61 2008 Multiphysics Object Oriented Simulation Environment INL researchers began developing the Multiphysics Object Oriented Simulation Environment (MOOSE) on a foundation of existing computer code and numerical libraries. The simulation tool went on to revolutionize predictive modeling, allowing scientists and engineers to develop applications that predict the behavior of nuclear fuels, materials and coolant under operating and accident conditions. MOOSE was released as open-source software in 2014 and has sired a menagerie of modeling applications describing phenomena in multiscale nuclear fuels (BISON, MARMOT), reactor physics (MAMMOTH, Rattlesnake), geology (FALCON), geochemistry (RAT), nuclear power plant systems/safety analysis (RELAP-7), and reactor engineering (Pronghorn). “ People were doing these simulations before, but they had to develop the entire code. Something that would take five years with a team of 10 people can now be done in one year with three people.” — Derek Gaston, INL computational mathematician