An Innovative Neutron Transport Method for Whole Reactor Core Criticality Analysis

Farzad_Rahnema
SPEAKER:
FARZAD RAHNEMA
DATE/TIME:
MON, 02/28/2011 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2011 Colloquium Series
Abstract:

A new coarse-mesh radiation transport (COMET) method for modeling and simulation of realistic reactor cores (e.g., operating water reactors) is presented at this colloquium. This innovative method has Monte Carlo accuracy while having computational efficiency that is several orders of magnitude better than achievable by stochastic and fine-mesh deterministic transport methods. Benchmark results in several whole-core problems typical of operating reactors are presented to demonstrate the accuracy and efficient of the method. The new method overcomes many of the limitations inherent in current whole-core (loosely coupled transport/diffusion theory) methods used in the industry. Notable limitations/approximations are single lattice transport theory calculations with approximate boundary conditions (e.g., full specular reflection), cross section homogenization, ad hoc de-homogenization (fuel pin reconstruction) and whole-core homogenized diffusion theory calculations. These approximations breakdown with increasing assembly and core heterogeneities, features encountered in advanced and next generation reactor designs. We first present an overview of current industry methods, research directions and critical gaps in the context of advanced and Generation IV nuclear reactors. The limitations of current methods and reactor design trends are highlighted as motivation for the developments of the advanced radiation transport methods by the Computational Reactor and Medical Physics Group (CRMPG) at Georgia Tech.

About the Speaker:

Dr. Farzad Rahnema received his PhD from the University of California in Los Angeles in 1981. He joined Georgia Institute of Technology in October 1992 and is currently Professor and Chair of the Georgia Tech Nuclear and Radiological Engineering and Medical Physics Programs. He also holds an adjunct Professor appointment at the Emory University Radiation Oncology Department. From 1981 to 1992, Dr. Rahnema was at General Electric Nuclear Energy and was responsible for Monte Carlo Benchmark Methods and GE’s 3-D Nuclear/Thermal Hydraulics BWR Core Simulator PANACEA used for core design and monitoring. He led the development of three versions (8-10) of the simulator.

Dr. Rahnema’s recent research activity and interest have been in the areas of reactor and medical physics methods development, transport theory, perturbation theory and variational methods. He is a Fellow of the American Nuclear Society (ANS) and Chair of the ANS Mathematics and Computation Division.

Reduced-Order Physics Models For Computationally Efficient Charged Particle Transport

Anil_Prinja
SPEAKER:
ANIL PRINJA
DATE/TIME:
MON, 02/14/2011 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2011 Colloquium Series
Abstract:

High-energy charged particles (electrons, light and heavy ions, from 10's keV to GeV and above) are ubiquitous in nuclear science and engineering, medical physics, space science, and advanced materials applications, but the computational complexity associated with the transport of charged particles can greatly exceed that of neutrons, photons and other neutral particles. The primary reason is that long range, Coulomb-field mediated elastic and inelastic collisions of energetic charged particles with target nuclei and electrons are characterized by extremely small collision mean free paths and near-singular differential cross sections. This extreme physics renders the computational modeling of the analog or true problem prohibitively expensive in both stochastic (Monte Carlo) and deterministic numerical settings. The condensed history (CH) Monte Carlo method, widely employed in electromagnetic and hadronic shower codes, attempts to circumvent this practical difficulty by advancing the particle in fixed large steps but inherent flaws limit the ultimate accuracy possible with this method.

In this talk, a new approach will be presented that obviates the need for CH-like approximations for computational expediency yet retains the “look and feel” of the single-event or event-by-event analog simulation. The essence of this method is the construction of a pseudo-transport problem with de-singularized collision operators, which are constrained to preserve certain moments of the corresponding analog collision operators. This moment-preserving or reduced-order physics model is developed through a variety of projection-based strategies that include stabilizing asymptotic higher order Fokker-Planck expansions by renormalization methods and using purely discrete as well as hybrid discrete-continuous kernel representations. The result is a systematic and robust, particle species independent methodology, which can achieve high accuracy and computational efficiency for energy straggling, angular spreading, and dose calculations. After some background material, the new formalism will be described in detail, followed by a presentation of several illustrative numerical results from a Monte Carlo implementation, and concluding with a discussion of some outstanding challenges.

About the Speaker:

Dr. Anil K. Prinja is currently Professor and Associate Chair of the Chemical and Nuclear Engineering Department at the University of New Mexico. He also holds the positions of Co-Director (former Director) of the Center for Nuclear Nonproliferation Science and Technology, and Co-Director of the interdisciplinary Medical Physics Program at UNM. Dr. Prinja obtained his Ph.D. (1980) and B.Sc. (1st Class Honors, 1976) in Nuclear Engineering from the University of London, UK, and was a Research Engineer at UCLA (1980-1987) prior to joining UNM. Dr. Prinja is a Fellow of the American Nuclear Society, and a recent recipient of the NNSA Defense Programs “Award of Excellence”.

Video:

Increased usage of Nuclear Power – Advantages and Challenges – Worldwide

Edward_Quinn
SPEAKER:
EDWARD L. QUINN
DATE/TIME:
MON, 02/07/2011 - 4:00PM TO 5:00PM
LOCATION:
3105 ETCHEVERRY HALL
Spring 2011 Colloquium Series
Abstract:

This presentation provides an overview of the Background, World Outlook, U.S. Outlook and challenges facing nuclear energy in its expansion worldwide. Major issues include demand for new energy sources and international prospects for nuclear, the path forward in the U.S. by DOE, NRC, and vendors and current and future challenges in the supply chain required to meet expected growth.

About the Speaker:

Mr. Quinn has over 35 years experience in managing nuclear and fossil utility contracts and personnel in support of both project and supplemental assignments at various utilities in the U.S. He is past President of the American Nuclear Society (ANS) (1998-1999). He has managed and performed projects in licensing and compliance, electrical and controls design, startup and operation, including Standards development for the Instrument Society of America (ISA) and the International Electrotechnical Commission (IEC) and is the author of over 50 papers and presentations on nuclear instrumentation and control subjects. He has been an instructor at the MIT Summer Reactor Safety Course for over 15 years, the IAEA for the past 5 years, and a Board member of three nuclear companies and the nuclear engineering programs at both Oregon State and The Ohio State University. He currently provides the licensing support for the six awarded IOM nuclear projects in China. In 2009, he was awarded the highest award in IEC, the 1906 Award, for the development of standards.

Mr. Quinn hold a B.S. in Electrical Engineering from Tufts University, Medford, MA, and a Masters in Management from Rensselaer Polytechnic Institute in Troy, N.Y.

Video:

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