Six LANL Employees Tested Positive For Iodine-125 In March Following Foreign Travel As Part Of Multi-Laboratory Team


On March 18, six employees from Los Alamos National Laboratory’s Nuclear Engineering and Nonproliferation Division Process Modeling and Analysis Group returned from official foreign travel and were later notified by another Laboratory of potential radiation contamination. Results from bioassay testing of the six employees were positive for the radionuclide Iodine 125 (I-125). The location of the site they visited has not be disclosed.

On April 3, LANL Radiation Protection Services (RP) dosimetry program personnel responding to contamination concerns at TA-03 Building 2322 and TA-35 analyzed the characterization equipment used during the foreign travel and found that it tested positive for I-125 contamination above the Department of Energy’s total reportable limit of 500 disintegrations per minute (dpm). According to a report in the DOE’s Occurrence Reporting System (ORPS), RP and Science & Technology Operations representatives identified, barricade and posted all areas of contamination concern.

The report indicates that the six LANL employees surveyed themselves and the characterization equipment prior to returning to LANL using a handheld alpha/beta detector and took swipe samples of the equipment. It appears from the report that survey results did not indicate contamination because neither the handheld unit nor the device used to measure the equipment swipes were designed to detect I-125. On March 18, the employees traveled from abroad with the equipment in Pelican cases.

Sources tell the Reporter the team traveled by commercial airlines and drove the characterization equipment home in their personal vehicles. On March 20 and 27, the six employees returned the equipment to LANL sites. On March 30 Pacific Northwest National Laboratory issued an update of concern for radiological uptake across various DOE laboratories and noted two PNNL employees who participated in the foreign travel activities tested positive for I-125 in thyroid count testing, the report states. After one of the six LANL employees received a thyroid count and results indicated a positive I-125 uptake, thyroid counts were scheduled for the other five employees.

On April 3, 2023, the other five LANL employees were analyzed via bioassay and results for all five indicated I-125 uptake. Personal items of one of the employees (clothing, Health Physics Analysis Laboratory (HPAL) evaluation of one individual’s personal items (clothing, backpack, and shoes) returned positive results for contamination. 

Later that day, several locations in labs, offices and storage areas where the characterization equipment had been placed had reported positive contamination results. The highest observed equipment contamination level as 5,600,000 dpm, found on a removable carrying strap. All characterization equipment used to confirm contamination was segregated and stored in a radiologically controlled area with the removable carrying strap sent for disposal, the report states.

The Los Alamos Reporter reached out to NNSA for more information and received an email response from an NNSA Headquarters spokesperson Shayeda Hassan confirming that a multi-laboratory team was exposed to “small amounts of Iodine-125” during an international site visit in mid-March.

“The team included 13 members from NNSA Headquarters, Los Alamos National Laboratory, Sandia National Laboratories, Savannah River National Laboratory, Lawrence Livermore National Laboratory and Pacific Northwest National Laboratory. Upon return to the United States, technical experts working with the traveling team raised concern of potential radioactive iodine exposure. All team members were tested for exposure. Results for some individuals  showed a detectable uptake of I-125, but at levels well below regulatory and administrative limits, and well below levels of any clinical concern,” Hassan said. “As a prudent step to manage risks, experts from NNSA’s Radiological Assistance Program visited the residences of some of the impacted team members to conduct testing on their belongings and made recommendations to the involved individuals, laboratory management, and the Department.”

Hassan said NNSA is committed to the health and safety of its employees as well as the general public.

“Immediate and proactive testing, informed by strong communications across the interagency, supported timely risk mitigation. We continue to review and improve safety processes to prevent similar incidents in the future,” she said.