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Information Notice No. 83-74: Rupture of Cesium-137 Source Used in Well-logging Operations
SSINS NO.: 6835 IN 83-74 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 November 3, 1983 Information Notice No. 83-74: RUPTURE OF CESIUM-137 SOURCE USED IN WELL-LOGGING OPERATIONS Addressees: All NRC licensees authorized to possess and use sealed sources containing byproduct or special nuclear material in well-logging operations. Purpose: The intent of this information notice is to alert licensees to a potentially serious problem identified as a result of an effort to remove a sealed source from its holder. The source removal effort resulted in the rupture of a cesium-137 sealed source and subsequent personnel and area contamination. Description of Circumstances: On the afternoon of September 14, 1983, Shelwell Services, Inc., authorized to use well-logging sources for well-logging operations reported to NRC Region III that, while attempting to remove a cesium-137 sealed source from its source holder, the source was inadvertently ruptured. The source holder is believed to be a stainless steel tube approximately 2.5 inches long and 1-5/8 inches in diameter, housing a nominal 2-curie cesium-137 sealed source capsule, containing powdered cesium chloride. The source holder was to be used in a density well-logging tool. At approximately 4:00 p.m. on September 13, the licensee was attempting to remove the cesium source from its holder and place it in a different holder to accommodate the density tool. Two licensee employees initially attempted to dislodge the source capsule by inserting a lubricant into the source holder and tapping the holder. The licensee had successfully removed other sources from source holders on previous occasions using this same method. After repeated unsuccessful attempts, three employees placed the source holder on a turning lathe and using a drill bit, attempted to push the source out of its holder. With the source holder concentrically spinning about the drill bit's axis, the source capsule was ruptured. When the holder was removed from the lathe, the source fell into a rag. The individuals noticed a hole in the source capsule. The licensee initially reported to the NRC contamination of about a ten-square-foot area within its facility with no resultant personnel or offsite contamination. However, because of inadequate surveys, the licensee failed to evaluate the 8308310063 . IN 83-74 November 3, 1983 Page 2 of 3 situation and take immediate corrective actions, to limit personnel exposure and spread of contamination. Radiation surveys were initially performed by the licensee and showed the instrument to go beyond,its highest range. Another radiation survey was performed using a different instrument and it also went off-scale. The licensee interpreted these observations to be instrument malfunctions and disregarded the off-scale readings. All individuals working in the area, (a total of eleven including the three working with the source) left the site at their usual quitting time unaware of the seriousness of the incident. This resulted in significant spread of contamination to numerous private homes and vehicles, in addition to personnel contamination. Lower levels of radioactivity were found at three business establishments. To date, NRC, DOE, and State of Ohio representatives have identified contamination at a total of fourteen private residences and three public places. Most of the contaminated areas identified were 0.2-mrem/hr, direct-surface-gamma, but several isolated spots in private residences showed radiation levels up to 2-10 mrems/hr and one as high as 100 mrems/hr. The three individuals involved in the source removal received some internal deposition of radioactive material, none of which exceeded regulatory limits. These individuals are undergoing examination under the direction of an NRC medical consultant. Film badges for these three individuals showed whole-body exposures of 13.48, 2.71, and 0.110 rems for the period August 25, 1983 through September 15, 1983. A consultant firm, hired by the licensee, has completed decontamination of residences, public establishments, and vehicles. A decontamination plan is to be submitted for approval to decontaminate the licensee's facility. Decontamination costs are estimated to be approximately $250,000. Initial surveys of onsite facilities showed significant contamination levels in three buildings. These levels ranged from 1.0 mrem/hr up to 600 mrems/hr. As a consequence of the accident, the licensee has been ordered to cease all operations, except those related to decontamination efforts, and to show cause why the license should not be revoked. Another well-logging incident recently occurred resulting in a significant spread of contamination. See Information Notice No. 83-32, dated May 26, 1983, titled, "Rupture of Americum-241 Source(s) Contained in a Well-Logging Device." In that incident, the licensee also failed to recognize immediately the spread of contamination resulting in extensive cleanup. Discussion: We suggest recipients review their procedures for well-logging source changes to ensure that source capsules cannot be ruptured or source containment breached during any operation. Written procedures should be established for installation and removal of sources from source holders and/or well-logging tools. Direct handling of bare sources should always be avoided. We also . IN 83-74 November 3, 1983 Page 3 of 3 suggest recipients review their procedures and training programs to ensure that appropriate and operable radiation monitoring equipment is available and used to alert personnel to possible source damage or high radiation levels, so that appropriate protective and remedial actions can be implemented. Emergency procedures should be developed to notify the radiation safety officer or other responsible individual if there appears to be a breach in a radioactive source and a possibility of contamination spread. In view of the potentially high cost of decontamination operations following an incident, you should review your insurance coverage and determine if it is adequate to pay for decontamination costs in the event of an incident. If you have any questions regarding this matter, please contact the Administrator of the appropriate NRC Regional Office or this office. James G. Partlow, Acting Director Division of Quality Assurance, Safeguards, and Inspection Programs Office of Inspection and Enforcement Technical Contact: J. R. Metzger, IE (301) 492-4947 Attachment: Recently Issued IE Information Notices .
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