The Experts below are selected from a list of 1050 Experts worldwide ranked by ideXlab platform

Toru Obara - One of the best experts on this subject based on the ideXlab platform.

  • burnup performance of otto cycle Pebble Bed Reactors with rox fuel
    Annals of Nuclear Energy, 2015
    Co-Authors: Toru Obara
    Abstract:

    Abstract A Pebble Bed high-temperature gas-cooled reactor (PBR) with rock-like oxide (ROX) fuel was designed to achieve high discharged burnup and improve the integrity of the spent fuel in geological disposal. The MCPBR code with a JENDL-4.0 library, which developed the analysis of the Once-Through-Then-Out (OTTO) cycle in PBR, was used to perform the criticality and burnup analysis. Burnup calculations for eight cases were carried out for both ROX fuel and a UO 2 fuel reactor with different heavy-metal loading conditions. The effective multiplication factor of all cases approximately equalled unity in the equilibrium condition. The ROX fuel reactor showed lower FIFA than the UO 2 fuel reactor at the same heavy-metal loading, about 5–15%. However, the power peaking factor and maximum power per fuel ball in the ROX fuel core were lower than that of UO 2 fuel core. This effect makes it possible to compensate for the lower-FIFA disadvantage in a ROX fuel core. All reactor designs had a negative temperature coefficient that is needed for the passive safety features of a Pebble Bed reactor.

  • optimization of start up fuel management for otto cycle Pebble Bed reactor
    Energy Procedia, 2015
    Co-Authors: Topan Setiadipura, Toru Obara
    Abstract:

    Abstract Fuel management of once-through-then-out (OTTO) cycle Pebble Bed Reactors (PBR) was studied, in particular the start-up condition of the core before it achieves the equilibrium condition. Optimum and simple fuel management performance in the start-up condition is important for the practical deployment of PBR. There is no option for fuel re-insertion in an OTTO cycle PBR, hence nuclear fuel utilization is an important factor not only in the equilibrium condition but also in the start-up condition. The purpose of the study was to find an optimum procedure to improve burnup performance of fuel management in startup of the OTTO cycle PBR. Initial Heavy Metal (HM) loading in the core, power density, and multiplication factors were the main parameters investigated. The target of the analysis was a small sized 10MW PBR. A newly developed code system for OTTO cycle PBR was used. The code system is capable of performing neutron transport and depletion calculations of the OTTO cycle PBR covering whole of its fuel management scheme from initial loading to equilibrium condition. In this study, fuel composition in the start-up condition was limited to the same composition (a single enrichment) as the fuel in equilibrium condition for simplicity of the whole fuel management. The equilibrium condition of the PBR was investigated first. Based on the equilibrium condition two start-up fuel management schemes, a mixed and top-bottom scheme, were investigated. It was found that mixed scheme is better compare to top bottom scheme in achieving efficient HM-loading. Mixed scheme also gave a lower maximum power density. For the chosen target equilibrium design with 10wt% enrichment and 12g-HM/Pebble the minimum initial HM-loading using mixed and top-bottom scheme was 97.1 kg and 161.9 kg, respectively. While the maximum power density at that minimum initial loading was 4.5 W/cm 3 and 4.9 W/cm 3 , respectively.

  • development of monte carlo based Pebble Bed reactor fuel management code
    Annals of Nuclear Energy, 2014
    Co-Authors: Topan Setiadipura, Toru Obara
    Abstract:

    Abstract A fuel management code for Pebble Bed Reactors (PBRs) based on the Monte Carlo method has been developed in this study. The code, named Monte Carlo burnup analysis code for PBR (MCPBR), enables a simulation of the Once-Through-Then-Out (OTTO) cycle of a PBR from the running-in phase to the equilibrium condition. In MCPBR, a burnup calculation based on a continuous-energy Monte Carlo code, MVP-BURN, is coupled with an additional utility code to be able to simulate the OTTO cycle of PBR. MCPBR has several advantages in modeling PBRs, namely its Monte Carlo neutron transport modeling, its capability of explicitly modeling the double heterogeneity of the PBR core, and its ability to model different axial fuel speeds in the PBR core. Analysis at the equilibrium condition of the simplified PBR was used as the validation test of MCPBR. The calculation results of the code were compared with the results of diffusion-based fuel management PBR codes, namely the VSOP and PEBBed codes. Using JENDL-4.0 nuclide library, MCPBR gave a 4.15% and 3.32% lower k eff value compared to VSOP and PEBBed, respectively. While using JENDL-3.3, MCPBR gave a 2.22% and 3.11% higher k eff value compared to VSOP and PEBBed, respectively. The ability of MCPBR to analyze neutron transport in the top void of the PBR core and its effects was also confirmed.

  • new numerical method for equilibrium cycles of high conversion Pebble Bed Reactors
    Journal of Nuclear Science and Technology, 1991
    Co-Authors: Toru Obara, Hiroshi Sekimoto
    Abstract:

    A new code PREC2 was developed by modifying the PREC code to solve equilibrium OTTO cycle of the Pebble Bed reactor. The effective multiplication factor at the equilibrium cycle can be chosen as an input. The PREC2 code can analyze high-coverter (or breeder) Reactors, for which the calculations by the SOR-Newton method employed in the PREC code can not be converged.

R N Slaybaugh - One of the best experts on this subject based on the ideXlab platform.

  • multiscale thermal hydraulic modeling of the Pebble Bed fluoride salt cooled high temperature reactor
    Annals of Nuclear Energy, 2021
    Co-Authors: A J Novak, R N Slaybaugh, Sebastian Schunert, Robert W Carlsen, Paolo Balestra, Richard C Martineau
    Abstract:

    Abstract The complex core geometry of Pebble Bed Reactors (PBRs) necessitates multiscale techniques for fast-turnaround design and analysis. This paper describes the multiscale model implemented in the Pronghorn PBR simulation tool and demonstrates application to steady-state analysis of the Mark-1 Pebble Bed Fluoride-Salt-Cooled High-Temperature Reactor (PB-FHR). Verification of the Pebble model with fully-resolved heat conduction shows that material-wise Pebble temperatures are predicted to within 10°C over a wide range in thermal conditions. Anisotropic drag models are correlated for the outer reflector blocks using COMSOL, providing closures for modeling of bypass flows. With a porous media model of the outer reflectors, the core bypass fraction and fuel, reflector, and structural material temperatures are predicted for a number of different inflow conditions. This work demonstrates the full-core analysis capabilities of the Pronghorn application and enables comprehensive reactor analysis with the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework.

  • validation of pronghorn friction dominated porous media thermal hydraulics model with the sana experiments
    Nuclear Engineering and Design, 2019
    Co-Authors: A J Novak, J W Peterson, David Andrs, R N Slaybaugh, Richard C Martineau
    Abstract:

    Author(s): Novak, AJ; Peterson, JW; Zou, L; Andrs, D; Slaybaugh, RN; Martineau, RC | Abstract: © 2019 Elsevier B.V. A significant challenge in the core modeling of Pebble Bed Reactors (PBRs) is the complex fuel-coolant structure. At the expense of approximating local flow and heat transfer effects, porous media models can provide medium-fidelity predictions of complicated thermal-fluid systems with significantly less computational cost than high-fidelity Computational Fluid Dynamics (CFD) models. This paper presents a new porous media code, Pronghorn – a fast-running core simulator intended to accelerate the design and analysis cycle for PBRs and provide boundary conditions for systems-level analysis. This paper describes the physical models in Pronghorn and demonstrates the capability of a friction-dominated model for predicting gas-cooled PBR decay heat removal by presenting simulation results for all 52 of the steady-state axisymmetric German SANA experiments, which include two different fluids and three different types of Pebbles. The Pebble temperature in all 52 cases is predicted with a mean error (predicted minus experimental) of +22.6 °C with standard deviation of 54.6 °C. To demonstrate Pronghorn's capability for modeling Bed-to-plenum heat and mass transfer, one open-plenum SANA experimental case is also simulated. A code-to-code comparison with Flownex and GAMMA shows that Pronghorn is comparable in accuracy to other porous media simulation tools, with the additional advantages of 1) an arbitrary equation of state; 2) 3-D unstructured mesh capabilities; and 3) multiphysics coupling to other Multiphysics Object-Oriented Simulation Environment (MOOSE) applications. Finally, the effect of several porous media closure selections, in particular the porosity, the near-wall treatment for effective solid thermal conductivity, the interphase drag and heat transfer, and the fluid thermal dispersion, on temperature predictions are quantified.

  • Validation of Pronghorn friction-dominated porous media thermal-hydraulics model with the SANA experiments
    eScholarship University of California, 2019
    Co-Authors: A J Novak, J W Peterson, R N Slaybaugh, Zou L, Andrš D, Rc Martineau
    Abstract:

    © 2019 Elsevier B.V. A significant challenge in the core modeling of Pebble Bed Reactors (PBRs) is the complex fuel-coolant structure. At the expense of approximating local flow and heat transfer effects, porous media models can provide medium-fidelity predictions of complicated thermal-fluid systems with significantly less computational cost than high-fidelity Computational Fluid Dynamics (CFD) models. This paper presents a new porous media code, Pronghorn – a fast-running core simulator intended to accelerate the design and analysis cycle for PBRs and provide boundary conditions for systems-level analysis. This paper describes the physical models in Pronghorn and demonstrates the capability of a friction-dominated model for predicting gas-cooled PBR decay heat removal by presenting simulation results for all 52 of the steady-state axisymmetric German SANA experiments, which include two different fluids and three different types of Pebbles. The Pebble temperature in all 52 cases is predicted with a mean error (predicted minus experimental) of +22.6 °C with standard deviation of 54.6 °C. To demonstrate Pronghorn's capability for modeling Bed-to-plenum heat and mass transfer, one open-plenum SANA experimental case is also simulated. A code-to-code comparison with Flownex and GAMMA shows that Pronghorn is comparable in accuracy to other porous media simulation tools, with the additional advantages of 1) an arbitrary equation of state; 2) 3-D unstructured mesh capabilities; and 3) multiphysics coupling to other Multiphysics Object-Oriented Simulation Environment (MOOSE) applications. Finally, the effect of several porous media closure selections, in particular the porosity, the near-wall treatment for effective solid thermal conductivity, the interphase drag and heat transfer, and the fluid thermal dispersion, on temperature predictions are quantified

  • Validation of Pronghorn friction-dominated porous media thermal-hydraulics model with the SANA experiments
    eScholarship University of California, 2019
    Co-Authors: A J Novak, J W Peterson, R N Slaybaugh, Zou L, Andrš D, Rc Martineau
    Abstract:

    A significant challenge in the core modeling of Pebble Bed Reactors (PBRs) is the complex fuel-coolant structure. At the expense of approximating local flow and heat transfer effects, porous media models can provide medium-fidelity predictions of complicated thermal-fluid systems with significantly less computational cost than high-fidelity Computational Fluid Dynamics (CFD) models. This paper presents a new porous media code, Pronghorn – a fast-running core simulator intended to accelerate the design and analysis cycle for PBRs and provide boundary conditions for systems-level analysis. This paper describes the physical models in Pronghorn and demonstrates the capability of a friction-dominated model for predicting gas-cooled PBR decay heat removal by presenting simulation results for all 52 of the steady-state axisymmetric German SANA experiments, which include two different fluids and three different types of Pebbles. The Pebble temperature in all 52 cases is predicted with a mean error (predicted minus experimental) of +22.6 °C with standard deviation of 54.6 °C. To demonstrate Pronghorn's capability for modeling Bed-to-plenum heat and mass transfer, one open-plenum SANA experimental case is also simulated. A code-to-code comparison with Flownex and GAMMA shows that Pronghorn is comparable in accuracy to other porous media simulation tools, with the additional advantages of 1) an arbitrary equation of state; 2) 3-D unstructured mesh capabilities; and 3) multiphysics coupling to other Multiphysics Object-Oriented Simulation Environment (MOOSE) applications. Finally, the effect of several porous media closure selections, in particular the porosity, the near-wall treatment for effective solid thermal conductivity, the interphase drag and heat transfer, and the fluid thermal dispersion, on temperature predictions are quantified

  • Pronghorn: Porous media thermal-hydraulics for reactor applications
    eScholarship University of California, 2018
    Co-Authors: A J Novak, J W Peterson, Zou L, Rc Martineau, R N Slaybaugh
    Abstract:

    © 2018 American Nuclear Society. All rights reserved. Pebble Bed High Temperature Reactors (HTRs) are characterized by many advantageous design features, such as excellent passive heat removal in accidents and large margins to fuel failure. However, a significant challenge in thermal-hydraulic core modeling of Pebble Bed Reactors is the double heterogeneity random packing of hundreds of thousands of fuel Pebbles and thousands of fuel particles per Pebble. A new porous media thermal-hydraulics code, Pronghorn, is under development to provide a fast-running, medium-fidelity core simulator and serve as a bridge between low-resolution system level codes and high-resolution Computational Fluid Dynamics (CFD) codes for multiscale analysis. Pronghorn is based on the Mul-tiphysics Object-Oriented Simulation Environment (MOOSE) finite element framework, and permits an arbitrary equation of state, unstructured mesh capabilities, modern software design, and the ability to couple to MOOSE fuels performance and systems-level Thermal-Hydraulic (T/H) codes. To address the wide variety in gas- and liquid-cooled Pebble Bed reactor designs, Pronghorn includes several different flow models, each most appropriate to a range of compressibilities and operating conditions. This paper reviews benchmarking efforts of a low-advection flow model appropriate for Loss of Forced Circulation (LOFC) simulations and introduces the new fully compressible flow model with preliminary validation by comparison to potential flow theory for low Mach number flow over a cylinder

Abderrafi M. Ougouag - One of the best experts on this subject based on the ideXlab platform.

  • computational and experimental prediction of dust production in Pebble Bed Reactors part ii
    Nuclear Engineering and Design, 2013
    Co-Authors: Mie Hiruta, Maziar Rostamian, Gabriel P. Potirniche, Abderrafi M. Ougouag, Gannon Johnson, Massimo F Bertino, L Franzel, Akira Tokuhiro
    Abstract:

    This paper describes the computational modeling and simulation, and experimental testing of graphite moderators in frictional contacts as anticipated in a Pebble Bed reactor. The potential of carbonaceous particulate generation due to frictional contact at the surface of Pebbles and the ensuing entrainment and transport into the gas coolant are safety concerns at elevated temperatures under accident scenarios such as air ingress in the high temperature gas-cooled reactor. The safety concerns are due to the documented ability of carbonaceous particulates to adsorb fission products and transport them in the primary circuit of the Pebble Bed reactor, thus potentially giving rise to a relevant source term under accident scenarios. Here, a finite element approach is implemented to develop a nonlinear wear model in air environment. In this model, material wear coefficient is related to the changes in asperity height during wear. The present work reports a comparison between the finite element simulations and the experimental results obtained using a custom-designed tribometer. The experimental and computational results are used to estimate the quantity of nuclear grade graphite dust produced from a typical anticipated configuration. In Part II, results from a helium environment at higher temperatures and pressures are experimentally studied.

  • computational prediction of dust production in Pebble Bed Reactors
    Nuclear Engineering and Design, 2012
    Co-Authors: Maziar Rostamian, Gabriel P. Potirniche, Abderrafi M. Ougouag, Joshua J. Cogliati, Akira Tokuhiro
    Abstract:

    Abstract This paper describes the computational modeling and simulation of graphite Pebbles in frictional contacts as anticipated in a Pebble Bed reactor. For the high temperature gas-cooled reactor, the potential dust generation from frictional contact at the surface of Pebbles and the subsequent lift-off and transport of dust and absorBed fission products are of safety concern at elevated temperatures under an air ingress accident. The aim of this work is to perform a computational study to estimate the quantity of the nuclear grade graphite dust produces from a typical anticipated configuration.

  • final report on utilization of tru triso fuel as applied to htr systems part i Pebble Bed Reactors
    2011
    Co-Authors: B. Boer, Abderrafi M. Ougouag
    Abstract:

    The Deep-Burn (DB) concept [ ] focuses on the destruction of transuranic nuclides from used light water reactor (LWR) fuel. These transuranic nuclides are incorporated into tri-isotopic (TRISO) coated fuel particles and used in gas-cooled Reactors with the aim of a fractional fuel burnup of 60 to 70% in fissions per initial metal atom (FIMA). This high performance is expected through the use of multiple recirculation passes of the fuel in Pebble form without any physical or chemical changes between passes. In particular, the concept does not call for reprocessing of the fuel between passes. In principle, the DB Pebble Bed concept employs the same reactor designs as the presently envisioned low-enriched uranium core designs, such as the 400 MWth Pebble Bed Modular Reactor (PBMR-400) [ ]. Although it has been shown in the previous Fiscal Year (FY) (2009) that a PuO2 fueled Pebble Bed reactor concept is viable, achieving a high fuel burnup while remaining within safety-imposed prescriBed operational limits for fuel temperature, power peaking, and temperature reactivity feedback coefficients for the entire temperature range, is challenging. The presence of the isotopes 239Pu, 240Pu, and 241Pu that have resonances in the thermal energy range significantly modifies the neutron thermal energy spectrum as compared to a standard, UO2-fueled core. Therefore, the DB Pebble Bed core exhibits a relatively hard neutron energy spectrum. However, regions within the Pebble Bed that are near the graphite reflectors experience a locally softer spectrum. This can lead to power and temperature peaking in these regions. Furthermore, a shift of the thermal energy spectrum with increasing temperature can lead to increased absorption in the resonances of the fissile Pu isotopes. This can lead to a positive temperature reactivity coefficient for the graphite moderator under certain operating conditions. Regarding the coated particle performance, the FY 2009 investigations showed that no significant failure is to be expected for the reference fuel particle during normal operation. It was found, however, that the sensitivity of the coating stress to the CO production in the kernel was large. The CO production is expected to be higher in DB fuel than in UO2 fuel, but its exact level has a high uncertainty. Furthermore, in the fuel performance analysis transient conditions were not yet taken into account. The effort of this task in FY 2010 has focused on the optimization of the core to maximize the Pebble discharge burnup level, while retaining its inherent safety characteristics. Using generic Pebble Bed reactor cores, this task will perform physics calculations to evaluate the capabilities of the Pebble Bed reactor to perform utilization and destruction of LWR used-fuel transuranics. The task will use established benchmarked models, and will introduce modeling advancements appropriate to the nature of the fuel considered (high transuranic [TRU] content and high burn-up). Accomplishments of this work include: •Core analysis of a HTR-MODULE design loaded with Deep-Burn fuel. •Core analysis of a HTR-MODULE design loaded with Deep-Burn fuel and Uranium. •Core analysis of a HTR-MODULE design loaded with Deep-Burn fuel and Modified Open Cycle Components. •Core analysis of a HTR-MODULE design loaded with Deep-Burn fuel and Americium targets.

  • Survey of dust production in Pebble Bed reactor cores
    Nuclear Engineering and Design, 2011
    Co-Authors: Joshua J. Cogliati, Abderrafi M. Ougouag, Javier Ortensi
    Abstract:

    Graphite dust produced via mechanical wear from the Pebbles in a Pebble Bed reactor is an area of concern for licensing. Both the German Pebble Bed Reactors produced graphite dust that contained activated elements. These activation products constitute an additional source term of radiation and must be taken under consideration during the conduct of accident analysis of the design. This paper discusses the available literature on graphite dust production and measurements in Pebble Bed Reactors. Limited data is available on the graphite dust produced from the AVR and THTR-300 Pebble Bed Reactors. Experiments that have been performed on wear of graphite in Pebble-Bed-like conditions are reviewed. The calculation of contact forces, which are a key driving mechanism for dust in the reactor, are also included. In addition, prior graphite dust predictions are examined, and future areas of research are identified.

  • spectral zone selection methodology for Pebble Bed Reactors
    Annals of Nuclear Energy, 2011
    Co-Authors: Ramatsemela Mphahlele, Abderrafi M. Ougouag, Kostadin Ivanov, Hans D Gougar
    Abstract:

    A methodology is developed for determining boundaries of spectral zones for Pebble Bed Reactors. A spectral zone is defined as a region made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. The spectral zones are selected in such a manner that the difference (error) between the reference transport solution and the diffusion code solution takes a minimum value. This is achieved by choosing spectral zones through optimally minimizing this error. The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates errors in each zone. The selection of these spectral zones is such that the core calculation results based on diffusion theory are within an acceptable tolerance as compared to a proper transport reference solution. Through this work, a consistent approach for identifying spectral zones that yield more accurate diffusion results is introduced.

A J Novak - One of the best experts on this subject based on the ideXlab platform.

  • multiscale thermal hydraulic modeling of the Pebble Bed fluoride salt cooled high temperature reactor
    Annals of Nuclear Energy, 2021
    Co-Authors: A J Novak, R N Slaybaugh, Sebastian Schunert, Robert W Carlsen, Paolo Balestra, Richard C Martineau
    Abstract:

    Abstract The complex core geometry of Pebble Bed Reactors (PBRs) necessitates multiscale techniques for fast-turnaround design and analysis. This paper describes the multiscale model implemented in the Pronghorn PBR simulation tool and demonstrates application to steady-state analysis of the Mark-1 Pebble Bed Fluoride-Salt-Cooled High-Temperature Reactor (PB-FHR). Verification of the Pebble model with fully-resolved heat conduction shows that material-wise Pebble temperatures are predicted to within 10°C over a wide range in thermal conditions. Anisotropic drag models are correlated for the outer reflector blocks using COMSOL, providing closures for modeling of bypass flows. With a porous media model of the outer reflectors, the core bypass fraction and fuel, reflector, and structural material temperatures are predicted for a number of different inflow conditions. This work demonstrates the full-core analysis capabilities of the Pronghorn application and enables comprehensive reactor analysis with the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework.

  • validation of pronghorn friction dominated porous media thermal hydraulics model with the sana experiments
    Nuclear Engineering and Design, 2019
    Co-Authors: A J Novak, J W Peterson, David Andrs, R N Slaybaugh, Richard C Martineau
    Abstract:

    Author(s): Novak, AJ; Peterson, JW; Zou, L; Andrs, D; Slaybaugh, RN; Martineau, RC | Abstract: © 2019 Elsevier B.V. A significant challenge in the core modeling of Pebble Bed Reactors (PBRs) is the complex fuel-coolant structure. At the expense of approximating local flow and heat transfer effects, porous media models can provide medium-fidelity predictions of complicated thermal-fluid systems with significantly less computational cost than high-fidelity Computational Fluid Dynamics (CFD) models. This paper presents a new porous media code, Pronghorn – a fast-running core simulator intended to accelerate the design and analysis cycle for PBRs and provide boundary conditions for systems-level analysis. This paper describes the physical models in Pronghorn and demonstrates the capability of a friction-dominated model for predicting gas-cooled PBR decay heat removal by presenting simulation results for all 52 of the steady-state axisymmetric German SANA experiments, which include two different fluids and three different types of Pebbles. The Pebble temperature in all 52 cases is predicted with a mean error (predicted minus experimental) of +22.6 °C with standard deviation of 54.6 °C. To demonstrate Pronghorn's capability for modeling Bed-to-plenum heat and mass transfer, one open-plenum SANA experimental case is also simulated. A code-to-code comparison with Flownex and GAMMA shows that Pronghorn is comparable in accuracy to other porous media simulation tools, with the additional advantages of 1) an arbitrary equation of state; 2) 3-D unstructured mesh capabilities; and 3) multiphysics coupling to other Multiphysics Object-Oriented Simulation Environment (MOOSE) applications. Finally, the effect of several porous media closure selections, in particular the porosity, the near-wall treatment for effective solid thermal conductivity, the interphase drag and heat transfer, and the fluid thermal dispersion, on temperature predictions are quantified.

  • Validation of Pronghorn friction-dominated porous media thermal-hydraulics model with the SANA experiments
    eScholarship University of California, 2019
    Co-Authors: A J Novak, J W Peterson, R N Slaybaugh, Zou L, Andrš D, Rc Martineau
    Abstract:

    © 2019 Elsevier B.V. A significant challenge in the core modeling of Pebble Bed Reactors (PBRs) is the complex fuel-coolant structure. At the expense of approximating local flow and heat transfer effects, porous media models can provide medium-fidelity predictions of complicated thermal-fluid systems with significantly less computational cost than high-fidelity Computational Fluid Dynamics (CFD) models. This paper presents a new porous media code, Pronghorn – a fast-running core simulator intended to accelerate the design and analysis cycle for PBRs and provide boundary conditions for systems-level analysis. This paper describes the physical models in Pronghorn and demonstrates the capability of a friction-dominated model for predicting gas-cooled PBR decay heat removal by presenting simulation results for all 52 of the steady-state axisymmetric German SANA experiments, which include two different fluids and three different types of Pebbles. The Pebble temperature in all 52 cases is predicted with a mean error (predicted minus experimental) of +22.6 °C with standard deviation of 54.6 °C. To demonstrate Pronghorn's capability for modeling Bed-to-plenum heat and mass transfer, one open-plenum SANA experimental case is also simulated. A code-to-code comparison with Flownex and GAMMA shows that Pronghorn is comparable in accuracy to other porous media simulation tools, with the additional advantages of 1) an arbitrary equation of state; 2) 3-D unstructured mesh capabilities; and 3) multiphysics coupling to other Multiphysics Object-Oriented Simulation Environment (MOOSE) applications. Finally, the effect of several porous media closure selections, in particular the porosity, the near-wall treatment for effective solid thermal conductivity, the interphase drag and heat transfer, and the fluid thermal dispersion, on temperature predictions are quantified

  • Validation of Pronghorn friction-dominated porous media thermal-hydraulics model with the SANA experiments
    eScholarship University of California, 2019
    Co-Authors: A J Novak, J W Peterson, R N Slaybaugh, Zou L, Andrš D, Rc Martineau
    Abstract:

    A significant challenge in the core modeling of Pebble Bed Reactors (PBRs) is the complex fuel-coolant structure. At the expense of approximating local flow and heat transfer effects, porous media models can provide medium-fidelity predictions of complicated thermal-fluid systems with significantly less computational cost than high-fidelity Computational Fluid Dynamics (CFD) models. This paper presents a new porous media code, Pronghorn – a fast-running core simulator intended to accelerate the design and analysis cycle for PBRs and provide boundary conditions for systems-level analysis. This paper describes the physical models in Pronghorn and demonstrates the capability of a friction-dominated model for predicting gas-cooled PBR decay heat removal by presenting simulation results for all 52 of the steady-state axisymmetric German SANA experiments, which include two different fluids and three different types of Pebbles. The Pebble temperature in all 52 cases is predicted with a mean error (predicted minus experimental) of +22.6 °C with standard deviation of 54.6 °C. To demonstrate Pronghorn's capability for modeling Bed-to-plenum heat and mass transfer, one open-plenum SANA experimental case is also simulated. A code-to-code comparison with Flownex and GAMMA shows that Pronghorn is comparable in accuracy to other porous media simulation tools, with the additional advantages of 1) an arbitrary equation of state; 2) 3-D unstructured mesh capabilities; and 3) multiphysics coupling to other Multiphysics Object-Oriented Simulation Environment (MOOSE) applications. Finally, the effect of several porous media closure selections, in particular the porosity, the near-wall treatment for effective solid thermal conductivity, the interphase drag and heat transfer, and the fluid thermal dispersion, on temperature predictions are quantified

  • Pronghorn: Porous media thermal-hydraulics for reactor applications
    eScholarship University of California, 2018
    Co-Authors: A J Novak, J W Peterson, Zou L, Rc Martineau, R N Slaybaugh
    Abstract:

    © 2018 American Nuclear Society. All rights reserved. Pebble Bed High Temperature Reactors (HTRs) are characterized by many advantageous design features, such as excellent passive heat removal in accidents and large margins to fuel failure. However, a significant challenge in thermal-hydraulic core modeling of Pebble Bed Reactors is the double heterogeneity random packing of hundreds of thousands of fuel Pebbles and thousands of fuel particles per Pebble. A new porous media thermal-hydraulics code, Pronghorn, is under development to provide a fast-running, medium-fidelity core simulator and serve as a bridge between low-resolution system level codes and high-resolution Computational Fluid Dynamics (CFD) codes for multiscale analysis. Pronghorn is based on the Mul-tiphysics Object-Oriented Simulation Environment (MOOSE) finite element framework, and permits an arbitrary equation of state, unstructured mesh capabilities, modern software design, and the ability to couple to MOOSE fuels performance and systems-level Thermal-Hydraulic (T/H) codes. To address the wide variety in gas- and liquid-cooled Pebble Bed reactor designs, Pronghorn includes several different flow models, each most appropriate to a range of compressibilities and operating conditions. This paper reviews benchmarking efforts of a low-advection flow model appropriate for Loss of Forced Circulation (LOFC) simulations and introduces the new fully compressible flow model with preliminary validation by comparison to potential flow theory for low Mach number flow over a cylinder

Richard C Martineau - One of the best experts on this subject based on the ideXlab platform.

  • multiscale thermal hydraulic modeling of the Pebble Bed fluoride salt cooled high temperature reactor
    Annals of Nuclear Energy, 2021
    Co-Authors: A J Novak, R N Slaybaugh, Sebastian Schunert, Robert W Carlsen, Paolo Balestra, Richard C Martineau
    Abstract:

    Abstract The complex core geometry of Pebble Bed Reactors (PBRs) necessitates multiscale techniques for fast-turnaround design and analysis. This paper describes the multiscale model implemented in the Pronghorn PBR simulation tool and demonstrates application to steady-state analysis of the Mark-1 Pebble Bed Fluoride-Salt-Cooled High-Temperature Reactor (PB-FHR). Verification of the Pebble model with fully-resolved heat conduction shows that material-wise Pebble temperatures are predicted to within 10°C over a wide range in thermal conditions. Anisotropic drag models are correlated for the outer reflector blocks using COMSOL, providing closures for modeling of bypass flows. With a porous media model of the outer reflectors, the core bypass fraction and fuel, reflector, and structural material temperatures are predicted for a number of different inflow conditions. This work demonstrates the full-core analysis capabilities of the Pronghorn application and enables comprehensive reactor analysis with the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework.

  • PBMR-400 BENCHMARK SOLUTION OF EXERCISE 1 AND 2 USING THE MOOSE BASED APPLICATIONS: MAMMOTH, PRONGHORN
    'EDP Sciences', 2021
    Co-Authors: Paolo Balestra, Sebastian Schunert, Robert W Carlsen, April J Novak, Mark D Dehart, Richard C Martineau
    Abstract:

    High temperature gas cooled Reactors (HTGR) are a candidate for timely Gen-IV reactor technology deployment because of high technology readiness and walk-away safety. Among HTGRs, Pebble Bed Reactors (PBRs) have attractive features such as low excess reactivity and online refueling. Pebble Bed Reactors pose unique challenges to analysts and reactor designers such as continuous burnup distribution depending on Pebble motion and recirculation, radiative heat transfer across a variety of gas-filled gaps, and long design basis transients such as pressurized and depressurized loss of forced circulation. Modeling and simulation is essential for both the PBR’s safety case and design process. In order to verify and validate the new generation codes the Nuclear Energy Agency (NEA) Data bank provide a set of benchmarks data together with solutions calculated by the participants using the state of the art codes of that time. An important milestone to test the new PBR simulation codes is the OECD NEA PBMR-400 benchmark which includes thermal hydraulic and neutron kinetic standalone exercises as well as coupled exercises and transients scenarios. In this work, the reactor multiphysics code MAMMOTH and the thermal hydraulics code Pronghorn, both developed by the Idaho National Laboratory (INL) within the multiphysics object-oriented simulation environment (MOOSE), have been used to solve Phase 1 exercises 1 and 2 of the PBMR-400 benchmark. The steady state results are in agreement with the other participants’ solutions demonstrating the adequacy of MAMMOTH and Pronghorn for simulating PBRs

  • validation of pronghorn friction dominated porous media thermal hydraulics model with the sana experiments
    Nuclear Engineering and Design, 2019
    Co-Authors: A J Novak, J W Peterson, David Andrs, R N Slaybaugh, Richard C Martineau
    Abstract:

    Author(s): Novak, AJ; Peterson, JW; Zou, L; Andrs, D; Slaybaugh, RN; Martineau, RC | Abstract: © 2019 Elsevier B.V. A significant challenge in the core modeling of Pebble Bed Reactors (PBRs) is the complex fuel-coolant structure. At the expense of approximating local flow and heat transfer effects, porous media models can provide medium-fidelity predictions of complicated thermal-fluid systems with significantly less computational cost than high-fidelity Computational Fluid Dynamics (CFD) models. This paper presents a new porous media code, Pronghorn – a fast-running core simulator intended to accelerate the design and analysis cycle for PBRs and provide boundary conditions for systems-level analysis. This paper describes the physical models in Pronghorn and demonstrates the capability of a friction-dominated model for predicting gas-cooled PBR decay heat removal by presenting simulation results for all 52 of the steady-state axisymmetric German SANA experiments, which include two different fluids and three different types of Pebbles. The Pebble temperature in all 52 cases is predicted with a mean error (predicted minus experimental) of +22.6 °C with standard deviation of 54.6 °C. To demonstrate Pronghorn's capability for modeling Bed-to-plenum heat and mass transfer, one open-plenum SANA experimental case is also simulated. A code-to-code comparison with Flownex and GAMMA shows that Pronghorn is comparable in accuracy to other porous media simulation tools, with the additional advantages of 1) an arbitrary equation of state; 2) 3-D unstructured mesh capabilities; and 3) multiphysics coupling to other Multiphysics Object-Oriented Simulation Environment (MOOSE) applications. Finally, the effect of several porous media closure selections, in particular the porosity, the near-wall treatment for effective solid thermal conductivity, the interphase drag and heat transfer, and the fluid thermal dispersion, on temperature predictions are quantified.

  • tightly coupled multiphysics algorithms for Pebble Bed Reactors
    Nuclear Science and Engineering, 2010
    Co-Authors: Hyeongkae Park, D A Knoll, Derek R Gaston, Richard C Martineau
    Abstract:

    We have developed a tightly coupled multiphysics simulation tool for the Pebble Bed reactor (PBR) concept, a specific type of very high temperature gas-cooled reactor. The simulation tool PRONGHORN...

  • tightly coupled multiphysics algorithms for Pebble Bed Reactors
    Nuclear Science and Engineering, 2010
    Co-Authors: Hyeongkae Park, D A Knoll, Derek Gaston, Richard C Martineau
    Abstract:

    We have developed a tightly coupled multiphysics simulation tool for the Pebble-Bed reactor (PBR) concept, a type of Very High-Temperature gas-cooled Reactor (VHTR). The simulation tool, PRONGHORN, takes advantages of the Multiphysics Object-Oriented Simulation Environment library, and is capable of solving multidimensional thermal-fluid and neutronics problems implicitly with a Newton-based approach. Expensive Jacobian matrix formation is alleviated via the Jacobian-free Newton-Krylov method, and physics-based preconditioning is applied to minimize Krylov iterations. Motivation for the work is provided via analysis and numerical experiments on simpler multiphysics reactor models. We then provide detail of the physical models and numerical methods in PRONGHORN. Finally, PRONGHORN's algorithmic capability is demonstrated on a number of PBR test cases.