Fission Systems and Radiation Transport

Radiation transport and fission systems engineering encompasses the broad scientific fields relevant to the application of fission for energy production and to the study and application of radiation interactions and radiation transport through matter.

Included are the areas of nuclear reactor theory such as neutron transport, thermal hydraulics, fuel cycle analysis, reactor kinetics, diagnostics, control and optimization. Significant effort is devoted to computational simulations of these processes and to applications of these simulations in overlapping areas such as radiation protection, radiation cancer therapy, radiation-hydrodynamics, kinetic theory and general computational physics. Read on for sample projects.

CASL — the Consortium for Advanced Simulation of Light Water Reactors

“It can be unambiguously stated that the CASL project has opened up an unprecedented opportunity for NERS grad students.”

The CASL project represents the largest effort in the fission area for U-M NERS. The department is part of a US Department of Energy “Research Hub” to produce a virtual reactor analyzing and understanding present challenges in nuclear power reactor operation, predicting problems that may arise during modern operational approaches and designing safer and more economical reactors for the future.

Research teams in NERS have interfaced simulations for heat generation and radiation transport in nuclear reactor cores, which improves the fidelity and accuracy of the results. Another goal is to simplify models while preserving accuracy for a faster virtual reactor program. Recently, they succeeded in coupling chemistry to the combined heat generation and radiation transport simulation, revealing how unwanted deposits build up on fuel rods during operation.

“It can be unambiguously stated that the CASL project has opened up an unprecedented opportunity for NERS grad students. The new MPACT (Michigan Parallel Characteristics Transport) code is being used throughout the national CASL project, and students whose work is embedded in MPACT are seeing their efforts used at national labs and in the nuclear industry,” said Edward Larsen. “I’m not aware that this kind of opportunity has ever existed for graduate students before, anywhere.”

For more information, visit the CASL website.

Faculty from NERS and ME are working on the CASL project, including Thomas Downar, Edward Larsen, John C. Lee, Wei Lu (ME), Annalisa Manera, William R. Martin, Michael Thouless (ME), Gary Was, and Won Sik Yang. In addition, Ronald Gilgenbach is on the CASL Board of Directors. NERS research faculty involved with CASL include Brendan Kochunas, Yuxuan Liu, and Victor Petrov. NERS staff who support the CASL project include Daniel Jabaay, Shannon Thomas, and Scott Wilderman. Approximately 12-15 PhD students are supported by CASL and carrying out PhD research related to the CASL project..

Thermal Hydraulics of Nuclear Reactors

Annalisa Manera’s team works on:

• high resolution experiments for the validation of Computational Fluid Dynamics (CFD) codes and for gaining more insight in single-phase and two-phase flow phenomena of interest for nuclear power plants applications
• the development of multi-scale multi-physics computer models for the investigation of nuclear power plant transient and stationary behavior
• the design and analysis of passive safety systems for Gen-III+ LWRs and NGNP reactors.

For more information, visit the Experimental and Computational Multiphase Flow Laboratory website.

Understanding Radiation Doses

Alex Bielajew and coworkers formulate analytical and numerical models of how electrons and photons move through matter. These fundamental calculations improve the precision of predictions for dose deposition in the human body and interpretations of radiation dosimeter readings, thereby reducing the total radiation dose needed to treat cancer through radiotherapy.

Neutron Transport, Fuel Optimization and Reactor Safety

John C. Lee’s research projects cover primarily three areas in fission systems and radiation transport:

• Time-dependent neutron transport algorithms as part of CASL. The algorithms will enable accurate and efficient transient calculations for the virtual reactor model under development for the entire consortium.
• Advanced probabilistic safety analysis for nuclear power plants. The research involves new safety analysis methods for current power plants as well as an inherently safe design under development. The new approaches will be used for developing enhanced guidelines for the management of severe accidents of the type that occurred at Fukushima in 2011 as well as for optimizing the design for the new concept on the drawing board.
• Optimization of nuclear fuel cycles. The project involves the development of efficient algorithms for obtaining optimal fuel assembly loading patterns in light water reactors without the need to evaluate a large number of possible patterns through stochastic processes.

Fission Faculty: William R. Martin, James P. Holloway, Edward Larsen, John C. Lee, Alex Bielajew, Thomas Downar, Annalisa Manera, Brian Kiedrowski, Xiaodong Sun, Won Sik Yang

Fission Research Faculty: Volkan Seker, Brendan Kochunas, Victor Petrov

Fission Adjunct Faculty: Forrest Brown, Ben Collins, Frederick Buckman