Ambient Dose Equivalent Rate Research Articles

Estimation of Ambient Dose Equivalent Rate Distribution Map Using Walking Survey Technique in Hirosaki City, Aomori, Japan.

At present, much emphasis is placed on the health risks associated with radioactivity present in the environment, especially since the accident at the Fukushima Daiichi Nuclear Power Plant. In this study, a walking survey was conducted in Hirosaki City using a NaI(Tl) scintillation spectrometer to estimate and map the distribution of the ambient dose equivalent rate to monitor the radiological safety of the general public in Hirosaki City, where many nuclear facilities are located nearby. The average (±standard deviation) ambient dose equivalent rate was 0.056 ± 0.020 µSv h-1. By comparison with the measurement data, it was found that the values of 85% of the data obtained using the walking survey technique deviated within ±20% relative to those obtained by spot measurements. Furthermore, the distribution of dose rates obtained in the nighttime survey was not significantly different from those obtained in the daytime.

Radiation imaging of a highly contaminated filter train inside Fukushima Daiichi Nuclear Power Station unit 2 using an integrated Radiation Imaging System based on a Compton camera

ABSTRACT The Fukushima Daiichi Nuclear Power Station (FDNPS) suffered a meltdown in the aftermath of the large tsunami caused by the Great East Japan Earthquake that occurred on 11 March 2011. A massive amount of radioactive substance was spread over a wide area both inside and outside the FDNPS site. In this study, we present an approach for visualizing a radioactive hotspot on a standby gas-treatment system filter train, a highly contaminated piece of equipment in the air-conditioning room of the Unit 2 reactor building of FDNPS, using radiation imaging based on a Compton camera. In addition to fixed-point measurements using only the Compton camera, data acquisition while moving using an integrated Radiation Imaging System (iRIS), which combines a Compton camera with a simultaneous localization and mapping device and a survey meter, enabled the three-dimensional visualization of the hotspot location on the filter train. In addition, we visualized the hotspot and quantitatively evaluated its radioactivity. Notably, the visualized hotspot location and estimated radioactivity value are consistent with the accident investigation report of the FDNPS. Finally, the extent to which the radioactivity increased the ambient dose equivalent rate in the surrounding environment was explored.

The neutron dose equivalent rate measurements by R3DR/R2 sp ectrometers on the international space station

The data from two Bulgarian-German instruments with the basic name “Radiation Risk Radiometer-Dosimeter” (R3D) are discussed. The R3DR instrument worked inside the ESA EXPOSE-R facility (2009–2010), while R3DR2 worked inside the ESA EXPOSE-R2 facility (2014–2016). Both were outside the Russian Zvezda module on the International Space Station (ISS). The data from both instruments were used for calculation of the neutron dose equivalent rate. Similar data, obtained by the Russian “BTNNEUTRON” instrument on the ISS are used to benchmark the R3DR/R2 neutron dose equivalent rate. The analisys reveals that the “BTNNEUTRON” and R3DR/R2 values are comparable both in the equatorial and in the South Atlantic Anomaly (SAA) regions. The R3DR/R2 values are smaller than the “BTNNEUTRON” values in the high latitude regions. The comparison with the Monte Carlo simulations of the secondary galactic cosmic rays (GCR) neutron ambient dose equivalent rates (El-Jaby and Richardson, 2015, 2016) also shows a good coincidence with the R3DR/R2 spectrometer data obtained in the equatorial and high latitude regions.

Оценка мощности амбиентного эквивалента дозы на лесных участках в юго-западных районах Брянской области

The large areas of forests in the Bryansk region are still contaminated with radionuclides released due to the accident at the Chernobyl NPP in April, 1986. The recovery of the economic and ecosystems potentials in the contaminated areas is the need to create a favorable living conditions for the population. This involves a full range of remediation activities in the contaminated areas aimed at the forests protection and regeneration. The aim of the work is to assess the ambient dose equivalent rate (ADER) in forest sites located in the zone of radioactive contamination. More than 1 thousand forest sites in the south-western part of the Bryansk region were surveyed from 2019 to 2022. The ADER and the density of the soil contaminated by Cs-137 for every surveyed forest site are available. The relationship between the ADER and the density of the soil radioactive contamination in various sites was analyzed. The dose rates were normalized with respect to the density of soil contamination. The ADER rates in the Bryansk forest areas ranged from 0.07 to 3.15 mSv/h. No reliable difference between the ADER in the areas of coniferous and deciduous forests was observed. There was reliable linear relationship between ADER and the density of soil contaminated by Cs-137. During forestry operations in radioactive contaminated areas the maximum permissible external radiation effective dose was the dose accumulated for the whole period of work in the forest sites with the average density of soil contaminated by Cs-137 of 450 kBq/m2.

Распределение мощности амбиентного эквивалента дозы гамма-излучения на особо охраняемых природных территориях Ростовской области

To monitor the ambient dose equivalent rate of gamma radiation in the ecosytems of the specially protected natural areas is necessary for identification of the areas with high radiation background and estimation of the background level of radiation contamination in the adjacent territories. The paper presents results of the study of ambient dose equivalent rate of gamma radiation in the dry and semidry steppes ecosystems. For these purposes six specially protected natural areas located in the Rostov Region were used as research objects. The ambient dose equivalent rate of gamma radiation was estimated with dosimeters-radiometers by the field method of pedestrian gamma ray shooting. For the analysis of the obtained results statistical methods were used. It was found that the distribution of the ambient dose equivalent rate of gamma radiation in the specially protected natural areas varied from 0.01 to 0.32 µSv/h. Arithmetic mean, geometric mean, modal and median values of the ambient dose equivalent rate of gamma radiation for all studied specially protected natural areas are 0.128 µSv/h; 0.120 µSv/h; 0.135 µSv/h and 0.135 µSv/h, respectively. It was found that the ambient dose equivalent rate of gamma radiation in the specially protected natural areas in the Rostov Region did not depend on soil types. The study results allow us to make the following conclusion: insignificant differences in the arithmetic mean values of the ambient dose equivalent rate of gamma radiation in the territories under consideration may be due to the peculiarities of their protection and use regimes, as well as due to the radioactive fallout released by the Chernobyl accident and the uncertainty in radioactivity measurement.

Estimation of Long-Time Radiation Doses by Measuring Ambient Dose Equivalent Rates in Date City, Fukushima Prefecture

Estimation of Long-Time Radiation Doses by Measuring Ambient Dose Equivalent Rates in Date City, Fukushima Prefecture

Radiation and Nuclear Physics Aspects of the Use of the Thorium Fuel Cycle in a Hybrid Fusion Facility

This paper presents the results of the experimental determination and computational simulation of the ambient dose equivalent rate for a metallic thorium cylindrical miniblock and the (n,2n), (n,f), and (n,γ) reaction rates in a thin 232Th metal foil irradiated with neutrons of the NG-24M generator spectrum. The ambient dose equivalent rate was determined by dosimeters-radiometers. The reaction rates were determined by the activation method using Ge spectrometers without destroying the irradiated samples. Computational simulations of ambient dose equivalent and reaction rates were performed, respectively, using the radiation transport codes PHITS, MCNP5, and KIR2, which use various nuclear data libraries: JEFF-3.2 and -3.3; JENDL4.0; ENDF/B-VII.0, -VII.1, and -VIII.0; ROSFOND; FENDL; and TENDL. The authors give an estimate of the 232U/233U relative accumulation upon natural thorium irradiation in a fusion facility blanket with defined neutron spectrum. The nonirradiated and irradiated thorium nuclide composition change simulation and visualization were performed using analytical solutions of an ordinary system of homogeneous linear differential equations describing nuclide transmutations.

Assessment of annual effective dose from external exposure in forests of the south-western districts of the Bryansk region of Russia: 2015–2021

During a stay in a radioactively contaminated forest, a person is inevitably exposed to ionizing radiation from the man-made radionuclides. The purpose of this study was to evaluate the external component of the annual effective dose due to exposure in the forests contaminated following the Chernobyl accident. The study was conducted in the south-western districts of the Bryansk region of Russia in the period 2015–2021. Field (in situ) gamma spectrometric measurements were carried out on 46 forest plots located in the areas of 27 settlements. As of 01.01.2017, the officially established values of soil contamination density with 137Cs in the territory of the settlements themselves were in the range from 33 to 2050 kBq/m2 . According to the field gamma spectrometry, the density of soil contamination with 137Cs on the forest plots varied from 21 to 1930 kBq/m2 . The density of soil contamination with 137Cs in forest was in good agreement with the officially established level of soil contamination with 137Cs in the nearby settlement: the ratio of one indicator to another ranged from 0.70 to 1.32 (mean = 0.94; median = 0.95). The scatter in the measured values of the ambient dose equivalent rate from 137Cs was quite significant: more than one order of magnitude, from 31 to 2700 nSv/h. The variability of the ambient dose equivalent rate from natural radionuclides was relatively small: from 13 to 29 nSv/h. Based on the obtained experimental data and on published values of the duration of human stay in forest, the annual effective dose to selected groups of population was estimated. The dose from natural radionuclides, even in the case of a prolonged stay in the forest (1400 hours per year for foresters), did not exceed 0.02 mSv/year. The estimated values of the effective dose from 137Cs varied very widely from 0.001 to 1.9 mSv/year, depending on the selected forest plot and population group. On the whole, the data obtained indicate that the officially established values of the density of soil contamination with 137Cs in a settlement can be directly used in dosimetric models to estimate the component of the effective dose to a person due to his/her staying in the forest which is located in the area of this settlement. The currently recommended conversion coefficient from the density of soil contamination with 137Cs in a settlement to the ambient dose equivalent rate from 137Cs in the nearby forest is 1.28 (nSv/h)/(kBq/m2 ). To estimate the effective dose from natural radionuclides, it is recommended to use the value of the ambient dose equivalent rate equal to 21 nSv/h.

Radiation situation in the territory of the uranium legacy site in the Bambakai Valley (Transbaikal Territory)

The article presents the results of a study of the current radiation situation at the uranium legacy site located in the territory of the Bambakai Valley (Transbaikal Territory), formed in the period from 1973 to 1989 due to the discharge of mine water. During the radiation survey, the method of pedestrian gamma survey was used to measure the ambient dose equivalent rate. Soil sampling was carried out to study the radionuclide specific activities in the soil. The activity of gamma-emitting radionuclides in the samples was measured with a stationary gamma spectrometer. The activities of 210Po and 210Pb were measured after their radiochemical extraction from samples. It was found that the values of ambient dose equivalent rate in the territory of the valley varied over the wide range from 0.1 to 1.4 µSv/h in the areas under manmade contamination. The estimated average value of the gamma background for this place is 0.14±0.02 µSv/h. The specific activities of 238U, 226Ra, 235U, 210Pb and 210Po in the surface 10-cm soil layer at the site are from 10-40 times higher than the background values. The most part of radionuclides in the soil is in the acid-soluble form. Effective doses of the workers involved in hay harvesting in the area of the fallow land do not exceed 1.5 µSv/year. Doses of terrestrial environmental media (grass, earthworms) are 100 and more times lower than the safe level of exposure to biota.

Radionuclides and Metals in the Parks of the City of Belgrade, Serbia: Spatial Distribution and Health Risk Assessment

In urban areas, forest patches and parks are usually the places where people spend most of their time outdoors. Because of poor environmental protection policy and insufficient investment in industry and energy, Serbia is often ranked among the European countries with the greatest environmental pollution. In recent years, ecological protests have been organized throughout the country with the aim of raising ecological awareness and resolving environmental issues. The topic has become particularly popular since the plans for opening new mining areas in western Serbia came to the fore. This study was conducted with the aim to investigate radioactivity levels and metals content in soil and foliage of the most popular parks in Belgrade, the capital and largest city of Serbia. Based on a GIS (geographic information system) approach, the spatial distribution maps of radionuclides (226Ra, 232Th, 40K, 7Be, and 137Cs) and metals (As, Cd, Cr, Co, Cu, Na, Ni, Pb, Zn, K, Ca, Mg, and Mn) were made. Ambient dose-equivalent rate in air was also measured. The annual effective doses and excess lifetime cancer risk from radionuclides were calculated. Health effects of exposure to heavy metals in soil were estimated by noncarcinogenic and carcinogenic risk assessment.

Estimation of the effect of GNSS positioning errors on the dose rate calculation concerning aerial radiation monitoring

Four global navigation satellite system (GNSS) receivers were installed in a helicopter to reduce positioning errors in aerial radiation monitoring. The effect of positioning errors on the conversion of the counting rate of the detector to the ambient dose equivalent rate at the ground level was evaluated. The positioning results obtained by receiving the centimeter-class augmentation signal known as the L-band experiment, which the Quasi-Zenith Satellite System generates on an experimental basis for a limited time, were used as the reference values. A comparison between horizontal and vertical positioning errors among four receivers demonstrated that the vertical errors were larger than the horizontal errors. They did not differ among receivers, whereas the horizontal errors varied according to the characteristics of the receivers, particularly in mountainous areas; the errors tended to be larger when the terrain change at the measurement point was larger. The median effects of the vertical and horizontal errors on the calculated values of the radiation dose rate at the ground level were 3%–6% and 1%–5%, respectively, and the maximum possible effect of the positioning error was 20%–32%. The fact that the receiver with the highest number of available satellites had larger errors than the other receivers indicated that the elevation angles of satellites and the augmentation signals play an important role in improving the positioning accuracy when the number of available satellites reduces in mountainous areas. This study has provided insight into selecting a suitable GNSS receiver for surveying by vehicles such as helicopters, aircraft, and drones, which are required to perform 3D positioning in complex terrains.

Near-range atmospheric dispersion of an anomalous selenium-75 emission

On May 15th of 2019, an anomalous emission of selenium-75 was detected at the stack of the Belgian Reactor 2 (BR2) in Mol. Although the release exceeded the prescribed limits for BR2, there was no harm to the population or food chain and so the event was classified as INES 1. However, it was very interesting from the perspective of near-range atmospheric dispersion. This publication brings together all available information at the near range – stack-monitored source term data, on-site meteorological data, ambient dose equivalent rates, deposition and concentration measurements – in one dataset that covers the initial puff release on May 15th, 2019 as well as a residual release through early November 2019. To demonstrate the consistency of this dataset, supporting atmospheric transport and dispersion calculations are performed using a Gaussian plume model. These calculations, in turn, are supported by near-range Flexpart calculations in the context of the residual release.

Assessment of Natural Radiation Exposure Due to 222Rn and External Radiation Sources: Case of the Far North, Cameroon.

This paper assesses public exposure to natural radioactivity from radon and external radiation sources in the Far North region, Cameroon, and studies the correlation between radon data obtained using several techniques. The RADTRAK, RadonEye, and Markus 10 detectors were used to measure radon concentrations in dwellings and soil, respectively. To understand radon variations in the study area, a correlation coefficient between radon in soil and in dwellings was determined. The ambient equivalent dose rate was measured using a RadEye PRD-ER, and the effective doses from internal and external radiation were determined. In soil, 20% of the measuring points had a concentration above 50 kBq m-3, the action value for radon exposure from soil according to Swedish Radiation Protection Institute regulations. After 90 d of measurement using RADTRAK, half of the concentrations in the dwellings were greater than or equal to 160 Bq m-3, which is above the WHO reference level of 100 Bq m-3. The ambient equivalent dose rate and the external and internal radiation effective dose were 0.08 μSv h-1, 0.6 mSv y-1, and 2.86 mSv y-1, respectively. These results reveal a strong correlation between the radioactivity level of a locality and its geological and mineralogical structure. Although these different results in general do not present a very high risk of radiological exposure for the public, it is nevertheless necessary that the rules of radiation protection are respected in order to reduce it.

Calculation of shielding performance of CRT concrete for proton therapy and optimal shielding design of treatment delivery room

Proton therapy is becoming increasingly popular worldwide, and its shielding must be considered. The cathode ray tube (CRT) material is a glass containing heavy metal elements, these materials have become a good choice for the production of radiation-proof concrete. In this study, the ability of concrete containing CRT fragments as shielding materials for proton therapy rooms is evaluated in terms of neutron shielding ability, neutron reflection ability, ambient dose equivalent rate, and induced radioactivity. In addition, this concrete is compared with commonly used ordinary concrete, boron-containing concrete, and barite concrete. The results show that with the increase of CRT content (10%–90%), the transmitted neutron fluence decreases continuously (5.06 × 10−10 – 1.77 × 10−10 cm−2/particle), and the reflection of neutrons gradually increases (2.64 × 10−9 – 3.20 × 10−9 cm−2/particle), resulting in an increased potential to patients. When 50% CRT concrete is used, the ambient dose equivalent rate is below 3.80 μSv/h/nA, and 90% CRT concrete is below 3.11 μSv/h/nA. The trend of radionuclide activity of induced radioactivity from 0 to 60 min after irradiation for concrete with different CRT contents is 2.74–5.38 × 10−3 Bq/cm3, and the maximum photon fluence is 8.13 × 102 cm−2. In conclusion, the optimization model of the three-layer shielding structure of ordinary concrete, high CRT content concrete, and boron-containing concrete is proposed with ambient dose equivalent rate less than 1.88 μSv/h/nA, minimizing the reflected neutrons to which the patient is exposed. This study shows the protection performance of CRT concrete is better than ordinary concrete and barite concrete.

Natural Radioactivity and Metals in Pit Lakes in Sweden Analyzed by Principal Component and Cluster Analysis

The aim of this work was to determine which parameters are sufficient to measure in order to describe the water quality of a pit lake and to identify patterns in the data among different kind of pit lakes. The data consisted of ambient dose equivalent rate, elemental and radionuclide concentration, pH, and specific conductance in surface water and sediment samples collected from different types of mines. Data were tested for normality and log-normality and used in principal component analysis (PCA) and hierarchical cluster analysis (HCA). The normality tests indicated that only 40K was normally distributed, while only the 234,238U isotopes were log-normally distributed. HCA performed on parameters measured in surface water provided clusters that in most cases separated the elements according to their chemical groups. However, when HCA was performed on pit lakes, the clustering seemed to indicate that surface water might not be the preferred sample to differentiate between different types of pit lakes. PCA of surface water data resulted in three components that explained 72% of the variance when pH, SC, concentration of the elements Mg, K, Ca, Cu, Zn, Sr, Pb, activity concentration of 234,238U and 210Po, and ambient dose equivalent rate were included. For surface sediment data, the PCA resulted in three components explaining 83% of the variance when the concentration of Na, Mg, Al, P, K, Ca, Rb, Sr, Y, Tl, activity concentration of 234Th, 226Ra, 210Pb, 232Th (series average), and 40K, and ambient dose equivalent rate were included.

Investigation of the radiation situation at the dumps of the mine No. 1 of the LPO "Almaz" five years after recultivation

Introduction. The work was completed on the remediation of dumps located in the area of nine tunnels of mine No. 1 of the Lermontov production association “Almaz” over 2014-2015. The article presents the results of a study of the radiation situation on these dumps five years after the remediation. Materials and methods. During the survey, the methods of pedestrian gamma survey were used using a portable spectrometric complex MKS-01A “Multirad-M” and soil sampling with subsequent measurement of the specific activity of radionuclides using a stationary gamma spectrometer manufactured by CANBERRA. The activity of 210Po and 210Pb was measured using a UMF-2000 radiometric setup after their radiochemical isolation. Results. After the remediation of the dump areas, where gamma ambient dose equivalent rate exceeds 0.5 μSv/h, areas significantly decreased and do not exceed 10% of the total dump area, with the exception of the dumps of tunnel No. 42. On the territory of all surveyed dumps, except for dumps of tunnels No. 10 and No. 26, there are areas where gamma ambient dose equivalent rate exceeds 0.6 μSv/h, which is prohibited in accordance with the adopted remediation criteria. Not all tunnel mouths are isolated. Limitations. It is assumed that comparing the content of radionuclides in soil with the criteria for classifying them as solid radioactive waste 238U and 230Th are in secular equilibrium. Measurements of the total alpha-activity in the soil and comparison with the recultivation criteria for this parameter were not carried out. Conclusion. At present, the radiation situation in some areas of all surveyed reclaimed dumps, except for the dumps of tunnels No. 10 and No. 26, does not meet the requirements established in the remediation project.

Low-cost radon monitoring with validation by a reference instrument

This article reports radon tracing using a low-cost, locally manufactured smart electronic device with comparison to a reference device. Developed for radiation protection and nuclear security, the proposed device consists of a ZP 1200 Geiger-Müller (GM) tube detector with low-cost components including an Arduino microcontroller board, a DHT11 temperature (T) and relative humidity (RH) sensor, and XBee-based Internet of Things (IoT) wireless transmission modules. The reference device measures radon concentration, temperature, and relative humidity in indoor spaces. Typically, the developed device provides data of atmospheric parameters (T, RH) and the ambient dose equivalent rate H*(10). From the ambient dose equivalent rate in µSv/h, the radon activity concentration (in Bq/m3) is determined using standard and recognized conversion coefficients. The coefficients vary according to the ambient radiation strength and range from 5500 to 8900 (Bq/m3)/(µSv/h). The developed device and the reference instrument were used for one month in several dwellings in the city of Yaoundé-Cameroon. Periodic average values of 27.5 ± 2.0 °C (developed device) and 26.2 ± 2.0 °C (reference) for temperature, 74.1 ± 6.4% (developed device) and 73 ± 6% (reference) for relative humidity, and 1500 ± 163 Bq/m3 (developed device) and 1465 ± 164 Bq/m3 (reference) of cumulated radon activity concentrations were obtained for a 24-hour period. Statistical analyzes carried out on the results of the devices provide a linear regression coefficient of R2 = 0.9978, demonstrating good agreement between the instruments.

РАДИАЦИОННАЯ ОБСТАНОВКА В РАЙОНЕ РАСПОЛОЖЕНИЯ РУДНИКА № 2 ЛЕРМОНТОВСКОГО ПРОИЗВОДСТВЕННОГО ОБЪЕДИНЕНИЯ «АЛМАЗ»

Purpose: Assessment of the current radiation situation around dumps of mine No. 2 of the Lermontov Production Association Almaz after remediation. Material and methods: The methods of pedestrian gamma survey using the portable spectrometric complex MKS-01A “Multirad-M”. Soil sampling was used to measure radionuclide specific activities. Activities of gamma emitting radionuclides were measured by a stationary gamma spectrometer of the CANBERRA Company. Activities of 210Po and 210Pb following radiochemical separation of these radionuclides were measured using the radiometric installation UMF-2000. Short-term measurements of radon EEC were carried out with aerosol alpha-radiometer RAA-20P2 Poisk. Results: After remediation, gamma ambient dose equivalent rate does not exceed 0,5 μSv/h at all dumps, with the exception of local areas around tunnels No. 9, 10 and 11. In the area around tunnel No. 9, gamma ambient dose equivalent rate reaches 0,55 μSv/h, in the area of tunnel No. 10–5 μSv/h and higher, and in the area of tunnel No. 11 – up to 0,9 μSv/h. In the areas around all tunnels, except for tunnel No.11, soil does not belong to solid radioactive waste. In a small area near tunnel No. 11, the content of radionuclides in the soil exceeds the criteria for classifying as solid radioactive waste. Radon EEC in the surveyed area generally did not exceed 30 Bq/m3. Increased values up to 200 Bq/m3 were registered in the area of tunnel dumps, the mouths of which were not fully isolated (tunnels No. 6, 7 and 10). Moreover, directly at the mouth of tunnel No. 10, radon EEC values reached 65000±11000 Bq/m3. Conclusions: At all surveyed remedied dumps, except for dumps of tunnels No. 10 and 11, the radiation situation in some areas does not meet the requirements established in the remediation project in accordance with the “Health Care Rules for the Closure, Conservation and Conversion of Enterprises for the Mining and Milling Radioactive Ores” and stay in these territories does not pose a hazard to the population.

Ambient dose equivalent rate from <sup>137</sup>Cs and natural radionuclides in one-story residential buildings in settlements of the Bryansk region in 2020–2021

Method of in situ gamma-ray spectrometry was used to discriminate contributions of 137Cs and natural radionuclides to ambient dose equivalent rate indoors in settlements located in the zones of radioactive contamination after the Chernobyl accident. The measurements using a portable scintillation gamma spectrometer-dosimeter were carried out in 115 individual one-story residential buildings in 46 settlements of the Bryansk region of Russia in the summer period of 2020–2021. According to official data, the average density of soil contamination with 137Cs in the settlements ranged from 27 to 533 kBq/m2. Based on the type of building materials that had been used to construct the walls, the surveyed houses were divided into three large groups: wooden (walls made of logs) – 51 buildings, stone (walls built of bricks and/or concrete panels) – 34 buildings, and frame-panel – 30 buildings. The latter had walls constructed of wooden panels with the inclusion of heat-insulating material. Outside, the walls of the frame-panel houses were lined with a layer of silicate (white) bricks. 70 houses were built before the accident and 37 – after the accident. In eight cases it was not possible to reliably estimate the period of construction. The total ambient dose equivalent rate ranged from 42 to 228 nSv/h (average = 77 nSv/h). The values of the ambient dose equivalent rate from natural radionuclides were in the range 27–122 nSv/h. The average values of the ambient dose equivalent rate from natural radionuclides in the groups of wooden, frame-panel, and stone houses were 42, 42 and 58 nSv/h, respectively. The difference between stone houses and panel houses was statistically significant (P < 0.01). The same difference was found between stone houses and wooden houses (P < 0.01). The average values of the ambient dose equivalent rate from 137Cs, normalized to the density of soil contamination with 137Cs, were 0.13, 0.16, and 0.05 (nSv/h)/(kBq/m2) in wooden, frame-panel, and stone houses, respectively. The normalized ambient dose equivalent rates from 137Cs in the group of stone houses were statistically significantly (P < 0.01) lower compared to the corresponding values for the groups of wooden houses and frame-panel houses. The small differences between frame-panel and wooden houses turned out to be statistically significant (P < 0.05). The median and mean values of the normalized ambient dose equivalent rate from 137Cs for houses built before the accident were lower compared to those for houses built after the accident. These differences were statistically significant (P < 0.01) for all groups of houses. The mean values of the normalized ambient dose equivalent rate from 137Cs and the ambient dose equivalent rate from natural radionuclides obtained in this study can be used to estimate the external effective dose to a person staying inside a one-story residential building. In this case, one should take into account not only the type of building materials used to construct the house, but also the time period of the construction: before or after the Chernobyl accident.

Radiological characterization of a uranium glass collectible by gamma spectrometry

The purpose of this work was the non-destructive characterization by gamma spectrometry of a collector's item in which uranium was used as a colouring agent. Such characterization was based on the calculation of the counting efficiency as a function of energy using the LabSOCS software from Canberra Industries. The activity concentrations obtained for the uranium isotopes were verified: i) from the measurement of two different positions of the test piece, ii) from the indirect calculation of the percentage by mass of U3O8 (wt%) and iii) from the ambient dose equivalent rate H*(10) using the MCNP code. The activity concentrations obtained for 238U (9031 ± 2919 Bq kg−1) and 235U (472 ± 23 Bq kg−1) led to the conclusion that it was natural uranium. The value of the rate of ambient dose equivalent H*(10) in contact was 390 nSv h−1, which corresponds to twice the natural background. The U3O8 content obtained was 0.213 ± 0.013%.