Two-phase flow patterns in turbulent flow through a dose diffusion pipe

A numerical investigation is carried out for turbulent particle-laden flow through a dose diffusion pipe for a model reactor system. A Lagrangian Stochastic Monte-Carlo particle-tracking approach and the averaged Reynolds equations with a k-e turbulence model, with a two-layer zonal method in the boundary layer, are used for the disperse and continuous phases. The flow patterns coupled with the particle dynamics are predicted. It is observed that the coupling of the continuous phase with the particle dynamics is important in this case. It was found that the geometry of the throat significantly influences the particle distribution, flow patterns and length of the recirculation region. The accuracy of the simulations depends on the numerical prediction and correction of the fluid phase velocity during a characteristic time interval of the particles. A numerical solution strategy for the computation of two-way momentum coupled flow is discussed. The three test cases show different flow features in the formation of a recirculation region behind the throat. The method will be useful for the qualitative analysis of conceptual designs and their optimisation

Nuclear Physics for Cultural Heritage

Nuclear physics applications in medicine and energy are well known and widely reported. Less well known are the many important nuclear and related techniques used for the study, characterization, assessment and preservation of cultural heritage. There has been enormous progress in this field in recent years and the current review aims to provide the public with a popular and accessible account of this work. The Nuclear Physics Division of the EPS represents scientists from all branches of nuclear physics across Europe. One of its aims is the dissemination of knowledge about nuclear physics and its applications. This review is led by Division board member Anna Macková, Head of the Tandetron Laboratory at the Nuclear Physics Institute of the Czech Academy of Sciences, and the review committee includes four other members of the nuclear physics board interested in this area: Faiçal Azaiez, Johan Nyberg, Eli Piasetzky and Douglas MacGregor. To create a truly authoritative account, the Scientific Editors have invited contributions from leading experts across Europe, and this publication is the combined result of their work. The review is extensively illustrated with important discoveries and examples from archaeology, pre-history, history, geography, culture, religion and curation, which underline the breadth and importance of this field. The large number of groups and laboratories working in the study and preservation of cultural heritage across Europe indicate the enormous effort and importance attached by society to this activity

Nuclear Forces and Nuclear Structure

After a historical review, I present the progress in the field of realistic NN potentials that we have seen in recent years. A new generation of very quantitative (high-quality/high-precision) NN potentials has emerged. These potentials will serve as reliable input for microscopic nuclear structure calculations and will allow for a systematic investigation of off-shell effects. The issue of three-nucleon forces is also discussed.Comment: Invited Talk presented at Nuclear Structure '98, Gatlinburg, Tennessee, August 10-15, 1998; 15 pages, 6 figures, aipproc2.sty and epsfig.st

Neutron capture cross section measurements of 238U, 241Am and 243Am at n_TOF

Proposal: Neutron capture cross section measurements of 238U, 241Am and 243Am at n_TOFThe increase of the world energy demand and the need of low carbon energy sources have triggered the renaissance and/or enhancement of nuclear energy in many countries. Fundamental nuclear physics can contribute in a practical way to the sustainability and safety of the nuclear energy production and the management of the nuclear waste. There exists a series of recent studies which address the most relevant isotopes, decay data, nuclear reaction channels and energy ranges which have to be investigated in more detail for improving the design of different advanced nuclear systems [1] and nuclear fuel cycles [2]. In this proposal, we aim at the measurement of the neutron capture cross sections of 238U, 241Am and 243Am. All three isotopes are listed in the NEA High Priority Request List [37], are recommended for measurements [1] and play an important role in the nuclear energy production and fuel cycle scenarios. The measurements will provide as well valuable nuclear structure data necessary for the improvement of nuclear models and the statistical interpretation of the nuclear propertiesPostprint (author's final draft

Evolution of Nuclear Spectra with Nuclear Forces

We first define a series of NN interaction models ranging from very simple to fully realistic. We then present Green's function Monte Carlo calculations of light nuclei to show how nuclear spectra evolve as the nuclear forces are made increasingly sophisticated. We find that the absence of stable five- and eight-body nuclei depends crucially on the spin, isospin, and tensor components of the nuclear force.Comment: 5 pages, 2 figures, submitted to Phys. Rev. Let

Neutrino nuclear response and photo nuclear reaction

Photo nuclear reactions are shown to be used for studying neutrino/weak nuclear responses involved in astro-neutrino nuclear interactions and double beta decays. Charged current weak responses for ground and excited states are studied by using photo nuclear reactions through isobaric analog states of those states, while neutral current weak responses for excited states are studied by using photo nuclear reactions through the excited states. The weak interaction strengths are studied by measuring the cross sections of the photo nuclear reactions, and the spin and parity of the state are studied by measuring angular correlations of particles emitted from the photo nuclear reactions. Medium-energy polarized photons obtained from laser photons scattered off GeV electrons are very useful. Nuclear responses studied by photo nuclear reactions are used to evaluate neutrino/weak nuclear responses, i.e. nuclear beta and double beta matrix elements and neutrino nuclear interactions, and to verify theoretical calculations for them.Comment: 8 pages, 6 figure

Don’t Give up on Nuclear Energy

The nuclear power plant failures at Three Mile Island and Chernobyl in the late 1970s and 1980s split Americans into two passionate camps. For some, nuclear plants posed serious threats to both environmental and national security, and, for others, nuclear energy remained the most viable path to clean, reliable power in the United States. But following the fervent debates of the late 20th century, the national conversation around nuclear power stagnated. A few ardent advocates and opponents notwithstanding, nuclear power left the public eye. Popular energy debates—especially among young people—now center around flashier topics like the Green New Deal, electric vehicles, and Greta Thunberg. In light of the collective avoidance of nuclear power, support in the U.S. recently reached an all-time low—although the slight majority opposition fails to tell the entire story. Rather than carefully researching the pros and cons of new advancements in nuclear power, many Americans maintain decades-old opinions, parrot the viewpoints of media personalities, or avoid thinking about nuclear energy entirely. While brushing a topic as difficult as nuclear power under the rug seems the most convenient option, one problem remains—Americans can’t afford to abandon nuclear power. First, let’s state the obvious: Anthropogenic contributions to climate change pose serious threats to the planet, and carbon dioxide released into the atmosphere plays a sizeable role in humanity’s impact on the environment. Crucially, though, nuclear plants generate vast amounts of power without directly emitting CO2. Furthermore, nuclear energy’s current technological capabilities—unlike other renewable technologies—can provide reliable baseload electricity in nearly every corner of the world. Yet the current state of nuclear power is what causes such angst among nuclear skeptics. Most nuclear plants came online between 1970 and 1990, and the infamous disasters of Three Mile Island, Chernobyl, and Fukushima originated from freak failures in dated technology. Additionally, traditional nuclear plants take billions of dollars and many years to build, all while creating the problem of non-disposable, highly radioactive waste. The perceived health risks of nuclear power, though, falter under further examination. In fact, the use of nuclear power over fossil fuels such as coal or natural gas prevented an estimated 1.8 million net deaths between 1971-2009. As for cost and waste-related worries, traditional nuclear plants do come with high capital costs and create radioactive waste, but the levelized costs of nuclear energy—the minimum price of electricity for the project to break even—tell a different story. In 2020, the levelized cost of nuclear plants coming online was $95.2/MWh, comparable to conventional coal ($95.1/MWh) and below conventional combustion turbine natural gas-fired plants ($141.5/MWh). Additionally, new technologies promise to change the landscape of nuclear power. Companies like NuScale Power, for example, propose a small, modular reactor with a simplified design capable of shipment by truck, rail, or barge and projected to be commercially available by 2025. This modular reactor greatly reduces construction and operating costs, consequently emerging as a viable option for clean, baseload power generation in smaller communities. Another company, TerraPower, has designed a nuclear reactor capable of utilizing fuel made from depleted uranium, the byproduct of traditional nuclear plants. Commercial use of this technology would reduce nuclear proliferation concerns, lower costs, and protect the environment by eliminating existing nuclear waste. Countless additional examples of advanced nuclear technologies exist, and it is in our best interests—environmentally and financially—to give them serious consideration. Even if modern nuclear plants fail to act as a panacea to the world’s energy problems, they may prove beneficial in regions lacking the necessary conditions to survive off solar, hydro, and wind power alone—at least until large scale storage and transportation of renewable energy becomes viable. Simply put, advanced nuclear power’s potential justifies significant investment in further research. Considering the climate-related challenges before us, to outwardly dismiss such an impactful technology would be foolish

Modelling the nuclear parton distributions

We review a semi-microscopic model of nuclear parton distributions, which takes into account a number of nuclear effects including Fermi motion and nuclear binding, nuclear meson-exchange currents and off-shell corrections to bound nucleon distributions as well as nuclear shadowing effect. We also discuss applications of the model to the lepton-nuclear deep-inelastic scattering, Drell-Yan process and neutrino total cross sections.Comment: 8 pages, 5 figures, Invited talk at 17th International workshop on Advanced Computing and Analysis Techniques in physics research (ACAT 2016), 18-22 January 2016 UTFSM, Valpara\'iso (Chile), to appear in Proceedings. arXiv admin note: text overlap with arXiv:1512.0329