Annette Cary, Tri-City Herald, October 28th, 2006
Hanford vitrification plant workers secure 130-foot stack
The skyline at Hanford’s vitrification plant changed Friday.
Bechtel National spent about four hours slowing lifting 125 tons of emission stacks 70 feet into the air to place them on top of the plant’s Low Activity Waste Facility.
“This is the first time we’ll see LAW looking like it will always look,” said Mike Lewis, manager of construction for Department of Energy contractor Bechtel National.
The building stands 70 feet tall and the 130-foot emission stacks bring the structure to 200 feet tall, about the height of a 17-story building.
The $12.2 billion vitrification plant is being built to immobilize Hanford’s worst radioactive waste inside glass logs for permanent disposal. The Low Activity Waste Facility will be the third-largest of the four large buildings at the plant, which will be surrounded by 25 support buildings.
The plant is planned to treat much of the 53 million gallons of radioactive and hazardous chemical waste now stored in underground tanks. It’s left from separating plutonium from irradiated fuel rods to produce plutonium for the nation’s nuclear weapons program from World War II through the Cold War.
Wastes will be separated at the Pretreatment Facility into low-activity radiation and high-level radiation components. The low-activity radiation waste will contain mostly hazardous chemicals with as much of the radioactive constituents removed as possible.
High-level radiation wastes can emit up to 5,000 rems of radiation an hour as measured on contact with the outside of a stainless steel container. The low-activity waste can have 0.4 rems per hour. That’s roughly the amount of natural background radiation a person would receive annually just by living in Washington state.
Silica and other glass-forming materials will be added to the waste and then the mixture will be melted to form glass.
That’s part of the need for the stacks raised Friday.
Gas from the two melters in the Low Activity Waste Facility will be cleaned and then released from the stacks, along with other air from the building’s ventilation system.
There’s no comparison to what was released from Hanford’s stacks during the plutonium production years, said Roy Schepens, manager of DOE’s Hanford Office of River Protection.
Emissions from the Low Activity Waste Facility will be filtered to remove small particles and sent through a scrubber that will use steam to settle out heavier particles before the air is released from the stacks.
The air emissions will have to meet standards of the Washington State Department of Ecology, the State Department of Health and the U.S. Environmental Protection Agency. Regulatory permits have been approved for the design of the stacks, but they still must receive operating permits.
The stacks will handle more than 110,000 cubic feet of air per minute that will be monitored and sampled before leaving the facility once operations begin.
The stack assembly that was lifted Friday includes three individual emission stacks, each between 4 and 5 feet in diameter, encased in an open steel framework.
Bechtel National used two cranes to lift the stack assembly to a standing position. The smaller crane slowly crawled toward the larger one holding the bottom end of the stacks as the larger crane lifted from the top of the stacks until the assembly was suspended.
“Slow and easy,” Lewis said as work began.
Then the 270-foot-tall crane lifted the stack assembly high enough to clear the building and swung it into place on the roof.
Bechtel National chose Friday for the lift because workers build at the site on 10-day shifts from Monday through Thursday. That cleared the area of all but 50 of the approximately 700 people usually at the construction site.
The contractor also carefully planned the lift with detailed drawings, computer calculations of the weight on both cranes, load tests of the components in the slings and a check of the credentials of those working on the project.
This week workers also finished the roofing and siding on the building. It’s “dried in,” as they say.
Now they’ll continue work inside where it’s warm and dry on electrical, heating and other systems, working toward a construction finish date for that building in 2012.
“If you go inside, it’s starting to look like a plant,” Schepens said.
Every day the look of the vitrification plant seems to change, said Dave Smith, president of the Central Washington Building and Construction Trades Council.
But “major milestones like today’s add emphasis to the accomplishments,” he said.
Share this:
