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SSINS No. 6835 IN 83-33 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON D.C. 20555 May 26, 1983 Information Notice No. 83-33: NONREPRESENTATIVE SAMPLING OF CONTAMINATED OIL Addressees: All nuclear power reactor facilities holding an operating license (OL) or a construction permit (CP). Purpose: This information notice is provided as notification of events that had potential radiological impact on the general public. It is expected that recipients will review the information for applicability to their facilities. No specific action or response is required. Description of Circumstances: Over the past several years, inadequate sampling of waste oil has resulted in incorrect determinations of waste oil contamination at three nuclear power plants. These events resulted in the inadvertent release of licensed material beyond the plant's radiologically controlled areas. In late 1980, a licensee attempted to mix the contents of waste oil drums, which included water, with a stirring rod. Oil and water within the drums were not adequately mixed. Subsequent analysis of the samples from these drums did not reveal that radioactive contamination was present. The drums were transferred outside the owner's protected area to await pickup by a waste oil vendor. The vendor subsequently pumped the oil from the drums until he reached water. The water was discharged to the ground surrounding the waste oil storage area. Several years of this practice resulted in an accumulation of radioactivity in the soil. Contact radiation readings on the soil's surface were as high as 100 mrem/hr. It was evident that unsampled water in the drums was significantly radioactive. Since stirring did not provide sufficient agitation to provide a homogenous mixture of oil and water, this licensee erroneously determined that the waste oil drums were free of contamination. In October 1982, another nuclear power plant was found to be sampling waste oil without assuring adequate mixing to obtain a representative sample. Their method of sampling, coupled with inadequate counting techniques, resulted in licensed material being released to a waste oil vendor, an unauthorized recipient. 8303040046 . IN 83-33 May 26, 1983 Page 2 of 2 In November 1982, it was discovered that another licensee had been releasing waste oil containing licensed material to a waste oil vendor. The licensee attempted to mix the contents of the waste oil drums employing a stirring rod on which two small propellers were mounted and driven by a variable speed drill. The licensee then obtained a one-liter sample from the drum for counting. This licensee performed an experiment in which the contents of a 55-gallon drum containing 75% waste oil and 25% water were mixed, employing the above technique. A sample was drawn from the drum and centrifuged. Only three percent of the sample was water. Upon discovering that this method of sampling was nonrepresentative, the licensee discontinued the method. Because of the obvious difficulty in obtaining a representative sample from oil-water mixtures, the amount of water in the waste oil should be minimized. The radioactive contamination may be present in only the oil or the water fraction, thereby potentially causing misleading results in even well mixed samples. Consequently, emphasis should be placed on (1) minimizing, if not eliminating, the amount of water in waste oil mixtures and (2) testing waste-oil sampling techniques to confirm that representative samples are being obtained. No written response to this information notice is required. If additional information is needed, with regard to this subject, please contact the Administrator of the appropriate NRC Regional Office. Edward L. Jordan, Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical Contact: C. Campbell, IE 301-492-9762 Attachment: List of Recently Issued IE Information Notices .
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