The OpenMC effort is taking place under one of the Exascale Computing Project (ECP) application projects called "Coupled Monte Carlo Neutronics and Fluid Flow Simulation of Small Modular Reactors (ExaSMR)."
It is a collaboration involving Oak Ridge National Laboratory, Argonne, MIT, and Idaho National Laboratory. The primary goal of the project is to enable coupled Monte Carlo neutron transport -- computational fluid dynamics at exascale that can be used to study small modular reactor designs.
OpenMC is one of the primary Monte Carlo codes that is being used in this project. For further information about the code development, see the website openmc.readthedocs.io/en/latest/.