The breeding blanket with integrated first wall (FW) is the key nuclear component for power extraction, tritium fuel sustainability, and radiation shielding in fusion reactors. The ITER device will ...address plasma burn physics and plasma support technology, but it does not have a breeding blanket. Current activities to develop “roadmaps” for realizing fusion power recognize the blanket/FW as one of the principal remaining challenges. Therefore, a central element of the current planning activities is focused on the question: what are the research and major facilities required to develop the blanket/FW to a level which enables the design, construction and successful operation of a fusion DEMO? The principal challenges in the development of the blanket/FW are: (1) the Fusion Nuclear Environment – a multiple-field environment (neutrons, heat/particle fluxes, magnetic field, etc.) with high magnitudes and steep gradients and transients; (2) Nuclear Heating in a large volume with sharp gradients – the nuclear heating drives most blanket phenomena, but accurate simulation of this nuclear heating can be done only in a DT-plasma based facility; and (3) Complex Configuration with blanket/first wall/divertor inside the vacuum vessel – the consequence is low fault tolerance and long repair/replacement time.
These blanket/FW development challenges result in critical consequences: (a) non-fusion facilities (laboratory experiments) need to be substantial to simulate multiple fields/multiple effects and must be accompanied by extensive modeling; (b) results from non-fusion facilities will be limited and will not fully resolve key technical issues. A DT-plasma based fusion nuclear science facility (FNSF) is required to perform “multiple effects” and “integrated” experiments in the fusion nuclear environment; and (c) the Reliability/Availability/Maintainability/Inspectability (RAMI) of fusion nuclear components is a major challenge and is one of the primary reasons why the blanket/FW will pace fusion development toward a DEMO.
This paper summarizes the top technical issues and elucidates the primary challenges in developing the blanket/first wall and identifies the key R&D needs in non-fusion and fusion facilities on the path to DEMO.
In a variety of applications using ionizing radiation, it is essential to ensure the safety of both individuals and equipment. To this end, excellent radiation shielding materials, including glasses ...and rare earth elements, such as Dy
, are currently being researched. The goal of this study is to explore the effect of Dy
on the radiation-shielding properties of the SiO
–PbO–B
–Dy
glass system; for clarity, it is abbreviated as Dy-X. Dy
is a good choice for use as a modifier in radiation shielding glasses since it has high density. Additionally, Dy
has good thermal stability and can be added to glass matrices without substantially affecting their physical features. The influence of increasing the amount of Dy
present in the glasses from 0 to 5 mol% on the linear attenuation coefficient (LAC) and effective atomic number (
) was studied using glasses with five distinct compositions and densities. In order to achieve this, the Phy-X program was utilized. The results demonstrate that Dy5 (with a composition of 55B
–25PbO–20SiO
–5Dy
) has the highest LAC value of the prepared glasses, while Dy0 has the lowest. We investigated the influence of Dy
on
at 0.284 MeV. The results show that the
values increase with increasing Dy
content. The
values were found to be 27.35, 27.94, 28.52, 29.09, 29.65, and 30.20 for Dy0, Dy1, Dy2, Dy3, Dy4, and Dy5, respectively. From the
results, we observed that increasing the Dy
content in the samples leads to an improvement in the shielding ability of the glass system. We compared the LAC of the Dy-X glasses with six glass systems at 0.662 MeV. All Dy0–Dy3 glasses have lower LAC values than all the TeO
–Li
O–ZnO glasses, but Dy4 has an LAC value greater than those of three of these glasses.
Background: Associations between nuclear disasters and
suicide have been examined to a limited extent. Aim: To clarify the suicide rates in
evacuation areas after the nuclear disaster in Fukushima, ...which occurred in March 2011.
Method: This descriptive study used monthly data from vital statistics between March 2009
and December 2015. Suicide rates in areas to which evacuation orders had been issued,
requiring across-the-board, compulsory evacuation of residents from the entire or part of
municipalities, were obtained and compared with the national average. Results: Male suicide
rates in evacuation areas increased significantly immediately after the disaster, and then
began to increase again 4 years after the disaster. Female suicide rates declined slightly
during the first year and then increased significantly over the subsequent 3-year period.
Moreover, male rates in areas where evacuation orders were issued for the total area
declined over the course of approximately 2 years, but then began to increase thereafter.
Analysis by age revealed postdisaster male rates in evacuation areas decreased for those
aged 50-69 years and increased for those aged ≤ 29 years and ≥ 70 years. Limitations: The
number of suicides among females and the female population in the evacuation area was small.
Conclusion: Our findings suggest the need to keep in mind that, when providing post-disaster
mental health services, suicide rates can eventually increase even if they initially
decrease.
This study explores the delaying of the formation of helium bubbles and blisters in pure titanium by hydrogen pre-implantation. Titanium, implanted with helium (40 KeV, 5 × 1017 ions/cm²), exhibited ...large bubbles that cause exfoliation after heat treatment, whereas hydrogen pre-implantation inhibited bubble growth at room temperature and reduced the exfoliation after heat treatment.
In the samples pre-implanted with hydrogen, we found evidence of helium diffusion delay by: (a) a fourfold reduction in bubble pressure (b) faceted cavities in the samples (c) a smaller increase in titanium lattice parameters (d) a 16-fold reduction in average bubble size and a sixfold reduction in bubble area fraction (e) a more than twofold decrease in exfoliation (f) a tendency toward the formation of larger bubbles as a result of heat treatment. We believe that it is reasonable to assume that the inhibition of helium diffusion between tetrahedral interstitial lattice sites takes place because of the occupation of the intermediate octahedral sites by hydrogen atoms.
Evidence for the opposite effect, that is inhibition of the diffusion of hydrogen in the presence of helium, is found in the retention of hydrogen in the specimens at elevated temperatures. This retention allowed the existence of titanium hydride after heat treatment at 680 °C. The present study sheds light on the intricate interplay between hydrogen and helium in titanium, providing insights into mechanisms that can potentially mitigate helium-induced damage in materials.
The public tends to exaggerate the dangers of nuclear energy, mistakenly associating it with various environmental problems such as ozone depletion and the production of CO2. First, we investigate ...the acquisition of misconceptions about nuclear energy. In Experiments 1 (N = 198, United Kingdom) and 2 (N = 204, France), participants were more likely to develop new negative misconceptions about nuclear energy, compared to renewables or even some fossil fuels. Participants were also more likely to attribute the emission of hazardous substances produced by renewables to nuclear energy than to the energy sources actually emitting it. This suggests that specific misconceptions about nuclear energy are likely the by-products of negative perceptions of nuclear energy. Second, we ask whether correcting specific misconceptions leads to less negative attitudes about nuclear energy. In Experiments 3 (N = 296, United Kingdom.) and 4 (N = 305, France), participants were exposed to pronuclear energy arguments, one of which informed them of its low CO2 emissions. This argument led to a decrease in the perception that nuclear energy contributes to climate change. Thus, even if specific misconceptions about nuclear energy derive from overall negative perceptions, addressing these misconceptions can still help align public opinion with expert opinion.
Public Significance Statement
We show that people are more likely to develop novel negative misconceptions about nuclear energy than about other energy sources. However, one of the most salient of these misconceptions-that nuclear energy emits large amounts of CO2-can be corrected, which then mitigates the perception that nuclear energy contributes to climate change.
Probabilistic fracture mechanics (PFM) simulates the behavior of cracked structures and propagates uncertainties from input parameters to a failure probability or its uncertain estimate. In nuclear ...technology, this approach supports the assessment of the rupture probability of highly reliable pipes, which is an important parameter for the safety analysis of a nuclear power plant. For the appropriate probabilistic modelling of a structure with consideration of uncertainties, but also for the analysis of PFM application cases, the question arises, which input parameter of a probabilistic model has a higher impact on the estimate of computed failure probability, and which has a minor impact. This question is associated with the sensitivity measures or importance factors of the input parameters and their ranking concerning their influence.
In this paper, six different approaches for the quantification of the sensitivity of parameters PFM evaluations are investigated: the amplification ratio, the direction cosine, the degree of separation, the analysis of the most probable failure point, the separation of uncertainty method, and the simple sample-based sensitivity study. Each method is described, visualized, applied to a common test case, and compared. The application case and the comparison are part of the Coordinated Research Project (CRP), “Methodology for Assessing Pipe Failure Rates in Advanced Water-Cooled Reactors (AWCRs)” by the International Atomic Energy Agency (IAEA), which is dedicated to the development of failure rates of piping in AWCRs. The participants used different PFM computer codes to analyze the test case and individual sensitivity methods to rank the input parameters, which motivated the comprehensive survey.
The predicted parameter ranking of the approaches is consistent between the methods and between different PFM codes, but the approaches differ in the scope and the required effort. A conclusion is drawn and recommendations for the six different approaches are given.
•Sensitivity measures in probabilistic fracture mechanics are compared.•Six parameter ranking methods with different starting points are evaluated.•The proposed sensitivity measures agree in their ranking.•The sensitivity ranking approaches differ in their scope and the required effort.
El artículo analiza los procesos de adquisición de centrales nucleares desarrollados en el siglo XX en el caso de Brasil, teniendo en cuenta los constreñimientos internacionales propios de sectores ...tecnológicos duales y las estrategias tecnológicas nacionales llevadas adelante en contextos semiperiféricos. Metodológicamente implementa un análisis basado en el process tracing, complementado con revisión bibliográfica y documental. Primero, examina el marco de condicionamientos externos, conformado por las acciones de cooperación técnica internacional y difusión controlada de tecnología impulsadas por las potencias nucleares en el contexto de Guerra Fría. Luego, analiza el caso de Brasil, identificando las estrategias de adquisición de centrales nucleares a partir de lazos de cooperación internacional establecidos previamente. Seguidamente, se analizan los diferentes resultados alcanzados en los dos casos estudiados. De esta forma, el trabajo busca contribuir al diálogo entre los campos de las Relaciones Internacionales y los Estudios Sociales de la Ciencia y la Tecnología.
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