Application of TDKENO for analysis of criticality excursion experiments

TDKENO is a hybrid stochastic/deterministic code that solves the time-dependent neutron transport equation with explicit representation of delayed neutrons. The code employs the improved quasi-static (IQS) methodology, which factors the flux into shape and amplitude functions. The space-, energy-, and angle-dependent shape is assumed to vary slowly over time while the purely time-dependent amplitude usually changes rapidly. TDKENO uses three different time steps in its solution algorithm. The first and largest of these is the shape time step. The three-dimensional Monte Carlo code KENO V.a is used to solve for the shape at these steps. The reactivity, generation time, and effective delayed neutron fractions are computed at a smaller time step by using an interpolated shape. Finally, the amplitude is determined at the smallest time step by using quadratically interpolated point kinetics parameters. This work focuses on the addition of thermal feedback to the TDKENO code and the calculation of several criticality excursion experiments.