Hanford’s tank farm contractor can do more to protect workers from brief exposures to high concentrations of chemicals, according to the just-released Hanford Tank Vapor Assessment Report.
“The current program is not designed to detect and is incapable of detecting and quantifying this type of transient exposure event,” the report said.
Since this spring 54 workers have received medical evaluations for possible exposure to chemical vapors released from Hanford waste and all have been released to return to work.
The study team made 40 recommendations for improvements to the Hanford contractor’s program to monitor for vapors that are difficult to measure and document and protect workers. That includes setting exposure limits for brief exposures, as well as for eight-hour shifts.
The tanks hold 56 million gallons of waste from the past production of plutonium for the nation’s nuclear weapons program.
Current efforts at the tank farms estimate chemical exposures from vapors released over eight-hour periods, according to the $1.6 million report commissioned by tank farm contractor Washington River Protection Solutions and independently led by the Savannah River National Laboratory in South Carolina. The Department of Energy paid for the study.
Hanford’s program addresses chemical exposures similar to industry programs that monitor for chronic exposure with an emphasis on protecting against long-term health effects that can result from cumulative or ongoing exposures.
But the symptoms workers have reported appear to be caused by concentrated chemical exposures over just seconds or minutes, the report said.
“Management must acknowledge the health risk associated with episodic releases of tank vapors,” the report said.
The chemical vapor protection program must be elevated to the same level as work to protect workers from radiological hazards and programs to prevent explosions and unplanned nuclear reactions within the tanks, it said.
Washington River Protection Solutions has begun addressing recommendations, based on preliminary information in an early draft of the report.
“We want this fixed and fixed once and for all,” said Dave Olson, Washington River Protection Solutions president. Work will continue in the tank farms for decades and vapors must be a known hazard that is effectively measured and controlled, he said.
The company will continue to work with the Tank Vapor Assessment Team that produced the report to develop a plan for implementing recommendations. The plan should be available before the end of the year, but full implementation could take several years. Some of the report’s recommendations are for cutting-edge technology and research projects.
The report recommended real-time detection equipment with alarms for individual workers and “escape” respiratory equipment that workers could carry with them to quickly put on when chemicals are detected.
It also discussed the possibility of modifying optical gas imaging cameras used in the petroleum industry to detect clouds of vapors before workers are exposed and to sound an alarm.
The key symptoms being reported by workers exposed to chemical vapors this year are upper respiratory irritation, such as sore throats, but workers are concerned that chemical exposure could lead to serious long-term health problems. In one incident this year, a worker was treated for chemical pneumonitis, an inflammation of the lungs caused by chemical exposure.
Workers already are being better protected with a requirement that they wear respirators in Hanford single-shell tank farms where underground tanks vent vapors into the atmosphere and in double-shell tank farms when active ventilation systems there are not working. The requirement was set in September based on the early draft of the report.
The tank farms already have a well-qualified and well-educated staff of industrial hygiene professionals, but more employees need to be hired to to make the protection program more effective, the report said.
The tank farm contractor already has added 56 positions to its industrial hygiene staff and is advertising to hire another 50 employees.
Some of the chemical vapors are vented from the head space of underground tanks and ongoing sampling of the spaces is needed, the report said. Earlier work to determine the types and chemicals in the space needs to be restarted.
The medical evaluations of workers and decisions on their compensation claims for illness and injury need to take into account the complex mixture of chemicals and the potential, short-term, episodic nature of the vapor incidents, the report said.
The tank farm contractor does not make decisions on medical issues or compensation claims, but provides exposure data.
The report also recommended pursuing more research by Pacific Northwest National Laboratory or other institutions to increase understanding of vapor exposure, effects and protective measures. Researchers could test vapor detection systems, model how plumes of vapors disperse or investigate how the vapors affect health, including over the long term.
The report recommended that changes to the infrastructure of the tank farms be accelerated to better protect workers. That includes using exhausters to actively vent tanks that now are passively vented and using air flow promoters on stacks to better disperse vapors they release. Using large fans to sweep air across tank farms and disperse vapors or smaller fans where vapors vent from tanks should also be investigated.
A fresh look at past recommendations that were deemed impractical is recommended. That includes “stacks in the sticks,” a proposal to vent vapors into the air a half mile away from areas where workers are based.
The report acknowledged that limiting the emissions of chemical vapors and worker exposure to them “represents an extraordinary challenge that cannot be easily addressed through traditional approaches.”
The vapors in the head space of the tanks may contain 1,500 different chemicals undergoing changes due to radiation, heat and chemical reactions. The chemicals and concentrations can vary from tank to tank.
There also are multiple places that chemical vapors can be released, including concrete-lined pits near the tanks, the temporary and permanent waste lines between tanks and the cabinets that workers open to take readings.
DOE said the report would be used to ensure enduring changes to protect workers at the tank farm.
The report has been posted online.