•Sampling location scheme and corresponding measurement techniques were described.•Measurement results of the chosen samples are presented.•Analysis showed no contamination of Mlaka and consequently, ...of Danube.•Presented results serve as baseline for the regular monitoring design.
This study deals with the design of the checkpoint system for monitoring the environmental radioactivity in the vicinity of the nuclear reactors. As the design site was selected the Vinča Institute of Nuclear Sciences in the capital city of the Republic of Serbia. There are situated two former nuclear research reactors with potential hazardous materials in controlled conditions. Due to the high risk of ecosystem contamination in the vicinity of various nuclear facilities such as reactor, radiological analyses of coastal soils, sediments and stream/river water were performed at the selected checkpoints. The investigation included determination of gross alpha and gross beta activities, gamma spectrometric analysis and analysis of 90Sr content in the collected environmental samples, as well as determination of 3H activity concentration, but only in water samples. Gross alpha activity ranged from 0.013 Bq/L to 0.057 Bq/L for water samples, from 130 Bq/kg to 280 Bq/kg for soil samples, and from 120 Bq/kg to 270 Bq/kg for sediment samples. Gross beta activity ranged from 0.128 Bq/L to 0.332 Bq/L for water samples, from 850 Bq/kg to 1600 Bq/kg for soil samples, and from 660 Bq/kg to 1200 Bq/kg for sediment samples. The main contribution to gamma radiation in water samples was made by 40K and 137Cs. The 226Ra/238U ratio ranged from 0.37 to 1.24 in soil and from 0.51 to 1.16 in sediment. 90Sr and 3H were detected in all studied samples. The presented results and the increased radiation risk in the above mentioned area show that the surrounding of the nuclear reactors and the exposure of the population to ionizing radiation must be constantly monitored.
Regulator halts assembly of fusion reactor Clery, Daniel
Science (American Association for the Advancement of Science),
2022-Mar-04, 2022-03-04, 20220304, Letnik:
375, Številka:
6584
Journal Article
Recenzirano
ITER must meet safety concerns before welding giant tokamak sections.
•The paper investigates RAVEN’s advanced methodologies to support nuclear safety analysis.•Discusses the comprehensive integration of RAVEN with various nuclear safety codes.•Showcases detailed case ...studies on severe nuclear accident scenarios.•Introduces innovative techniques in uncertainty quantification with RAVEN.•Explores potential future developments in nuclear risk assessment tools.
As the horizon of nuclear energy expands with the advent of small modular reactors, Generation IV reactors, and fusion reactors, there is a growing perspective that the licensing process could benefit from a more comprehensive approach. Moving beyond traditional deterministic and probabilistic risk assessment analyses might pave the way for a novel safety analysis paradigm propelled by the increasing computational power at our disposal.
This paper explores different methodologies that can improve the outcomes of nuclear safety analysis. These range from uncertainty quantification techniques, aimed at enhancing the precision of safety margins, to deploying dynamic event trees by driving system code simulations, capturing the potential evolutions of severe accidents. These methodologies offer a better understanding of the management and consequences of nuclear accident scenarios, significantly improving the accuracy and efficiency of safety predictions compared to traditional methods.
Specific case studies illustrate the practical application of these advanced techniques, demonstrating substantial improvements in predicting and managing the dynamics of severe accidents. These findings underscore the effectiveness of these methodologies in enhancing risk assessment capabilities and informing decision-making processes for nuclear safety management. The paper also emphasizes the importance of adaptability and continuous evolution, a call for action to address emerging nuclear safety concerns and highlights the utility of advanced tools like RAVEN.
The quest for controlled fusion energy has been ongoing for over a half century. The demonstration of ignition and energy gain from thermonuclear fuels in the laboratory has been a major goal of ...fusion research for decades. Thermonuclear ignition is widely considered a milestone in the development of fusion energy, as well as a major scientic achievement with important applications in national security and basic sciences. The US is arguably the world leader in the inertial connement approach to fusion and has invested in large facilities to pursue it, with the objective of establishing the science related to the safety and reliability of the stockpile of nuclear weapons. Although signicant progress has been made in recent years, major challenges still remain in the quest for thermonuclear ignition via laser fusion. Here, we review the current state of the art in inertial connement fusion research and describe the underlying physical principles.
This study investigates the nuclear radiation attenuation characteristics of bioactive glasses with the system (26-x)Na2O-xBaO-29CaO–45P2O5, where x represents the molar percentage of BaO (0, 5, 10, ...15). For this purpose, several parameters of shielding gamma radiation, such as the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), effective atomic number (Zeff), effective electron density (Neff), atomic cross-section (ACS), electronic cross-section (ECS), equivalent atomic number (Zeq), and transmission factor (TF) were calculated. The calculations were performed across different photon energy ranges (0.015–15 MeV) using Phy-X/PSD software and validated using the WinXCOM program. The results obtained from both the software platforms exhibited a high degree of agreement. Among the investigated glasses, the BNCP-15 glass, which had the highest BaO concentration, demonstrated the highest values for MAC, LAC, Zeff, Neff, ACS, ECS, and Zeq, while displaying the minimum values for HVL, TVL, MFP, and TF. For example, the LAC values at 15 MeV were found to be 0.056, 0.063, 0.070, and 0.077/cm for BNCP-0, BNCP-5, BNCP-10, and BNCP-15, respectively. Consequently, the BNCP-15 glass exhibited superior radiation attenuation performance in comparison to the other BNCP glasses examined in this study.
•Four bioactive glasses (Na2O–BaO–CaO–P2O5) are investigated for radiation attenuation purposes.•Phy-X/PSD and WinXCOM program are employed for shielding parameters.•Significant influence of BaO content on radiation attenuation characteristics is observed.•High-BaO bioactive glasses are recommended for diverse radiation attenuation uses.
The motivation for transitioning away from zirconium-based fuel cladding in light water reactors to significantly more oxidation-resistant materials, thereby enhancing safety margins during severe ...accidents, is laid out. A review of the development status for three accident tolerant fuel cladding technologies, namely coated zirconium-based cladding, ferritic alumina-forming alloy cladding, and silicon carbide fiber–reinforced silicon carbide matrix composite cladding, is offered. Technical challenges and data gaps for each of these cladding technologies are highlighted. Full development towards commercial deployment of these technologies is identified as a high priority for the nuclear industry.
Magnesium batteries appear a viable alternative to overcome the safety and energy density limitations faced by current lithium-ion technology. The development of a competitive magnesium battery is ...plagued by the existing notion of poor magnesium mobility in solids. Here we demonstrate by using ab initio calculations, nuclear magnetic resonance, and impedance spectroscopy measurements that substantial magnesium ion mobility can indeed be achieved in close-packed frameworks (~ 0.01-0.1 mS cm
at 298 K), specifically in the magnesium scandium selenide spinel. Our theoretical predictions also indicate that high magnesium ion mobility is possible in other chalcogenide spinels, opening the door for the realization of other magnesium solid ionic conductors and the eventual development of an all-solid-state magnesium battery.
•A review on numerical modelling of nuclear flashing flows is provided.•Consideration of interphase slip with a two-fluid model is often necessary.•Thermal, velocity and pressure effects all affect ...the vaporization rate.•Poly-disperse models considering different interfacial topologies are promising.
The flashing flow is a relevant multiphase phenomenon in many technical applications including nuclear safety analysis, which has been the subject of intense research for several decades. Numerical studies have evolved from one-dimensional to multi-dimensional. A variety of methods has been proposed, while a broad consensus does not exist yet. The present work aims to present an overview of available models and assess their limitations and perspectives by conducting an extensive literature survey. The final focus was put on recent progresses of computational fluid dynamics simulations. Some consensus on modelling interfacial slip, phase change mechanism and bubble size is identified. Since flashing scenarios often accompanying with high void fraction and broad bubble size range, a poly-disperse two-fluid model is recommended. Thermal phase change model is superior to pressure phase change, relaxation and equilibrium models for practical flashing problems, however incorporation of pressure effects is desirable. Major challenges comprise improving closure models for interphase transfer, bubble dynamics processes, interfacial area as well two-phase turbulence. For this purpose, high-resolution high quality experimental data are important, which are lacking in many cases. Considering that heterogeneous gas structures often exist in flashing flows, multi-field approaches able to handle different shapes of gas-liquid interface and including the shape effect in closure models are recommended for further study.
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