Virginia Tech Transport Theory Group (VT3G)

The Virginia Tech Transport Theory Group (VT³G), led by Dr. Alireza Haghighat, is engaged in the development of hybrid, 3-D, multi-scale, parallel particle transport algorithms and codes, and their applications to nuclear energy, nuclear security and non-proliferation and radiation therapy.

In order to make neutronics codes beneficial for design and the operational phases of the nuclear industry, these codes should be accurate and efficient to allow for fast assessment of quantities and real-time analysis of their distributions within a nuclear system. This, however, often comes at the expense of the accuracy of such codes. The recent development of RAPID, however, is a game changer, as it provides detailed solutions in real-time using a single computer core. With its web application, VRS-RAPID, a real-time simulation can be performed on a laptop or smart phone.

The RAPID code system has various applications such as reactor physics, nuclear power plant design, material accountability, particle shielding & detection, nuclear medicine.

CLICK HERE for a presentation on 'Computational Particle Transport theory and Achieving Solutions in Real Time' by Prof. Haghighat

CLICK HERE for an overview of 'RAPID Code System,' its capabilities and applications.

Experimental benchmarking of the RAPID code system and its comparison to the Serpent Monte Carlo predictions

Above figures show that RAPID calculated reaction rates of Gold dosimeters positioned axially (within the core of the JSI TRIGA reactor) are in excellent agreement with the measured data. Similar results are achieved by the Serpent Monte Carlo code, but significantly larger uncertainties.

These additional diagrams demonstrate that RAPID results in excellent agreement with experimental data.

Computational time - RAPID vs. Serpent

The above table demonstrate that RAPID yields accurate results in significantly (several orders of magnitude) shorter time than the Serpent code.

Research Topics

Code development

Multi-stage, Response-function particle Transport (MRT) methodologies (see information on MRT and RAPID)
Hybrid parallel numerical (S_n, Method of Characteristic, Ray-Tracing & Fictitious Quadrature) particle transport theory methods
Automated variance reduction techniques for fixed-source and eigenvalue Monte Carlo calculations, e.g., CADIS - Consistent Adjoint Driven Importance Sampling
Development of advanced particle transport codes: PENTRAN, TITAN, A3MCNP, INSPCT-s, AIMS, TITAN-IR, RAPID.
Development and benchmarking of new algorithms for the RAPID code-system for: nuclear fuel burnup (bRAPID), MRT-based detector response (DRF-RAPID), and transient particle transport simulations (tRAPID).
Development of mesh and input generator for PENTRAN and TITAN code system, PENMSHXP
Development of a collaborative Virtual Reality Systems (VRS) for Scientific Computing.

Applications of modeling and simulation algorithms and codes

Nuclear power, security and nonproliferation, and medicine
Advanced reactor core designs (molten salt and solid fuel)
Reactor physics and shielding
Image reconstruction in medical devices
Generation of multigroup nuclear cross sections
Sensitivity, perturbation methods and uncertainty quantification

MRT Methodology

The VT³G efforts in code and algorithms development and 31-years long know-how has culminated in the establishment of the physics-based Multi-stage Response-function Transport (MRT) methodology. In this methodology, the analysis of a complex nuclear system is partitioned into stages. For each stage, response functions or coefficients are pre-calculated once with a large amount of detail within a range of validity of certain parameters. These coefficients are then coupled by means of a linear system of equations that is solved in real-time, allowing for the calculation of a wide number of different cases within the database validity range.

The Real-time Simulation for Particle Transport and In-situ Detection (RAPID) Code System is based on the MRT methodology. For further information on RAPID please visit the RAPID website.

VT³G Code & Algorithms Timeline

Collaborations

Virginia Tech Centers & Groups

Collaboration with the ICTAS' Global Energy and Materials Initiative for the establishment of the Multiphysics for Advanced Reactors Simulation (MARS) Center.
Collaboration with the VT's Center for Neutrino Physics for modeling and optimization of the CHANDLER Detector.
Collaboration with the ARC Visionarium for the creation of a Virtual Reality System for the code VT³G's code RAPID, known as VRS-RAPID.

Universities and National Labs

Georgia Institute of Technology
Idaho National Lab
Idaho State University
Massachusetts Institute of Technology
North Carolina State University
Oak Ridge National Lab
Ohio State University
Paul Scherrer Institute, Switzerland
Politecnico di Torino, Italy

Industry
Framatome
Holtec International
Southern Nuclear
TerraPower
Westinghouse

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Publications

Journal Articles

V. Mascolino, A. Haghighat, and N. Roskoff, “Evaluation of RAPID for a UNF Cask Benchmark Problem,” EPJ Web of Conferences, EDP Sciences, 153, 05025, 2017. DOI: 10.1051/epjconf/201715305025

N. Roskoff, A. Haghighat, and V. Mascolino, “Experimental and Computational Validation of RAPID,” EPJ Web of Conferences, EDP Sciences, 2017, in press.

A. Haghighat, K. Royston, and W. Walters, “MRT Methodologies for Real-Time Simulation of Nonproliferation and Safeguards Problems,” Annals of Nuclear Energy, 87, pp.61-67, 2016.

N. Roskoff, W. Walters, and A. Haghighat, “Application of the subgroup decomposition method (SDM) for reactor simulation,” EPJ Web of Conferences, Vol. 106, EDP Sciences, 2016.

W. Walters, A. Haghighat, S. Sitaraman, and Y. Ham “Development of INSPCT-S for Inspection of Spent Fuel Pool,” Journal of ASTM International (JAI), 1550, pp. 690-705, 2012.

M. Wenner and A. Haghighat, “A Fission Matrix Based Methodology for Achieving an Unbiased Solution for Eigenvalue Monte Carlo Simulations,” Progress in Nuclear Science and Technology, 2, pp. 886-892, 2011.

Conference Proceedings

N. Roskoff, A. Haghighat, M. Millet, and C. Leidig, “Benchmarking of the RAPID Tool for a Subcritical Facility,” Proc. 57th INMM Annual Meeting, Atlanta, GA, July 24-28, 2016.

N. Roskoff, A. Haghighat, and V. Mascolino “Analysis of RAPID Accuracy for a Spent Fuel Pool with Variable Burnups and Cooling Times,” Proc. Advances in Nuclear Nonproliferation Technology and Policy Conference, Santa Fe, NM, September 25-30, 2016.

W. Walters, N. Roskoff, and A. Haghighat, “A Fission Matrix Approach to Calculate Pin-wise 3D Fission Density Distribution,” Proc. M&C 2015, Nashville, Tennessee, April 19-23, 2015.

W. Walters, N. Roskoff, and A. Haghighat, “Use of the Fission Matrix Method for Solution of the Eigenvalue Problem in a Spent Fuel Pool,” Proc. PHYSOR 2014, Kyoto, Japan, Sep. 28-Oct 3, 2014.

W. Walters, A. Haghighat, M. Wenner, S. Sitaraman, and Y. Ham “A Methodology for Determination of Detector Response for Inspection of a Spent Fuel Pool,” Proc. PHYSOR 2010, Pittsburgh, PA, May 9-14, 2010.

W. Walters, “Development of a Calculation Methodology to Determine Detector Response in a Spent Fuel Pool,” M.S. Thesis, University of Florida, 2009.

Contributors

Prof. Alireza Haghighat — Director Nuclear Science and Engineering Lab, Professor of Nuclear Engineering at Virginia Tech

Dr. William Walters — Assistant Professer of Nuclear Engineering at Penn State

Nathan Roskoff — PhD Candidate, Nuclear Engineering Program at Virginia Tech

Valerio Mascolino — PhD Candidate, Nuclear Engineering Program at Virginia Tech