On February 27, 1996, a worker at the Los Alamos Chemistry and Metallurgy Research facility left the site with alpha contamination on his personal clothing. Radiological control technicians (RCTs) detected two spots of alpha contamination measured 1,200 dpm on the heel of his personal shoe and 300 dpm on his right pants leg. The probable contaminants are isotopes of plutonium and uranium. This is significant because of the loss of control of radioactive material and its appearance where the general public could be affected. (ORPS Reports ALO-LA-LANL-CMR-1996-0006)
After one employee detected contamination on his hands while exiting a work area, RCTs investigated and found three other workers who were involved in the same work that day. One employee had already gone home, so the RCTs contacted him there. Following the discovery of the alpha contamination, the RCT and employee removed and properly packaged the contaminated clothing. He detected no other contamination on the employee. He also surveyed the employee's home, automobile, and areas where the employee had been since leaving work, including a barber shop. No other contamination was detected. All four employees submitted nasal smears, which tested negative.
Analysts performed an isotopic analysis of the contamination on the employee's shoe, identifying the contamination as plutonium-239. They later identified the contamination on the pants as uranium-235. Contamination in the room where the four had worked included alpha and beta emitting uranium isotopes. Their activities did not involve plutonium-239. Facility RCTs are still searching for the source of the plutonium-239 and the alpha-emitting contamination on the second worker's hands.
The Chemistry and Metallurgy Research facility manager, facility division director and group leaders met on February 29, and discussed corrective actions, including a standdown of programmatic activities. They determined that complacency to radiological hazards and failure to enforce radiological controls were contributing causes of recent incidents. Another contributing cause was determined to be the technique of portal frisking with anti-c's on, which shields the affects of alpha contamination on personal clothes under the protective clothing. During the standdown, the facility manager and group leaders told workers that all personnel will be held accountable for their actions.
OEAF engineers reviewed the facility's occurrence reports and noticed that, although the total number of reportable events appears to be decreasing, some of the decrease may be the result of a change in reporting requirements in 1994. More importantly, the fraction of events coded 01D, loss of control of radiological material / spread of contamination, has been increasing.
Reportable Events from ORPS Data
These events underscore the need for enforcing radiological controls at the worker level. Complacency to radiological contamination must be avoided through the development of effective controls. NRC Information Notice 94-16, Recent Incidents Resulting in Offsite Contamination, cites similar occurrences in the commercial nuclear industry. Weekly Summary 93-11 reported a similar off-site contamination event at Michigan State University Superconducting Cyclotron Laboratory, a nuclear research facility where a staff scientist left site with 300,000 dpm/100 cm2 carbon-14 from a leaking target and traveled 1000 miles home, leaving a trail of contamination.
DOE 5400.5, Radiation Protection of the Public and the Environment, and 10CFR835; Occupational Radiation Protection, Final Rule; provide limits for public and qualified worker exposure and contamination. DOE/EH-0256T, Radiological Control Manual, revision 1, identifies controls and techniques to preclude contamination. Chapter 1, "Excellence in Radiological Control" provides guidance in establishment and maintenance of control programs.
KEYWORDS: contamination control
FUNCTIONAL AREAS: operations, decontamination