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Information Notice No.80-09 – Possible Occupational Health Hazard Associates with Closed Cooling Systems for Operating Power Plants
SSINS: 6870 Accession No.: 7912190681 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 March 7, 1980 Information Notice No. 80-09 POSSIBLE OCCUPATIONAL HEALTH HAZARD ASSOCIATES WITH CLOSED COOLING SYSTEMS FOR OPERATING POWER PLANTS As a result of information that the causative agent for meningoencephalitis, the amoeba Naeglaria fowleri, had been found in warm water ponds in Florida and Texas where two fatalities were reported, NRC initiated a study by Oak Ridge National Laboratory on the occurrence of Naeglaria in power plants with closed cycle cooling systems. For seven power stations examined (6 fossil, 1 nuclear), this study confirmed the presence of pathogenic Naeglaria at three plants including the nuclear plant (Dresden). Recently, Northern States Power Company (NSP), while monitoring the Prairie Island Nuclear Generating Plant closed cooling system for the amoeba, did identify the presence of Naeglaria. Although the Minnesota Department of Health does not consider the existence of the organism to be a public health threat, it was recognized as a possible occupational health hazard. Plant personnel were instructed to wear rubber gloves when coming into contact with the circulating water and to wear respirators when working in the area of the cooling towers. In November 1979, NSP conducted a special chlorination program at Prairie Island that was designed by Dr. Richard Tyndall of Oak Ridge to eradicate this organism. Chlorine concentrations in the circulating water system was raised to 2.0 mg/l (measured as free chlorine) for a period of six hours to destroy both the amoebae and its encysted form. This program also included dechlorination prior to discharge and intensive monitoring to document chlorine concentrations, the impacts of chlorinated cooling tower draft and sampling to determine the efficacy of the special chlorination program in destroying Naeglaria. Preliminary results indicate that the program was successful in reducing the number of organisms present by two to three orders of magnitude. It is recognized that there have been no reported cases of meningoencephalitis reported among power plant personnel to date; however, the seriousness of the disease (if contracted) and the confirmed presence of Naeglaria at four plants, leads us to inform all licensees with closed cycle cooling water systems of the potential occupational hazard and advise that they take appropriate action. No written response to this Information Notice No. is required. If you desire additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
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