Radioactivity Concentration Research Articles

Flood risk assessment of the Narmada Basin, India, under climate change scenarios

ABSTRACT Climate change has led to a significant rise in the occurrence of extreme events such as floods and droughts. It is essential to accurately assess the hazards linked to climate change to effectively tackle flood risks in the future. This study investigates the risk of flooding in the Narmada Basin under climate change scenarios. Future precipitation data of global climate models are used to create intensity–duration–frequency curves and peak flows are estimated using a hydrological model. These peak flows serve as inputs for the hydraulic model to simulate floods across various return periods. The fuzzy inference system (FIS) is employed to optimize releases and reduce peak flows to mitigate flood impacts. The findings indicate that the extent of flooding and maximum water depths increase with higher return periods and future scenarios, and optimizing the reservoir releases, decreases the extent of flooding. This decrease in inundation area ranges from approximately 9 to 10% in the Bargi-to-Indira Sagar section to 20–23% in the Indira Sagar-to-Omkareshwar Sagar segment. In the Omkareshwar Sagar-to-Sardar Sarovar segment, the flooded area diminishes by 17–18% under the Radioactive Concentration Pathway (RCP) 4.5 and by 12–14% under the RCP 8.5 scenarios.

Estimation of the Effective Radiation Dose in Nuclear Medicine Workers from Dhaka by Measuring Radioactivity in Urine Sample Resulting from Internal Exposure

This study estimates the effective doses and activity concentration from 151 urine samples which are collected from 15 (Fifteen) occupational workers at National Institute of Nuclear Medicine and Allied Science (NINMAS) in Dhaka, Bangladesh. The radioactivity concentration in urine sample is due to intake of I-131, Tc-99m and F-18. The samples have been analyzed using High Purity Germanium (HPGe) detector. The radioactivity of I-131 and Tc-99m was found 0.91 ± 0.26 BqL-1 to 504.49 ± 6.03 BqL-1 and 0.15 ± 0.21 BqL-1 to 191.19 ± 6.98 BqL-1 respectively. Radioactivity of F-18 was found from 0.031 ± 0.022 BqL-1 to 0.282 ± 0.065 BqL-1. The effective doses of occupational workers have been also calculated using the radioactivity concentration and the dose coefficient according to ICRP publication 78. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 64−80

Metabolism and disposition of zamicastat in rats

The metabolism and disposition of zamicastat, a reversible dopamine β-hydroxylase (DβH) inhibitor, developed for treatment of Pulmonary Arterial Hypertension (PAH), were investigated in rats after oral and intravenous administration of [14C]-zamicastat. Zamicastat was rapidly absorbed and widely distributed to peripheral tissues, with total radioactivity almost completely recovered 168 h post-dose. Its main route of excretion was via faeces, whilst urine and expired air had minor roles. Maximum plasma concentration of zamicastat-related radioactivity occurred in the first hours, remaining quantifiable up to 144 h. The unchanged zamicastat plasma peak was 2 h post-dose and declined to low levels over 24 h. Zamicastat metabolism occurs largely during the first 8 h with only one metabolite identified in the latest time-point (96 h), the isocyanic acid/thiocyanic acid (tautomeric forms). Zamicastat metabolic pathway involved multiple reactions comprising desulphurisation, oxidative desulphurisation, N-debenzylation followed by further oxidation or N-acetylation, and the unexpected multistep metabolic pathway leading to isocyanic acid/thiocyanic acid.

Pharmacokinetic analysis and simplified uptake measures for tumour lesion [18F]F-AraG PET imaging in patients with non-small cell lung cancer.

The novel positron emission tomography (PET) imaging tracer, [18F]F-AraG, targets activated T-cells, offering a potential means to improve our understanding of immune-oncological processes. The aim of this study was to determine the optimal pharmacokinetic model to quantify tumour lesion [18F]F-AraG uptake in patients with non-small cell lung cancer (NSCLC), and to validate simplified measures at different time intervals against the pharmacokinetic uptake parameter. Ten patients with early-stage NSCLC and three patients with advanced NSCLC underwent a dynamic PET scan of minimal 60min. Venous and/or arterial blood sampling was obtained at maximum seven time points. Tumour lesion time activity curves and metabolite-corrected input functions were analysed using single-tissue reversible (1T2k), two-tissue irreversible (2T3k) and two-tissue reversible (2T4k) plasma input models. Simplified uptake measures, such as standardised uptake value (SUV) and tumour-to-blood (TBR) or tumour-to-plasma ratio (TPR), were evaluated for different time intervals. Whole-blood and plasma radioactivity concentrations showed rapid clearance of [18F]F-AraG. Metabolite analysis revealed a low rate of metabolism, at 70min p.i., on average, 79% (SD = 9.8%) of the total radioactivity found in blood corresponded to intact [18F]F-AraG. The time activity curves were best fitted by the 2T3k model. Strong positive correlations were found for SUV (body weight (BW), lean body mass (LBM) or body surface area (BSA) corrected), TBR and TPR for any time interval between 20 and 70min p.i. against the 2T3k-derived Ki. The correlation of TBR at 60-70min p.i. with 2T3K-derived Ki (r (df = 20) = 0.87, p < 0.01), was stronger than for SUVBW (r (df = 20) = 0.80, p < 0.01). Tumour lesion [18F]F-AraG uptake in patients with NSCLC is characterised by a 2T3k model. TBR and TPR show most potential for simplified quantification of tumour lesion [18F]F-AraG uptake in patients with NSCLC.

Evaluation of Radioactivity Concentration and Hazard Indices in ash Some Hospitals Incinerators in Baghdad / Al Resafa

Due to their harmful effects on human health and their tendency to cause cancer, radionuclide concentrations and risk indicators have been measured in hospital incinerator ash. This was done by collecting samples ash of Hospitals Incinerators, examining them, and identifying the risks that emerged from the examination. Three samples Only taken for the study from certain hospitals affiliated with the Baghdad Al-Rusafa Health Department. High purity germanium gamma spectrometer (HPGe) were used to analyze the samples. The concentrations of potassium isotopes (K-40) range from (147.1±16.5 to 214.4±21.1 Bq/kg), While the range of concentrations for Ra-226 isotopes is (7.52±1 to 19±1.8 Bq/kg), and lead (Pb-212) isotope concentrations ranged from (10.1±1.1 to 11.1±1.5 Bq/kg). In addition, the isotope concentration of actinium (Ac-228) is 8.05±1. Radium equivalent (), risk index , annual effective dose equivalent radioactivity level index ), absorbed dose rate D, and lifetime cancer risk were calculated. The results showed that no radiation risk Only indicated by any of the risk indicators. This indicates that the ash from the hospital incinerator does not pose any radioactive danger.

Determination the concentration for uranium in phosphrous fertilizers by using nuclear track detector CR-39

The aim of this research was to study the concentrations of Uranium in the phosphorus fertilizers using Nuclear track detector (CR-39). Our present investigation is based on the study of 10 types samples for different kinds of phosphorus fertilizers which were available in the local market Some of them were Iraqi made and the others from different countries like, (Iran, Italy, Holland, Lebanon and Jordan) .. The result obtained shows that the Uranium concentration in phosphorus fertilizers samples varies from (3.59ppm) to(2.59ppm). Based on the radioactive concentration of Uranium in the samples all the results obtained between(3.59ppm) in the Iraqi super phosphate to (2.59ppm) in the mixture Iraqi phosphate fertilizer are within the international levels as given by IAEA (International atomic Energy Agency) date if compares that equal by 12ppm .

Long-Term Effects of 90Sr and 239+240Pu Contaminated on the Seafloor Sediment on the Transfer through Marine Food Web: Sensitivity to the Physical Property- and Sediment-Related Parameters

This study, as a follow-up to the &lt;sup&gt;137&lt;/sup&gt;Cs study of Kim et al. (2023), performs a set of sensitivity experiments on ocean physical properties and sediment-related parameters based on initial bottom contamination of &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu in the upper sediment layer. Both studies utilizes the Extended BURN model proposed by Bezhenar et al. (2016). The initial contamination levels were set to 3 and 0.4 Bq/kg, respectively, based on observations off the coast of Fukushima. The sensitivity experiments were divided into EXP-WOHAD, which examined the effects of the vertical diffusion coefficient and vertical sediment flux, and EXP-WHAD, which investigated the effects of ocean currents. The results of the EXP-WOHAD experiments showed that both radionuclides are more sensitive to sediment fluxes than to vertical diffusion coefficients. For both &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu, transport was dominated by transport to the intermediate sediment layer rather than to seawater. Specifically, for &lt;sup&gt;239+240&lt;/sup&gt;Pu, transport to seawater was insignificant due to its strong sorption properties in sediments. In terms of bioaccumulation, &lt;sup&gt;90&lt;/sup&gt;Sr accumulated most in fish and invertebrates, while &lt;sup&gt;239+240&lt;/sup&gt;Pu accumulated most in invertebrates, followed by zooplankton. Notably, &lt;sup&gt;239+240&lt;/sup&gt;Pu showed high bioaccumulation despite its low initial sediment contamination. The changes in radioactivity concentrations in the EXP-WHAD experiments were similar to those in the EXP-WOHAD experiments, and the bioaccumulation trends in biota were also comparable. This study confirms that the accumulation of radionuclides in seawater, intermediate sediments, and biota is sensitive to the marine physical environment and varies by nuclide. When the sediment flux increased by a factor of 100, the remaining radioactivity levels of &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu in biota after 100 years showed a significant reduction, decreasing by more than 900 and 30,000 times, respectively; it highlighting the importance of parameterization according to the physical environment of the area of interest.

Intensive agriculture, a pesticide pathway to >100 m deep groundwater below dryland agriculture, Cordoba Pampas, Argentina

Groundwater pesticide pollution in shallow groundwater is a well-established global phenomenon. However, deep aquifers are widely thought to be naturally protected from such modern contaminants, by confining geological barriers and upwards hydraulic gradients. Here we document pervasive pesticide pollution in >100 m deep artesian wells in a sedimentary aquifer below dryland agriculture. The vertical distribution of key groundwater markers, including numbers and concentrations of pesticides, stable (δ18O & δ2H) and radioactive (3H &14C) isotopes and ion concentrations were used to develop a conceptual model of pollutant transport to deep groundwater. Tritium, stable isotope and pesticide distributions in unconfined groundwater indicate that water table rise to <1 m below the surface (due to anthropogenic landscape modification and periodic flooding), has created a rapid pollutant ‘doorway’ to groundwater. Despite a lack of deep borehole pumping for irrigation, these rising water tables have permanently inverted previously upward hydraulic gradients towards the underlying semi-confined aquifer in some areas. Physical heterogeneities and/or leaky domestic boreholes then act as preferential transport avenues for surface pollutants to both unconfined and semi-confined groundwater. These pathways allow small aliquots of highly contaminated surface water and modern unconfined groundwater to mix with the pre-existing pre-modern deep groundwater, resulting in mixed isotopic signatures in deep wells (e.g., radiocarbon <5 pMC but detectable tritium) and detections of multiple synthetic pesticides in the deep aquifer, including AMPA at concentrations up to 4.93 µg/L and Metolachlor up to 0.015 µg/L. Our results demonstrate how semi-confined deep groundwaters may be contaminated by current agricultural techniques even where deep groundwater exploitation is limited. We urge measures to eliminate these pollutant pathways.

Interlaboratory comparison of gross alpha/beta activity of drinking water over a decade

Interlaboratory comparison exercises for determining the gross alpha and beta activity concentrations in drinking water, organized by the National Institute for Radiological Protection (NIRP), China CDC, have been carried out since 2012. The purpose of this study is to assess the accuracy and precision of gross alpha and beta analyses of low-level radioactivity concentrations. Natural water samples were used for the comparison, and the performance of the participating laboratories was evaluated with respect to the reference values using the Z-score performance indicator. The comparison data from 2012 to 2022 were analyzed, where the percentage of laboratories with acceptable results was 80–92%, and the dispersion of the measurement results across laboratories became smaller over time. The results demonstrate that these exercises can help laboratories to resolve issues in gross α/β analysis and improve the consistency of the measurement results.

Total Radiological Dose and Safety Assessment of Workers in Radioactive Liquid Waste Storage Location in Al Tuwaitha Site

This study aims to determine the total effective dose (external and internal) in the radioactive liquid Waste Hall (WH) in the Radiochemistry Laboratories building (RCL) in Al- Tuwaitha site in order to estimate the radiation risk for workers in this place. The external effective dose was calculated by an indirect method using ThermoLuminescent Dosimeters (LiF: Mg, Ti (TLD-100)) by placing them in the waste hall for one month. The internal effective dose was estimated by collecting eight air samples (environmental samples) from different locations in WH using an air sampler pump (Sniffer) to collect air samples loaded with particles or dust which are deposited on cellulose filter papers (φ 125mm). This was done for two flow rates the lowest and the highest values of the air sampler pump of 5CFM and 20CFM, respectively.The filter papers were chemically treated using the digestion method. The radionuclides in these samples were measured using a gamma spectrometry system equipped with a high-purity germanium detector (HPGe), and the radioactivity concentration was measured using a gross alpha beta gamma system. The results showed 137Cs of low concentration was deposited on the filter paper. The total annual effective dose rate (external and internal) results showed that the highest in WH was (6358.97μSv/year) for the low probability scenario and (1589.74 μSv/year) for the realistic scenario.

Association between 99mTc-PSMA SPECT/CT imaging and prostate-specific antigen (PSA) and alkaline phosphatase (ALP) levels post-endocrine therapy in patients with prostate cancer and bone metastases

AimTo investigate the association between positive lesions detected by 99mTc-PSMA SPECT/CT and blood levels of prostate-specific antigen (PSA) and alkaline phosphatase (ALP) in patients with prostate cancer (PCa) and bone metastasis undergoing endocrine therapy. MethodsA retrospective analysis was performed on 43 patients diagnosed with PCa bone metastasis who underwent endocrine therapy. PSA, ALP, whole body bone imaging and 99mTc-PSMA SPECT/CT imaging were collected from all patients (Among them, 17 cases were re-examined 99mTc-PSMA SPECT/CT imaging). According to the results of the first 99mTc-PSMA SPECT/CT imaging for detecting bone metastasis, all cases were divided into two groups: positive group and negative group. The relationship between 99mTc-PSMA imaging and PSA and ALP was analyzed by ROC curve. Fisher exact probability method was used to examine the changes in imaging radioactivity uptake, PSA, and ALP levels in 17 patients after treatment, and P < 0.05 was statistically significant. ResultsAll 43 patients had different degrees of radioactive concentrations on whole-body bone imaging. The first 99mTc-PSMA SPECT/CT imaging showed positive bone metastases in 31 cases and negative bone metastases in 12 cases. ROC curve analysis of PSA and ALP, AUC were 0.778 and 0.770, respectively. When PSA > 1.13 ng/mL, 99mTc-PSMA SPECT/CT imaging diagnostic sensitivity was 93.55%, and specificity was 66.67%. When ALP was >86U/L, the diagnostic sensitivity of 99mTc-PSMA SPECT/CT imaging was 64.52%, and the specificity was 83.33%. In 17 cases, the PSA level decreased in 7 and increased in 10. There were 10 cases of increased ALP and 7 cases of decreased ALP levels. In the second 99mTc-PSMA imaging lesion, there were 9 cases with decreased or no uptake, and 8 cases with increased uptake or number of lesions. The changes in 99mTc-PSMA uptake by Fisher’s exact probability method were statistically significant (P < 0.05, P = 0.006, and P = 0.006, respectively), and ALP level was not statistically significant (P = 0.563). Conclusion99mTc-PSMA SPECT/CT imaging can detect PCa bone metastases, which are related to PSA levels. When PSA > 1.13 ng/mL, the sensitivity of diagnosis and detection of positive bone metastases is higher, and when ALP is >86U/L, 99mTc-PSMA imaging has higher specificity.

THE CONCENTRATION OF NATURAL RADIATION SOURCES (NRS), MAINLY 238U, 232Th, and 40K, IN BUILDING MATERIALS (SAND, CLAY BRICKS, AND CONCRETE BLOCKS) USED ALONG KANGUNDO ROAD, NAIROBI KENYA

This research aimed at assessing the concentration of Natural Radiation Sources (NRS), mainly 238U, 232Th, and 40K, in building materials (sand, clay bricks, and concrete blocks) used along Kangundo Road in Nairobi City County. Human exposure to ionising radiation is largely due to Natural Radiation Sources (NRS). These radioactive elements with long half-lives are found in the Earths lithosphere and in construction materials with radiation levels varying due to their geology. A purposive random sampling method was deployed in this work to collect samples of building materials for analysis. The radioactivity concentration levels in the sampled building materials were determined using a NaI (TI) spectrometer at Kenyatta University laboratory. The activity concentration of 40K varied from 151 ± 8 to 2392 ± 120 Bq/kg, 238U varied from 27 ± 2 to 412 ± 21 Bq/kg and 232Th ranged from 54 ± 3 to 612 ± 31Bq/kg. More than 70 per cent of the samples analysed had activity concentration surpassing the world permissible limits of 420 Bq/kg, 33 Bq/kg, 45 Bq/kg for 40K, 238U and 232Th respectively. The study therefore recommended that assessment of radioactivity concentration for samples with high radioactivity values.

Assessment of Natural Radioactivity in Cements (Local and Imported) in Mali

&amp;lt;i&amp;gt;Background&amp;lt;/i&amp;gt;: In this article, the radioactivity concentrations of U-238, Th-232 and K-40 (NORM) and radiological hazard parameters in different types of cements commonly used in Mali and available on the Malian market have been analyzed. The obtained values of NORM concentrations and radiological hazards in seven (07) cements samples will permit to the AMARAP to estimate the exposure (gamma rays) from the buildings and dwellings made by these cements. It will permit also to determine any over exposure (determinist effects which are an immediate tissue reaction due to the high exposition of ionizing radiation) and minimize as well the associated risk due to low doses (stochastic effects). &amp;lt;i&amp;gt;Materials and Methods&amp;lt;/i&amp;gt;: The health impact due to the exposure of radionuclides from these cements was evaluated by the determination of specific activity of radionuclides U-238, Th-232 and K-40 using gamma spectrometry analysis. The radiological hazards such as Absorbed Dose Rate (Ḋ) Annual Effective Dose (Ė) Internal and External Dose indexes (H&amp;lt;sub&amp;gt;in&amp;lt;/sub&amp;gt; and H&amp;lt;sub&amp;gt;ex&amp;lt;/sub&amp;gt;) were evaluated in these cements samples. &amp;lt;i&amp;gt;Results&amp;lt;/i&amp;gt;: The range of specific activities for U-238 vary from 21.77 ± 1.50 to 145.31 ± 7.70 Bq/kg, for Th-232 from 8.85 ± 0.52 to 73.56 ± 3.82 Bq/kg and for K-40 from 104.27 ± 5.63 to 351.97 ± 18.08 Bq/kg. The peak of U-238 wasn’t detected only in one (01) sample (CIM04). The highest value of specific activity was reported in sample CIM07 (DANGOTE). The values of radiological hazard such as Ḋ, Ė, H&amp;lt;sub&amp;gt;in&amp;lt;/sub&amp;gt; and H&amp;lt;sub&amp;gt;ex&amp;lt;/sub&amp;gt; from this work were within the dose criteria limits given by international organizations (ICRP and UNSCEAR) and national standards. &amp;lt;i&amp;gt;Conclusion&amp;lt;/i&amp;gt;: This study shows the analyzed cements do not pose any significant source of radiation hazard and are safe for use in the construction of dwellings even if the risk (stochastic effect) associated with low dose exists. Special attention and more analyzes must be done on them for more protection of public health.

Development of 16N monitoring system for real-time detection of small leakage in reactor coolant systems

This paper introduces a16N monitoring system designed for the real-time detection of minor coolant leaks in nuclear reactors. Conventional coolant leak detection methods in nuclear power plants rely on observing changes in sump tank water levels, as guided by Nuclear Regulatory Commission standards. However, these methods are slow and often inaccurate, particularly for detecting small leakages of less than 0.5 gallons per minute (gpm). Such delays pose risks of corrosion from boric acid and potential safety hazards due to mechanical or thermal fatigue at critical junctions. To address these challenges, we have developed a Reactor Coolant System (RCS) leakage detection system that can swiftly identify small coolant leaks. This system employs beta-ray emissions from 16N, a nuclide predominantly produced during reactor operation and accounting for 90.4% of the total radioactivity in the APR1400 RCS coolant. High-energy beta-rays emitted by 16N are ideal for monitoring due to their significant energy levels, which distinguish them from other nuclides. This system is specifically designed for installation within the annulus zone of the reactor containment, where it captures air near reactor pipes to measure 16N beta-rays. Given the short half-life of 16N (7.13 s), direct measurement is challenging; hence, we use an indirect method to determine calibration factors between dose rate with count rate and estimate radioactivity concentrations based on simulation data and experimental measurements with a surrogate 90Sr/Y source. This system can enhance the safety protocols of nuclear plants by enabling early detection of leaks. Our findings demonstrate that this system can detect leaks as small as 0.01 gpm within seconds, significantly improving response times compared to conventional methods.

Radioactivity concentration of 14C in the air of 14C urea breath test rooms and the resulting internal dose to medical staff

ObjectiveTo monitor the radioactivity concentration of 14C in the air of rooms used to perform 14C urea breath tests, and evaluate the contamination status of 14C released during such tests, and assess the occupational health risk to medical staff working in such areas. Methods14CO2 in air was absorbed from the air and turned into calcium carbonate through a chemical reaction. Then, calcium carbonate was prepared into a suspension in a low-potassium glass vial. The sample was analyzed using a low-background liquid scintillation counter. ResultsThe radioactivity concentrations of 14C in air of the breath-test rooms in hospitals and physical examination institutions range from 1.35 to 18.41 Bq/m3. The annual committed dose for medical staff was estimated to be between 2.01 × 10−2 and 2.74 × 10−1 μSv. ConclusionsOur results reveal a significant increase of 14C radioactivity concentration in the air of breath-test rooms, but the resulting committed dose is much lower than the limits prescribed by the International Commission on Radiological Protection (ICRP). However, the potential risk of long-term exposure to low-dose radiation should be paid more attention.

Recursive analytical solution for nonequilibrium multispecies transport of decaying contaminant simultaneously coupled in both the dissolved and sorbed phases

Multispecies transport analytical models that solve advection-dispersion equations (ADEs) are efficient tools for evaluating the transport of decaying contaminants and their sequential products. This study develops a novel semi-analytical model to simulate the multispecies transport of decaying contaminants, considering nonequilibrium sorption and decay in both dissolved and sorbed phases. First-order reversible kinetic sorption equations with decay processes are coupled to ADEs. Recursive analytical solutions, using the Laplace transform and generalized integral transform, are developed to address the mathematical complexity of the governing equations. The model's simulation results show excellent agreement with both numerical models and existing analytical solutions. Applied to a four-member radionuclide decay chain, the model reveals that including decay in the sorbed phase results in a lower concentration of the first member and avoids underestimating the radioactivity concentrations of daughter elements. These differences in dissolved radioactivity concentrations between models with and without sorbed phase decay may impact health risk assessments for radioactive waste disposal. Finally, this study provides a more sophisticated mathematical tool for analyzing multispecies transport in real field conditions where nonequilibrium sorption processes predominantly occur.

Estimation of natural radioactivity and radiological hazards in aggregate (stone dust) used as building materials in South Africa

ABSTRACT In this study, the radioactivity concentrations of natural radionuclides (Uranium-238, Thorium-232, and Potassiumi-40) in aggregate/stone dust samples used for building construction purposes have been measured with thallium-doped sodium iodide (NaI(TI)) detector. The samples’ associated radiological hazard risks were calculated using standard radiological expressions. The mean values of Uranium-238, Thorium-232, and Potassiumi-40 activity concentrations in the studied Quarries’ samples were above the World mean values of 35, 30, and 400 Bq.kg−1 for radioactivity concentrations in building materials. The lowest and highest values of all the estimated radiological hazard indices were recorded in samples Afrisam C 5 and Afrimat 3.

Status of the transfer state of 137Cs in zooplankton and surface water fish off Fukushima during 2018–2021

Radiocaesium introduced to coastal waters by the accident at the Fukushima Dai-ichi Nuclear Power Station (F1NPS) elevated the radioactivity level in biota. The radionuclide level in zooplankton, concentration of 137Cs radioactivity in surface water fish decreased rapidly, which was the primary food source for planktivorous fish, was recognized as not to be depurated at the same level prior to the accident. To evaluate the possible cause of this phenomenon, zooplankton and surface water fish were collected off Fukushima during 2018–2021, and the presence of radioactive particles was also examined. The concentrations of stable Cs and 137Cs radioactivity were analysed along with aluminium which was an indicator element of Cs that originated from suspended particles which were attached to or ingested by zooplankton. As a result, radioactive particles were often found in coastal zooplankton samples, and stable Cs and 137Cs of this inorganic fraction were identified. After removal of this excess radioactivity, the 137Cs radioactivity in whole-body tissue of zooplankton was derived. However, the level in the soft part of zooplankton during 2018–2020 was still greater than the levels which existed before 2010. Since habitat seawater was understood to not be a substantial source of 137Cs, then 137Cs transfer along the food chain, possibly from phytoplankton or detritus of enhanced radioactivity were suggested as important sources of 137Cs. In addition, enhanced 137Cs radioactivity in zooplankton was considered consequently elevate radioactivity levels in surface-dwelling water fish off Fukushima. Although the radioactivity level was not radiologically significant in relation to seafood safety limit, enhanced 137Cs radioactivity levels in biota was demonstrated in southern waters off Fukushima. In contrast, derived 137Cs/133Cs atom ratios of fish and seawater south of 37°E and west from 142°E indicated that radiocaesium transfer between fish and the environment was in an equilibrium state, showing the environment beyond these geographical coordinates had returned to the pre-accident state.

Analysis of carbon‐14 discharges from Korean nuclear power plants

AbstractThe routine practice accompanying the operation of nuclear facilities involves the discharge of radioactive effluents from nuclear power plants (NPPs). Regulation of this discharge to the environment hinges on three criteria: radioactivity concentration, public dose, and radioactivity. Among these, radioactive carbon‐14 holds particular significance as it possesses an extensive half‐life of 5730 years, making it a primary source of radiation dose to communities residing around NPPs. In Korea, the monitoring of carbon‐14 discharges from pressurized water reactors (PWRs) in gaseous effluents has been ongoing since 2012, whereas before 2012, monitoring exclusively focused on carbon‐14 discharges from pressurized heavy water reactors (PHWRs). Analysis of carbon‐14 discharges from Korean PHWRs indicates that their emission constituted less than 1% of total radioactive effluents over the past two decades. In the context of Korean PWRs, carbon‐14 discharge monitoring was absent from 2002 to 2011, resulting in an absence of data regarding such discharges during that period. After introducing carbon‐14 discharge monitoring in gaseous effluents from Korean PWRs, emissions from 2012 to 2021 contributed 3% of the total gaseous effluents. These findings indicate that despite being the primary contributor to public dose, carbon‐14 discharges from NPPs constitute a minor portion of the radioactive effluent discharge.

Assessment of natural radioactivity concentration in the soil samples from the Churchandpur and Ukhrul districts of Manipur, India.

The natural radioactivity concentration was studied for 40 soil samples of the Churchandpur and Ukhrul districts of Manipur, India, by using gamma-ray spectroscopy. The average radioactivity concentration of 226Ra, 232Th and 40K in Churchandpur was found as 39.9 (range: 30-56), 72.1 (range: 57-93) and 564.1 (range:360-867) Bqkg-1 respectively, whereas, in Ukhrul, average radioactivity for the same was found as 30.3 (range: 16-54), 54.2 (range:24-89) and 637.1(range:103-901) Bqkg-1, respectively. The calculated radioactivity parameters were compared with the world average values. The measured radium equivalent activity (Raeq), absorbed dose rate ($\dot{\mathrm D}$), annual effective outdoor dose(Ė) and the external hazard index (Hex) were observed as 165 (range: 63.7-234.8) Bqkg-1, 77.6 (36.9-108.0) nGyh-1, 0.11 (0.05-0.13) mSvy-1 and 0.5 (0.1-0.6), respectively. This study aims to provide baseline data for radionuclide present in the Churchandpur and Ukhrul districts of Manipur.