Discharges of liquid radioactive wastes from nuclear power plants have been well below the limits specified by the aec. A review of reported data has indicated that the type of reactor design (i. e., pressurized water or boiling water reactor) has had no apparent effect on the quantity or character of liquid wastes discharged to the environment except for trit­ium. There are also indications that, again with the exception of tritium, the power level of the reactor may have relatively little effect on the total quantity of liquid wastes leaving the plant. Thus, it is believed that proper in-plant waste management may be the most significant mechanism for the effective reduction in the level of radioactive wastes discharged.

The principal or critical radionuclides found in liquid wastes effluent during the field studies were determined to be 131I, 90Sr, 89Sr, 60Co, and 137Cs. In establishing a surveillance program for the water environment at an operating nuclear plant, these radionuclides and their pathway to hu­man exposure should be examined.

Tritium in the Environment. One of the radionuclides resulting from the operation of nuclear power plants that has recently been the focal point of attention is tritium. Although tritium is considered to be one of the less hazardous radionuclides, its continued production, unavoidable release, and long radioactive half-life (12.3 years) will lead to increased levels in the environment as the number of nuclear power plants increases. Because tritium is an isotope of hydrogen, it can be metabolized in the form of tritiated water and incorporated into body fluids and tissues, al­though most of the tritium ingested would pass through the human body fairly rapidly, with a biological half-life of about 12 days.

The mechanisms for production of tritium in nuclear reactors have been well documented (Peterson et al., 1969; Ray, 1968-1969; Weaver et al., 1969). Data on tritium concentration levels in rivers on which nu­clear facilities are located is routinely obtained by the Bureau of Radio­logical Health and the results are periodically reported in Radiological

Health Data and Reports* Surveillance of tritium in waters of the United States will be expanded as the number of nuclear plants increases. Envi­ronmental tritium concentrations measured during 1967-1968 ranged from 200 to 8400 pCi/1. Calculated population exposure rates from con­tinuous ingestion of water containing these concentrations would corre­spond to 0.03 to 1.4 mrem/yr. By comparison, the normal average popu­lation exposure rate from all natural sources of radioactivity is about 100 mrem/yr (cosmic rays, 30 mrem; terrestrial gamma, 50; internal radionu­clides, 20).

The tritium currently found in the environment is largely due to fall­out from previous atmospheric testing of nuclear weapons, and the levels are generally decreasing. These data and calculations made by the Bureau of Radiological Health indicate that tritium discharges from currently op­erating nuclear power plants would have little if any detectable effect on tritium concentrations in the environment. Present tritium discharge levels are only a small fraction of presently accepted maximum permissible con­centrations and accordingly do not constitute a significant hazard to pub­lic health. However, the anticipated growth of nuclear power with an in­crease in the number of both power reactors and fuel reprocessing plants will result in increased quantities of tritium’s being discharged to the en­vironment. This potential source of population exposure will require con­tinued monitoring and evaluation by public health agencies to ensure that tritium in the environment does not reach levels hazardous to public health.