Atomic Energy Research Articles

Investigation of the Effects of Ion Sources and RF Power on the Neutron Production Rate at SNRTC-IEC Fusion Device

Studies on an inertial electrostatic confinement (IEC) device are generally focused on increasing particle production. One way to achieve this is to increase the number of ion sources. In this study, the deuterium-deuterium fusion reaction was carried out in the IEC Saraykoy Nuclear Research and Training Center (SNRTC-IEC) fusion device (previously at the Turkish Atomic Energy Authority, now reestablished as the Turkish Energy, Nuclear and Mineral Research Agency) at cathode voltage of 85 kV and pressure of 5 × 10−4 mbars, and the effect of ion sources and radio-frequency (RF) power on the neutron production rate was investigated. To ensure a high concentration of ions in the center of the cathode, three inductively coupled plasma deuterium ion sources were added to this device. As the number of ion sources increased from one to three, the neutron production rate increased from 2.3 × 104 to 3.6 × 105n/s. Two ion source configurations were used to examine the effect of RF power. It was observed that when the RF power was increased from 40 to 200 W, the neutron production rate increased linearly from 4.6 × 104 to 1.7 × 105 n/s.

Ambient Deposition of Single Atoms for Enhancement of Nanostructured Metal Oxide Electrode Catalytic Performance

Single-atom decoration represents cutting-edge technology for enhancing heterogeneous catalysis by utilizing the unique capabilities of catalysts at the atomic level. However, the high surface energy of single atoms often causes them to aggregate, forming nanoparticles [1]. To address this challenge, we first modify the surface structure by synthesizing nanostructured support layers, such as TiO2 nanotubes, TiO2 nanosheets, and NiO nanosponge. Especially TiO2 nanotubes and NiO nanosponge pose relevant support layers due to their favorable attributes, including a high surface-to-volume ratio, abundance, and excellent chemical stability, while TiO2 nanosheets serve as model system. Vertically aligned, well-ordered, self-organized oxide nanostructures can be conveniently fabricated through anodization, allowing precise control over the geometry of the nanotubes and nanopores [2,3]. Well-defined atomic-scale defects on the surface of the supports are generated to immobilize single-atom co-catalysts. Therefore, defect engineering techniques typically require high-temperature thermal reduction. We present more gentle defect-engineering approaches, including room-temperature sonochemical treatment or UV-light irradiation. By combining these approaches, we are able to effectively trap Pt and Ir single atoms.We present a direct method utilizing UV-light radiation to induce point defects, specifically Ti3+ and oxygen vacancies (VO) onto the surface of TiO2 nanosheets and efficiently decorate them with Pt single atoms [4]. Our findings demonstrate that sonochemically treated TiO2 nanotubes provide a remarkable substrate for single-atom decoration from dilute solutions, resulting in promising performance in H2 evolution catalysis and renewable energy conversion. Additionally, the role of V single-atom decoration in ultrasonic treatment of support materials is investigated.Thermal annealing in a reductive atmosphere induces the formation of numerous defects, facilitating the anchoring of single Ir atoms onto the surface of annealed NiO nanostructures. Additionally, the novel ultrasound-driven method stabilizes these Ir atoms within the porous structure. By employing both approaches, we effectively trap Ir single atoms, thereby enhancing the efficiency of the oxygen evolution reaction in electrocatalysis [5].The characterization of the electrodes is conducted using microscopy techniques (FESEM, TEM, and HAADF-STEM) and spectroscopy (XPS and ToF-SIMS) [6]. Gas chromatography is employed to evaluate the H2 photocatalytic performance of TiO2 electrodes, while linear sweep voltammetry is utilized to assess the H2 and O2 electrochemical activity of NiO electrodes [5]. Our findings highlight the significant enhancement of photo- and electrocatalytic efficiency of nanostructured oxide electrodes modified with highly stable single-atom co-catalysts by gentle treatments.

Quantification of Hydrogen and Transition Metals in the Cathode Catalyst Layer of Anion Exchange Membrane Electrolyzer By Ion Beam Techniques

Anion Exchange Membrane Water Electrolyzer (AEMWE) has increased interest in H2 production at low cost and high scalability. The efficiency is strongly dependent on the membrane electrode assembly (MEA) with appropriate ionomer and catalyst layers. Herein, we report AEMWE with MoNi4-MoO2 cathode catalyst layer in ionomer-free Catalyst Coated Substrate (CCS) configuration. The optimized MEA for AEMWE demonstrated the superior performance of 225 mA/cm2 at 2V with more than 48 hours of durability. The X-ray diffraction confirmed the NiMoO4 phase transformation to MoNi4-MoO2 and SEM-EDS was used to study the morphology and elemental composition of the deposited catalyst. X-ray photoelectron Spectroscopy demonstrated the dominant metallic MoO2 formed after H2/Ar annealing. Rutherford Backscattering Spectroscopy (RBS) was also employed to measure the depth composition profile of the catalyst layer exhibiting the reduction of Ni concentration in the bulk after annealing. Further, we introduce hydrogen depth profiling by Nuclear Reaction Analysis (NRA) via the resonant 1H(15N,αγ)12C reaction as a versatile method for the highly depth-resolved visualization of hydrogen(H) in the near-surface region, including transitions of hydrogen between the surface and the bulk, and between shallow interfaces of the nanostructured cathode catalyst layer. The diffusion of the H atoms was observed with a 40% atomic percent of Hydrogen after H2/Ar annealing of the catalyst for 180 minutes (about 3 hours) and decreased to 10% atomic percent of hydrogen after 24 hours of electrolyzer operation. This technique also enabled the measurement of the zero-point vibrational energy of hydrogen atoms absorbed on the surfaces of the catalyst layer. Overall, this work better explains the cathode catalyst degradation effects and hydrogen diffusion in the cathode catalyst layer responsible for voltage and mass transfer losses in AEM electrolyzers.

Validation of McCARD Monte Carlo Calculation Code Against NAA Experiments Using Rare Earth Element Certified Reference Material Activated at JRTR

Rare earth elements (REEs) are widely used in several high-tech modern industries. Quantification of REEs demonstrates a technical challenge that requires the use of special scientific techniques. These techniques commonly introduce uncertainties that may propagate not only during the sample preparation phase but also in subsequent measurement and analysis phases. The Jordan Atomic Energy Commission is starting up a REE investigation program utilizing many of its available physical and chemical analytical capabilities, one of which is the Neutron Activation Analysis Facility (NAAF) at the Jordan Research and Training Reactor (JRTR). The NAAF provides accurate and relatively quick analytical services for better estimations of REEs in the unknown samples of interest without the need for any chemical processing prior to or after sample activation. In this paper, we present analytical results of routinely conducted instrumental neutron activation analysis (NAA) experiments using REE certified samples. To optimize future NAA investigations, first, a time-dependent Monte Carlo code at the JRTR, named Monte Carlo Code for Advanced Reactor Design and Analysis (McCARD), is herein validated via comparing its calculation results of the activation process against the presented results of the NAA experiments. The certified REE samples were activated in a well-thermalized NAA vertical activation hole within the reactor reflector region. Detailed neutronics and burnup calculations as well as transmutations were performed using McCARD. Ultimately, this study aims to assess the accuracy and reliability of the McCARD calculation models as a part of the effort of setting up a dedicated REE analysis laboratory at the JRTR. This study shows very good agreement between both obtained results—NAA experiment and McCARD calculations—with confidence levels noted to be more than 90% for almost all REE elements.

Long-range Corrected Density Functional Theory Including a Two-Gaussian Hartree-Fock Operator for High Accuracy Core-excitation Energy Calculations of Both the Second- and Third-Row Atoms (LC2gau-core-BOP).

In the previous work, LCgau-core-BOP, which includes the short-range interelectronic Gaussian attenuating Hartree-Fock (HF) exchange to the long-range HF exchange, showed high accuracy core-excitation energies from 1s orbitals of the second-row atoms (1s → π*, 1s → σ*, 1s → n*, and 1s → Rydberg), but underestimates the core-excitation energies from 1s orbitals of the third-row atoms. To improve this, we added one more Gaussian attenuating HF exchange to LCgau-core-BOP. We named it LC2gau-core-BOP, which achieves a mean absolute error (MAE) of 0.6 and 0.3 eV for core excitation energies of the second- and third-row atoms of the tested small molecules, respectively. We found that the inclusion of the short-range interelectronic HF exchange at a distance ranging from 0.2 to 0.6 a.u. contributes to the increase of performances on 1s orbital energy calculations of the second-row atoms, while the inclusion of more short-range interelectronic HF exchange at a distance ranging from 0 to 0.2 a.u. does to the increase of performance on 1s orbital energy calculations of the third-row atoms. It is notable that all of these improvements were accomplished using flexible Gaussian attenuating HF exchange inclusion. LC2gau-core-BOP shows deviations of less than 0.8 eV from experimental values for all of the core-excitation energies of the tested medium-size molecules consisting of thymine, oxazole, glycine, and dibenzothiophene sulfone. Moreover, by optimizing one parameter of the OP correlation functional, LC2gau-core-BOP provides atomization energies over the G3 test set with an accuracy comparable to that of B3LYP.

Chemical Separation of Copper from the Printed Circuit Board of Dead Electronic Gadget Cell Phone Set (Samsung J-2)

The increasing popularity of electronic devices among the public has increased electronic waste (e-waste). Most electronic devices become obsolescent after their use and generate hazardous chemicals if not disposed properly. The conducting networks in all electronic gadgets are made up of Copper (Cu) that can be retrieved by the chemical segregated method. In this experiment, a hydrometallurgical technique was used as acid leaching, selective recovery of Cu from the leachate using the group separation methods and measured the Cu metal separated from the acid leach. 5.05 g CuO is extracted which is equivalent to 4.03 g of Cu from the Samsung J-2 cell phone having an initial weight of 18.33 g PCBs. Atomic Absorption Spectroscopy (AAS) and Energy Dispersed X-ray analysis (EDX) techniques are used for the characterization of the extract. The recovery of Cu from this technique is about 93 % of the PCB board of Samsung J-2 mobile set.

Validation and parametric study of FFRD model in DRACCAR code

The recent revision of Emergency Core Cooling System (ECCS) regulations in Korea has necessitated the consideration of Fuel Fragmentation, Relocation, and Dispersal (FFRD) phenomena in nuclear reactor safety analyses. Consequently, the Korea Atomic Energy Research Institute (KAERI) has developed and integrated the FFRD model into the domestically licensed safety analysis code, SPACE. Globally, US NRC’s FRAPTRAN and IRSN’s DRACCAR are available for evaluating FFRD phenomena. The FRAPTRAN code incorporates the FFR model, developed by Quantum Technology, while the fuel dispersal model is currently not included. In contrast, the DRACCAR code functions as an integrated analysis platform capable of modeling multi-dimensional thermal, hydraulic, mechanical, and chemical phenomena during a Loss of Coolant Accident (LOCA). This study conducts a thorough examination of the FFRD model in the DRACCAR code and validates its applicability through analysis using the Halden IFA-650 tests. The results demonstrate satisfactory predictive capabilities. Furthermore, a parametric study of key FFRD model parameters enhances the understanding of the FFRD model in the DRACCAR code. The development of detailed physical models in the FFRD model could significantly enhance the performance of the DRACCAR code, warranting the establishment of a comprehensive framework for these advancements. In the future, code-to-code comparisons between the DRACCAR code and other domestically developed integrated analysis platforms will be conducted to investigate various phenomena in depth.

Quantification of natural uranium and its risk evaluation in groundwater of Chikkaballapur district in Karnataka, India.

The present study focused on the distribution of uranium in groundwater samples collected from various sources in the Chikkaballapur district and its associated risk in humans. Seventy-five groundwater samples were collected during pre-monsoon and post-monsoon seasons and were analysed for uranium concentration along with different water quality parameters. The uranium concentration ranged from 0.23 to 285.23µg/L in the pre-monsoon season and from 0.02 to 107.87µg/L in the post-monsoon season. More than 90% of samples, except a few, were under the safe limits of 60µg/L as directed by the Department of Atomic Energy (DAE) of India's Atomic Energy Regulatory Board (AERB). The study analysed physicochemical parameters like pH, total dissolved solids (TDS), nitrate, total hardness, phosphate, sulphate and fluoride in collected water samples. Out of all samples, few samples noted higher values of TDS, nitrate and fluoride. Their correlation along with uranium is detailed in the study. Owing to its slightly elevated content, an evaluation of the radiological and chemical hazards associated with uranium consumption was analysed. When the risk resulting from chemical toxicity was evaluated, relatively few samples had a hazard quotient (HQ) score higher than 1, which suggested that the people were vulnerable to chemical danger. This study also evaluates the dangers of elevated uranium levels in groundwater samples to the general public's health. It also acknowledges the importance of routinely evaluating and treating the drinking water sources in the region.

A Multi-Objective Optimization Design for Enhancing Space Utilization and Minimizing Cutting Time in Nuclear Facility Component Decommissioning

According to the International Atomic Energy Agency’s requirements for the minimization of radioactive waste, nuclear facility components need to be cut into smaller blocks and packaged in waste containers during decommissioning. Therefore, it is important to increase the space utilization (SU) of the cut blocks in the containers while reducing the cutting time (CT). In engineering practice, increasing SU often leads to longer CTs, which poses a great challenge to improve the efficiency of the nuclear decommissioning process. To overcome this challenge and to determine the optimal operational parameters, this paper introduces a multi-objective optimization design method for cutting and packaging nuclear facility components. The goal is to increase SU while concurrently reducing CTs, ultimately minimizing the waste and reducing the decommissioning cost. First, we project the intricate three-dimensional (3D) irregular parts packing problem onto a two-dimensional plane to simplify the complexity inherent in 3D parts packing and to formulate a packing optimization model. Second, we employ the Morris method to perform global sensitivity analysis on critical parameters, including cutting angle, height, component radius, and plate thickness parameters, throughout the cutting process of nuclear facility components. This analysis produces global sensitivity indicators for each parameter, facilitating a precise assessment of the sensitivity values associated with different operational parameters. Finally, we formulate a multi-objective design optimization model for cutting and packing nuclear facility components that yields a series of alternative operating parameter solutions upon solving it. This methodology offers a resolution for the selection of optimal operational parameters in the decommissioning process of nuclear facility components, thereby attaining optimal outcomes in waste disposal and furnishing guidance for subsequent decommissioning activities.

An efficient method to generate near-ideal hollow beams of different shapes for box potential of quantum gases.

Ultracold quantum gases are usually prepared in conservative traps for quantum simulation experiments. The atomic density inhomogeneity, together with the consequent position-dependent energy and time scales of cold atoms in traditional harmonic traps, makes it difficult to manipulate and detect the sample at a higher level. These problems are partially solved by optical box traps made of blue-detuned hollow beams. However, generating a high-quality hollow beam with high light efficiency for the box trap is challenging. Here, we present a scheme that combines the fixed optics, including axicons and prisms, to pre-shape a Gaussian beam into a hollow beam with a digital micromirror device (DMD) to improve the quality of the hollow beam further, providing a nearly ideal optical potential of various shapes for preparing highly homogeneous cold atoms. The highest power-law exponent of potential walls can reach a value over 100, and the light efficiency from a Gaussian to a hollow beam is also improved compared to direct optical shaping by a mask or a DMD. Combined with a one-dimensional optical lattice, a nearly ideal two-dimensional uniform quantum gas with different geometrical boundaries can be prepared for exploring quantum many-body physics to an unprecedented level.

The Future Needs of External Beam Radiotherapy in Portugal Until 2040

AimsExternal beam radiotherapy (EBRT) is essential to offer an effective cancer treatment, but it needs to be accessible, well-timed, and high-quality. There is a global lack of radiotherapy infrastructure and investment that compromises the cancer outcomes. The authors aim to quantify the future needs of EBRT until 2040 to cover the future demand. Materials and methodsBased on the Global Cancer Observatory estimate for new cancer cases in Portugal for 2040 it was calculated the optimal number of EBRT courses. The OUP is the proportion of new cancer cases that should receive EBRT at least once. In line with the International Atomic Energy Agency (IAEA) DIrectory of RAdiotherapy Centres and European SocieTy for Radiotherapy and Oncology - Health Economics in Radiation Oncology guidelines, we estimated the number of EBRT machines / Megavoltage (MV) units needed. Also, the authors followed the IAEA staffing guidelines. ResultsThe calculated median increase in the optimal number of EBRT courses for the year 2040 was found to be 18% when compared to the requirements in 2020. The projected number of optimal EBRT courses for 2040 was estimated to be approximately 34.000. Consequently, a range of 18 to 30 new EBRT machines/ MV units will need to be installed to adequately address the growing demand. To meet this demand, it is anticipated that a total of 28 to 46 radiation oncologists, 22 to 36 medical physicists, and 61 to 102 radiation therapists will be required. ConclusionThe deficit of EBRT machines / MV units in Portugal will require a change in the cancer related – policies and an investment to offer full access to EBRT treatments.

Quantifying donor site morbidity in anterior cruciate ligament reconstruction using peroneus longus tendon autograft

Objectives: The objective of this study was to assess the donor site morbidity in patients having anterior cruciate ligament reconstruction (ACLR) using peroneus longus tendon (PLT) autograft. Methods: A prospective cohort study was conducted at the orthopedic department of Pakistan Atomic Energy Commission General Hospital, Islamabad, from July 2021 to July 2023. A total of 150 patients aged between 20 and 40 years with an anterior cruciate ligament injury requiring ligament reconstruction were included in the study. Exclusion criteria included previous ankle ligamentous injuries, fractures or surgeries around the ankle, and high-risk sports like football. After the ACLR surgery, the patients were assessed for pain, range of motion (ROM), and muscle power in the 6th week, 3rd month, and 6th month. Return to jogging without discomfort at the ankle during 1st min of jogging was assessed at six months. Results: Of the 150 patients, 142 (94.6%) were male and 8 (5.4%) were female. The mean age of participants was 32.53 ± 4.78 years. Pain and loss of ROM around the ankle were reduced after six months compared to three months and six weeks, that is, P < 0.05. Muscle power was increased after six months (n = 152; 94.0%) (P < 0.001). In the 6th month, 133 patients (88.7%) were able to jog without discomfort around the ankle joint during the 1st min of jogging, but 17 patients (11.3%) started jogging after six months without discomfort at the ankle joint during the 1st min of jogging (P < 0.001). Conclusion: ACLR using the PLT autograft resulted in a good functional outcome, smooth rehabilitation with an early return to sports, and minimal complications at the donor site.

Legal boundaries: Ensuring protection amidst threats to the Zaporizhzhya Nuclear Power Plant in the Ukraine

This article aims to examine the protection accorded to nuclear power plants in international law, based on the example of the Zaporizhzhya Nuclear Power Plant in the context of the current Russian aggression against Ukraine and the ensuing international armed conflict. The authors attempt to answer the question of the legality of the attacks against the Zaporizhzhya Nuclear Power Plant. The research methods used are institutional-legal analysis and, supplementarily, a critical literature analysis. The institutional-legal analysis focuses on the examination of international treaties like Additional Protocol I to the Geneva Conventions, which constitutes the main legal reference point in this article, as well as on other documents that may not be binding (such as resolutions adopted by the International Atomic Energy Agency's General Conference or the Board of Governors, as well as statements and reports of other International Atomic Energy Agency's and United Nations' bodies). The main conclusion is that Russian attacks against the Zaporizhzhya Nuclear Power Plant were and continue to be illegal on multiple fronts. While the legal regulations appear adequate and capable of meeting the challenge posed by Russian attacks and occupation of the Zaporizhzhya Nuclear Power Plant, the problem lies with the political will of Russia to respect these rules.

Transfer functions for QA /QB international regulatory limits for the safe transport of radioactive materials

This paper presents a proposed revision of the International Atomic Energy Agency transport regulations, related to the A 1 and A 2 limit values used to determine the radioactive transport classification. Based on the ‘Q system’, a novel methodology was introduced to derive QA and QB values related to scenarios involving external exposure from a distant source. These values are key parameters that respectively represent the total effective dose and total equivalent dose to the skin, from all primary and secondary particles contributing to radiation exposure. The International Working Group (WG A 1/A 2) is established and associated with the TRANSSC Technical Expert Group on Radiation Protection. A review of the A 1 and A 2 values is performed in response to identified limitations within the existing Q system. The followed approach is based on Monte Carlo simulations that enabled the development of transfer functions aimed at reducing computational time and increasing the flexibility of dose evaluations for any radionuclide with known particle emission spectra. This method allows updating the QA and QB values to account for future data evolutions (decay data, fluence-to-dose conversion coefficients) and standardizing the calculation of regulation limits across all referenced radionuclides and scenarios related to external exposure. The transfer functions are established using three Monte Carlo simulation codes—FLUKA, Geant4, and MCNP—and address the previous limitations of the ‘Q system’, reflecting the latest International Commission for Radiation Protection recommendations and improvements in calculation techniques. The results of the WG show consistent agreement across the codes, with minor discrepancies observed at low primary energies due to statistical uncertainties and different handling of stopping power for electrons/positrons in the codes. This revised approach aligns with current standards and recommendations, ensuring that the radiological consequences of transport accidents are acceptable for the new A 1 and A 2 limits from a radiological protection perspective.

Tensile and creep properties of small specimens of reduced-activation ferritic steel F82H, and the correlation to standard specimen data

Background A reduced-activation ferritic/martensitic (RAFM) steel, F82H steel, is the primary candidate structural material for fusion reactor blanket. Small specimen test technique is essential to develop the blanket materials using limited irradiation volume in high flux neutron field. An international collaboration activity “Towards the Standardization of Small Specimen Test Techniques for Fusion Applications” has been initiated under the framework of the International Atomic Energy Agency Coordinated Research Project for Phase I from 2017 to 2021, and Phase II from 2022 to 2026. The present paper reports the preliminary results on tensile and creep tests as a summary of the above Phase I activity. Methods Tensile and creep tests were conducted at 550 and 650°C, using flat-plate SSJ type small specimens with various gauge thickness ranged from 0.14 to 1.2 mm, while gauge length and width are 5 and 1.2 mm, respectively. In addition, round bar type standard specimens with a gauge geometry of 6 mm in diameter and 30 mm in length was also tested for comparison. Results Tensile yield stress, ultimate tensile strength and uniform elongation were independent of the gauge thickness of SSJ specimens, and agreed with the data from the standard size specimens. On the other hand, total elongation was decreased with decreasing the thickness. In creep tests, rupture time was decreased with decreasing the gauge thickness of SSJ specimens. Standard size specimens exhibited shorter rupture time than the SSJ specimens. Conclusions The SSJ type specimens provided similar tensile parameters to those from the standard specimen, except total elongation. Creep rupture time of the SSJ specimens were different from the standard specimen, and decreased with decreasing the gauge thickness.

A Review of Fluoride Removal from Phosphorous Gypsum: A Quantitative Analysis via a Machine Learning Approach.

This review comprehensively explores fluoride removal from phosphogypsum, focusing on its composition, fluorine-containing compounds, characterization methods, and defluorination techniques. It initially outlines the elemental composition of phosphogypsum prevalent in major production regions and infers the presence of fluorine compounds based on these constituents. The study highlights X-ray photoelectron spectroscopy (XPS) as a pivotal method for characterizing fluorine compounds, emphasizing its capability to determine precise binding energies essential for identifying various fluorine species. Additionally, the first-principle density functional theory (DFT) is employed to estimate binding energies of different fluorine-containing compounds. Significant correlations are observed between the total atomic energy of binary fluorides (e.g., of alkali metals, earth metals, and boron group metals) and XPS binding energies. However, for complex compounds like calcium fluorophosphate, correlations with the calculated average atomic total energy are less direct. The review categorizes defluorination methods applied to phosphogypsum as physical, chemical, thermal, and thermal-combined processes, respectively. It introduces neural network machine learning (ML) technology to quantitatively analyze and optimize reported defluorination strategies. Simulation results indicate potential optimizations based on quantitative analyses of process conditions reported in the literature. This review provides a systematic approach to understanding the phosphogypsum composition, fluorine speciation, analytical methodologies, and effective defluorination strategies. The attempts of adopting DFT simulation and quantitative analysis using ML in optimization underscore its potential and feasibility in advancing the industrial phosphogypsum defluorination process.

Proposal of database of radiological characterization for decommissioning nuclear power plants

AbstractIn Korea, Kori Unit 1 was permanently closed in 2017 and scheduled for decommissioning. Kori Unit 1 is currently scheduled to undergo system decontamination and to be decommissioned by December 2038. Measures to properly control and remove radiological hazards must be established to go through decommissioning a nuclear power plant (NPP). Radiological characterization must precede NPP decommissioning. Radiological characterization generates a lot of data during this process. The consistency of radiological characterization data is important for systematically decommissioning NPPs. However, the data generated from radiological characterization may not be systematically managed because a database of radiological characterizations for Kori Unit 1 has not been properly established. Therefore, this study has proposed a database to be filled during radiological characterization in terms of occupational radiation exposure of personnel and decommissioning waste safety using key performance indicators presented by the International Atomic Energy Agency. From the perspective of occupational exposure, databases have been proposed for operational history investigations, decommissioning source term calculations, and investigation of the level of radiological contamination. From the perspective of the safety of decommissioning waste, databases were proposed for operational history investigation, decommissioning source term calculation, investigation of the level of radiological contamination, and investigation of radiological characteristics of decommissioning waste.

Impact of safety regulation on rare event occurrence: The case of nuclear power plants in Korea

Climate change mitigation and energy supply security are the most important issues worldwide. To attain carbon neutrality and restrict global warming to 1.5°C, expediting investments in energy sectors and facilitating the expansion of clean energy is imperative. Nuclear power generation, as a base load, contributes to the energy transition because it is low-carbon and can be deployed on a large scale; however, particular challenges arise due to the risk of accidents, radioactive waste management problems, and public acceptance. Considering the similarity between macroeconomic data and nuclear power generation data from a time-series perspective, this study estimates the frequency of rare event (RE) occurrence in nuclear reactors using macro time-series methodology. We employ the Bayesian Markov Chain Monte Carlo method, developed by Barro and Jin (2021), to estimate the likelihood of RE occurrences for the reactors using the panel data of electricity production (MWh) obtained from the International Atomic Energy Agency's Power Reactor Information System. The findings indicate that the frequency of RE occurrences significantly decreases as nuclear safety regulations strengthen and the regulatory workforce increases. Despite the limitations of being directly utilized as practical indicators for safety performance, observing its similar pattern with the World Association of Nuclear Operators performance indicators provides insights for policy implications in intermediate safety management aimed at preventing major disaster incidents.

Experimental and molecular dynamics multiscale study on sintering and interfacial reaction of Fe2O3/CaO particle system

High-temperature sintering and solid-state reaction within the intricate Fe2O3/CaO system are pivotal factors influencing material characteristics. The current work focused on the sintering and reaction behavior of Fe2O3/CaO particles at high temperatures with a multiscale study of in-situ high-temperature stage microscopy (HTSM) and molecular dynamics (MD). The laws governing atomic migration and the evolution of crystal structure during the sintering process were simulated at the nanoscale. The results elucidated that a heightened heating rate fosters particle shrinkage and concomitant reduction in surface area. The sintering activation energy (Esin) exhibited an increment proportional to the linear shrinkage of the particles. Furthermore, an augmented potential barrier in advanced stages impeded subsequent sintering behavior. Augmented temperature promoted the particle shrinkage and sintering neck formation, culminating in pore closure and a diminution in the free surface. However, this promotional effect attenuated with escalating temperatures. Particle shrinkage and sintering neck formation are contingent upon atomic migration and diffusion, with the growth of sintering necks primarily reliant on atom diffusion along the surface of the sintering necks. The atomic diffusion activation energy was determined to be 49.5 kJ/mol within the temperature range of 1073–1473 K. Within the Fe2O3/CaO system, the preferential generation of Ca2Fe2O5 (C2F) over CaFe2O4 (CF) was found, leading to a decrease in the atomic diffusion barrier and an enhancement of the diffusivity, with the latter dominating in later stages. The highest mobility of O2–, Fe3+, and Ca2+ was discerned in CF, and the sintering shrinkage of the particles predominantly hinges on the generation of CF.

Role of independent research at AERB for ensuring safety of nuclear facilities in India.

The mission of Atomic Energy Regulatory Board (AERB) of India is to ensure that the use of ionising radiation and nuclear energy in India does not cause unacceptable impact on the workers, members of the public and to the environment. AERB has the mandate to carry out detailed safety review for the siting, construction, commissioning, operation and decommissioning of nuclear and radiation facilities established within the country. To deliver and maintain a strong, credible and technically sound regulation, AERB has established the Safety Research Institute (SRI) at Kalpakkam with a robust technical infrastructure and wide knowledge base. This paper highlights the independent safety research activities carried out at SRI and its role to support and facilitate the decision-making process by AERB at various stages of regulatory review for ensuring safety of the nuclear facilities in India.