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Information Notice No. 83-32: Rupture of Americium-241 Source(s) Contained in a Well Logging Device
SSINS No.: 3835 IN 83-32 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 May 26, 1983 Information Notice No. 83-32: RUPTURE OF AMERICIUM-241 SOURCE(S) CONTAINED IN A WELL LOGGING DEVICE Addressees: All NRC licensees holding a specific license to possess and use sealed sources containing byproduct or special nuclear material in well logging tools. Purpose: The intent of this information notice is to alert licensees to a potentially generic problem identified in well logging tool recovery operations. Such a problem in Region I resulted in the rupture of an americium-241 sealed source(s). Description of Circumstances: On August 19, 1982, a well logging tool being used in coal exploration became stuck at the 420-foot level in a drill hole of 950 feet total depth. The tool included two sealed sources, each containing 250 millicuries of americium-241 as powdered oxide. The licensee began recovery operations including the use of drilling to enlarge the drill hole above the level of the stuck device. The licensee had successfully retrieved stuck tools on nine previous occasions using the same approach. The suspension cable used to lower the tool down the drill hole is designed to release at the point of attachment to the well logging tool when extra tension is exerted on the cable. In this case, when the tool initially became stuck the cable broke off about 80 feet above the device. On August 27, 1982, while drilling at a level which was thought to be well above the level of the stuck tool, one or both of the americium-241 sources was ruptured and contaminated the drilling mud used to cool and lubricate the bit. The most probable cause of the rupture was that the sources were drawn up to the drill by the remaining length of cable. The mud was discharged to a nearby retention basin and recirculated. The americium-241 contamination was not detected during licensee surveys because the survey instrument used was not sufficiently sensitive. Licensee representatives, believing the americium-241 sources still intact, replaced the first drilling rig with one more suited to planned recovery procedures and sent the first drilling rig to a second site nearby. On September 1, 1982, licensee representatives identified americium-241 contamination in the retention basin and immediately notified the NRC. Radiological surveys and evaluations identified americium-241 contamination at both drilling sites, involving hand tools and approximately 6,500 square yards of ground. Contamination levels ranged from 100 to greater than 1,000,000 disintegrations per minute per 100 square centimeters. Surveys at 20 private . IN 83-32 May 26, 1983 Page 2 of 2 residences, a motel, and the licensee's corporate offices identified contaminated shoes and clothing at the motel and contamination at nine private residences ranging from 20 to 600,000 disintegrations per minute per 100 square greater than 1,000,000 disintegrations per minute per 100 square centimeters. Surveys at 20 private residences, a motel, and the licensee's corporate offices identified contaminated shoes and clothing at the motel and at nine private residences ranging from 20 to 600,000 disintegrations per minute per 100 square centimeters. Seven of the homes in which contaminated articles were found belonged to work crew members; two homes belonged to local residents who had walked onto the drilling site before the identification of the contamination incident. All contaminated articles were bagged and returned to the original site for storage. No contamination on personnel was identified. The licensee is presently decontaminating the equipment and the site. Discussion: The above information identifies means whereby the integrity of a sealed source(s) can be jeopardized by well logging tool recovery procedures. This information notice is provided as an early notification of a possibly significant matter that is under review by the NRC staff. We suggest recipients review their procedures for well logging recovery to ensure that drilling or hole enlargement is not permitted during such operations until a clean break of the wireline is made at the point of attachment to the down-hole device. We also suggest recipients review their procedures to ensure that continuous monitoring of the surface (well head and/or mud discharge) will be made with a suitable survey instrument or logging tool (minus the source) in order to immediately alert the operators to possible source damage so that contamination can be properly controlled. If you have any questions regarding this matter, please contact the Administrator of the appropriate NRC Regional Office. James M. Taylor, Director Division of Quality Assurance, Safeguards, & Inspection Programs Office of Inspection & Enforcement Technical Contact: J. Metzger 492-4947 Attachment: List of Recently Issued IE Information Notices .
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