Nuclear Accident Research Articles

Multiple relocation cases in disaster-related deaths after the Fukushima nuclear accident

IntroductionRelocation after a disaster often has negative health effects on vulnerable people, particularly older adults. However, little is known about the number of repeated evacuations and relocations after disasters among those experienced disaster-related deaths. This case series aimed to summarize the secondary problems and mortality risks in patients involved in relocation after disasters.MethodsWe analyzed and summarized the data on 520 disaster-related deaths in Minamisoma City, a municipality near the Fukushima Daiichi Nuclear Power Plant, focusing on the number of relocations. Herein, we describe the cases of three individuals over 80 years old, who died after eight or more relocations, which were certified as disaster-related deaths.ResultsWe discuss following three cases, which are (1) a female patient in her 90s who had a stroke and was completely disabled, (2) a female patient in her 80s whose cancer was detected later due to her failing to see her family doctor, and (3) a male patient in his 80s whose regular postoperative treatment was disrupted following cancer recurrence.DiscussionOur findings indicate that evacuation led to the worsening of chronic diseases and eventually to post-disaster death. Prolonged wide-area evacuation and repeated relocation likely interrupted the continuum of care and led to the failure of adequate care provision. To reduce the loss of human life, it is necessary to review the number of wide-area evacuations and relocations over the medium to long term after large-scale disasters, including nuclear disasters, which may occur in the future. Simultaneously, it is important to establish a medical system at the evacuation site so that disaster victims can continue to receive medical care even after evacuation or relocation.

Seismic fragility analysis of nuclear containment structure with Bayesian cloud analysis framework

Nuclear containment structure plays a critical role in safe operation of nuclear power plant. Seismic safety of nuclear power plant structures has become a hot issue in nuclear engineering community following Fukushima nuclear accident. Seismic fragility analysis, as a key element in probabilistic safety assessment of nuclear power plants, is widely used in nuclear power plant structures. This study presents an innovative method for seismic fragility analysis of engineering structures. The proposed methodology combines conventional Cloud analysis method and Bayesian framework. The accuracy and efficiency of the proposed methodology were demonstrated by a single-degree-of-freedom system, heavy computational efforts but high accuracy seismic fragility analysis method was adopted for comparison. Seismic fragility analysis of a typical prestressed concrete nuclear containment structure was analyzed using the proposed method. Results indicated that method proposed in this study can improve the accuracy of seismic fragility analysis. Furthermore, with the enhance of performance level, the increasing ratios for median seismic capacity of the nuclear containment structure was decreasing.

FDXR gene expression and micronucleus frequency in Type 2 diabetes mellitus patients and their importance in case of radiation exposures

Analysis of gene expression (e.g. Ferredoxin Reductase: FDXR) changes in the blood samples have shown potential as predictive markers of disease, prognosis for therapy as well as triage and dose estimation in radiation-exposed populations. Similarly, quantification of micronuclei (MN) formation has been presented as a rapid cytogenetic marker for those applications. It was cautioned that the reliable utilization of these markers for prediction of disease, therapy prognosis, and dose estimation depends upon the information on known variables that affect these markers. Literature suggests that advanced glycation end products/oxidative stress in diabetic conditions can alter the levels of DNA damage and gene expression, and impact the segregation of the exposed from unexposed during nuclear disasters. Therefore, we investigated the influence of Type 2 diabetes mellitus (T2DM) on baseline expression of the FDXR and frequency of MN. Peripheral blood samples were collected from healthy volunteers (HV) (n = 60; 43 males and 17 females) and T2DM patients (n = 60; 32 males and 28 females), and performed real-time quantification of FDXR gene expression and analysis of MN frequency using microscopy. The basal level of FDXR gene expression (2.55 folds) (p < 0.01) and the frequency of MN is significantly (p < 0.01) higher (4 folds) in T2DM patients when compared to HV. Further, subgroup analysis found that gender, alcohol, smoking, duration of T2DM, complications, and medications increased both the expression of the FDXR gene and frequency of MN in T2DM; nevertheless, the increase was not significant, except for gender (p < 0.05) and medication (p < 0.05) on the frequency of MN. Overall results indicate that the T2DM patients showed a higher basal level expression of the FDXR gene and MN frequency when compared to HV and suggest an altered metabolic condition in T2DM is a confounding factor that impacts the levels of those markers. The increased levels of these markers might need to be considered to monitor medical radiation exposures and reliable biodosimetry during large-scale radiological accidents.

Dynamic range limitations of non-coherent continous-wave THz photomixing systems with broadband detectors.

The dynamic range of non-coherent continuous-wave (CW) THz photomixing (PM) systems with broadband detectors can be significantly limited by various parasitic effects. Specifically, we examine the generation of parasitic (i) THz and (ii) IR radiation, and (iii) higher harmonics in CW THz PM emitters. (i) The parasitic broadband THz radiation, spanning from 100 to 250 GHz with a total output power of 20 nW, results from not perfectly clean laser spectra. As a result, for a frequency-flat Golay cell detector, the PM-system dynamic range is limited to 32.8 dB at 500 GHz, 26.7 dB at 1 THz, and 8.5 dB at 2.3 THz. In the case of detectors with a frequency-declining responsivity, the dynamic range can drop by ∼10 dB more. (ii) The IR radiation leaking from a PM emitter (≈20 μW) is sensitive to the PM emitter bias, which results in its modulation with an amplitude of about 1.3 μW, when a standard PM-emitter bias modulation is applied. The detected IR radiation could be confused for the THz signal. (iii) Parasitic generation of higher harmonics in PM systems can also limit the system's dynamic range or create spectral artifacts. However, we show that the harmonics are low at least at ∼1 THz and above. Specifically, they are less than 400 pW for fundamental frequencies above 750 GHz, which is more than 43 dB below the power of the fundamental harmonic. The above-stated values were obtained for a commonly-used PIN-diode photomixer mounted on a Si lens and 1.5 μm distributed-feedback lasers. In general, suppression of these parasitic signals is crucial for non-coherent CW THz PM systems.

Analysis of the radiation accidents prevalence in nuclear medicine in the Russian Federation

Radiation events (accidents) appearance is an integral part of the use of ionizing radiation sources in medicine in general and nuclear medicine in particular. To minimize the negative impact on patients, workers, and public due to such events, it is necessary to have reliable information about real prevalence of the radiation events (accidents). The current work presents the analysis of the radiation accidents with medical ionizing radiation sources registered in the “Data bank of radiation accidents and incidents” of the Rospotrebnadzor Information and Analytical Centre for Radiation Safety and the results of workers questionnaires conducted in 25 nuclear medicine departments (about 30% of all nuclear medicine departments in the Russian Federation). The results of the analysis showed that the most common registered radiation accidents in the “Data bank of radiation accidents and incidents” are identification of passengers with high external dose rate as well as identification of waste contaminated by medical radionuclides. The results of the questionnaire showed that the most common radiation accidents (events) in nuclear medicine are contamination of work clothes or work surfaces with radionuclides, or patient fluids containing radionuclides; conducting examination without proper referral; extravasation of radiopharmaceutical. Existing systems of identification and registration of radiation accidents do not allow to identify radiation events (accidents) specific to nuclear medicine. The further research aimed at developing a classification of radiation events (accidents) in medicine and methods for responding to such events are feasible.

Decision tree insights analytics (DTIA) tool: an analytic framework to identify insights from large data records across fields of science

Abstract Supervised machine learning (SML) techniques have been developed since the 1960s. Most of their applications were oriented towards developing models capable of predicting numerical values or categorical output based on a set of input variables (input features). Recently, SML models’ interpretability and explainability were extensively studied to have confidence in the models’ decisions. In this work, we propose a new deployment method named Decision Tree Insights Analytics (DTIA) that shifts the purpose of using decision tree classification from having a model capable of differentiating the different categorical outputs based on the input features to systematically finding the associations between inputs and outputs. DTIA can reveal interesting areas in the feature space, leading to the development of research questions and the discovery of new associations that might have been overlooked earlier. We applied the method to three case studies: (1) nuclear reactor accident propagation, (2) single-cell RNA sequencing of Niemann-Pick disease type C1 in mice, and (3) bulk RNA sequencing for breast cancer staging in humans. The developed method provided insights into the first two. On the other hand, it showed some of the method’s limitations in the third case study. Finally, we presented how the DTIA’s insights are more agreeable with the abstract information gain calculations and provide more in-depth information that can help derive more profound physical meaning compared to the random forest’s feature importance attribute and K-means clustering for feature ranking.

Pre-disaster family visits and post-evacuation return to Fukushima among psychiatric inpatients evacuated to out-of-area hospitals after the nuclear accident.

This study aimed to elucidate the effects of pre-evacuation family hospital visits on post-evacuation returns to Fukushima Prefecture (hometown) among psychiatric inpatients who mandatorily evacuated to hospitals outside the prefecture because of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Of the inpatients in Fukushima, 44 were admitted to a hospital in the nearby Soso district on March 11, 2011, and were therefore included in the current analysis. We collected information on their discharge after the evacuation and family visits before the evacuation by reviewing the medical records of both the evacuation destination and former hospitals. The average durations from the accident to post-evacuation return among patients with and those without former family visits were 681.8 days (standard error [SE] = 163.3) and 1,027.8 days (SE = 152.0), respectively. The log-rank test showed a tendency of earlier return to Fukushima among inpatients who had received family visits to the hospital before evacuation (p = .073). The results highlight the critical need for close collaboration between psychiatric medical practitioners and families, to not only support patients' community reintegration into daily life but also facilitate a timely return to their hometowns following long-distance evacuation caused by an unforeseen large-scale disaster.

Posttraumatic negative cognitions in nurses affected by the Great East Japan Earthquake: A longitudinal study two years after the nuclear power plant accident

This study elucidated mental health changes in 39 nurses in Fukushima Prefecture one to two years after the Great East Japan Earthquake. Posttraumatic stress disorder symptoms improved, but posttraumatic negative cognitions worsened significantly. Factors including stress during the disaster, nursing-related stressors, and lack of disaster nursing experience contributed to negative cognitions. However, higher resilience and social support were associated with fewer negative cognitions. The complexity and uniqueness of radiation disasters may have influenced the nurses' negative thoughts. To address these issues, hospital administrators should reduce occupational stress, provide flexibility in work choices during disasters, and offer organizational support for nurses.

Characteristics of exposure to radioactive iodine during a nuclear incident.

During a nuclear accident, numerous products of nuclear fission are released, including isotopes of radioactive iodine. Among them is iodine-131, with a half-life of 8.02 days, which emits β radiation. For decades, it has been effectively and safely used in medicine. However, in the event of a nuclear accident, uncontrolled exposure can have harmful biological effects. The main sources of internal contamination with iodine-131 are contaminated air, food and water. The most exposed organ is the thyroid gland, where radioactive iodine accumulates via the Na+/I- symporter (NIS). NIS does not distinguish between radioactive iodine isotopes and the stable isotope iodine-127, which is essential for the synthesis of thyroid hormones. Exposure to radioactive iodine during a nuclear accident is primarily associated with papillary thyroid cancer, whose incidence begins to increase a few years after exposure. Children and adolescents are at the highest risk, and the risk is particularly significant for individuals living in iodine-deficient areas. Ensuring an adequate iodine supply is therefore crucial for lowering the risk of the harmful effects of exposure to radioactive iodine at the population level. Protecting the thyroid with potassium iodide tablets significantly reduces radiation exposure, as stable iodine prevents the entry of radioactive iodine into the thyroid. Such protection is effective only within a narrow time window - a few hours before and after the exposure and is recommended only for those under 40 years of age, as the risks of excessive iodine intake outweigh the potential benefits in older individuals.

A Review of the ICRP Publication 146: Radiological Protection of People and the Environment in the Event of a Large Nuclear Accident

A Review of the ICRP Publication 146: Radiological Protection of People and the Environment in the Event of a Large Nuclear Accident

Does long-term radiation exposure in Chornobyl impact the reproductive structures of Nuphar lutea (Linné) Smith?

The 1986 Chornobyl Nuclear Power Plant accident caused radioactive contamination of water bodies within the Pripyat River floodplain, resulting in the accumulation of radionuclides by macrophytes, which are fundamental species in water ecosystems. Yellow water lily Nuphar lutea (L.) Smith., a macrophyte playing a significant role in the formation of vegetation cover in aquatic ecosystems, is commonly considered as a bioindicator of water pollution. In this study, we investigate the potential of N. lutea as an indicator of radionuclide contamination in water bodies, particularly through changes in its reproductive structures, such as pollen viability, morphology of pollen grains, seeds, and fruits. Our findings reveal that pollen viability remains stable at total absorbed dose rates below 14.4 μGy/h, with only 1–4% of sterile grains. However, beyond this threshold the percentage of sterile grains increases nearly fivefold, pointing to high internal plant exposure to 90Sr. A similar trend was observed in the allometry and size of pollen grains, where small and flattened grains are formed in the reservoir with the highest external radiation dose rate (≥14.4 μGy/h). On the other hand, while morphometric parameters of fruits are influenced by radiation, their variation appears to be the result of a combination of physicochemical factors and the trophic status of a water body. Our research highlights the adverse impact of long-term radiation exposure on the male reproductive system of N. lutea and shows the potential of using the pollen grains sterility as an indicators of heavily radionuclide-contaminated water bodies. Additionally, we observed gradual changes in a pollen allometric length-to-width coefficient as the radiation dose level increases.

Compact Substrate Integrated Waveguide Cubical Dielectric Resonator Antenna for fifth-generation applications

A comprehensive analysis of a wideband Cubical Dielectric Resonator Antenna is presented, specifically designed for 5G-NR wireless communication applications, focusing on the N257, and N258 frequency bands. This antenna exhibits symmetrical radiation patterns, a wider bandwidth, improved efficiency, and substantial gain characteristics. The design employs a low-loss substrate-integrated waveguide structure to enhance gain while reducing cross-polarization effects. This is accomplished through an innovative approach of establishing boundary conditions using copper wire stitching for vias, superseding the conventional soldering iron method, which guarantees minimal radiation leakage, compact dimensions, and reduced losses. The perforated dielectric resonator antenna possesses higher mode excitations, and implementing metallic strips on two resonator surfaces facilitates the simultaneous excitation of fundamental and higher-order modes, thereby yielding a broadband response. The overall dimensions of the antenna are 15.29 × 8.42 × 3.8 mm3(1.3×0.7×0.3)λ03, which facilitates a measured impedance bandwidth of 8.2 GHz, spanning from 24.4 to 32.6 GHz (28.7%), accompanied by a high gain of 8.1 dBi and efficiency levels reaching up to 94%. The prototype is constructed utilizing the standard printed circuit board technique, and simulation outcomes are derived using the High-Frequency Structure Simulator (HFSS).

Опыт лечения пораженных при аварии на Чернобыльской АЭС в условиях специализированного стационара

Summary. The purpose of the study is to analyze and summarize the experience of treating those affected by a radiation accident at the Chernobyl nuclear power plant (Chernobyl nuclear power plant) in a specialized hospital. Materials and research methods. The research materials are documented experience in organizing treatment and treating those injured in the Chernobyl accident with acute radiation injury. Research methods – analytical method and method of generalization. The results of the study and their analysis. 129 patients were sent to a specialized hospital in Moscow in the first two days, 84 of which were diagnosed with acute radiation disease (OLB) II-IV Art. severity. As the main diagnostic criteria for the early diagnosis of patients used: the timing and severity of the primary general and local (leather) reaction, the severity of lymphopenia and neutrophilic leukocytosis and other criteria. The main directions of early treatment of the affected were: – prevention and treatment of infectious complications; – detoxification therapy; – correction of water-electrolyte metabolism, parenteral nutrition in connection with common burns, oropharyngeal syndrome, intestinal syndrome, etc.; – pre-transplantation: HLA-typification of patients, the selection of donors, the actual transplantation of bone marrow from the donors of relatives and cells of the embryonic human liver (in the absence of donors) affected with irreversible damage to the bone marrow; – replacing therapy with blood cells. Based on the results of the study, the following conclusions were made: – the complex of medical measures was highly effective; – there were practically no fatal outcomes due only to infection in patients with bone marrow, even severe and extremely severe, form of OLB, not complicated by burns, radial enteritis or acute secondary disease due to bone marrow transplantation; – none of the patients died from hemorrhagic syndrome, most had no signs of bleeding even with deep and prolonged thrombocytopenia (&gt; 2–4 weeks); – the successful treatment of those affected in the Chernobyl accident was prepared by many years of experience in the work of the Clinical Division of Radiation Medicine of the Institute of Biophysics of the USSR Ministry of Health – State Research Center – Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency for the treatment of those affected in other radiation accidents.

Development of a three-dimensional variational data assimilation system for 137Cs based on WRF-Chem model and applied to the Fukushima nuclear accident

Abstract Nuclear explosions and accidents release large amounts of radionuclides that harm human health and the environment. Accurate forecasting of nuclide pollutants and assessment of the ramifications of nuclear incidents are necessary for the emergency response and disaster assessment of nuclide pollution. In this study, we developed a three-dimensional variational (3Dvar) system to assimilate 137Cs based on the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) model. The distribution of 137Cs after the Fukushima nuclear accident in Japan on 15 March 2011 was analysed. The 137Cs background field at 06:00 UTC was assimilated using a 3Dvar system and surface observational data to optimise the 137Cs analysis field. Compared with the background field, the root mean square error (RMSE) and mean bias in the 137Cs analysis field decreased by 98% and 94%, respectively. The average fraction of predictions within factors of 2 (FAC2), 5 (FAC5), and 10 (FAC10) increased from 0.67, 0.72, and 0.72 to 0.90, 1.00, and 1.00, respectively. This substantial enhancement indicated the effectiveness of the 3DVar system in mitigating the uncertainty associated with the background field. Two 12 h forecast experiments were conducted to gauge the advancement in 137Cs forecasting facilitated by data assimilation (DA). The control experiment was conducted without DA, whereas the assimilation experiment was conducted with DA. Compared with the control experiment, the average FAC2, FAC5, and FAC10 in the assimilation experiment increased by 28%, 30%, and 29%, respectively. The average RMSE decreased by 33%. The mean bias and correlation coefficient increased by 41% and 36%, respectively. These results indicated that the 3Dvar method improves the forecast accuracy of 137Cs concentration.

Bimetallic Fe–Cu metal-organic frameworks for capturing of radioactive iodine in solution and vapor phases

Effectively removing radioactive iodine from the environment is critical for mitigating the risks associated with nuclear accidents. This research presents a brand-new Fe-Cu-BTC metal-organic framework (MOF) composite that works very well to absorb iodine. We employed a facile one-pot solvothermal method to achieve epitaxial growth of Fe-BTC on a Cu-BTC substrate. A full analysis using SEM, EDS, FTIR, XRD, BET, TEM, XPS, Raman, and TGA/DTA showed that the composite was successfully made while the crystalline structure of the CuBTC was kept. It was amazing how well the Fe-Cu-BTC composite could absorb iodine, reaching maximum capacities of 217.92 mg/g in solution and 623.21 mg/g in vapor phases, respectively, within the time limits given. The material demonstrated remarkable stability and recyclability, retaining its structural integrity and efficiency over five consecutive adsorption-desorption cycles. The high BET surface area of 820.35 m/g, pore volume of 0.328 cm/g, and pore diameter of 2.950 nm of the composite contributes to its superior adsorption performance. The composite exhibits exceptional stability under acidic conditions with a pH of 2>8.Studies of the adsorption isotherm and kinetics showed that the Langmuir and pseudo-second-order models correctly describe how iodine binds, with R² values of 0.995 and 0.994, respectively. XPS and Raman spectroscopy with peak values (72.21, 104.4, and 167.04) cm-1 confirmed the formation of polyiodides (I₃⁻ and I₅⁻) on the MOF surface, suggesting a physical adsorption mechanism.The Fe-Cu-BTC composite has a controlled synthesis, millimeter-scale dimensions, a porous structure, is very stable, and can be recycled easily. It looks like it could be a good way to capture and store iodine from a variety of environmental sources, such as reprocessing plant off-gas streams and liquid effluents.

Design and application of a shipborne underwater radiation detector array for the monitoring of seawater radioactivity

A navigable online monitoring system for marine radioactivity was developed to cope with possible large-scale marine nuclear pollution incidents. This system used a NaI(Tl) detector array mounted on a ship to collect radioactive data across wide marine areas rapidly. High volume-efficiency aids the system in rapidly identifying radionuclides exceeding standard levels. This feature enables the system to monitor the seawater in a wide area within a shorter time and promptly detect marine nuclear pollution incidents. Monte Carlo simulations were used to optimize the number of NaI(Tl) crystals and the detector spacing for enhancing the volume-efficiency of the system. Three Φ3" × 6″ NaI(Tl) detectors and the mounting bracket with a fixed detector spacing of 30 cm were fabricated based on the simulation outcomes. The volume-efficiency for 137Cs of the system was around six times higher than that for the buoy-based monitoring system with a 3-inch NaI(Tl) detector. The theoretical volume-efficiency curve, which was calculated through Monte Carlo simulation, was verified in a standard liquid source. The minimum detectable activity concentration (MDC) for radioisotopes of the system under various radioactive measurement durations was discussed, such as the MDC for 137Cs for 5 min measurement was 0.152 Bq/L. Marine radioactivity measurement experiments were conducted in the sea near the Tianwan nuclear power plant in Lianyungang, China. The test results showed that the activity concentration of 40K was 11.4 Bq/L. The results of navigation monitoring were consistent with those of sampling and laboratory measurement, which verified the stability and accuracy of the system.

High-risk nuclide screening and parameter sensitivity analysis based on numerical simulation and machine learning

During nuclear accidents, large quantities of radionuclides will be released into the environment, posing serious health hazards to local residents. The screening of high-risk nuclides is critical for the development of subsequent nuclear emergency response measures. In order to overcome the shortcomings of traditional screening methods, a machine learning method was proposed to screen high-risk nuclides and predict their contamination to groundwater more effectively. The performances of Support Vector Machine (SVM), Random Forest (RF) and Back Propagation Neural Network (BPNN) algorithms were compared, and sensitivity analyses of the initial leakage concentration ratio (C0/Cp), distribution coefficient (Kd) and decay coefficient (λ) on the model outputs were performed. Results showed that RF classification model achieved the highest prediction accuracy for screening high-risk nuclides. The contribution of the input parameters ranked as Kd > λ > C0/Cp. BPNN regression model was found to be the best for predicting when high-risk nuclides would pollute groundwater. The output was negatively correlated with C0/Cp and positively correlated with Kd and λ, with the parameter influence ranking as Kd > C0/Cp > λ. The contribution of Kd mainly came from itself, and the contribution of C0/Cp and λ mainly due to their interaction with other parameters.

Dosimetric calibration of anatomy-specific ultra-high dose rate electron irradiation platform for preclinical FLASH radiobiology experiments.

FLASH radiation therapy (RT) offers a promising avenue for the broadening of the therapeutic index. However, to leverage the full potential of FLASH in the clinical setting, an improved understanding of the biological principles involved is critical. This requires the availability of specialized equipment optimized for the delivery of conventional (CONV) and ultra-high dose rate (UHDR) irradiation for preclinical studies. One method to conduct such preclinical radiobiological research involves adapting a clinical linear accelerator configured to deliver both CONV and UHDR irradiation. We characterized the dosimetric properties of a clinical linear accelerator configured to deliver ultra-high dose rate irradiation to two anatomic sites in mice and for cell-culture FLASH radiobiology experiments. Delivered doses of UHDR electron beams were controlled by a microcontroller and relay interfaced with the respiratory gating system. We also produced beam collimators with indexed stereotactic mouse positioning devices to provide anatomically specific preclinical treatments. Treatment delivery was monitored directly with an ionization chamber, and charge measurements were correlated with radiochromic film measurements at the entry surface of the mice. The setup for conventional dose rate irradiation utilized the same collimation system but at increased source-to-surface distance. Monte Carlo simulations and film dosimetry were used to characterize beam properties and dose distributions. The mean electron beam energies before the flattening filter were 18.8 MeV (UHDR) and 17.7 MeV (CONV), with corresponding values at the mouse surface of 17.2 and 16.2 MeV. The charges measured with an external ion chamber were linearly correlated with the mouse entrance dose. The use of relay gating for pulse control initially led to a delivery failure rate of 20% (±1 pulse); adjustments to account for the linac latency improved this rate to<1/20. Beam field sizes for two anatomically specific mouse collimators (4 × 4 cm2 for whole-abdomen and 1.5 × 1.5 cm2 for unilateral lung irradiation) were accurate within<5% and had low radiation leakage (<4%). Normalizing the dose at the center of the mouse (∼0.75cm depth) produced UHDR and CONV doses to the irradiated volumes with>95% agreement. We successfully configured a clinical linear accelerator for increased output and developed a robust preclinical platform for anatomically specific irradiation, with highly accurate and precise temporal and spatial dose delivery, for both CONV and UHDR irradiation applications.

Behavior of high-velocity oxygen fuel sprayed chromium-coating on Zircaloy-4 fuel cladding under loss-of-coolant accident conditions

This study represents the steam-oxidation testing of High-Velocity Oxygen Fuel (HVOF) sprayed pure chromium (Cr) coatings on Zircaloy-4 cladding substrates for accident-tolerant-fuel (ATF) claddings. The research aims to address the critical need for improved accident tolerance in fuel cladding materials, particularly considering severe nuclear accidents. For the first time, pure Cr coatings, applied through HVOF spraying are investigated for their potential to provide enhanced oxidation resistance under high temperature steam conditions, which are representative of loss-of-coolant accident scenarios. The studies focus on the microstructural analysis, oxidation kinetics, and mechanical properties of the Cr-coated Zircaloy-4 cladding substrates when subjected to steam oxidation at temperature 1200 °C.

Numerical study for atmospheric transport of radioactive materials for hypothetical severe nuclear accident under different meteorological conditions

A study for atmospheric transport is essential for the consequence assessment of severe nuclear accidents since radionuclides could be released from the nuclear facility into the atmosphere and cause radioactive pollution in the environment. Atmospheric transport behaviors are strongly related with meteorological conditions, which can obviously influence the transport and diffusion characteristics of radioactive materials in the atmosphere; thus, it is meaningful to investigate the coupling effects between meteorological processes and transport behaviors of radioactive materials. To evaluate the influence of meteorological conditions on atmospheric transport, meteorological parameters for different seasons were first acquired by the weather research forecast model. Furthermore, atmospheric transport behaviors of radioactive materials were simulated by the meso-scale numerical model under different meteorological conditions, and numerical analyses were conducted toward transport and deposition behaviors of radioactive materials. In addition, the influence of FDDA (four-dimensional data assimilation) on meteorological parameters and atmospheric transport behaviors was researched. The present study is important for strengthening consequence assessment for severe nuclear accident and made it possible to apply the data assimilation technology in further research works.