Department of Energy (DOE) and other federal research, test, and material reactors with decades-long operating history can provide useful information to today’s advanced reactor designers and the overall nuclear safety community. An ANS panel series begun in 2021 and updated in 2023, reported on follow-up work in response to upset conditions at the Oak Ridge National Laboratory’s (ORNL’s) High Flux Isotope Reactor (HFIR) and the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) Reactor, respectively. While neither event in 2018 and 2021 resulted in significant radiological exposure, each of the affected reactor facilities paused operations to review fuel fabrication, training, operations, quality assurance, conduct causal analyses and other activities before returning to operation. Earlier panel sessions at the 2021 and 2023 ANS Winter Conferences provided initial and follow-up reports on where the two reactor facilities stood in their recovery efforts. The present session includes ATR and potentially an additional DOE reactor to the panel. With this expanded panel, the discussion includes how the collective experience in operations in these U.S. flagship research reactors may benefit the designs and provide safety insights for the new generation of RTRs as well as planning for small modular reactor, microreactor, and other reactor types.