On February 21, 1996, an organic analysis sampler was contaminated when 3 to 4 milliliters of radioactive brine sprayed his face while working with sample test containers in the Chemistry and Metallurgy Research facility at Los Alamos National Laboratory. Alpha contamination on his upper lip measured 11,000 dpm/100 cm2 and initial nasal smears measured contamination of 350/10,380 dpm alpha and 310/5,500 dpm beta. The contaminants included plutonium-239 and americium-241. Radiological control technicians (RCTs) decontaminated the employee. This event is significant because the procedures used and the safety equipment worn were not adequate to prevent the accident. (ORPS Report ALO-LA-LANL-CMR-1996-0005)
The sampler and a second organic analysis sampler were taking headspace gas samples from five unpressurized test containers in accordance with an analytical chemistry procedure. The test containers were part of the Actinide Source-Term Waste Test Project to obtain analytical data on concentration of actinides in brine that is in continuous contact with transuranic wastes. Each sampler was trained to radiological worker II level and wore Anti-C labcoats, two pairs of gloves, booties, and safety glasses as required by procedure, and posted entry requirements.
The samplers attached a vacuum manifold to the test container with a quick-connect/disconnect and used a syringe attached to the manifold to draw a gas sample. After drawing the sample, they removed the syringe, cleaned the manifold, disconnected it from the container, and cleaned and covered the quickconnect/disconnects.
The samplers noticed the headspace gas pressure indicated 9.0 psig on the fourth container. The first sampler connected the manifold to the container and opened a shut-off valve to lower the pressure, but it would not go below 5.0 psig. He suspected that a quick-connect/disconnect was blocked with salt from the brine solution. His attempt to clear the blockage by connecting helium to the manifold was unsuccessful, so he disconnected the manifold and discharged the pressure in the manifold into a waste container and went to lunch.
After lunch, the first sampler and a third sampler reconnected the manifold to the test container and after conducting many different tests were able to reduce the pressure to 2.5 psig. Repeating the procedure he followed before lunch, the first sampler covered the disconnect on the manifold with masslinn, disconnected the manifold from the test container, and proceeded to a radioactive waste container to discharge any remaining pressure in the manifold. As he moved to the waste container, the quick-connect/disconnect discharged 3 to 4 milliliters of liquid through the masslinn onto his gloves, clothing, safety glasses, and face. Because he was talking to the other sampler, liquid also entered his mouth. Tasting brine, he immediately spit into the waste container. The other sampler took the manifold, placed a cap over the end of the quick-connect/disconnect, and placed the manifold on a cart. He self-monitored and found no contamination on his person. He then monitored the first sampler's face and found more than 10,000 dpm around his mouth. He obtained assistance from an RCT. The RCT did not detect contamination outside the radiological buffer area.
The contaminated sampler removed his Anti-Cs and went to a decontamination area where he removed his contaminated personal shirt. Health physics personnel used soap, water, and tape to decontaminate his face to less than 100 dpm.
After his mouth was rinsed several times with water, swabs showed no detectable activity. RCTs had him submit a second set of nasal smears after his face was decontaminated.
Results were 0/76 alpha and 0/48 beta. The sampler dressed in supplemental clothing and self-monitored with two separate Eberline PCM-2 whole-body monitors. There was no detectable activity. An RCT at the Occupational Medicine facility monitored him and found 100 dpm alpha on the right side of his face, which he decontaminated with soap and water. Policy and program analysis personnel placed him on a prompt action bioassay schedule and a whole-body count.
Policy and program analysis personnel said there is a potential that the sampler's committed effective-dose equivalent could exceed 0.1 rem. This is based on the initial nasal smear results and the possibility that a small amount of the sample entered the mouth. Facility managers said that, although the samplers followed procedures, the contamination still occurred, indicating a weakness in the procedure or in engineering controls provided to protect employees. They will evaluate the adequacy of these controls to determine how to prevent a recurrence. Since the program began in 1995, over 450 gas samples and 345 brine samples were taken without a personal contamination incident.
The project leader issued a group-level stop-work order for sampling pending completion of the investigation and implementation of corrective actions. He will also conduct a stored-energy safety review of the incident and then review sampling procedures against the stored-energy review.
Sampling procedures will be modified based on the review and lessons learned from this incident.
This event illustrates the importance of fully evaluating all potential hazards, no matter how small. Procedures and prescribed personal protective equipment should consider the working conditions of the system, such as potentially pressurized contaminated fluids that could be ingested. DOE/EH-0256T, Radiological Control Manual, section 361, states that primary emphasis should be placed on engineered features to contain plutonium and to prevent airborne and surface contamination. Low levels of plutonium in the body are difficult to measure and biological removal processes are slow.
KEYWORDS: contamination, intake
FUNCTIONAL AREAS: radiation protection, chemistry