-lThe stated topic of this symposium is, "We want to discuss the radiation protection measures after a nuclear mass disaster by which large areas have become so severely contaminated with radioactive material that it constitutes a major hazard for the public." Fortunately it is not possible to document directly this topic because such an event has never occurred, We are forced then to look for other situations that may provide relevant information and guidance to our discussions. There were three incidents that occurred following atmospheric nuclear weapons test detonations, and although they have been reported previously, bear recounting for they do show (a) what decisions were made and on what bases (b) the manner in which the decisions were carried out and (c) the results of the protective actions taken. (Figure 1) There was a relatively heavy fallout on the Marshall Islands in the Pacific following an atomic test detonation on March 1, 1954 that required the evacuation of 239 inhabitants. There was also a situation in 1953 when, as a precautionary measure, about 4500 persons in St. George, Utah were asked to remain indoors for a period of two hours and in 1962 countermeasure: were instituted by local and state health authorities in Salt Lake City in the State of Utah to reduce the levels of iodine-131 in the milk consumed by the public, DOE ARCHIVES The Pacific incident in 1954 illustrates the necessity of, and benefits to be derived from, good safety plans that are fully implemented. The St. George, Utah incident in 1953 shows the favorable results from a program of education of local officials and the public and the close cooperatio. with the local authorities, The Salt Lake City, Utah incident in 1962