According to DOE-EM, introduction of the waste simulant represents another step toward vitrifying (solidifying in glass) Hanford’s radioactive tank waste later this year.
“Our progress in cold commissioning is the result of decades of preparation, dedication, and collaboration between the department and our contractor partners and is another step toward safely addressing Hanford tank waste,” said Brian Harkins, acting manager of DOE-EM’s Hanford Field Office.
The process: During operational testing, ammonia and nitrous oxide–producing chemicals were introduced into the LAW Facility melters to replicate tank waste. According to DOE-EM, the plant and its systems will be tested with chemicals in simulated tank waste over the next few months to validate that all systems and equipment run safely and appropriately before radiological components are introduced later this year.
Once full-scale operations begin, the facility will process an average of 5,300 gallons of tank waste per day, mixing the treated waste with glass-forming materials, heating it to 2,100°F, and pouring it into stainless steel containers for safe, long-term disposal. Approximately 3.5 containers, weighing a total of 21 metric tons, will be produced each day, according to DOE-EM.
To begin treating Hanford’s nearly 56 million gallons of radioactive and chemical waste as soon as possible, DOE-EM initiated a direct-feed low-activity waste program in 2016. Under the program, tank waste is separated to remove the more radioactive portion (cesium and solids) so that the resulting low-activity waste can be fed directly to the LAW Facility for vitrification.
Ammonia leak: According to an inspector report by the Defense Nuclear Facilities Safety Board the WTP was put in a take cover condition twice during the week of April 28–May 2 because of a leak in the plant’s ammonia reagent system. Five thousand gallons of ammonia, used to treat nitrogen oxides in LAW Facility melter off-gas, is stored at the WTP.
While the leak resulted in high ammonia concentrations near the ammonia storage facility, it did not result in any “substantial ammonia exposures” to site workers, according to the DNFSB.
The DNFSB report noted that contractor personnel were working at the time to identify and repair or isolate the ammonia leak source.
