Coupled Multiphysics Simulations of Heat Pipe Microreactors Using DireWolf

Abstract

program, the DireWolf software application's objective is to provide the nuclear community with a design and safety analysis simulation capability. Based upon the NEAMS program Multiphysics Object-Oriented Simulation Environment (MOOSE) computational framework, DireWolf tightly couples nuclear microreactor physics, reactor physics, radiation transport, nuclear fuel performance, heat pipe thermal hydraulics, power generation, and structural mechanics to resolve the interdependent nonlinearities. DireWolf is capable of simulating both steady and transient normal reactor operation and several postulated failure scenarios. We will present the fundamental physics of heat pipe-cooled nuclear microreactors and the MOOSE-based software employed in DireWolf. Both steady and transient results for coupled reactor physics, radiation transport, and nuclear fuel performance are demonstrated.

Advanced Measurement and Visualization Techniques for High-Temperature Heat Pipe Experiments

“…While HPs are straightforward and reliable devices, they are subject to several heat transport limitations that must be considered for safe operation. These limits are plotted in Figure 3, and can be described as follows [16]:…”

“…The two bounding limits that do not result in catastrophic failure of the HP are the sonic and viscous limits, that are represented with dashed lines which effectively limit the amount of heat flux that can be transferred by the HP. Adapted from [16].…”

“…Matthews et al [16] pointed out that of these five limits, the capillary, boiling, and entrainment limits are considered 'catastrophic' HP failures from which normal operation is not recoverable without a reactor shutdown. The remaining two limits are considered 'bounding' limits, resulting in decreased heat fluxes at the evaporator and condenser side of the HP.…”

“…These steps are necessary so that vendors employing the software for design and safety applications have confidence in the validity of computational results. The key to developing a useful advanced modeling and simulation capability for a given physical system is a rigorous validation paradigm primarily founded in integrating advanced modeling and simulation development with a stringent multiscale, multiphysics experimental program that is repeatable and delivers data with quantifiable uncertainties [16].…”

Status Update on the Development of Transducers and Bonding Techniques for Enabling Acoustic Measurements of Damage in Microreactor Components

“…The primary differences between microreactors and light-water reactors or small modular reactors are that microreactors (1) may be fully assembled in a factory and shipped to a desired location, (2) can be transported with multimodule transportation, and (3) may be controlled remotely and semiautonomously [2]. The MRP is primarily focused on developing heat pipe-cooled reactors [3,4], gas-cooled reactors [5], and liquid metal-cooled reactors. The MRP is developing two nonnuclear systems to serve as experimental test beds to evaluate the thermal-hydraulic and thermomechanical behavior of microreactor components.…”