 An out-of-pile corrosion test program was carried out for Hastelloy-N, which indicated extremely low corrosion rates at MSRE conditions.Capsules exposed in the Materials Testing Reactor showed that salt fission power densities of more than 200 W/cm3 had no adverse effects on compatibility of fuel salt, Hastelloy-N, and graphite.Fluorine gas was found to be produced by radiolysis of frozen salts, but only at temperatures below about .