No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
A Fusion-Oriented Neutronics Modeling and Multiphysics Coupling System
Nuclear Science and Engineering
Abstract
A system has been developed to fulfill the entire coupled multiphysics analysis cycle for the design and analysis of complex fusion reactor components. It provides advanced modeling capability for converting computer-aided-design geometries to Monte Carlo (MC) geometries by employing constructive solid geometries and unstructured meshes. It also realizes the generic multiphysics coupling of the MC neutronics, computational fluid dynamics, and finite element thermal and structural analyses. This system is a seamless, extensible, and generic system that has been intensively verified for fusion applications.
... Partially, these γ photons are absorbed in the material, generating a fluctuating athermal dynamic steady-state population of high-energy electrons. Some of the energetic γ quanta escape from the materials back into the reactor environment, producing additional physical effects, different from those directly associated with neutron exposure [112,113]. ...
The effects of neutron irradiation on materials are often interpreted in terms of atomic recoils, initiated by neutron impacts and producing crystal lattice defects. In addition, there is a remarkable two-step process, strongly pronounced in the medium-weight and heavy elements. This process involves the generation of energetic γ photons in nonelastic collisions of neutrons with atomic nuclei, achieved via capture and inelastic reactions. Subsequently, high-energy electrons are excited through the scattering of γ photons by the atomic electrons. We derive and validate equations enabling a fast and robust evaluation of photon and electron fluxes produced by the neutrons in the bulk of materials. The two-step n-γ-e scattering creates a nonequilibrium dynamically fluctuating steady-state population of high-energy electrons, with the spectra of photon and electron energies extending well into the mega-electron-volt range. This stimulates vacancy diffusion through electron-triggered atomic recoils, primarily involving vacancy-impurity dissociation, even if thermal activation is ineffective. Tungsten converts the energy of fusion or fission neutrons into a flux of γ radiation at the conversion efficiency approaching 99%, with implications for structural materials, superconductors, and insulators, as well as phenomena like corrosion, and helium and hydrogen isotope retention.
... The code that we have developed, ENRICO (Exascale Nuclear Reactor Investigative COde), is to our knowledge the first such general code geared toward coupled neutronic and thermal-hydraulic calculations that meets these constraints. Qiu et al. describe a multiphysics coupling system designed for fusion energy applications that appears to be capable of handling multiple MC and CFD codes [15]; however, the coupling is done only in one direction, with the heat source from the MC code used as a source in the CFD solve. Data transfers were also done through file I/O rather than in memory. ...
While the literature has numerous examples of Monte Carlo and computational fluid dynamics (CFD) coupling, most are hard-wired codes intended primarily for research rather than as standalone, general-purpose codes. In this work, we describe an open source application, ENRICO, that allows coupled neutronic and thermal-hydraulic simulations between multiple codes that can be chosen at runtime (as opposed to a coupling between two specific codes). In particular, we outline the class hierarchy in ENRICO and show how it enables a clean separation between the logic and data required for a coupled simulation (which is agnostic to the individual solvers used) from the logic/data required for individual physics solvers. ENRICO also allows coupling between high-order (and generally computationally expensive) solvers to low-order “surrogate” solvers; for example, Nek5000 can be swapped out with a subchannel solver.
ENRICO has been designed for use on distributed-memory computing environments. The transfer of solution fields between solvers is performed in memory rather than through file I/O.We describe the process topology among the different solvers and how it is leveraged to carry out solution transfers. We present results for a coupled simulation of a single light-water reactor fuel assembly using Monte Carlo neutron transport and CFD.
... To our knowledge, ENRICO is the first such general code geared toward coupled neutronic and thermal-hydraulic (TH) calculations (using an MC solver for neutronics) that is capable of using multiple solvers for the same physics field (for example, switching between two different MC codes). Qiu et al. describe a multiphysics coupling system designed for fusion energy applications that appears to be capable of handling multiple MC and CFD codes 26 ; however, the coupling is done only in one direction, with the heat source from the MC code used as a source in the CFD solve. Data transfers were also done through file I/O rather than in memory. ...
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, general-purpose applications. In this work, we describe 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). The application has been designed such that the control flow logic, domain mapping, nonlinear fixed-point iteration, solution transfers, and convergence checks are all agnostic to the underlying physics solvers used. Special emphasis has also been placed on enabling efficient execution on distributed-memory computing environments. The transfer of solution fields between solvers is performed in memory rather than through filesystem input/output. Additionally, solvers can be configured to run on overlapping or disjoint sets of processes.
To date, coupling with the OpenMC and Shift MC codes, the Nek5000 CFD code, and a simplified heat diffusion and subchannel solver has been implemented in ENRICO. We present results for coupled simulations of a single light water reactor fuel assembly based on the NuScale reactor using various combinations of the physics solvers. For this problem, the coupled simulations are shown to converge in about four Picard iterations. A comparison of the heat source and temperature distributions computed by ENRICO using OpenMC coupled with Nek5000 and Shift coupled with Nek5000 illustrates remarkable agreement between the codes.
... An advanced neutronics multi-physics code coupling system is presented in [21]. It represents an interface system of CAD-based MC neutronics modelling in CSG and UM geometries integrated with computational fluid dynamics, finite element thermal and structural analyses. ...
MCNP6 is simply and accurately described as the merger of MCNP5 and MCNPX capabilities, but it is
much more than the sum of those two computer codes. MCNP6 is the result of five years of effort by the MCNP5
and MCNPX code development teams. These groups of people, residing in Los Alamos National Laboratory’s
(LANL) X Computational Physics Division, Monte Carlo Codes Group (XCP-3), and Decision Applications Division, Radiation Transport and Applications Team (D-5), respectively, have combined their code development efforts to produce the next evolution of MCNP.While maintenance and bug fixes will continue for MCNP5 1.60 and MCNPX 2.7.0 for upcoming years, new code development capabilities only will be developed and released in MCNP6. In fact, the initial release of MCNP6 contains 16 new features not previously found in either code. These new features include the abilities to import unstructured mesh geometries from the finite element code Abaqus, to transport photons down to 1.0 eV, to transport electrons down to 10.0 eV, to model complete atomic relaxation emissions, and to generate or read mesh geometries for use with the LANL discrete ordinates code Partisn. The first release of MCNP6, MCNP6 Beta 2, is now available through the Radiation Safety Information Computational Center, and the first production release is expected in calendar year 2012. High confidence in the MCNP6 code is based on its performance with the verification and validation test suites, comparisons to its predecessor codes, the regression test suite, its code development process, and the underlying high-quality nuclear and atomic databases.
McCad is a geometry conversion tool developed at KIT to enable the automatic bi-directional conversions of CAD models into the Monte Carlo (MC) geometries utilized for neutronics calculations (CAD to MC) and, reversed (MC to CAD), for visualization purposes. The paper presents the latest improvements of the conversion algorithms including improved decomposition, void filling and an advanced interface for the materials editing and assignment. The new implementations and features were tested on fusion neutronics applications to the DEMO and ITER NBI (Neutral Beam Injector) models. The results demonstrate greater stability and enhanced efficiency of McCad conversion process.
Since the transition from ITER or DEMO to a commercial power reactor would involve a significant change in system and materials options, a parallel R&D path has been put in place in Europe to address these issues. This paper assesses the structural materials part of this program along with the latest R&D results from the main programs. It is shown that stainless steels and ferritic/martensitic steels, retained for ITER and DEMO, will also remain the principal contenders for the future FPR, despite uncertainties over irradiation induced embrittlement at low temperatures and consequences of high He/dpa ratio. Neither one of the present advanced high temperature materials has to this date the structural integrity reliability needed for application in critical components. This situation is unlikely to change with the materials R&D alone and has to be mitigated in close collaboration with blanket system design.
Large computer networks such as corporate intranets and the
Internet are inherently heterogeneous due to such factors as
increasingly rapid technological change, engineering trade-offs,
accumulation of legacy systems over time, and varying system costs.
Unfortunately, such heterogeneity makes the development and maintenance
of applications that make the best use of such networks difficult. The
Common Object Request Broker Architecture specification created by the
Object Management Group provides a stable model for distributed
object-oriented systems that helps developers cope with heterogeneity
and inevitable change. Applications written to the CORBA standard are
abstracted away from underlying networking protocols and transports,
instead relying on object request brokers to provide a fast and flexible
communication and object activation substrated. The abstractions
provided by CORBA ORBs are currently serving as the basis for
applications in a wide variety of problem domains, including
telecommunications, finance, medicine, and manufacturing, running on
platforms ranging from mainframes down to test and measurement
equipment. This article first provides an overview of the Object
Management Architecture, then describes in detail the CORBA component of
that architecture, and concludes with a description of the OMG
organization along with some of its current and future work
MCNP-A General Monte Carlo N-Particle Transport Code, Version 5, Volume I,” LA-UR-03-1987
- Monte Carlo
- Team
salome-platform.org/user-section/about/med (current as of
- Salome Med Library
Current Status of the CAD Interface Program McCad for MC Particle Transport Calculations
- Grosse D Tsige H
3D modeling and numerical simulation
- Cascade Open
- Technology
Blanket Test Case Definition
- Kecskés S Boccaccini L
Nuclear Data Libraries for Advanced Systems-Fusion Devices
- Sawan M
TRIPOLI-4 R Version 8 User Guide
- Brun E
The MCNP6 Book on Unstructured Mesh Geometry: User Guide
- Martz R