[en] The use of liquid sodium as the primary coolant in fast-breeder reactors poses potential health concerns because of the chemical toxicity of sodium oxides and the radioactive toxicity of ²⁴Na and ²²Na. The paper describes some procedures which can significantly reduce the radiation dose to the body from ²⁴Na and ²²Na which might be accidentally inhaled or ingested. Studies with rats indicate that the retention time of the sodium isotopes which have exchanged with the body sodium pool can be reduced by a factor of 10 by ingestion of high levels of stable sodium. In addition, the ingestion of a sodium salt at the time or immediately after the inhalation incident could result in at least 60% or more of the inhaled radioactive sodium being excreted before it exchanges with the body sodium pool. The combined effects of both immediate and sustained sodium ingestion in rats can result in a radiation dose from ²²Na of only 4% or less of that which would result if no additional salt is administered. The dose reduction for ²⁴Na would not be as much as that for ²²Na but would be significant. The tolerance for high levels of stable sodium intake in humans will be discussed and optimum intakes will be suggested which will provide the maximum radioactive sodium excretion with minimum harm to the physiological processes of the body. (author)