Utilization of radiometric data for mapping primary and secondary sources of gamma radiation and radon/thoron release potentials in Ireland.

Background: This paper presents a novel approach to predict and map radon and thoron levels. We developed separate radon and thoron prediction maps for Ireland and introduced a system for producing high-resolution 3D radiation maps which may be used for planning purposes in residential areas, recycling and demolishing waste depots, and quarries of building and construction material. Additionally, we highlight the critical need to monitor thoron alongside radon in indoor surveys, as thoron's shorter half-life and higher energy levels may pose a greater health risk. Methods: We utilized Tellus radiometric survey data and indoor radon measurement records to investigate the spatial correlation between elevated indoor radon activity and anomalies in radioelement concentrations. We also estimated the degree of thoron interference in indoor radon surveys conducted in Ireland using CR-39 detectors. Field and laboratory surveys were performed to produce high-resolution radiation maps for four Irish quarries and estimate the radon and thoron potential of these quarries. Results: Our initial findings suggest that thoron may be the primary health issue in some parts of Ireland, surpassing radon. For example, our map shows that the expected thoron potential in county Donegal is significantly higher than that for radon. Our radon and thoron exhalation tests on building material samples from four random quarries confirm this. We also estimate that over 20% of the elevated indoor radon activity recorded by the EPA using CR-39 detectors may be attributed to thoron-related sources. Conclusion: This study contributes to a better understanding of the prevalence and impact of radon and thoron in Ireland, helping to determine the main radiological health issue related to indoor air quality in the country. Thoron's impact on indoor air quality and health has been understudied in Ireland, necessitating more comprehensive studies and monitoring programs to accurately assess the prevalence and impact of both radon and thoron.

[Assessment of the radiation risk to health caused by the intake of Cs-137 and Sr-90 radionuclides from food in the able-bodied population of the Samara region].

Monitoring of the content of technogenic radionuclides (Cs-137 and Sr-90) in foods is one of the key areas in ensuring radiation safety of the population, taking into account the current radiation situation. The greatest risk to health is food produced or imported from the territories that have been subjected to man-made radiation accidents. The purpose of the research was to assess the radiation risk caused by oral intake of radionuclides based on the study of the actual nutrition of the adult population and contamination of food with Cs-137 and Sr-90 radionuclides. Material and methods. The specific activity of Cs-137 and Sr-90 radionuclides (median and 90 percentile) was assessed by gamma spectrometric method in 1235 samples of food produced in the Samara region and imported from outside. Data on the actual nutrition of 894 respondents aged 18 to 68 years (in the autumn-winter period) were obtained by the 24-hour dietary recall using the automated software package Nutri-prof (version 2.9). Based on the data obtained, effective annual doses of internal radiation were calculated, information was obtained on the risks of malignant neoplasms, including in the long-term period under various scenarios of internal radiation. Results. Radiometric studies of food samples did not reveal deviations from hygienic standards. The highest median values of Cs-137 specific activity were observed in samples of forest mushrooms (1.23 Bq/kg), wild berries (0.97 Bq/kg), fish and fish products (0.96 Bq/kg). The highest median values of Sr-90 specific activity were also observed in samples of forest mushrooms (3.86 Bq/kg), fish and fish products (2.71 Bq/kg). The radiation risk under various scenarios of Cs-137 intake was regarded as «negligible¼, while the risk was regarded as «small¼ when consuming food contaminated with Sr-90. The number of additional cases of malignant neoplasms at the admission of Cs-137 in the median values of specific activity is 0.38 per year, at maximum values - 0.57 per year, at the admission of Sr-90 - 2.04 per year and 3.30 cases per year, respectively. Conclusion. The implementation of radiation monitoring of food, especially those imported from areas of high radiation risk, is a necessary condition for ensuring radiation safety of the population. It is also necessary to take into account the stochastic effect of the influence of small doses of internal exposure on the organism when consuming food, which make a significant contribution to the formation of the dose of internal radiation.

Dose-rate coefficients for external exposure to radionuclides uniformly distributed in soil to an infinite depth.

Using a database on external exposures to environmental sources provided by the International Commission on Radiological Protection, monoenergetic and nuclide-specific dose-rate coefficients have been evaluated for volumetric sources with a uniform distribution to an effectively infinite depth in soil. Organ equivalent and effective dose rates for the public (newborns; 1-, 5-, 10-, and 15-year-old children; and adults), ambient dose equivalent rates, and air kerma free-in-air rates at 1 m above the ground were computed. This was performed using the weighted-integral method for monoenergetic photon and electron sources in an energy region of 10-2 to 8 MeV with 25 energy points to obtain the respective monoenergetic dose-rate coefficients. Then, based on these data, the dose-rate coefficients for 1252 radionuclides of 97 elements were evaluated. In those computations, the dose contribution from bremsstrahlung generated by electrons in the soil was also considered. In addition, dose-rate coefficients for the primordial radioactive decay chains of the thorium, uranium, and actinium series, as well as the decay of 137Cs with 137mBa in secular radioactive equilibrium, were obtained using the Bateman equation. For verification, the results of the effective dose rates for the 40K, 50V, thorium, and uranium series, as well as 137Cs/137mBa, were compared with those of previous studies and agreed within 10% for most cases. The results showed that the present dose-rate coefficients for radionuclides uniformly distributed to an infinite depth in soil were computed using appropriate procedures and can be used to assess external doses to the public, living on landfill soils containing naturally occurring radionuclides.

Co-designing of a prototype mobile application for fetal radiation dose monitoring among pregnant radiographers using a design thinking approach.

This study aimed to develop a prototype mobile application to enhance fetal dosimetry among pregnant radiographers in #### through a design thinking approach. Eleven participants were recruited to engage in a participatory design workshop, which encompassed five stages: Empathise, Ideate, Define, Prototype and Test. The participants were divided into two teams. Qualitative datasets from the workshop included field notes and FIGMA screens. The data were analysed through thematic analysis, from which three major themes emerged: (1) Unsafe working environments for pregnant radiographers, (2) The need for enhanced fetal radiation dose monitoring by pregnant radiographers as an occupational health and safety requirement, and (3) Co-designing of the prototype mobile application, PregiDose. The participants contributed towards a prototype mobile application which addressed challenges experienced in the real-life setting. Hence, the prototype can be used as an effective framework by which to guide the development of the final artefact.

Adaptation of FDMT to include process-based models and consider regional aspects following radionuclide deposition events.

Experience from earlier nuclear accidents has clearly shown the need for maintaining and developing appropriate modelling capabilities. Dealing with complex issues such as human exposure following a nuclear accident necessitates the implementation of a set of interconnected models such as FDMT. FDMT is an integrated module within the two main European decision support systems for radiological emergency preparedness, ARGOS and JRODOS, to simulate the transfer of radionuclides along terrestrial food chains and to predict their activity concentrations in foodstuffs. In order to make the module more fit-for-purpose, FDMT has been implemented in a new modelling platform (ECOLEGO) which provides a high degree of flexibility with regard to conducting developmental work. This paper presents improvements in FDMT further through either the incorporation of new models or further elaboration of existing ones, as well as updates in default parameters. Models have also been made more fit-for-purpose through consideration of regional-specific parameters. Specific improvements include modelling developments related to dry deposition, radioactive particle weathering, radiocaesium transfer influenced by soil characteristics and, for a region-specific case, animal uptake. In addition, the paper presents new pathways and parameters (and updated values) to be considered for making FDMT more adapted for Norwegian conditions. Overall, the improvements made in the present work should significantly reduce the uncertainties associated with the outputs of the FDMT models.

Usefulness and limitations of various detector systems for estimation of131I thyroid activity following an RN event.

Following a radiological or nuclear (RN) event, rapid measurement of131I in members of the public is of utmost importance, and much equipment is needed for a high throughput. In this study, three gamma cameras (GCs), two thyroid uptake meters (TUMs) and one whole-body counter (WBC) were calibrated for activity measurements of131I in the thyroid. Minimum detectable activity was derived for the GCs, the TUMs and the WBC giving that a committed effective dose (CED) in the interval 2.0-85µSv, 13-700µSv and 0.52-6.4µSv, and thyroid absorbed doses in the interval 0.075-2.1 mGy, 0.48-17 mGy, and 0.020-0.15 mGy, respectively, can be assessed for children, adolescents, and adults. These numbers are based on 10 min measurement, performed at 1, 3 and 7 d after intake, and the CED includes intake by ingestion and inhalation of aerosols Type F, with an activity median aerodynamic diameter of 1µm. For a fractional signal loss of 63% due to dead time, a CED up to 2.0, 84 and 3.6 Sv and thyroid absorbed dose up to 47 Gy, 2000 Gy and 88 Gy for the three systems, respectively, can be assessed for children and intake by ingestion as a worst-case scenario in terms of CED, measured 7 d after intake. This study demonstrates the potential and limitations of using equipment readily available at larger hospitals for estimation of131I content in thyroid, which could increase the measurement capability following an RN event.

Assessment of physicochemical properties and radioactivity in groundwater at households living in bac Lieu province, vietnam.

This paper presents findings on groundwater physiochemical composition and radioactivity levels in households in Bac Lieu province, Vietnam. Through discriminant analysis, it was observed that groundwater quality exhibits spatial variations corresponding to saline intrusion zones. The paired-samples T-tests revealed significantly different ratios of Ra-224, Ra-226, and Ra-228 isotopes between Na-Cl and Ca-Na-HCO3 water types. All three water types had a ratio of Ra-226/Ra-228 of approximately one, indicating the presence of groundwater aquifers beneath the crust and fluvial marine sediment. Furthermore, strong associations between sulfate and calcium suggest that CO2 enrichment in groundwater aquifers indicates anoxic aquatic environments. Twenty-five of the thirty-three evaluated samples exceeded the national technical regulations for domestic water quality with parameters such as chloride, sulfate, sodium, gross alpha, or total dissolved solids. Fifteen samples exceeded gross alpha's allowable contamination threshold of 0.1 Bq/L. The combination of Ra-226 and Ra-228 did not surpass the U.S. Environmental Protection Agency's recommended limit of 0.185 Bq/L. However, nineteen samples exhibited annual committed effective doses of radium isotopes for infants that exceeded the WHO recommendation of 0.1 mSv/year.

Radioecological characteristics of Siberian roe deer (Capreolus pygargus Pal., 1771) inhabiting locations of nuclear weapon tests.

This paper reports the activity concentrations of 137Cs, 90Sr, 239+240Pu, 241Am, and 3Н in the form of tritiated water (НТО) and organically bound tritium (ОBТ) in the tissues and organs of roe deer (Capreolus pygargus Pal., 1771) that inhabit the 'Degelen' test location of the Semipalatinsk Test Site. Tissues and organs were sampled from six deer by killing. The activity concentrations of specific radionuclides in the samples were measured using γ-, α-, and ß-spectrometry. The radionuclide activity concentrations in the tissues and organs showed considerable variation, for example, 0.6-170 Bq kg-1 for 137Cs and 0.3-2.8×103 Bq kg-1 for 90Sr. The activity concentrations of radionuclides in animal muscular tissue did not exceed permissible values for the meat of wild animals. The tissues and organs in the roe deer were arranged as follows in descending order of their ability to accumulate 137Cs and 90Sr: for 137Cs, muscular tissue-kidneys-lungs-spleen-heart-liver-bone tissue; for 90Sr, bone tissue-liver-lungs-muscular tissue-spleen-heart-kidneys. The activity concentrations of 241Am and 239+240Pu did not exceed the minimum detectable activity. Therefore, no quantitative values could be determined for 241Am, and the 239+240Pu activity concentration could be derived for only one sample: 0.5±0.1 Bq kg-1 (liver). The distribution pattern of these radionuclides in the tissues and organs of the roe deer could not be determined because of insufficient data. The HTO volumetric activity in the tissues and organs of the examined animals ranged from 2.6×10-2 to 77 kBq l-1; activity concentration of OBT, 3.0×10-2 to 16 kBq kg-1; and OBT-to-HTO ratios, 2.0×10-3 to 5.3×102. This ratio can serve as an indicator of how long the examined animals stay in radioactively contaminated ecosystems. Within the 'Degelen' site, the activity concentrations of 90Sr and tritium, in the form of HTO and OBT, are expected to be high in the bone tissues, soft tissues, and organs, respectively.

Development of a High-Resolution Indoor Radon Map Using a New Machine Learning-Based Probabilistic Model and German Radon Survey Data.

BACKGROUND: Radon is a carcinogenic, radioactive gas that can accumulate indoors and is undetected by human senses. Therefore, accurate knowledge of indoor radon concentration is crucial for assessing radon-related health effects or identifying radon-prone areas. OBJECTIVES: Indoor radon concentration at the national scale is usually estimated on the basis of extensive measurement campaigns. However, characteristics of the sampled households often differ from the characteristics of the target population owing to the large number of relevant factors that control the indoor radon concentration, such as the availability of geogenic radon or floor level. Furthermore, the sample size usually does not allow estimation with high spatial resolution. We propose a model-based approach that allows a more realistic estimation of indoor radon distribution with a higher spatial resolution than a purely data-based approach. METHODS: A multistage modeling approach was used by applying a quantile regression forest that uses environmental and building data as predictors to estimate the probability distribution function of indoor radon for each floor level of each residential building in Germany. Based on the estimated probability distribution function, a probabilistic Monte Carlo sampling technique was applied, enabling the combination and population weighting of floor-level predictions. In this way, the uncertainty of the individual predictions is effectively propagated into the estimate of variability at the aggregated level. RESULTS: The results show an approximate lognormal distribution of indoor radon in dwellings in Germany with an arithmetic mean of 63 Bq/m3, a geometric mean of 41 Bq/m3, and a 95th percentile of 180 Bq/m3. The exceedance probabilities for 100 and 300 Bq/m3 are 12.5% (10.5 million people affected) and 2.2% (1.9 million people affected), respectively. In large cities, individual indoor radon concentration is generally estimated to be lower than in rural areas, which is due to the different distribution of the population on floor levels. DISCUSSION: The advantages of our approach are that is yields a) an accurate estimation of indoor radon concentration even if the survey is not fully representative with respect to floor level and radon concentration in soil, and b) an estimate of the indoor radon distribution with a much higher spatial resolution than basic descriptive statistics. https://doi.org/10.1289/EHP14171.

Radiological impact assessment of natural radioactivity in soil and water in Cape Coast North, Central Region of Ghana.

The objective of the study is to evaluate natural radioactivity and its radiological impact on the health of the populace within Cape Coast North. Soil and water samples were taken and analysed using a high purity germanium (HPGe) detector. Results for the average activity concentrations of 226Ra, 232Th, and 40K in soil samples range from 15.0 to 60.8 Bq/kg with a mean of 20.9 ± 7.2 Bq/kg, 16.3 to 97.2 Bq/kg with a mean of 43.8 ± 2.4 Bq/kg, and 4.7 to 411.4 Bq/kg with an average of 140.6 ± 4.2 Bq/kg, respectively. The absorbed dose rate in air and outdoor annual effective dose to the public were estimated to be 46.6 nGyh-1 and 0.1 mSv, respectively, which fell below the recommended average. The average activity concentrations of 226Ra, 232Th, and 40K in water samples were 1.4, 0.4, and 1.2 Bq/L, respectively. The annual effective dose is 0.4 mSv, which is greater than the WHO recommended level of 0.1 mSv/y.

Cavity ionization chamber responses in the JAEA and the NMIJ high-energy photon reference fields for radiation protection.

A dosimeter should ideally be calibrated in a reference field with similar energy and doserate to that which the dosimeter is being used to measure. Environments around nuclear reactors and radiation therapy facilities have high-energy photons with energies exceeding that of60Co gamma rays, and controlling exposure to these photons is important. The Japan Atomic Energy Agency and National Metrology Institute of Japan have high-energy reference fields with energies above several megaelectronvolts for different types of accelerators. Their reference fields have different fluence-energy distributions. In this study, the energy dependencies of the two-cavity ionization chambers, which are often used by secondary standard laboratories, were experimentally and computationally evaluated for each high-energy field. These results agreed well within the relative expanded uncertainties (k= 2), and their capabilities for air kerma measurements in each high-energy reference field were confirmed. Therefore, the capabilities of the air-kerma measurements were verified in the two high-energy reference fields.

Systematic review of statistical methods for the identification of buildings and areas with high radon levels.

Radon is a natural and radioactive noble gas, which may accumulate indoors and cause lung cancers after long term-exposure. Being a decay product of Uranium 238, it originates from the ground and is spatially variable. Many environmental (i.e., geology, tectonic, soils) and architectural factors (i.e., building age, floor) influence its presence indoors, which make it difficult to predict. However, different methods have been developed and applied to identify radon prone areas and buildings. This paper presents the results of a systematic literature review of suitable statistical methods willing to identify buildings and areas where high indoor radon concentrations might be found. The application of these methods is particularly useful to improve the knowledge of the factors most likely to be connected to high radon concentrations. These types of methods are not so commonly used, since generally statistical methods that study factors predictive of radon concentration are focused on the average concentration and aim to identify factors that influence the average radon level. In this paper, an attempt has been made to classify the methods found, to make their description clearer. Four main classes of methods have been identified: descriptive methods, regression methods, geostatistical methods, and machine learning methods. For each presented method, advantages and disadvantages are presented while some applications examples are given. The ultimate purpose of this overview is to provide researchers with a synthesis paper to optimize the selection of the method to identify radon prone areas and buildings.

Use of real-time electronic extremity dosimeters for monitoring and optimisation of radiopharmacy technique.

Radiopharmacy staff members are subject to extremity radiation doses, particularly to the fingertips. Dosemeters, such as, thermoluminescent detectors (TLDs) are currently used for monitoring fingertip doses. This study aimed to use real-time dosemeters to monitor radiopharmacy extremity doses to identify specific procedural steps associated with higher fingertip doses and, subsequently, reduce dose through promotion of optimised radiation protection practises. Five radiopharmacy operators were monitored using an ED3 active extremity dosemeter with a detector attached to each tip of the index fingers. Dose rate and accumulated dose data were matched to the handled radioactivity data, of99mTc-labelled radiopharmaceuticals only, with the dose per activity (µSv MBq-1) calculated for each step. Once baseline dose data was established, an educational session identified technique adjustments toward improved radiation protection. A subsequent monitored session was undertaken with the dose data compared to quantify changes in operator doses. Radiopharmacy steps which significantly contributed to extremity doses were identified. The average accumulated dose per activity across all procedural steps for the99mTc-labelled radiopharmaceuticals for all operators before the educational session was 0.042 ± 0.045µSv MBq-1and 0.042 ± 0.041µSv MBq-1(n= 89) for non-dominant and dominant index fingertips, respectively, and 0.030 ± 0.044µSv MBq-1and 0.031 ± 0.032µSv MBq-1(n= 97), respectively, afterwards. Overall, there was an average 40.7% reduction in the total extremity dose received after the educational session. Real-time electronic extremity dosemeters for monitoring radiopharmacy extremity dose presented as a useful tool for incorporation into radiation protection education and training, towards optimised radiopharmacy technique.

Correction factors for induced radioactivity: comparing simplified continuous and periodic irradiation scenarios in medical cyclotron decommissioning.

The use of a Monte Carlo code in the assessment of residual radioactivity for decommissioning of a medical cyclotron facility requires a reasonable approximation to the facility's history of operations. A periodic irradiation scenario simulating the cyclotron's daily operation for radioisotope production is generally considered reasonable, but its implementation in the code's input file can be cumbersome because more than thousands of irradiation cycles must be modeled. In practice, two simplified scenarios with continuous irradiation are commonly used instead: (i) omitting the downtime between two irradiation periods and (ii) extending the irradiation duration across the entire operational lifespan of the facility, albeit with a reduced beam current to maintain workload consistency. A systematic comparison of residual radionuclide productions across various half-lives under these three scenarios was performed. This technical note presents the resulting correction factors for the two simplified continuous irradiation models, enhancing their applicability in estimating radioactive inventories under a range of circumstances.

Comparison of MCNP and Microshield Dose Savings Determinations for Remote Methods of Transuranic Contamination Characterization.

The maturation of robotic and remote systems presents opportunities to expand the use of technologies that have typically been restricted to high-dose/high-risk nuclear work for moderate- or low-risk work to further reduce radiation exposure to workers. This study quantifies the potential dose savings achieved through the use of robotic techniques for characterizing transuranic-contaminated waste items and compares dose estimates from a simplistic, user-friendly deterministic radiation transport code and a more robust, complex Monte Carlo code. Three scenarios of transuranic-contaminated waste items described in published reports are modeled using representative source geometries in MicroShield and MCNP radiation transport codes. Estimated dose rates are determined at points ranging from 30 cm to 300 cm from the face of the waste item to represent the increase in distance allowed by robotic or remote system implementation for characterization activities. The dose rate savings are then converted to detriment cost savings using a dollar-per-person-dose conversion factor to provide a financial context. The radiation transport simulations show no consistent bias in estimated dose rate by varying simulation methodology or using geometrical simplifications-in some cases, MicroShield produces higher dose rate estimates while MCNP estimates are higher in other cases. In the MCNP simulations, the volume source geometry consistently produces a higher dose rate than the slab source geometry, but the MicroShield dose rate estimates do not display the same trend. Dose savings range from 1.60 × 10-5 µSv h-1 to 1.75 × 101 µSv h-1 with associated detriment cost savings from < 0.010 USD/person-h to 14 USD/person-h.

Neutron activation of stable isotopes in soil and groundwater from a radionuclide production facility, South Africa.

The neutron activation of stable isotopes in environmental matrices, such as soil and groundwater, is a critical aspect of assessing the impact of radionuclide production facilities on the surrounding ecosystem. The envisioned Low-Energy Radioactive Ion Beams (LERIB) facility at the iThemba LABS, South Africa is anticipated to generate significant sources of ionising radiation. The study investigated the possible repercussions of neutron irradiation stemming from the facility, focusing on the activation of stable isotopic compositions in the environment. The investigation employed a combination of experimental and analytical techniques to characterize the neutron activation products in soil and groundwater samples collected from the vicinity. Samples were collected from designated areas for background radiological measurements and were irradiated with neutrons for a period of 1 h. The induced radioactivity measured by the High Purity Germanium detector included 24Na, 22Na, 54Mn, 52Mn, and 46Sc. The application of Darcy's law for groundwater velocity suggests that radionuclides in groundwater will migrate at an average flow velocity of 0.8 m/day. The isotopes with longer half-lives have count rates at background concentrations; therefore, environmental impacts on the site and surrounding communities might be minimal.

Radionuclide Solid:liquid partitioning in an aged, reducing-grout wasteform recovered from a disposal facility.

The Saltstone Disposal Facility on the Savannah River Site in South Carolina disposes of Low-Level Waste in a reducing-grout waste form. Reducing grout is presently being evaluated as a subsurface disposal waste form at several other locations in the United States, as well as in Europe and Asia. The objective of this study was to collect core samples directly from the Saltstone Disposal Facility and measure desorption distribution coefficients (Kd; radionuclide concentration ratio of saltstone:liquid; (Bq/kg)/Bq/L)) and desorption apparent solubility values (ksp; radionuclide aqueous concentration (moles/L)). An important attribute of this study was that these tests were conducted with actual aged, grout waste form materials, not small-volume simulants prepared in a laboratory. The reducing grout is comprised of blast furnace slag, Class F fly ash, ordinary portland cement, and a radioactive salt waste solution generated during nuclear processing. The grout sample used in this study underwent hydrolyzation in the disposal facility for 30 months prior to measuring radionuclide leaching. Leaching experiments were conducted either in an inert (no oxygen) atmosphere to simulate conditions within the saltstone monolith prior to aging (becoming oxidized) or they were exposed to atmosphere conditions to simulate conditions of an aged saltstone. Importantly, these experiments were designed not to be diffusion limited, that is, the saltstone was ground finely and the suspensions were under constant agitation during the equilibration period. Under oxidized conditions, measured Tc Kd values were 10 mL/g, which was appreciably greater than the historical best-estimate value of 0.8 mL/g. This difference is likely the result of a fraction of the Tc remaining in the less soluble Tc(IV) form, even after extensive oxidation during the experiment. Under oxidized and reducing conditions, the measured Ba and Sr (both divalent alkaline earth metals) Kd value were more than an order of magnitude greater than historical best-estimate values of 100 mL/g. The unexpectedly high Ba and Sr Kd values were attributed to these radionuclides having sufficient time to age (form strong bonds) in the sulfur-rich saltstone sample. Apparent ksp values under reducing conditions were 10-9 mol/L Tc and 10-13 mol/L Pu, consistent with values measured with surrogate materials. Measured apparent Ba, Sr, and Th ksp values were significantly greater than historical best-estimates. The implications of the generally greater Kd values and lower ksp values in these measurements is that these cementitious waste forms have greater radionuclide retention than was previously estimated based on laboratory studies using surrogate materials. This work represents the first leaching study performed with an actual aged, reducing-grout sample and as such provides an important comparison to studies conducted with surrogate materials, and provides high pedigree data for other programs around the world evaluating reducing grouts as a wasteform for subsurface nuclear waste disposal.

Comparative analysis of the dispersion modeling and dose projection results performed under BARCO international project.

Radiological assessments on zones to take protective actions in case of a nuclear or radiological emergency involve a series of real-time forecasts of radiological impact on the public at various distances from the release point, using actual weather or forecast data, information on the source term or facility status, and primary radiation monitoring data. This practice is implemented during the operation of emergency centers around the world in order to promptly report the occurrence and possible consequences of radiological accidents in the country and abroad in the event of a possible transboundary impact. Since the Chornobyl disaster, a lot of emergency exercises, research programs and projects, in particular, benchmarking, have served as international platforms for improving modeling capacity in atmospheric dispersion. This activity is carried out both on the basis of past severe accidents with significant atmospheric releases and corresponding radiological consequences, and on the basis of specific conditional (hypothetical) events that are developed in accordance with the purpose of the study. The paper is focused on the comparison results performed under the international project "Benchmarking on Assessment of Radiological COnsequences" (BARCO) conducted in 2020-2021 between five technical support organisations - members of the European Technical Safety Organisations Network (ETSON). The work contains a short overview of relevant international activity conducted in the past, a description of the BARCO project and its objectives, a list of participants, project tasks, initial data (source term, meteorology, list of benchmarking quantities, approach to data exchange, codes used). The study presents some of comparative analysis results obtained via two techniques such as code-to-code analysis (CTCA) and matched-pair analysis (MPA). The results discussion concentrates on the overall recommendations for code users. Conclusions provide the main outputs of the project.

Adsorption rate of uranium and thorium isotopes in soil and plants grown in a high background radiation area.

An important method for measuring radionuclide activity is alpha spectrometry. Ten soil samples were collected from the studied area. The activity concentrations of 238U and 234U in the collected soil samples ranged between 135 and 218 Bq kg-1 and between 117 and 183 Bq kg-1, respectively. 232Th, 230Th and 228Th activity concentrations ranged between 101 and 339, between 122 and 234 and between 106 and 385 Bq kg-1, respectively. When calculating the amount of radionuclide transport across the food chain, assessment models usually employ a transfer factor. Through root uptake, U and Th are transferred from the soil to food plants. To monitor the movement of radionuclides from the uranium series in diverse environments, it may be possible to use the ratios of uranium and thorium isotopes. Uranium mobility in soil depends on different physicochemical, organic and enzymatic factors and mechanisms. The high mobility of uranium is the main reason for the accumulation of uranium in the soil at root level and the possibility of its transfer to plants. A group of plants were selected that are grown in this area and the population relies on them mainly to meet their food needs. The concentration and transfer factor values of uranium isotopes were the highest in roots as compared with leaves and stems. Uranium in plants accumulates in roots and is then transferred to leaves. The mobility of uranium in plant tissues is constrained because it frequently adsorbs cell wall components. As a result, concentrations are frequently higher in tissues located in lower parts of the plant, with root surfaces having the highest concentrations.

Decrease in radiocesium adsorption of illite induced by soil organic matter: Quantity or quality?

Organic matter blocks highly selective frayed edge sites on clay minerals and reduces radiocaesium adsorption. The effects of different soil organic matter on Cs adsorption on illite have been investigated. The quantity and quality of soil organic matter was varied by extracting from three contrasting soils and varying extraction conditions. Extracted organic matter was quantified, and analysed using UV and fluorescent spectroscopy. Cs adsorption was markedly lower in soil aqueous extracts, than in simple electrolyte solution at the same ionic strength (IS). Part of the decrease was attributed to soluble soil potassium. After correction for ionic strength and potassium, the relative distribution coefficient of Cs, KdIS,K, decreased with increasing dissolved organic carbon (DOC) concentration. The correlation between KdIS,K and DOC was largely unchanged by taking into account any of the measured spectral parameters. We find no evidence that molecular size and composition of organic coatings determine their effect on the Cs adsorption properties of illite.