There is no turning back at the vitrification plant at the Hanford site after heating up of the world’s largest radioactive waste melter began on Saturday, 20 years after construction of the plant began.
The 300-ton furnace now has to stay hot around the clock, as it first makes practice glass and then vitrifies radioactive waste for the first time in the nuclear reserve.
The glazing prepares the waste for final disposal.
“Permanently removing and solidifying the waste from Hanford’s tanks is one of the most important elements of the entire clean-up mission, and heating up the furnace is an extremely important step in that process,” said David Reeploeg, Tri-City Development Council vice president for federal programs and the Executive Director for Hanford Communities, a coalition of Hanford-area local governments.
The Department of Energy’s goal is to begin vitrifying radioactive waste, some of which has been stored in underground tanks since World War II, by the end of 2023.
The 580-square-mile Hanford Nuclear Reservation near Richland in eastern Washington produced about two-thirds of the country’s plutonium for its nuclear weapons program from World War II through the Cold War.
Uranium fuel irradiated at Hanford was chemically reprocessed to remove plutonium. The mix of radioactive and other hazardous chemical waste from reprocessing was stored in underground tanks, many of which are prone to leaks. They hold 56 million gallons of the waste until it can be treated for disposal.
The furnace being heated is the first of two at the $17 billion facility’s Low Activity Waste Facility and is expected to operate continuously for at least five years.
“When we complete the heat-up of the first melter, it will be another significant step in commissioning the waste treatment and immobilisation facility for future operations,” said Val McCain, project manager for Bechtel National.
Bechtel is the contractual partner for the construction, commissioning and start-up of the waste treatment and vitrification plant in preparation for the treatment of radioactive waste.
DOE and Bechtel plan to take a “disciplined approach” to heating the first furnace to 2,100 degrees Fahrenheit, said Brian Vance, DOE’s Hanford site manager.
Workers are expected to spend about two weeks gradually heating up the furnace while adding glass beads in batches to be melted during the first test run. The resulting molten glass is poured into a stainless steel container and removed from the building.
Once the smelter is fully operational and begins treating radioactive waste, the vitrified radioactive waste it produces will be buried at the Integrated Disposal Facility, a lined landfill site in central Hanford.
Initially, the vitrification plant will treat only some of the least radioactive tank waste, known as low-level waste.
Construction of the facility’s high-level waste facility has mostly stalled since 2012 when technical problems emerged, prompting the DOE to initially shift its focus to treating low-level waste.
DOE faces a federal court deadline to treat high-level radioactive waste in addition to initial treatment of low-level waste by 2033 and to have the Vit plant fully operational by 2036.
Slowly heat up the Hanford melter
Heat-up of the first furnace has begun with temporary start-up heaters, with heat-up to gradually transition to operational heating elements as the molten glass rises in the furnace and reaches their electrodes.
Bubblers are inserted into the melter to keep the waste mixed and prevent hot spots from forming.
Heating is done gradually to slowly dry out the insulation in the melter.
The temperature of the melter cannot be lowered now without damaging the melter’s insulation or the refractory, which can harden and become ineffective as the temperature cools.
Once the furnace temperature reaches 2,100 degrees, the next one to two months will be used to evaluate and verify the initial process.
Fluid Controls and Components, a Richland company, is supplying 108,000 pounds of glass beads or frits needed for the non-radioactive start-up of the low-level waste facility.
It mimics waste by dissolving into a solid form at high temperatures.
“It was our first time dealing with frit,” said Russ Watson, Richland’s vice president as the company worked on the first shipment. “The chemistry and physical profile of the frit was very complex. The specifications were strict and the monitoring process extensive.”
Lessons learned from heating up the first melter will be used to start the same process for the second of two melters at the low-level waste facility.
Once both are at operating temperature, the plant will next heat up a non-radioactive tank scrap simulant with a glass former as part of the preparation for the treatment of radioactive waste.
Since the melters have an expected lifespan of five years, preparations have begun to assemble replacement melters to have them ready when the original melters need to be replaced.
Hanford Glazing Plant
Commissioning the first furnace “required a tremendous amount of hard work and determination,” Reeploeg said.
Significant progress has been made over the past two years to prepare the vitrification plant for the start of waste treatment, Vance said.
Construction of parts of the plant needed to treat low-level waste was completed in early 2021.
The low-level waste facility is supported by the Vit plant analytical laboratory, which ensures the quality of the glass waste form produced; the sewage disposal plant, which will help with waste treatment during treatment; and 14 support structures that provide services such as water purification and electrical power.
In the summer of 2021, Hanford workers completed construction of the 3,500-foot pipeline between the tank farms, which will store waste to be treated, and the vitrification plant.
The line uses a reinforced tube within a tube to prevent leakage when the waste is transported to the vitrification plant in batches.
Work began earlier this year to pre-treat tank waste to prepare it for vitrification.
The Tank Side Cesium Removal System, or TSCR, began operations in January as the first industrial-scale processing of radioactive tank waste in preparation for disposal in the history of the Hanford site.
Waste that has been pre-treated to remove high-level radioactive waste components so that it can be treated as low-level radioactive waste is stored until the vitrification plant is operational.