Gamma Radionuclides Research Articles

Enhanced formula-based method to estimate burnup, initial enrichment, and cooling time using limited gamma-ray source data of reference PWR spent nuclear fuel assemblies

This study proposes a framework to develop a model for estimating burnup (BU), initial enrichment (IE), and cooling time (CT) of spent nuclear fuel (SNF) overcoming the limitations of existing models in determining IE. Database (DB) of gamma-ray sources for PWR SNF was generated using ORIGAMI. Target gamma radionuclides were selected based on the ease and credibility of measurement. The concept of Product of Powers of Radioactivity (PPR) was suggested, and PPRs for modeling were selected through evaluation of all possible PPRs. Functions established for PPRs were applied to estimate BU, IE, and CT (BIC) of PWR SNF assemblies. Optimized PPR combinations for estimating BU, IE, and CT respectively, as well as three variables simultaneously with the highest accuracy, were suggested. The estimation model proposed in this study enhanced IE estimations, maintaining the reliability of BU and CT estimations. The above framework enables construction of intuitive BIC estimation models using only a small amount of data. This can help hasten the development of estimation models for SNF from various reactor types. Consequently, it is expected to contribute to the safety and safeguards of SNF management by improving the verification that SNF meets acceptance criteria and conforms to the declared information.

Beyond traditional methods: Exploring strippable gel based on deep eutectic solvent for efficient radioactive surface decontamination

AbstractThis study introduces a technique for decontaminating radioactive surfaces by employing a gel, herein termed as radiation decontamination gel with eutectic liquids (RADGEL), composed of a deep eutectic solvent and polyvinyl alcohol, with the goal of enabling reuse of the surface post‐decontamination. The decontamination effectiveness of RADGEL underwent thorough evaluation through trials conducted on different simulated surfaces, achieving decontamination efficiency up to 99.9% for alpha as well as gamma radionuclides. The various parameters influencing decontamination factors such as amount of complexing agent used, polymer film thickness, nature, and magnitude of radioactivity, as well as surface characteristics of substrates to be decontaminated were optimized. Additionally excellent mechanical strength of RADGEL, affirms its potential as practically efficient, cost‐effective, and safe option for surface decontamination. The Fourier‐transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis suggest RADGELs capability for both physical and chemical interactions with contaminants, thus highlighting its comprehensive decontamination efficacy. The outcomes of this study carry substantial implications for the decontamination of surfaces contaminated with various types of radionuclides.

Influence of the type of fuel used on the content of gamma radionuclides in the soot from the smoke ducts of the home furnaces

Abstract This paper presents the results of the measurements of gamma radioactive isotopes in soot samples from 15 different chimneys of household furnaces fired with various types of solid fuel. Soot samples were collected by the chimney sweep during the mandatory periodic cleaning of the chimneys. The γ-spectrometry technique using the high-purity germanium (HPGe) detector was employed for radiometry of the above-mentioned soot. It was found that the determined activity of gamma isotopes in soot is at a level similar to that in fly ash from power plants around the world. Artificial 137Cs was detected only in the soot from the combustion of biofuel or mixed fuel. The results obtained were chemometrically analyzed to find the relationship between the fuel used and the gamma isotope content in the soot. The analysis of 137Cs, 40K, 228Th, and 226Ra is sufficient to differentiate between the soot obtained and tested, and it varied with the fuel type burned (fossil fuels/biofuels).

Radioactivity of inert construction and demolition waste from Hong Kong and environmental assessment for marine trial reclamation in Guanghai Bay

Inert construction and demolition waste from Hong Kong (HK public fills) has been used for marine trial reclamation in the Guanghai Bay (GHWT) of the Chinese Mainland. However, an environmental assessment of HK public fills is necessary due to higher radioactivity in HK soils than typical global levels. Here, radiation dose rate, gamma radionuclides and gross beta of HK public fills were analyzed. The origin information was explored using natural primordial radionuclides as fingerprints. Our data show that radiation dose rate of HK public fills before disposal was 0.14–0.54 (0.33 ± 0.03) μSv/h (n = 16,722 data with 2787 ships) in 2014, which is less than the GHWT background. Monthly detection of 238U, 226Ra, 210Pb, 232Th, 228Th, 40K, and gross beta in HK public fills was conducted on three random ships. Their specific activities were <6.27–155.5, 58.7–98.7, <7.83–238.2,97.9–168.6, 87.1–136.0, 463.1–1,018, and 1047–1658 Bq/kgDW, respectively. These results suggest that the radioactivity levels of HK public fills are essentially the same as the GHWT background. The study assessed potential risks using various indices icluding Raeq (Radium equivalent activity), Hex (External radiation hazard index), Hin (Internal radiation hazard index), Iγ (Gamma index), AUI (Activity utilization index), AUI (Activity utilization index), E (Annual effective dose), AGDE (Annual gonadal dose equivalent), RLI (Representative level index), Din (Indoor air absorbed dose rate), Dout (Outdoor air absorbed dose rate), and ELCR (Excess lifetime cancer risk). The study suggests that HK public fills should be used for the trial reclamation rather than building-house materials. This provides valuable insights for the resource utilization and minimizing environmental pollution of HK public fills. The aim is to offer fundamental technical assistance for future waste resource utilization, ecological protection, and restoration in the Guangdong-Hong Kong-Macao Greater Bay Area.

Investigation and assessment of natural radioactivity in commercial animal feeds in Texas

Commercial animal feed in Texas was characterized by determining natural gamma emitters including 40K,137Cs, and Uranium (235U and 238U) and Thorium (232Th) series to obtain basic radioactivity values. The measured activity concentration of natural radionuclides in animal feed was low enough for safe consumption by animal and largely depended on the type of animal feed.40K was the predominant radionuclide showing the highest activity concentration in animal feed. The radioactivity concentration of 214 Bi and 214Pb in 238U decay series was 1.39 and 1.33 Bq/kg in corn, respectively, lower than in other animal feed types. On the other hand, the vitamin/mineral mix samples showed higher concentrations of 214 Bi (9.04 Bq/kg) and 214Pb (10.19 Bq/kg). Beef cattle feed, poultry feed, and vitamin/mineral mix exhibited higher activity concentration of 228Ac and 212Pb in 232Th decay series. Gamma radionuclides appeared to be highly and significantly correlated within each decay series. 235U was present at low levels in all feed samples while the anthropogenic radionuclide of 137Cs was not detected irrespective of the type of animal feed. This study highlights an importance of establishing a current baseline of radioactivity concentration in animal feed in Texas in which the largest animal feed consumption in the US exists.

Natural radioactivity assessment of coal combustion residues produced in Indian thermal power plants using high-purity germanium detector

Abstract Huge amount of coal combustion residue (CCR) is being generated in India every year. Since coal contains some natural radionuclides, the CCR may contribute to the enhanced natural radiation background. Hence, it is important to monitor the natural radioactivity levels in Indian CCR samples. The present study aims to estimate the natural radioactivity levels in CCRs produced in Indian thermal power plants. Accordingly, six CCR samples from different thermal power plants were collected and packed to achieve secular equilibrium among daughter products of 226Ra. The samples were counted for activity of gamma radionuclides using high purity germanium detector based high resolution gamma spectrometer. Results show that 40K is the most abundant among analyzed radionuclides, and the lowest was observed for 226Ra. Secular equilibrium was observed between 228Ra and 228Th, whereas no equilibrium was observed between 226Ra and 238U. The activity concentration for 226Ra and its daughter products (214Pb and 214Bi) was found to be similar in CCR sample before and after equilibrium, indicating that progenies are in secular equilibrium in CCR. The X ray diffraction analysis of CCR indicates the presence of aluminosilicate as major fraction, which has potential of trapping of 226Ra and daughter products. The values observed are very low and similar to those observed in naturally occurring radioactive materials such as coal, soil, and sediment, hence are not of radiological concern with respect to human/environment.

The correlation between small papillary thyroid cancers and gamma radionuclides Cs-137, Th-232, U-238 and K-40 using spatially-explicit, register-based methods

A steep increase of small papillary thyroid cancers (sPTCs) has been observed globally. A major risk factor for developing PTC is ionizing radiation. The aim of this study is to investigate the spatial distribution of sPTC in Sweden and the extent to which prevalence is correlated to gamma radiation levels (Caesium-137 (Cs-137), Thorium-232 (Th-232), Uranium-238 (U-238) and Potassium-40 (K-40)) using multiple geospatial and geostatistical methods. The prevalence of metastatic sPTC was associated with significantly higher levels of Gamma radiation from Th-232, U-238 and K-40. The association is, however, inconsistent and the prevalence is higher in densely populated areas. The results clearly indicate that sPTC has causative factors that are neither evenly distributed among the population, nor geographically, calling for further studies with bigger cohorts. Environmental factors are believed to play a major role in the pathogenesis of the disease.

Influence of phosphate fertilizers on the radioactivity of agricultural soils and tobacco plants in Kenya, Tanzania, and Uganda

Three brands of NPK fertilizers that contain variable concentrations of natural radioactivity are commonly used in tobacco plantations in Kenya, Tanzania, and Uganda. Tobacco plants are known for hyper-accumulation of natural radionuclides, particularly 238U. This study investigated if the elevated radioactivity in phosphate fertilizers could enhance radioactivity in soils and tobacco plant leaves. The 232Th, 238U, and 40K radionuclide levels in NPK-fertilized soils and tobacco leaves were measured using gamma-ray spectroscopy. The research included a one-year reference experiment with tobacco growing in plots, a ten-year semi-controlled experiment in well-managed tobacco farms, and a field survey of radioactivity in soils and tobacco leaves at three traditional tobacco fields in Migori (Kenya), Urambo (Tanzania), and Kanungu (Uganda). The findings demonstrated that soils and tobacco leaves exposed to NPK fertilizers with increased radioactivity had activity concentrations of 232Th, 238U, and 40K that were considerably higher (at all sites) than in the control samples (with no use of NPK fertilizers). As the continued application of NPK fertilizers raises concentrations of 232Th, 238U, and 40K in agricultural soils, the study assessed radiological risks for humans from exposure to agricultural soils enriched with phosphate fertilizers, and it was found to be below the exposure limit of 1 mSvy-1 suggested by the International Commission on Radiological Protection (ICRP). However, tobacco consumers, both by snuffing and smoking, may face significant radiological risks, as the snuffing and smoking resulted in effective doses that were 2.41 to 6.53 and 1.14 to 2.45 times greater than the average yearly dose that the general public receives from inhalation of natural radionuclides (United Nations Scientific Committee on Atomic Radiations estimates). Furthermore, the results indicate that the lifetime excess cancer risk for tobacco snuffers and smokers ranged from 5 × 10-5 to 24.48 × 10-3 and 2.0 × 10-5 to 9.18 × 10-3, respectively. The influence of phosphorus-derived fertilizer containing relatively high natural radioactivity, potential human radiation exposure, and radiological risk due to gamma radionuclides is estimated and discussed. The results reveal that applying phosphate fertilizers enhances natural radioactivity in soil and is subsequently influenced by soil to tobacco plant uptake. Therefore, the study recommends that countries use fertilizers with lower radionuclide content to conserve soil quality and reduce gamma-emitting radionuclides in tobacco plants.

Analysis of gamma-emitting radionuclides in soils around high energy accelerators

ObjectiveTo investigate the specific activities of gamma radionuclides in the soils around high energy accelerators, and to analyze the influence of rays emitted by nuclides with characteristic peaks at similar energy points on nuclide measurement results, in order to provide reference for the accurate identification of radionuclides. MethodsGR5021 high-purity germanium gamma spectroscopy system was used to measure the specific activities of gamma-emitting radionuclides 226Ra, 232Th, 238U, 40K and artificial radionuclides 54Mn, 52Mn, 7Be, 22Na, 59Fe, 95Zr in six soil samples around three kinds of high energy accelerators, and the theoretical counts of the characteristic peak of 835.7 ​keV were compared with the measured counts of the characteristic peak of 54Mn. ResultsThe specific activity ranges of gamma-emitting radionuclides 226Ra, 232Th, 238U and 40K in the soils around three kinds of high energy accelerators were 55.5–171, 34.9–99.9, 21.9–79.3 and 247–680 Bq/kg, respectively. The specific activities of artificial radionuclides 52Mn, 7Be, 22Na, 59Fe and 95Zr were basically lower than the minimum detection limit. A characteristic peak was found at the energy point of 835.7 ​keV in six soil samples, and the corresponding total absorption peak counts were from 228Ac of 232Th ​decay daughter. ConclusionsThe specific activities of gamma-emitting radionuclides were at the normal natural background levels. The specific activities of artificial radionuclides were basically lower than the minimum detection limits. For 232Th, when its specific activity is above 40 Bq/kg, characteristic peak of its decay daughter 228Ac could be misjudged as characteristic peak of 54Mn.

Scattering of gamma radiation by air in the ambient environment using gamma ray spectrometry

The intensity of gamma radiation reduces as it traverses through matter. The gamma radiation from earth’s surface is attenuated by non-radioactive burden between the ground and the detector. The relative intensity of unscattered to scattered gamma radiation by air in ambient atmosphere is measured using in-situ gamma spectrometric method. The air thickness up to 300 cm is used for studying attenuation of terrestrial gamma radiation. No significant attenuation is measured up to 100 cm thickness of air between the detector and the ground. The attenuation by air is found to increase with increasing thickness of air. Also, the attenuation of terrestrial gamma radionuclides (40K) is found higher than 238U and 232Th as 40K has lower energy compared to them.

A statistical evaluation of the liquid effluent release from NPP based on analytical methods with low detection limits

Eight liquid effluent samples from nuclear power plants (NPP) were analyzed for 63Ni, 131I, and gamma radionuclides using methods with low detection limits. The sum of the radionuclides activity concentrations of the effluent samples from NPPs A and B were closely lower than the operator’s results with a maximum of decreasing to 29%, while from NPP C were much lower with a maximum of decreasing to 5%. The unlisted radionuclides account for 5.0–889%. It was indicated that the statistics method of the discharge amount could be established based on a regular investigation of the radionuclide characteristics based on analytical methods with low limits of detection.

Calibration of whole body counter for assessment of internal dose in the human body

In the Malaysian Nuclear Agency (Nuklear Malaysia), the ORTEC Whole Body Counter System, bed type was used for assessing internal dose due to intake of gamma radionuclides in the human body. In this study, the performance of ORTEC Whole Body Counter System includes energy calibration, counting efficiency, validation test and minimum detectable activity (MDA) for the radionuclides of interest (ROI) has been investigated using ORTEC whole body counter phantom and mixed standard sources having gamma energies between 59.5 keV and 1836.2 keV. Later, the whole body counting was performed to determine the existence of any gamma radionuclides in the body. The result of the energy calibration was within the tolerance limit of ± 5%. The counting efficiency varies between 0.0000881 cps/Bq and 0.000332 cps/Bq. The results of the validation test show that the bias (Br) and repeatability (SBr) are within the acceptable range of -0.25 ≤ Br ≤ +0.50 and SBr ≤ 0.40, respectively. The MDA for each ROI of I-131, Cs-137 and Co-60 were 165.4 ± 10.0 Bq, 144.6 ± 11.5 Bq and 167.3 ± 30.5 Bq, respectively. A total of 14 volunteers from Postgraduate Educational Course in Radiation Protection and Safety of Radioactive Sources (PGEC-16) were invited to perform the whole body counting. Each volunteer was scanned for 1200 s with the bed speed of 0.065 inch/s. The results show that there is no internal exposure found for all monitored person. Consequently, it can be concluded that the ORTEC Whole Body Counter System (WBC) is now ready to be used for internal dose assessment.

RESULTS OF WBC-MONITORING OF FIREFIGHTERS PARTICIPATING IN RESPONSE TO CHORNOBYL FOREST FIRES IN APRIL-MAY 2020.

of this study was to determine the levels of radionuclides in the rescuers' bodies of the SES during firefighting in the exclusion zone of the Chornobyl nuclear power plant and to assess the dose of internal radiation dueto this receipt. From 06.04.2020 to 19.05.2020 in the State Institution «National Research Center forRadiation Medicine of the National Academy of Medical Sciences of Ukraine» (NRCRM) measurements of the contentof incorporated gamma radionuclides on whole body counters (WBC) operational class «Screener-3M» (Minimumdetected activity (MDA) is 300-500 Bq for 5 minutes of measurement at 137Cs) and expert high-sensitivity WBC (MDAis 20 Bq for 10 minutes of measurement at 137Cs). 470 people (523 measurements) in three groups of personnel ofthe SES of Ukraine who took part in the forest fire liquidation in the exclusion zone in the period from April 4 toMay 5, 2020 were examined. Mathematical and spectrometric methods are used in the work. In the vast majority (95 %) of the personnel of the SES of Ukraine, examined at the WBCoperational class «Screener-3M» (more than 500 measurements), the assessment of the values of the individualeffective dose of internal radiation due to 137Cs in the body during firefighting, assuming that it receipt occurredduring operation in the exclusion zone, did not exceed the minimum dose detected by MDD (5-14 μSv). The average value of the effective dose of internal radiation in the group of personnel of the State Emergency Service ofUkraine in Kyiv, which participated in the elimination of forest fires in the exclusion zone from April 4 to May 5, 2020(26 people) studied at the expert WBC, is 2.5 ± 1.1 μSv, in the group of personnel of the SES of Ukraine in Cherkasyregion, which participated in the fire on April 19-24, 2020 (9 people) - 2.2 ± 0.6 μSv, in the group of personnel ofthe SES of Ukraine in the Kyiv region, which took part in the elimination of the forest fire in the exclusion zone onApril 4 - May 5, 2020 (42 people) - 4.4 ± 2.4 μSv. Maximum values of 5.1 μSv, 3.5 μSv, 11.8 μSv in the groups ofKyiv city, Cherkasy and Kyiv regions, respectively, which is much lower than the basic dose limit for the populationfrom man-made sources of 1000 μSv · year-1 according to the Law of Ukraine about protection of the person againstinfluence of ionizing radiation.

Improving detection sensitivity of a low background BEGe spectrometer by pulse shape discrimination using rise-time ratio

To improve detection sensitivity for interesting radionuclides in measurements of environmental samples by Broad Energy Germanium detectors, the Pulse Shape Discrimination method using rise-time ratio is introduced. A certified soil sample and a typical squid-ash sample were measured by a well-shielded BEGe spectrometer. Minimum Detection Activities for the 722.9 keV and 949.8 keV peaks from the squid-ash sample were decreased by about 26% and 35% respectively. The method performs well especially when the main background comes from gamma radionuclides in samples.

Effect of regional oceanographic processes to the distribution of radionuclides in the coasts of Kalimantan

The present status of marine radioecology condition at the coastal of Kalimantan was determined based on monitoring of the radionuclides concentration in marine compartment of West, South and East Kalimantan. The characteristicof Pacific Ocean contribute to the distribution of radionuclide in Kalimantan from the Indonesian Through Flow (ITF) that passes through the Makassar Strait. The aim of this research is to determine the concentration of radionuclides and regional oceanographic effects on the distribution of radionuclides in the coasts of Kalimantan. Gamma radionuclides activity concentration were measured using High Purity Spetrometer Gamma Detector (HPGe) that is integrated with Genie 2000 software analysis. Modelling processes and field observation from previous study become reflelction of Kalimantan regional sea characteristic. The result of this research shows that the baseline data that represented natural and antrophogenic radionuclides are comparable with other regions in Indonesia. The concentration of natural radionuclides in the sediments showed that there are no contamination of Naturally Occurring Radioactive Material (NORM) and 137Cs.

RESULTS OF WBC/MONITORING OF FIREFIGHTERS PARTICIPATING IN RESPONSE TO CHORNOBYL FOREST FIRES IN APRIL–MAY 2020

Objective.of this study was to determine the levels of radionuclides in the rescuers’ bodies of the SES during firefighting in the exclusion zone of the Chornobyl nuclear power plant and to assess the dose of internal radiation due to this receipt. Materials and methods. From 06.04.2020 to 19.05.2020 in the State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine» (NRCRM) measurements of the content of incorporated gamma radionuclides on whole body counters (WBC) operational class «Screener-3M» (Minimum detected activity (MDA) is 300–500 Bq for 5 minutes of measurement at 137Cs) and expert high-sensitivity WBC (MDA is 20 Bq for 10 minutes of measurement at 137Cs). 470 people (523 measurements) in three groups of personnel of the SES of Ukraine who took part in the forest fire liquidation in the exclusion zone in the period from April 4 to May 5, 2020 were examined. Mathematical and spectrometric methods are used in the work. Results and conclusions. In the vast majority (95 %) of the personnel of the SES of Ukraine, examined at the WBC operational class «Screener-3M» (more than 500 measurements), the assessment of the values of the individual effective dose of internal radiation due to 137Cs in the body during firefighting, assuming that it receipt occurred during operation in the exclusion zone, did not exceed the minimum dose detected by MDD (5–14 μSv). The average value of the effective dose of internal radiation in the group of personnel of the State Emergency Service of Ukraine in Kyiv, which participated in the elimination of forest fires in the exclusion zone from April 4 to May 5, 2020 (26 people) studied at the expert WBC, is 2.5 ± 1.1 μSv, in the group of personnel of the SES of Ukraine in Cherkasy region, which participated in the fire on April 19–24, 2020 (9 people) – 2.2 ± 0.6 μSv, in the group of personnel of the SES of Ukraine in the Kyiv region, which took part in the elimination of the forest fire in the exclusion zone on April 4 – May 5, 2020 (42 people) – 4.4 ± 2.4 μSv. Maximum values of 5.1 μSv, 3.5 μSv, 11.8 μSv in the groups of Kyiv city, Cherkasy and Kyiv regions, respectively, which is much lower than the basic dose limit for the population from man-made sources of 1000 μSv · year-1 according to the Law of Ukraine about protection of the person against influence of ionizing radiation. Key words: forest fire, Chornobyl Exclusion Zone, internal irradiation, whole body counters, 137Сs.

Preliminary studies on the spatial distribution of artificial 137Cs and natural gamma radionuclides in the region of the Ojców National Park, Poland

Abstract The aim of the research is to obtain preliminary information about the spatial distribution of gamma radionuclides in the soils taken from the Ojców National Park with emphasis on the behaviour of artificial radionuclides, with 137Cs as a representative. The natural radionuclides 40K, 226Ra (uranium series), and 228Th (thorium series), which are considered as background radiation, were also determined. In total, 18 soil samples were collected during the summer periods in 2015-2017, while the sampling points were selected with respect to differences in rainfall and local topography gradient. The method was based on gamma-ray spectrometry performed on high-purity germanium (HPGe) gamma detector (relative efficiency 34%). 137Cs was mostly deposited in the top soil layers, with activity in the range of 27.9÷586.6 Bq·kg-1. We found strong positive correlation of the 137Cs activity with the soil organic matter content, and at the same time, its dependence on the rainfall amount. Consequently, the soil types and local climate can control the spatial distribution of 137Cs on a small spatial scale. The quantity of natural radionuclides was highly similar in all samples with the following mean values: 38.0 Bq·kg-1for 228Th, 33.1 Bq·kg-1for 226Ra, and 479.9 Bq·kg-1for 40K.

Measuring and analyzing the radioactivity released from construction floor materials

ABSTRACTThis study measures the radioactivity contained in samples of floor materials used in construction. We would like to use the study as a basic document for the nation’s health and environment. Among construction floor materials, we chose pantheon, red pearl, royal pearl, and tan brown as samples and put them on a detector of high-purity germanium (HPGe) analysis by using a multichannel analyzer (MCA). In order to measure the concentrations of radionuclides, we set the measurement times at 1000 seconds, 4000 seconds, 7000 seconds, and 10,000 seconds, analyzed the concentrations of gamma radionuclides. As a result, Bi-214, Pb-214, Ra-226, and K-40 were detected in pantheon when the measurement time was 10,000 seconds, and Bi-214 was the highest, with a 0.08 Bq/g concentration. For red pearl, we detected Rn-222, K-40, Th-234, Bi-214, Pb-214, and Ra-226. Here, Rn-222 was the highest with a 4.8 Bq/g concentration. For royal pearl, we detected Rn-222, K-40, Th-234, Bi-214, Pb-214, and Ra-226, and Rn-222 was the highest, with a 7.0 Bq/g concentration. Finally, for tan brown, we detected Rn-222, K-40, Bi-214, and Pb-214. Rn-222 was the highest with a 3.8 Bq/g concentration. Though we have detected only low-level radionuclides, we still need to monitor the concentration of radionuclides from time to time.

The activity of selected gamma radionuclides in the Tatra National Park

Cesium is naturally occurring active metal, represented by one stable isotope 133Cs, and number of artificial, unstable, isotopes. The most common artificial isotope of cesium is 137Cs, present in the environment of the Tatra Mountains due to nuclear weapon testing in late `50, and nuclear reactor accident in Chernobyl in 1986. However in recent years the growth in biofuels use for power generation can be the next source of 137Cs emission. Burning wood cultivated on grounds contaminated by 137Cs can introduce secondary emission of this isotope to the atmosphere.This paper presents the results of determination of gamma emitting radionuclides artificial 137Cs and natural 40K in soil samples from the Tatra Mountains. Results show some differences in the vertical distribution of examined radionuclides. It was found that the change of activity of 137Cs in the soil samples depends mostly on the soil density and on the concentration of organic material. The state of “zero” 137Cs activity was developed in the form of maps.

Design of a new comprehensive continuous monitoring system for environmental radioactive aerosol

In order to comprehensive monitoring the radioactive isotopes from nuclear facilities, we developed a dual channel spectral monitoring instrument, and realized synchronous measurement for alpha, beta and gamma radionuclides. This article focuses on how to ensure its accuracy, stability and efficiency. First is the accuracy. In order to lower the interference of environmental and detector performance variation, the zero phase shift filter was designed to ensure the accuracy of characteristic peak position. Lorenz fitting algorithm was designed to reduce the effect of spectral low-energy tailing. Multi thread processing was introduced to ensure that there was sufficient time to complete our complex algorithms. Second is the stability. The complicated measuring process was decomposed into several sub-states. A state monitoring method was set up to timely dispose the abnormal operation. Third is the efficiency. Sampling process and measurement process were designed in synchronous to save monitoring time, which is especially useful for environmental low level radioactive monitoring. Continuous test for seven days shows that the detection limit is less than 0.0003Bq/m3 for U, 239Pu, and less than 0.048Bq/m3 for beta and 137Cs.