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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Software For Advanced Large-scale Analysis Of Magnetic Confinement For Numerical Design, Engineering & Research (salamander)

As magnetic confinement fusion energy gains traction internationally to enable abundant energy production, designing components for fusion systems is a pressing challenge. During the planned lifetime of a fusion device, components evolve in extreme environments and must withstand large, repeated thermal loads and bombardment by 14 MeV neutrons, plasma ions, and neutral particles (deuterium, tritium, and helium), corrosive conditions, etc. All these physical processes take place simultaneously, interact in intricate ways, and impose important constraints that can affect performance. Experimental data is rare and costly to obtain, making design particularly challenging. Predictive computational frameworks must be an integral part of an accelerated and cost-effective design process by modeling fusion system performance in simulated environments. To better understand component degradation and operational impacts on their performance, the Software for Advanced Large-scale Analysis of MAgnetic confinement for Numerical Design, Engineering & Research (SALAMANDER) is designed as an open-source, fully integrated, multiphysics, multiscale, NQA-1 compliant framework facilitating 3D, high-fidelity fusion system modeling. To that end, SALAMANDER is a MOOSE-based framework, and therefore leverages MOOSE upstream libraries such as PETSc and libMesh to deliver sophisticated finite element, finite volume, and nonlinear solver technology for fusion energy simulations. SALAMANDER couples MOOSE physics module capabilities—such as thermal hydraulics, heat conduction, Navier-Stokes, and thermomechanics—with tritium transport via TMAP8, neutronics via Cardinal, and nascent particle-in-cell capabilities. Direct simulation Monte Carlo methods will be used to address neutral transport near the walls. By coupling all these physics in an integrated application, SALAMANDER will enable high-fidelity modeling of irradiation levels and plasma exposure conditions of plasma facing components and their impact on heat and tritium distributions, as well as the resulting mechanical constraints experienced by the plasma facing components and performance of blanket systems. Furthermore, SALAMANDER will be particularly suited for engineering studies thanks to the stochastic tool module readily available in MOOSE, allowing for extended uncertainty quantification and risk analysis studies. It is also able to use computer-aided design (CAD) meshes to model complex geometries, which is indispensable for fusion systems. SALAMANDER therefore supports design, safety, engineering, and research projects for magnetic confinement fusion systems

Simon, Pierre-Clement [Idaho National Laboratory (↗
DOE OSTI2021

Measurements of Neutron Scattering from a Copper Sample Using a Quasi-Differential Method in the Region from 2 keV to 20 MeV

Neutron scattering from a copper sample was measured at Rensselaer Polytechnic Institute utilizing the quasi-differential method. The measurement spanned the energy range from 0.5 to 20 MeV using the high-energy scattering system and from 2 keV to 0.5 MeV using the new mid-energy scattering system. Copper was selected as a material of interest to measure due to large discrepancies between experiments and simulations of the Zeus benchmark. The Zeus benchmark consists of a copper reflected highly enriched uranium system, and the angular distribution of copper scattering was thought to potentially be the cause of the discrepancy. The copper measurements found differences in the scattering response particularly in the incident energy region from 1 to 2 MeV for the high-energy measurement and from 2 to 4 keV in the mid-energy system. These differences are particularly noticeable at angles near 90 deg in the high-energy system and back angles in the mid-energy system. Additionally, for ENDF/B-VIII.0 there is a large discrepancy at the forward angle in the energy range around 0.5 MeV. For these reasons, a new evaluation of copper scattering utilizing these results is recommended and perhaps could help to improve the agreement with the Zeus benchmarks.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

On the issue of neutron source development for a laser-driven nuclear-thermonuclear reactor

We discuss the feasibility of developing a high-power thermonuclear neutron source driven by laser pulses. Using one-dimensional numerical simulations for targets made in the form of double-sided cones, for an absorbed Nd-laser energy of ∼ 1 MJ (at the second and third harmonics) and pulse duration of 10 – 20 ns it is possible to achieve a neutron yield at a level of 10{sup 16} – 10{sup 17} per shot. This neutron yield is a prerequisite to the commencement of work to develop a hybrid nuclear-thermonuclear reactor. (paper)

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Soft Matter Sample Environments for Time-Resolved Small Angle Neutron Scattering Experiments: A Review

With the promise of new, more powerful neutron sources in the future, the possibilities for time-resolved neutron scattering experiments will improve and are bound to gain in interest. While there is already a large body of work on the accurate control of temperature, pressure, and magnetic fields for static experiments, this field is less well developed for time-resolved experiments on soft condensed matter and biomaterials. We present here an overview of different sample environments and technique combinations that have been developed so far and which might inspire further developments so that one can take full advantage of both the existing facilities as well as the possibilities that future high intensity neutron sources will offer.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Thermal Model Heat Rate Predictions of the AGR-5/6/7 Experiment

Several fuel and material irradiation experiments have been planned for the U.S. Department of Energy Advanced Gas Reactor Fuel Development and Qualification Program, which supports the development and qualification of tristructural isotropic (TRISO) coated particle fuel for use in high-temperature gas-cooled reactors. The goals of these experiments are to provide irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, support development of fuel performance models and codes, and provide irradiated fuel and materials for post-irradiation examination and safety testing. Originally planned and named as separate fuel experiments, but subsequently combined into a single test train. AGR-5/6/7 will test low-enriched uranium oxycarbide (UCO – a heterogeneous mixture of uranium oxide and uranium carbide) TRISO fuel. The AGR-5/6 portion of the experiment will provide data to support qualification of the selected reference fuel design, while the AGR-7 portion will serve as a margin test, irradiating the fuel beyond normal operating conditions. During irradiation, the temperature in each capsule is controlled by varying the helium / neon gas mixture flowing through the capsule until the desired thermocouple temperature is reached. Further adjustments can be made by changing the lobe power and the neutron filter. Three neutron filters are available to use as the experiment burns up the fissionable fuel. A thermal finite element model has been created for the five capsules comprising the AGR-5/6/7 experiment. Heat rates from a physics analysis are imported into the model along with fast neutron fluence. Graphite shrinkage due to the fast neutron fluence is incorporated into the model. Gas gaps change as a function of fast neutron fluence. Radiation heat transfer is a major contributor in this model. This is a large model with more than 1 million finite element brick elements. More than 150 different parts are modeled in the finite element model and communicate with each other from a heat transfer sense. More than 50 thermocouples are used in the experiment and are compared to actual measurements. The experiment is composed of five separate stainless steel capsules all welded together. This paper presents a method used to predict the gas mixture in the event that all of the thermocouples fail in a particular capsule. Curve fitting of heat rates from previous cycles and projecting them into the future is the basis of the method.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Structural and Reorientational Dynamics of Tetrahydroborate (BH4-) and Tetrahydrofuran (THF) in a Mg(BH4)2 3THF Adduct: Neutron-Scattering Characterization

Metal borohydrides are considered promising materials for hydrogen storage applications due to their high volumetric and gravimetric hydrogen density. Recently, different Lewis bases have been complexed with Mg(BH4)2 in efforts to improve hydrogenation/dehydrogenation properties. Notably, Mg(BH4)2 xTHF adducts involving tetrahydrofuran (THF; C4H8O) have proven to be especially interesting. This work focuses on exploring the physicochemical properties of the THF-rich Mg(BH4)2 3THF adduct using neutron-scattering methods and molecular DFT calculations. Structural analysis, based on neutron diffraction measurements of Mg(11BH4)2 3TDF (D-deuterium), has confirmed a lowering of the symmetry upon cooling, from monoclinic C2/c to P[1 with combining macron] via a triclinic distortion. Vibrational properties are strongly influenced by the THF environment, showing a splitting in spectral features as a result of changes in the bond lengths, force constants, and lowering of the overall symmetry. Interestingly, the orientational mobilities of the BH4- anions obtained from quasielastic neutron scattering (QENS) are not particularly sensitive to the presence of THF and compare well with the mobilities of BH4- anions in unsolvated Mg(BH4)2. The QENS data point to uniaxial 180 degree jump reorientations of the BH4- anions around a preferred C2 anion symmetry axis. The THF rings are also found to be orientationally mobile, undergoing 180 degree reorientational jumps around their C2 molecular symmetry axis with jump frequencies about an order of magnitude lower than those for the BH4- anions. In contrast, no dynamical behavior of the THF rings is observed with QENS for a more THF-deficient 2Mg(BH4)2 THF adduct. This lack of comparable THF mobility may reflect a stronger Mg2+-THF bonding interaction for lower THF/Mg(BH4)2 stoichiometric ratios, which is consistent with DFT calculations showing a decrease in the binding energy with each additional THF ring in the adduct. Based on the combined experimental and computational results, we propose that combining THF and Mg(BH4)2 is beneficial to (i) preventing weakly bound THF from coming free from the Mg2+ cation and reducing the concentration of any unwanted impurity in the hydrogen and (ii) disrupting the stability of the crystalline phase, leading to a lower melting point and enhanced kinetics for any potential hydrogen storage applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Development of a high fidelity model of the CROCUS experimental reactor

Measurements of scalar flux distributions with fine spatial and energy resolutions are needed to remedy one of the validation shortcomings of the novel neutronics full core solvers, such as MPACT and nTRACER. While a very detailed resolution of the flux can be calculated with such codes, only a limited experimental data set is available to check their accuracy. Such type of measurements are on-going at the zero power reactor CROCUS, operated at the Laboratory for Reactor Physics and System Behaviours of the EPFL, thanks to the development of advanced miniature neutron detection systems. This kind of experimental data would provide the community with a suitable benchmark for the validation of high fidelity neutronics solvers. In parallel, a multi-physics solver for steady-state and transient analysis of nuclear reactors, named GeN-Foam, has been developed. Based on the finite-volume OpenFOAM library, GeN-Foam provides us with enough flexibility to analyze non-conventional reactor geometries such as that of CROCUS. While CROCUS heterogeneities cannot be modeled by MPACT and nTRACER for the moment, GeN-Foam offers a unique opportunity to build a high fidelity model which mimics these codes' method to reach sub-pin simulation resolution. This document aims at describing the work achieved to get from the existing GeN-Foam model of the CROCUS reactor based on a structured mesh and using the neutron diffusion, the first high-fidelity model using discrete ordinates method as an approximation to neutron transport and an unstructured mesh for inter lattice water gap description and sub-pin heterogeneous modeling. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2012

Neutron source in the MCNPX shielding calculating for electron accelerator driven facility

Argonne National Laboratory (ANL) of USA and Kharkov Inst. of Physics and Technology (KIPT) of Ukraine have been collaborating on the design development of an experimental neutron source facility. It is an accelerator driven system (ADS) utilizing a subcritical assembly driven by electron accelerator. The facility will be utilized for performing basic and applied nuclear researches, producing medical isotopes, and training young nuclear specialists. Monte Carlo code MCNPX has been utilized as a design tool due to its capability to transport electrons, photons, and neutrons at high energies. However the facility shielding calculations with MCNPX need enormous computational resources and the small neutron yield per electron makes sampling difficulty for the Monte Carlo calculations. A method, based on generating and utilizing neutron source file, was proposed and tested. This method reduces significantly the required computer resources and improves the statistics of the calculated neutron dose outside the shield boundary. However the statistical errors introduced by generating the neutron source were not directly represented in the results, questioning the validity of this methodology, because an insufficiently sampled neutron source can cause error on the calculated neutron dose. This paper presents a procedure for the validation of the generated neutron source file. The impact of neutron source statistic on the neutron dose is examined by calculating the neutron dose as a function of the number of electron particles used for generating the neutron source files. When the value of the calculated neutron dose converges, it means the neutron source has scored sufficient records and statistic does not have apparent impact on the calculated neutron dose. In this way, the validity of neutron source and the shield analyses could be verified. (authors)

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

The phase diagram of quantum chromodynamics in one dimension on a quantum computer

The quantum chromodynamics (QCD) phase diagram, which reveals the state of strongly interacting matter at different temperatures and densities, is key to answering open questions in physics, ranging from the behaviour of particles in neutron stars to the conditions of the early universe. However, classical simulations of QCD face significant computational barriers, such as the sign problem at finite matter densities. Quantum computing offers a promising solution to overcome these challenges. Here, we take an important step toward exploring the QCD phase diagram with quantum devices by preparing thermal states in one-dimensional non-Abelian gauge theories. We experimentally simulate the thermal states of SU(2) and SU(3) gauge theories at finite densities on a trapped-ion quantum computer using a variational method. This is achieved by introducing two features: Firstly, we add motional ancillae to the existing qubit register to efficiently prepare thermal probability distributions. Secondly, we introduce charge-singlet measurements to enforce colour-neutrality constraints. This work pioneers the quantum simulation of QCD at finite density and temperature for two and three colours, laying the foundation to explore QCD phenomena on quantum platforms.

Quantum information↗
DOE OSTI2025

Signature of 0 + excited state and shape coexistence in 94 Kr through 93 Kr(d,p) 94 Kr reaction

A measurement of the excitation spectrum of 94 Kr via one-neutron transfer to the ground state of 93 Kr using the 93 Kr(d,p) 94 Kr reaction at 8A MeV, observing the outgoing protons, performed with the IRIS facility at TRIUMF is reported. Two states in 94 Kr, at 1.50±0.14 MeV and 2.20±0.14 MeV, were observed. An adiabatic-wave approximation analysis of the differential cross sections leads us to identify the lower energy state as being populated with neutron transfer to the 3 s1/2 orbital. This leads to the first observation of the lowest 0 + excited state in 94 Kr, hence signaling shape co-existence. Theoretical calculations performed within the in-medium similarity renormalization group framework are presented that also show the existence of a low-energy 0 + state, aligning qualitatively with the observation.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

Neutron Fluence and Energy Reconstruction with the LNE-IRSN/MIMAC Recoil Detector MicroTPC at 27 keV

The French Institute for Radiation protection and Nuclear Safety (IRSN), designated by the French Metrology Institute (LNE) for neutron metrology, is developing a time projection chamber using a Micromegas anode: microTPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize the energy distribution of neutron fluence in the energy range 8 keV - 5 MeV with a primary procedure. The time projection chambers are gaseous detectors able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulation of the detector response. The μTPC is a new reliable detector able to measure energy distribution of the neutron fluence without unfolding procedure or prior neutron calibration contrary to usual gaseous counters. The microTPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27 keV and 144 keV are shown and compared to the complete detector response simulation. This work shows the first direct reconstruction of neutron energy and fluence, simultaneously, at 27.2 keV in a continuous irradiation mode. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

What can neutron stars reveal about the equation of state of dense matter?

Neutron stars are astrophysical objects of extremes, reaching the highest densities we can observe in the cosmos, and probing matter under conditions that cannot be recreated in terrestrial experiments. In August 2017, the first neutron-star merger has been observed, which provided compelling evidence that these events are an important site for r-process nucleosynthesis. Furthermore, the gravitational-wave signal of such events might shed light upon the nature of strongly interacting matter in the neutron-star core. To understand these remarkable events, reliable nuclear physics input is essential. In this contribution, I explain how to use chiral effective field theory and advanced many-body methods to provide a consistent and systematic approach to strongly inter- acting systems from nuclei to neutron stars with controlled theoretical uncertainties. I will discuss recent results for the equation of state relevant for the nuclear astrophysics of neutron stars and neutron-star mergers.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Hybrid reduced order modeling for assembly calculations

While the accuracy of assembly calculations has considerably improved due to the increase in computer power enabling more refined description of the phase space and use of more sophisticated numerical algorithms, the computational cost continues to increase which limits the full utilization of their effectiveness for routine engineering analysis. Reduced order modeling is a mathematical vehicle that scales down the dimensionality of large-scale numerical problems to enable their repeated executions on small computing environment, often available to end users. This is done by capturing the most dominant underlying relationships between the model's inputs and outputs. Previous works demonstrated the use of the reduced order modeling for a single physics code, such as a radiation transport calculation. This manuscript extends those works to coupled code systems as currently employed in assembly calculations. Numerical tests are conducted using realistic SCALE assembly models with resonance self-shielding, neutron transport, and nuclides transmutation/depletion models representing the components of the coupled code system. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2015

Methodology comparison for gamma-heating calculations in material-testing reactors

The Jules Horowitz Reactor (JHR) is a Material-Testing Reactor (MTR) under construction in the south of France at CEA Cadarache (French Alternative Energies and Atomic Energy Commission). It will typically host about 20 simultaneous irradiation experiments in the core and in the beryllium reflector. These experiments will help us better understand the complex phenomena occurring during the accelerated ageing of materials and the irradiation of nuclear fuels. Gamma heating, i.e. photon energy deposition, is mainly responsible for temperature rise in non-fuelled zones of nuclear reactors, including JHR internal structures and irradiation devices. As temperature is a key parameter for physical models describing the behavior of material, accurate control of temperature, and hence gamma heating, is required in irradiation devices and samples in order to perform an advanced suitable analysis of future experimental results. From a broader point of view, JHR global attractiveness as a MTR depends on its ability to monitor experimental parameters with high accuracy, including gamma heating. Strict control of temperature levels is also necessary in terms of safety. As JHR structures are warmed up by gamma heating, they must be appropriately cooled down to prevent creep deformation or melting. Cooling-power sizing is based on calculated levels of gamma heating in the JHR. Due to these safety concerns, accurate calculation of gamma heating with well-controlled bias and associated uncertainty as low as possible is all the more important. There are two main kinds of calculation bias: bias coming from nuclear data on the one hand and bias coming from physical approximations assumed by computer codes and by general calculation route on the other hand. The former must be determined by comparison between calculation and experimental data; the latter by calculation comparisons between codes and between methodologies. In this presentation, we focus on this latter kind of bias. Nuclear heating is represented by the physical quantity called absorbed dose (energy deposition induced by particle-matter interactions, divided by mass). Its calculation with Monte Carlo codes is possible but computationally expensive as it requires transport simulation of charged particles, along with neutrons and photons. For that reason, the calculation of another physical quantity, called KERMA, is often preferred, as KERMA calculation with Monte Carlo codes only requires transport of neutral particles. However, KERMA is only an estimator of the absorbed dose and many conditions must be fulfilled for KERMA to be equal to absorbed dose, including so-called condition of electronic equilibrium. Also, Monte Carlo computations of absorbed dose still present some physical approximations, even though there is only a limited number of them. Some of these approximations are linked to the way how Monte Carlo codes apprehend the transport simulation of charged particles and the productive and destructive interactions between photons, electrons and positrons. There exists a huge variety of electromagnetic shower models which tackle this topic. Differences in the implementation of these models can lead to discrepancies in calculated values of absorbed dose between different Monte Carlo codes. The magnitude of order of such potential discrepancies should be quantified for JHR gamma-heating calculations. We consequently present a two-pronged plan. In a first phase, we intend to perform compared absorbed dose / KERMA Monte Carlo calculations in the JHR. This way, we will study the presence or absence of electronic equilibrium in the different JHR structures and experimental devices and we will give recommendations for the choice of KERMA or absorbed dose when calculating gamma heating in the JHR. In a second phase, we intend to perform compared TRIPOLI4 / MCNP absorbed dose calculations in a simplified JHR-representative geometry. For this comparison, we will use the same nuclear data library for both codes (the European library JEFF3.1.1 and photon library EPDL97) so as to isolate the effects from electromagnetic shower models on absorbed dose calculation. This way, we hope to get insightful feedback on these models and their implementation in Monte Carlo codes. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

Neutron-fragment and Neutron-neutron Correlations in Low-energy Fission

A computational method has been developed to simulate neutron emission from thermal-neutron induced fission of {sup 235}U and from spontaneous fission of {sup 252}Cf. Measured pre-emission mass-yield curves, average total kinetic energies and their variances, both as functions of mass split, are used to obtain a representation of the distribution of fragment velocities. Measured average neutron multiplicities as a function of mass split and their dependence on total kinetic energy are used. Simulations can be made to reproduce measured factorial moments of neutron-multiplicity distributions with only minor empirical adjustments to some experimental inputs. The neutron-emission spectra in the rest-frame of the fragments are highly constrained by ENDF/B-VII.1 prompt-fission neutron-spectra evaluations. The n-f correlation measurements of Vorobyev et al. (2010) are consistent with predictions where all neutrons are assumed to be evaporated isotropically from the rest frame of fully accelerated fragments. Measured n-f and n-n correlations of others are a little weaker than the predictions presented here. These weaker correlations could be used to infer a weak scission-neutron source. However, the effect of neutron scattering on the experimental results must be studied in detail before moving away from a null hypothesis that all neutrons are evaporated from the fragments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Radiation tolerance survey of selected silicon photomultipliers to high energy neutron irradiation

A key feature of silicon photomultipliers (SiPMs) that can hinder their wider use in medium and high energy physics applications is their relatively high sensitivity to high energy background radiation, with particular regard to high energy neutrons. Dosages of 1010 neq/cm2 can damage them severely. In this study, some standard versions along with some new formulations are irradiated with a high intensity 241AmBe source up to a total dose of 5 × 109 neq/cm2. Key parameters monitored include dark noise, photon detection efficiency (PDE), gain, and voltage breakdown. Only dark noise was found to change significantly for this range of dosage. Analysis of the data indicates that within each vendor's product line, the change in dark noise is very similar as a function of increasing dose. At present, the best strategy for alleviating the effects of radiation damage is to cool the devices to minimize the effects of increased dark noise with accumulated dose.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗