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Showing papers in "Nuclear Science and Engineering in 2021"


Journal ArticleDOI
TL;DR: In this paper, the authors present a light water reactor simulation that is either high-fidelity, requiring hundreds of node-hours, or low fidelity, requiring only seconds to run on a common workstation.
Abstract: Traditional light water reactor simulations are usually either high fidelity, requiring hundreds of node-hours, or low fidelity, requiring only seconds to run on a common workstation. In current re...

14 citations


Journal ArticleDOI
TL;DR: In this paper, the optimization of measurement of environmental samples is achieved by putting the sample closer to the detector to increase the full-energy peak efficiency, which leads to decrease of the detecti...
Abstract: The optimization of measurement of environmental samples is achieved by putting the sample closer to the detector to increase the full-energy peak efficiency, which leads to decrease of the detecti...

11 citations


Journal ArticleDOI
TL;DR: A standard approach to solving the S N transport equations is to use source iteration with diffusion synthetic acceleration (DSA), which is widely used and effective on many probabilistic problems as mentioned in this paper.
Abstract: A standard approach to solving the S N transport equations is to use source iteration with diffusion synthetic acceleration (DSA). Although this approach is widely used and effective on many prob...

10 citations


Journal ArticleDOI
TL;DR: In this paper, new multiphysics coupling capabilities for molten salt reactor (MSR) analysis have been developed in the Virtual Environment for Reactor Applications (VERA), which consists of two main main components.
Abstract: New multiphysics coupling capabilities for molten salt reactor (MSR) analysis have been developed in the Virtual Environment for Reactor Applications (VERA). This development consisted of two main ...

10 citations


Journal ArticleDOI
TL;DR: In this paper, a variety of normal operation and accident scenarios can generate thermal stresses large enough to cause cracking in ceramic fuel pellets, which can lead to reduced heat removal in fuel pellets.
Abstract: A variety of normal operation and accident scenarios can generate thermal stresses large enough to cause cracking in ceramic fuel pellets. Cracking in fuel pellets can lead to reduced heat removal,...

9 citations


Journal ArticleDOI
TL;DR: The molten chloride salt fast reactor (MCFR) with Th-U fuel cycle is attracting more and more attention because of its excellent performance, such as high solubility of actinides, superior breeding and superior performance as mentioned in this paper.
Abstract: The molten chloride salt fast reactor (MCFR) with Th-U fuel cycle is attracting more and more attention because of its excellent performance, such as high solubility of actinides, superior breeding...

8 citations


Journal ArticleDOI
TL;DR: In this paper, the complex structure of a pool-type sodium-cooled fast reactor may lead to uncertainty and asymmetry of flow and temperature field distributions under a pump stuck accident.
Abstract: The complex structure of a pool-type sodium-cooled fast reactor may lead to uncertainty and asymmetry of flow and temperature field distributions under a pump stuck accident. This phenomenon has ob...

8 citations


Journal ArticleDOI
TL;DR: In this article, a beta radioluminescent battery with different radioisotopes is studied, and different parameters of the proposed structure are optimized, including the luminescent luminance.
Abstract: In this paper, a beta radioluminescent battery with different radioisotopes is studied, and different parameters of the proposed structure are optimized. These parameters include the luminescent la...

8 citations


Journal ArticleDOI
TL;DR: A methodology for estimating a key problem-dependent parameter, the feedback intensity, required by the nearly optimally partially converged coarse mesh finite difference (NOPC-CMFD) method is developed and observed to result in a substantial reduction, up to 40%, of the run time in whole-core cycle depletion problems.
Abstract: In a companion paper, we present the theoretical development of a new robust, relaxation-free iteration scheme for multiphysics k-eigenvalue problems. These types of problems are essential to the s...

8 citations


Journal ArticleDOI
TL;DR: Detailed verification and experimental validation of the formulations and algorithms of the Multi-stage Response-function Transport (MRT)–based Real-time Analysis for Particle-transport and In-situ Detection (RAPID) code system is presented.
Abstract: In this paper, detailed verification and experimental validation of the formulations and algorithms of the Multi-stage Response-function Transport (MRT)–based Real-time Analysis for Particle-transp...

7 citations


Journal ArticleDOI
TL;DR: In this article, the optimal batch size growth for the Wielandt method and the Superhistory method is proposed to accelerate the fission source convergence in a high dominance ratio system.
Abstract: Abstract In a high dominance ratio system, the problem of slow fission source convergence is faced during the Monte Carlo criticality calculation. The Wielandt method and the Superhistory method have been proven to reduce the dominance ratio. Still, the Wielandt method and the Superhistory method have also proven to be unable to accelerate the convergence of the fission source. With the estimation of errors in the cumulative fission source and the batch size optimization methodology, the optimal batch size growth for the Wielandt method and the Superhistory method is proposed. Compared with the direct simulation with the optimal batch size growth, the Wielandt simulation and the Superhistory simulation better use the optimal batch size growth. A single fuel rod model was tested, and the results show that the new method is helpful for the acceleration of fission source convergence.

Journal ArticleDOI
TL;DR: In this article, a robust scheme for coupled physics nuclear reactor calculations with coarse mesh finite difference is presented, focusing specifically on high-fidelity whole-core transport calculations with finite difference.
Abstract: This paper presents a new robust scheme for coupled physics nuclear reactor calculations. We focus specifically on high-fidelity whole-core transport calculations with coarse mesh finite difference...

Journal ArticleDOI
TL;DR: In this paper, the first 10 years (2011-2020) of radiation test object (RTO) operations at the National Criticality Experiments Research Center (NCE) were studied.
Abstract: The work presented in this paper focuses on the first 10 years (2011–2020) of radiation test object (RTO) operations at the National Criticality Experiments Research Center. RTOs are subcritical co...

Journal ArticleDOI
TL;DR: Yttrium hydride is considered as a moderator material for micro-reactor concepts because of its excellent hydrogen retainment capacity at high temperatures as mentioned in this paper, but it is not suitable for nuclear power plants.
Abstract: Yttrium hydride is being considered as a moderator material for microreactor concepts because of its excellent hydrogen retainment capacity at high temperatures. These types of reactors, operating ...

Journal ArticleDOI
Bin Zhang1, Jian Deng1, Maolin Jing1, Tao Xu1, Xiaowei Jiang1, Jianqiang Shan1 
TL;DR: A newly developed suppression pool model based on the self-developed severe accident analysis code Integrated Severe Accident Analysis (ISAA), which combines the advantages of the dedicated vent flow model and the SPARC-90 model to analyze the suppression pool’s thermal-hydraulic behavior is presented.
Abstract: The suppression pool is an important component in a boiling water reactor nuclear power plant. Under design-basis, loss-of-coolant accident conditions, pressure in the containment increases. Gas fl...

Journal ArticleDOI
TL;DR: In this article, a practical, practical, and implemening approach is proposed to evolve a dynamical system under extreme physical disorder toward the equilibrium state characterized by an inverse power law power spectrum.
Abstract: A dynamical system under extreme physical disorder has the tendency to evolve toward the equilibrium state characterized by an inverse power law power spectrum. In this paper, a practical, implemen...

Journal ArticleDOI
TL;DR: In this article, a cross-section adjustment method based on Bayesian theory was developed for adjusting the independent crosssection set that is given by dividing the cross-sectional set, while all cross sections hav...
Abstract: We developed a cross-section adjustment method based on Bayesian theory for adjusting the independent cross-section set that is given by dividing the cross-section set. While all cross sections hav...

Journal ArticleDOI
TL;DR: In this paper, the first 10 years (2011-2020) of the Godiva IV operation at the National Criticality Experiments Research Center (NCERC) were studied, focusing on the first five years of its operation at NCERC.
Abstract: The work presented in this paper focuses on the first 10 years (2011–2020) of Godiva IV operations at the National Criticality Experiments Research Center (NCERC). Godiva IV is a fast burst critica...

Journal ArticleDOI
TL;DR: The postulated dual-failure accident, i.e., loss of primary coolant flow along with impairment of the emergency coolant injection system, leads to peak fuel temperatures.
Abstract: The postulated dual-failure accident, i.e., loss of primary coolant flow along with impairment of the emergency coolant injection system, leads to peak fuel temperatures. It is well known that the ...

Journal ArticleDOI
TL;DR: In this article, the mass yield distribution in the epi-cadmium neutron-induced fission of 237Np has been carried out by measuring the cumulative yields of fission products within the mass ranges of 78 to 117 and 123 to 157.
Abstract: Abstract Mass yield distribution in the epi-cadmium neutron-induced fission of 237Np has been carried out by measuring the cumulative yields of fission products within the mass ranges of 78 to 117 and 123 to 157. A radiochemical and off-line gamma-ray spectrometric technique was used for the measurement. From the cumulative yields of the fission products, mass chain yields were obtained by applying the charge distribution correction. Mass yield distribution parameters such as the full-width at tenth-maximum of light and heavy mass wings, the peak-to-valley (P/V) ratio, and the average light mass and heavy mass () as well as the average number of neutrons were obtained. The mass yield data in the epi-cadmium neutron-induced fission of 237Np were compared with the similar data in thermal and 14.5- to 14.7-MeV neutrons to examine the role of excitation energy in nuclear structure effect and P/V ratio.

Journal ArticleDOI
Dean Wang1
TL;DR: In this paper, the linear prolongation coarse-mesh finite difference (lpCMFD) scheme was combined with the method of successive overrelaxation (SOR) for neutron t...
Abstract: We present the new iterative method lpCMFD-SOR, which combines the linear prolongation coarse-mesh finite difference (lpCMFD) scheme with the method of successive overrelaxation (SOR) for neutron t...

Journal ArticleDOI
TL;DR: In this article, uncertainty quantification of lead (Pb) and bismuth (Bi) sample reactivity worth is numerically determined using the SCALE6.2 code system and experimental results obtained from the solid-moderated...
Abstract: Uncertainty quantification of lead (Pb) and bismuth (Bi) sample reactivity worth is numerically determined using the SCALE6.2 code system and experimental results obtained from the solid-moderated ...

Journal ArticleDOI
TL;DR: An open source application, the Exascale Nuclear Reactor Investigative COde (ENRICO), which enables coupled neutronic and thermal-hydraulic simulations between multiple codes that can be chosen at run time (as opposed to a coupling between two specific codes).
Abstract: While the literature has numerous examples of Monte Carlo (MC) and computational fluid dynamics (CFD) coupling, most are hardwired codes intended primarily for research rather than as stand-alone, ...

Journal ArticleDOI
TL;DR: In this paper, the authors discussed the possibility of steam explosion and the formation of a debris bed when a molten corium jet falls into subcooled coolant during a severe accident of a nuclear plant.
Abstract: Jet fragmentation greatly influences the possibility of steam explosion and the formation of a debris bed when a molten corium jet falls into subcooled coolant during a severe accident of a nuclear...

Journal ArticleDOI
TL;DR: In this paper, a dynamic mode decomposition (DMD) is applied to time-series data obtained by the pulsed-neutron source (PNS) and Rossi-α methods to estimate the fundamental mode component of prompt neutron decay constant α in a subcritical system.
Abstract: Abstract To robustly estimate the fundamental mode component of prompt neutron decay constant α in a subcritical system, dynamic mode decomposition (DMD) is applied to time-series data obtained by the pulsed-neutron source (PNS) and Rossi-α methods. For the statistical uncertainty quantification of α by DMD, randomly sampled virtual data are used for the DMD procedure. The applicability of DMD is demonstrated by analyzing the experimental results by the PNS and Rossi-α methods, which are performed at the Kyoto University Critical Assembly (KUCA). When applying the DMD to the PNS and Rossi-α experimental data, a constant signal was added to the experimental data to remove the background constant component. The application results indicate that DMD enables one to robustly estimate the fundamental mode component of α in the PNS and Rossi-α methods.

Journal ArticleDOI
TL;DR: In this article, the thermal scattering law (TSL) for uranium and its compounds may be sensitive to crystal binding and Doppler broadening of epithermal neutron resonances.
Abstract: Scattering of thermal neutrons and Doppler broadening of epithermal neutron resonances in uranium and its compounds may be sensitive to crystal binding. The thermal scattering law (TSL) for uranium...

Journal ArticleDOI
TL;DR: In this article, a framework for evaluating thermal neutron scattering cross sections that provide S (α, β ) data and covariance data for hydrogen in light water is presented, and the cross-section is analyzed.
Abstract: This paper details and implements a framework for evaluating thermal neutron scattering cross sections that provide S ( α , β ) data and covariance data for hydrogen in light water. This methodolog...

Journal ArticleDOI
TL;DR: In this article, the authors proposed an approach called ICSCREAM (Identification of penalizing configurations using SCREening And Metamodel) to identify the critical configurations (or penalizing, in the sense of a prescribed safety margin) of several input parameters (called "scenario======inputs"), under the uncertainty on the other input parameters.
Abstract: In the framework of risk assessment in nuclear accident analysis, best-estimate computer codes, associated to a probabilistic modeling of the uncertain input variables, are used to estimate safety margins. A first step in such uncertainty quantification studies is often to identify the critical configurations (or penalizing, in the sense of a prescribed safety margin) of several input parameters (called “scenario inputs”), under the uncertainty on the other input parameters. However, the large CPU-time cost of most of the computer codes used in nuclear engineering, as the ones related to thermal-hydraulic accident scenario simulations, involve to develop highly efficient strategies. This work focuses on machine learning algorithms by the way of the metamodel-based approach (i.e., a mathematical model which is fitted on a small-size sample of simulations). To achieve it with a very large number of inputs, a specific and original methodology, called ICSCREAM (Identification of penalizing Configurations using SCREening And Metamodel), is proposed. The screening of influential inputs is based on an advanced global sensitivity analysis tool (HSIC importance measures). A Gaussian process metamodel is then sequentially built and used to estimate, within a Bayesian framework, the conditional probabilities of exceeding a high-level threshold, according to the scenario inputs. The efficiency of this methodology is illustrated on two high-dimensional (around a hundred inputs) thermal-hydraulic industrial cases simulating an accident of primary coolant loss in a pressurized water reactor. For both use cases, the study focuses on the peak cladding temperature (PCT) and critical configurations are defined by exceeding the 90%-quantile of PCT. In both cases, the ICSCREAM methodology allows to estimate, by using only around one thousand of code simulations, the impact of the scenario inputs and their critical areas of values.

Journal ArticleDOI
TL;DR: In this article, a meshed debonding model for tristructural isotropic (TRISO) fuel particles is introduced for better examining the potential effects of interface debonding.
Abstract: This work introduces a meshed debonding model intended for use with tristructural isotropic (TRISO) fuel particles. The ability to better examine the potential effects of interface debonding betwee...

Journal ArticleDOI
TL;DR: In this paper, the analytical discrete ordinates (ADODE) method is used to develop a solution to a one-dimensional model of particle transport in ducts that includes wall migration.
Abstract: Abstract The analytical discrete ordinates (ADO) method is used to develop a solution to a one-dimensional model of particle transport in ducts that includes wall migration. Particle reemission from the wall is described by a nonlocal, exponential displacement kernel. Since the governing transport equation of the model is not directly amenable to a solution by the ADO method, an alternative transport equation is derived first. For an approximation based on a half-range quadrature of order , the ADO solution of the alternative equation becomes available once techniques of linear algebra are used to solve a quadratic eigenproblem of order for the eigenvalues and eigenvectors. The solution is expressed as a superposition of 4N modes, which are constructed from 2N positive/negative pairs of separation constants (the reciprocals of the square roots of the eigenvalues) and associated eigenvectors. Compatibility conditions that the solution must satisfy in order to also solve the governing equation of the model result in a reduction of the number of relevant modes to 2N + 2, just two in excess of the number of modes in the solution of the problem without wall migration. Highly accurate numerical results for the reflection and transmission probabilities are reported for isotropic and monodirectional incidence.