On May 5, 1994, radiation safety department personnel reported the loss of a performance check source at the Pantex Plant. They described the source as a plutonium disk of unknown isotope identified as no. A6128. Radiation safety personnel believe the source activity level to be in the range of 0.0021 to 0.0152 microcuries based on historical data for similar check sources. The potential exists for the source to have an activity level greater 0.003 microcuries, which would place it under the controls established by DOE N 5400.9, Sealed Radioactive Source Accountability. (ORPS Report ALO-AO-MHSM-PANTEX-1994-0072)
Investigators stated that the loss of the performance check source was discovered on January 24, 1994, during the semiannual site-wide inventory of sealed sources conducted by radiation safety department personnel from January through May 5, 1994. They checked the source database and noted that the source was last verified in its correct location in December 1993. Radiation safety personnel conducted a search for the source in parallel with the semiannual inventory. They began the search at the last recorded location and checked all known storage locations, but they were unable to locate the source.
Radiation safety personnel took the conservative approach and assumed the source exceeded the level of exempt quantities and submitted the occurrence notification. Investigators, however, were concerned with the time delay of approximately three months when the source was identified as missing until notification was filed. Although facility personnel immediately conducted a search for the missing source and continued the effort as part of the inventory process, the loss of source accountability should have been reported in a timely fashion in accordance with DOE 5000.3B, Occurrence Reporting and Processing of Operations Information.
The Radiation Safety Department personnel use a database to track and control radioactive sources. They have implemented procedures to control check-out and check-in processes for measurement equipment containing check sources similar to the missing source following a previous lost-source event.
NS has reported numerous events associated with control and accountability of radioactive sources
in the Weekly Summary. In several instances, workers received radiation exposure. These events
involved improper storage; loss of accountability; incorrect labeling, shipping, and receipt
inspection; improper disposal; inadequate postings for storage areas; access control weaknesses;
training deficiencies; and lack of procedural guidance for controlling sources. DOE site personnel
should review the guidelines for source control and accountability in DOE/EH-0256T, rev. 1,
Radiological Control Manual, part 3, section 431, and DOE N 5400.9.
(Glenn S. Searfoss - RPI (301) 540-2396)