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Brendan Kochunas

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Brendan Kochunas is an Assistant Research Scientist in the Department of Nuclear Engineering and Radiological Science. Dr. Kochunas work focus on high performance computing methods, especially parallel algorithms for the 3D Boltmann Transport Equation. He is the lead developer and primary author of the MPACT (Michigan Parallel Characterstics based Transport) code. Currently, leading the development of MPACT and its application within CASL (www.casl.gov) constitutes his research activities.

Dr. Kochunas is the lead instructor of MICDE course Methods and Practice of Scientific Computing. He has created a novel and integrated class curriculum that immerse U-M students in many HPC tools and resources, and teaches them to effectively use these in scientific computing research.

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Alec Thomas

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High power laser plasma interactions are interesting for applications such as the generation of energetic, directional electron, photon, ion and neutron beams or inertial fusion energy. Because of the strong electric and magnetic fields that lead to extremely far from equilibrium distributions, describing realistic high power laser interactions with plasma typically requires codes using a fully kinetic description. Professor Thomas’ research involves collisional plasma simulation using Vlasov-Fokker-Planck codes, including implicit methods using Krylov solvers for heat transport problems relating to inertial fusion energy. He is also interested in plasma simulation using particle-in-cell methods, including coupling the plasma code to very energetic photons using a Monte-Carlo method, for ultra intense short pulse laser interactions in radiation dominated regimes.

3D Particle-in-cell simulation of a laser driven particle accelerator succumbing to hosing and filamentation instabilities.

3D Particle-in-cell simulation of a laser driven particle accelerator succumbing to hosing and filamentation instabilities.

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Sara Pozzi

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Prof. Pozzi’s group is interested in developing new tools and techniques for the detection and characterization of special nuclear material: highly enriched uranium and weapons grade plutonium. Their research has applications in the areas of nuclear safeguards, nuclear nonproliferation, and homeland security.

The performance assessment of existing techniques – and the development of new, more advanced ones – rely on accurate simulation of realistic threat scenarios. The analysis of non-threat scenarios is also crucial to correctly evaluate the detection probability and to minimize the occurrence of false positive alarms. Pozzi’s group develops Monte Carlo codes and analytical methods to investigate the physics of the fission and detection processes. We also perform experiments to improve and validate these models.

Imaging a radioactive neutron source to determine source location: simulation and measurement shown

Imaging a radioactive neutron source to determine source location: simulation and measurement shown

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Edward Larsen

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His research interests are the development of analytic and computational methods for nuclear reactor, neutron transport, nonlinear radiative transfer, electron transport and medical physics problems. (Essentially, anything concerning radiation interactions with matter.) His theoretical work involves the derivation of exact, asymptotic, and computational solutions and the analysis of their mathematical and physical properties. His applied work involves (a) the development of approximation theories for special types of transport phenomena, (b) the implementation and testing of numerical approximation schemes and iteration methods for deterministic transport problems and (c) the implementation and testing of variance reduction schemes for Monte Carlo problems.
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William R. Martin

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Martin’s research involves development of advanced methods for high fidelity analysis of nuclear reactors, with both Monte Carlo methods and deterministic methods. The methods utilize a high-dimensional phase space (7 independent variables) with large data structures that depend nonlinearly on the solution and are big enough to require domain decomposition. Hybrid techniques combining Monte Carlo and deterministic methods yield huge sparse matrices that require innovative storage and inversion algorithms.

Fission source eigenmodes for a 2D full-core, pressurized water reactor using Monte Carlo to estimate the entries of a 2500×2500 fission matrix, a theoretically full but practically sparse matrix of spatial transition rates.

Fission source eigenmodes for a 2D full-core, pressurized water reactor using Monte Carlo to estimate the entries of a 2500×2500 fission matrix, a theoretically full but practically sparse matrix of spatial transition rates.

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Thomas Downar

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One of the more challenging multi-physics problems in engineering is the solution of the coupled temperature/fluid and neutron/nuclide fields in a nuclear reactor core during accident conditions. The research in Professor Downar’s group over the years has focused on the development of high performance computational methods for solving the Boltzmann Transport Equation (BTE) to determine the neutron and photon flux distributions in a nuclear reactor during normal operating and transient accident conditions. The computer code PARCS developed by Professor Downar and his research group is currently used by the U.S. Nuclear Regulatory Commission NRC to certify the safety performance of all the nuclear reactors operating in the U.S. Currently, Tom’s group is developing the next generation reactor code, MPACT, based on the 3D Method of Characteristics as part of the U.S. Department of Energy’s 120 million dollar Nuclear Reactor Simulation Hub, CASL. The target computational platforms for MPACT are leadership class computers such as TITAN at ORNL with hundreds of thousands of processors.

Neutron Fission Distribution in a Nuclear Reactor Core

Neutron Fission Distribution in a Nuclear Reactor Core