Seminar: Hybrid Time-dependent 3-D Transport with Explicit Representation of Delayed Neutrons

Abstract

When an initially delayed critical or subcritical system is perturbed to the point that results in a supercritical state (delayed or prompt), the fission yield of the system exhibits a time-dependent behavior that is a function of many system specific parameters or features.  Some of these parameters and features include the fissionable material type, neutron interactions in the system, enrichment, the reactivity insertion rate and amount, and heat capacity and heat transfer features of the materials including any cooling mechanisms. As such, the neutronic behavior of fissionable materials that are perturbed accidentally or intentionally through mechanisms such as removal or addition of absorbers (e.g., rapid or slow control rod movement), density changes (moderator intrusion, etc.), temperature change, etc. is especially challenging to analyze because of non-stationary materials and due to multi-disciplinary nature of the solution to the problem.  The most rigorous solution methodology involves time-dependent solution of the governing equations for three-dimensional (3-D) geometries.  The methodology is also referred to as the spatial kinetics. Accurate simulation of spatial kinetics also requires accurate simulation of feedback mechanisms.

TDKENO is a computer program that uses a hybrid method for solving the time-dependent, 3-D Boltzmann transport equation with explicit representation of delayed neutrons. The methodology used for the time variable is the improved quasi-static (IQS) method, which is a flux factorization method. TDKENO is considered hybrid (stochastic/deterministic) because it utilizes the Monte Carlo codes KENO V.a and KENO-VI to compute the flux shape at a given time while the time-dependent solution to the kinetics equations is deterministic.

This presentation will focus on the recent development activities of TDKENO for application to transient analysis of TREAT (Transient REActor Test facility) facility at Idaho National Laboratory. TREAT was originally designed to enable a short high-energy neutron pulse leading to rapid energy deposition within mockups of fast reactor fuel elements under controlled conditions without harm to the reactor itself. The development and application of the IQS method will be presented along with the latest results from TDKENO for modeling some of the temperature-limited TREAT transients.

About the Speaker

Dr. Sedat Goluoglu is currently a professor in the Department of Materials Science and Engineering, Nuclear Engineering Program at the University of Florida. Dr. Goluoglu received his Ph.D. in Nuclear Engineering from the University of Tennessee, Knoxville in 1997. Prior to joining the University of Florida, Dr. Goluoglu was a senior research and development staff at the Oak Ridge National Laboratory responsible for the development and implementation of continuous energy Monte Carlo criticality, shielding and depletion tools of SCALE code system. His areas of expertise and interest include methods and code development for static and time-dependent neutron transport, reactor physics applications and methods development, nuclear criticality safety analyses and methods development, neutron and gamma cross section data processing methods and tools, sensitivity and uncertainty analyses and methods development. Dr. Goluoglu is an active member of the American Nuclear Society since 1992. He currently serves as the Chair of Nuclear Criticality Safety Division and as a member of the National Program Committee. In the past, he has served in various capacities including vice-chair of NCSD (2014-2015), Technical Program Chair, ANS 2013 Annual Meeting, Assistant Technical Program Chair, ANS 2011 and 2012 Winter Meetings, Assistant General Chair, NCSD Topical Meeting, Knoxville, TN 2005.

Hosted by Professor Lei R. Cao