazard parameters were calculated based on United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Variation in concentration of natural radionuclides at different sampling areas could be attributed to organic matter content and sediment particle size. The radiological health hazards to the people living nearby sampling areas and the people who handle the marine sediments are within limits recommended by UNSCEAR

Dose effect for South Serbians due to U-238 in natural drinking water

The use of depleted uranium ammunition in South Serbia during the 1999 Kosovo conflict raised a great deal of public concern in the Balkans. Radioactivity levels of U-238 in 20 wells and lake water samples were checked from the viewpoint of internal radiation exposure for South Serbian subjects. We have measured U-238 concentration using inductively coupled plasma mass spectrometry, whereas thermal ionisation mass spectrometry has been used for the measurement of isotope ratios, e.g. U-234/U-238 and U-235/U-238. The concentration of uranium in water samples varies in the range 1.37-63.18 mBq/L. U-234 belongs to the U-238 natural radioactive decay series, and at secular equilibrium, the abundance ratio, U-234/U-238, corresponds to the ratio of their half-lives. The U-234/U-238 activity ratio varies in the range 0.88-2.2 and U-235/U-238 isotope ratio varies from 0.00698 to 0.00745. These findings indicate that uranium in water was a mixture of natural and anthropogenic origin. The annual effective dose due to U-238 was estimated to be in the range 9.2 X 10(-5)-2.1 X 10(-3) mSv.Workshop on Internal Dosimetry, Oct 02-05, 2006, Montpellier, Franc