Pantex Changing Procedures After Technician Receives ‘Higher Than Anticipated’ Dose
NS&D Monitor
3/13/2015
The Pantex Plant is bolstering its procedures after an instrument technician was exposed to a “higher than anticipated” radiation dose while doing maintenance work in a nuclear materials storage building. The unidentified worker was exposed Jan. 23 while performing maintenance in a Special Nuclear Materials Storage Facility at Pantex.
George Rangel, a spokesman for Pantex contractor Consolidated Nuclear Security, said the worker’s exposure was well below regulatory limits, but that the plant took a series of corrective steps after the worker’s exposure. “Upon learning of the incident, immediate actions were taken to re-emphasize with workers the importance of adhering to procedures and work package instructions, providing additional training to supervisors and involving radiation safety experts before proceeding with similar types of work that may be planned in other areas of the plant to ensure worker safety,” Rangel said. “This specific worker’s annual exposure for the end of January measured less than 1/100th of the annual (federal) regulatory limit, which is 5,000 milirem per year.”
No Internal Ingestion or Inhalation
Pantex, he said, sets a lower limit of 200 millirem for workers. A person living near the plant typically receives a yearly radiation dose of 620 millirem from naturally occurring and manmade sources of radiation, according to information from Pantex. “There was no internal ingestion or inhalation,” Rangel said. “Moving forward, the worker’s annual radiological dosimeter measurement will be factored into the type of work assigned to the worker for the remainder of the year to ensure they remain below the conservative Pantex limit.”
Pantex employees are monitored with special badges called thermoluminescent dosimeters, which measure radiation from neutrons, gamma and X-rays. To reduce exposures, sites such as Pantex follow As Low as Reasonably Achievable standards that are followed throughout the nuclear weapons complex. “We take worker safety seriously as the safety and health of our employers is paramount and a daily absolute in the work performed at Pantex and operations are conduct using As Low as Reasonably Achievable principles,” Rangel said.
Worker Performed Additional Scope of Work, Increasing Exposure Time
According to information from the Defense Nuclear Facilities Safety Board, the technician was working on a ladder calibrating heat monitoring systems as part of a yearly surveillance. According to an incident report, the worker was performing extra maintenance beyond the scope of an initial work order. “While performing this activity, the work team decided to remove some unused instrument wires from the facility. Both of these activities require the technician to be on a ladder, and they decided it would be best to accomplish both activities at the same time. … This increased the exposure time for the technician.”
A follow-up critique said the extra maintenance work should have been covered under a different work order, which would have required proper hazard screenings and a determination of whether the work posed an Unreviewed Safety Question. Pantex did not release the specific location where the exposure incident occurred.
Pits Lead to Bulk of Exposures at Site
At Pantex, workers periodically inventory plutonium storage containers in Zone 4, a heavily guarded bunker complex where tons of plutonium pits, the cores of nuclear weapons, are stored. “The operations that contribute the majority of the dose to Pantex workers are operations that expose them to large numbers of bare weapons pits (the pits contain significant quantities of Special Nuclear Materials),” according to a 2014 government report on Pantex worker exposures. Such operations include weapons assembly and disassembly operations, weapons dismantlements, operations used to requalify nuclear weapons components and nuclear material storage operations. In 2013, no individual worker’s dose exceeded the Pantex limit, according to the report.
In 2013, Pantex monitored more than 3,000 people. Of those, 330 had measurable TED (total effective dose equivalent), a 3 percent decrease from 2012. The TED to Pantex workers in 2013 was 21.829 person REMs, a 34 percent decrease from the total person-REM dose in 2012. “The primary reasons for the decreased population dose in 2013 were a turnover to a new work control software system and several facility safety upgrades. Consequently, the workload was lower in 2013,” the report said.
