Three series of destructive reactor experiments were examined from the viewpoint of fission product dispersal to the environment and fission product retention in the fuel, coolant, and structural surroundings.The experiments included the following: the Boiling Reactor Experiment (BORAX-I), 1954; Special Power Excursion Reactor Test (SPERT-I), 1962; and Systems for Nuclear Auxiliary Power Transient Reactor test series (SNAPTRAN) 2/10A-3, 1964; and SNAPTRAN-2, 1966. All but SNAPTRAN-2 were carried out in a water medium. Particular emphasis was placed on the release behavior of iodine fission products since it is these that have the highest radiological effectiveness. The results of the studies showed that when fuel is damaged in a water medium essentially all of the radioiodine is retained in the water. Essentially none was volatilized and dispersed to the atmosphere. In the case of fuel damage in an air medium (SNAPTRAN-2), 70% of the radioiodine was released to the atmosphere. Release fractions for the noble gas fission products were also evaluated. These ranged from a low of 3 to 4% in SNAPTRAN-2/10A-3 (water medium) to a high of 75% in SNAPTRAN-2 (air medium). These data, along with those for radioiodine, confirm the effectiveness of water as a medium for limiting the release of fission products to the environment from damaged fuel.