Report traces the timeline of contamination

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Tick-tock: Materials originated at UNLV

By The Staff

This is the conclusion of a two-part series that began in Friday’s edition.

A 116-page federal report delves into the background of how the radioactive contamination accident happened at the Los Alamos National Laboratory’s Neutron Center in August.

The report traces a timeline back to 2010 at the Luján Center, which is a national facility for defense and civilian research in nuclear and condensed-matter sciences, hosting scientists from national laboratories, universities, industry and international research facilities. One type of experiment conducted there is irradiation of sample materials in a neutron beam.

The report goes on to state that between 2010 and 2012, Luján Center personnel worked with personnel from the University of Nevada, Las Vegas, to irradiate samples of powdered praseodymium technetate, neodymium technetate and lutetium technetate.

Each of the three samples contained Technetium-99 (Tc-99), an intrinsically radioactive isotope that emits low energy beta particles.

The report concluded that it is difficult to know that a sample canister contains Tc-99 if the canister is not clearly marked and/or labeled. The lutetium technetate sample was later determined to be the source of the contamination in the August 2012 incident.

The samples were prepared at the university in 2010, put into empty sample canisters (provided by Luján Center personnel), sealed and shipped to the Luján Center.

The shipping containers and packaging were clearly marked to indicate that they contained radioactive material.

However, the canisters themselves were not marked to indicate they contained a hazardous or radioactive material, nor was there a process at the Luján Center for doing so. They were only marked “Pr,” “Nd” and “Lu,” respectively.

Because it was only marked “Lu,” someone looking at the third sample canister, separated from its paperwork, would probably have surmised that it contained lutetium, which (if not activated) is a mostly nonradioactive element that may be harmful if inhaled but that otherwise has low toxicity. That person would have had no indication of the technetate (i.e. radioactive) contents from the markings alone.

The report stated that Luján Center safety personnel assumed that the canisters would not be opened, but would be returned to the university. Beyond this assumption, no additional controls were established to ensure that the sample canisters were not opened. Each of the sample canisters had a cap with six screw holes that could be used to connect the cap to the canister.

Screws were only threaded into three of the six available holes to secure the caps. No engineering analysis was performed to verify that the use of three screws provided an adequate seal for the expected environments that the canisters would experience.

Two of the samples were irradiated at the Luján Center in late 2010 and returned to storage. The third, containing lutetium technetate, was irradiated in January 2012.

Following irradiation, positive control of the third sample was lost.

The report concluded that internal management processes at the Luján Center were not sufficient. Comprehensive chain of custody procedures had not been implemented and the third canister cannot be accounted for between January and August 2012.

On Aug. 20, an instrument operator in the Luján Center put Tungsten powder into a sample canister and sealed it with a cap and three screws. The canister was to be used in a procedure to align an experimental apparatus.

It was later discovered that this sample canister was built using parts from the lutetium technetate sample canister.

When retrieved during the investigation, the internal contents of the canister were found to be contaminated with Tc-99.

Based on the record of the spread of contamination, created later by the operating contractor, the spread of contamination began Aug. 20, probably when the third sample canister was mistakenly opened for re-use.

Based on interviews, irradiated canisters containing powders that were thought to be non-hazardous were sometimes opened in the work area. Once opened, their contents were put into other containers, and the canisters were reused to hold other samples. This was true even though multiple personnel agreed that this was contrary to the requirement to use a glove box (assisted by a radiological control technician) when opening a canister of irradiated powders.

Management processes tolerated deviation from expectations by facility personnel, both in terms of work expectations and with respect to storage and control of materials and equipment.

Furthermore, it was not unusual for sample canisters to be separated from paperwork that would positively identify their contents. Canisters were not systematically and uniquely identified and standard log keeping was not employed to enable positive correlations between canister markings and their precise contents.

Given these conditions, the report said that an accident of this type was inevitable and not attributable to the actions of any single individual.

Rather, the accident was the result of management conditions and routine practices — developed over years — that were incompatible with a non-routine hazard.

The report came up with the following conclusions:

• This accident also was (and its recurrence is) completely preventable.
• Simple, common and effective management practices can ensure understanding and compliance with process and sample control requirements.
• Clear, simple, and reliable engineered controls can ensure positive identification, awareness and control of hazardous or intrinsically radioactive materials and prevent uninformed opening of canisters that should not be opened.
• Appropriate oversight focus can more systematically sample facility operations to provide a positive assurance that adequate management processes are being followed.
• An aspect of the environment at the Luján Center that deserves special focus is the high concentration of personnel from diverse and multi-cultural backgrounds. Proactive efforts are warranted to ensure that awareness of cultural differences (beyond language proficiency) are reflected in management and employee training, to ensure process development, training and implementation will be effective.