Conveners
Thermal Neutron Scattering Law: I
- Daniel Siefman
Thermal Neutron Scattering Law: II
- Ayman Hawari
Thermal Neutron Scattering Law: III
- Giovanni Romanelli
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Gilles Noguere (CEA, DES, IRESNE Cadarache)28/07/2022, 06:00
The thermal scattering laws (TSLs) take into account the crystalline structure and atomic motions of isotopes bound in materials. This paper presents the CINEL code, which was developed to generate temperature-dependent TSLs for solid, liquid and free gas materials of interest for nuclear reactors.
CINEL is able to calculate TSLs from the phonon density of states (PDOS) of materials under...
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Giovanni Romanelli (Università degli Studi di Roma Tor Vergata and ISIS Neutron and Muon Source)28/07/2022, 06:24
Abstract
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Thermal neutron cross sections of hydrogenous materials are a fundamental ingredient for the simulation and design of, amongst other things, neutron moderators at research centres and nuclear reactors. However, experimental thermal cross sections are available for just a handful of materials (see, e.g., Ref. 1]). In order to match the level of detail in modern Monte Carlo nuclear... -
Dr Esben Klinkby (Seaborg Technologies)28/07/2022, 06:36
In recent years, molten salt reactor (MSR) concepts have seen renewed interest both within academia and emerging industry. Several widespread reactor concepts are developed, sharing the feature that the fissile fuel is dissolved in a molten fluoride or chloride salt which remains liquid over a wide temperature range at atmospheric pressure. One of the attractive features of MSRs is precisely...
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Douglas Di Julio (European Spallation Source ERIC)28/07/2022, 06:48
The design of neutron sources, using Monte-Carlo radiation transport codes, relies on the usage of thermal scattering libraries in the ACE format. These libraries are derived from models of neutron interactions in the materials of interest. We report here on the development of such libraries for applications related to cold and very-cold neutron sources [1]. For this purpose, we have used...
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Mr Jonathan P. W. Crozier (North Carolina State University)28/07/2022, 07:00
Uranium Carbide (UC) is a nuclear fuel material, whose crystal binding may affect doppler broadening of epithermal neutron absorption resonances and scattering behavior of thermal neutrons. Currently, there is no Thermal Scattering Law (TSL) evaluation for UC in the ENDF/B-VIII.0 database. Ab-initio lattice dynamics (AILD) techniques are used to calculate the phonon spectrum using...
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Dr Tanvir Ahmed (Department of Nuclear Engineering, North Carolina State University)28/07/2022, 07:12
Hydrogen fluoride (HF) is a material commonly used in nuclear fuel processing and manufacturing. As HF is commonly used directly in conjunction with various forms of uranium, an accurate representation of the thermal cross sections is vital to criticality safety. To generate the thermal scattering cross sections for HF, a classical molecular dynamics (MD) simulation of the flexible HF system...
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Yaron Danon (Rensselaer Polytechnic Institute)28/07/2022, 07:50
In recent years there has been resurgence in the field of thermal scattering law (TSL) evaluations and experiments. This comes after years that this field was dormant with little updates to ENDF evaluations. Evaluated TSL is based on atomistic calculations that in most cases results in a phonon spectrum that can be processed to create the scattering kernel for use in applications. The...
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Dr Daniel Siefman (Lawrence Livermore National Laboratory)28/07/2022, 08:14
Pulsed-neutron die-away experiments (PNDA) can be useful benchmarks to validate neutron thermal scattering laws (TSLs). The experiment uses a neutron generator to impinge a short (~10-4 s) mono-energetic neutron pulse on a target sample. After the pulse, the neutron population within the sample moderates and reaches thermal equilibrium with a fundamental spatial mode and characteristic...
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Dr Vaibhav Jaiswal (Institut de Radioprotection et de Sûreté Nucléaire (IRSN))28/07/2022, 08:26
Thermal scattering law for ice based on neutron time-of-flight experiments carried out at the SEQUOIA spectrometer at the Oak Ridge National Laboratory
Vaibhav Jaiswal$^{1,*}$, Luiz Leal$^1$, and Alexander I. Kolesnikov$^2$
$^1$Insititut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Roses, France
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$^2$Neutron Scattering Sciences Division, Oak Ridge National Laboratory,... -
Andrej Trkov28/07/2022, 08:38
Many transition metals react with hydrogen to form stable metal hydrides. Metal hydrides are technologically attractive materials because of their ability to store large amounts of hydrogen. There is considerable interest in zirconium hydrides in the nuclear industry because they are used as neutron moderators in nuclear reactors. TRIGA reactors have a unique fuel composition: a homogeneous...
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361. Advanced Modeling and Simulation Methods for Evaluation of Thermal Neutron Scattering MaterialsChris Chapman (Oak Ridge National Laboratory)28/07/2022, 08:50
With the rise of interest in thermal neutron scattering data for advanced reactor, criticality safety, and shielding applications, new experimental data is required both for evaluations of new materials or for re-evaluations (or validations) of previously evaluated materials. New experimental data is evaluated in a 3-step process: 1) computing the phonon characteristics (e.g....
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Dr Florencia Cantargi (Atomic Energy Commission of the Argentine Republic, Argentine Neutron Beam Laboratory, Argentina.)28/07/2022, 09:02
VESUVIO is a spectrometer at the ISIS Neutron and Muon Source, Rutherford Appleton Laboratory (United Kingdom) that allows the measurement of the total cross-section of a sample material by the transmission and time of flight techniques, over a range of five decades in energy (10$^{-3}$ to 10$^{2}$ eV). At the same time, it allows a precise determination of the effective temperature of each...
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Jose Ignacio Marquez Damian (European Spallation Source)28/07/2022, 09:40
NJOY+NCrystal is an open source tool which can be used to generate thermal neutron scattering libraries in a format that supports both coherent and incoherent elastic components for crystalline solids. The tool is based on a customized version of NJOY2016 [1] which calls the thermal scattering software NCrystal [2] for the calculation of the elastic components. The libraries can both be...
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Thomas Kittelmann (European Spallation Source ERIC)28/07/2022, 10:04
Initially born out of the needs of the ESS Detector Group to enhance the realism of thermal neutron scattering in Geant4-based detector design studies, the NCrystal project has grown into a generic backend for such modelling -- which is both flexible, efficient, and available under a liberal open source license. In this contribution we present the project, including both design philosophy, an...
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Dr N. Colby Fleming (Department of Nuclear Engineering, North Carolina State University)28/07/2022, 10:16
The Full Law Analysis Scattering System Hub (FLASSH) is an advanced code which evaluates the thermal scattering law (i.e. TSL, S($\alpha$,$\beta$)) for thermal scattering cross sections and resonance Doppler broadening. These features in the cross section are both fundamentally driven by target atom vibrations, which are impacted by the nature of the chemical binding and temperature of the...
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Paul Romano (Argonne National Laboratory)28/07/2022, 10:28
This paper describes methods for processing and use of thermal neutron scattering data in OpenMC. OpenMC relies on NJOY to process thermal scattering ENDF evaluations into ACE files, which are then converted to HDF5 files by OpenMC's Python API. This process is fully automated with OpenMC producing an NJOY input deck containing appropriate options for each module and covering every temperature...
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Mr Yongqiang Tang (Xi'an Jiaotong University)28/07/2022, 10:40
Accurately describing the scattering behavior of thermal neutrons can guarantee the accuracy of neutronics calculation. The thermal neutron scattering law (TSL) data is used to describe the scattering property of a materials. In this work, some efforts have been made to improve the accuracy of TSL data. The anisotropic displacement parameters method is used to remove the cubic approximation in...
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Dr Iyad Al-Qasir (Department of Mechanical and Nuclear Engineering, University of Sharjah, Sharjah 27272, UAE)
Graphite has been of significant scientific interest since the inauguration of nuclear technology, through the search for a high-purity grade to be used as a neutron moderator in Chicago-Pile 1, the first nuclear reactor. Currently, the Very High-Temperature Gas-Cooled Reactor is graphite-moderated and uses graphite as a significant structural component. Furthermore, nuclear graphite is a...
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