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Tue April 26, 2011
Questions remain about piping Hanford's nuclear waste
One of the most difficult challenges at the Hanford Nuclear Reservation is moving radioactive waste from point “A” to point “B.” The federal government is spending billions of dollars on a waste treatment plant. Piping that radioactive waste across the desert is sort of like getting ketchup out of a bottle. But it’s a whole lot more complicated and dangerous.
From the farthest of Hanford’s waste tanks to the new treatment plant it’s just seven miles as the crow flies. But the technical challenges engineers have to overcome to make that journey are enormous.
Tom Fletcher is one of the top guys in charge of that 53-million-gallons of radioactive tank waste.
“I’m going to have every finger and toe crossed that that machine turns on successfully and we transfer successfully, because it’s a history-making event when we make that first glass log.”
Glass logs about the size of telephone polls. That’s what the sludge will be when it comes out of the treatment plant for long term storage.
But in its current state, that radioactive toxic brew acts like ketchup.
It’s what scientists call a non-Newtonian liquid. That’s right, it doesn’t follow the laws of Isaac Newton – you know the ones about gravity and motion.
Walt Tamosaitis is an engineer and manager and has worked for about 40 years in the chemical and nuclear industries.
“If you turn a ketchup bottle upside down it won’t flow out. You have to squeeze the bottle or pound on the bottle in order to instill a sheer, a motion inside. Once the fluid gets a motion, it becomes thinner and it flows. That’s a non-Newtonian material.”
And that’s a problem for pumping. At first you have to pump really hard to get the sludge moving. Later though, you pump less hard to keep that same speed. But the sludge also contains heavy particles, like plutonium. Imagine chocolate chips in your ketchup.
“The chocolate chips will sit in the ketchup and not fall to the bottom of the bottle. But if you shook the dickens out of that bottle the chocolate chips would fall to the bottom because the ketchup would thin out.”
The same thing could happen if you were pumping sludge through a pipeline. So why do we care?
“A plugged pipeline is a very bad thing. In a chemical plant the vessels and the pipelines are like the heart and arteries in your body. If you have a problem in the heart like the vessels, or the pipe, like the arteries, it’s history. You have a bad problem.”
Tamosaitis says radioactive particles could possibly accumulate and make gas. The worst case scenario is what engineers call a criticality or explosion.
In fact, Tamosaitis says he was taken out of his job for raising some of these very questions with the waste treatment plant. His removal from his position at a key Hanford contractor last year is now the focus of an investigation by the Defense Nuclear Facilities Safety Board. But Tamosaitis isn’t alone. I talked to other experts on Hanford sludge who share the same concerns. And they told me there are other technical challenges that remain unsolved:
- What happens if government workers ever have to stop the flow in the pipelines?
- How do you clear clogs?
- And how do you keep the sludge the same consistency from batch to batch so you know how it will act?
That last one is the big-daddy question that Mike Thien is working on in an oversized garage in Pasco.
Thien mixes water and various powders in what looks like an industrial-sized fish tank. This simulated waste is like a milkshake in a massive blender. He takes a sample, to see if that little bit is the same as everything else in the tank.
“This is critically important because if we can not demonstrate that we can accurately sample and deliver tanks; that would mean we’d have to find another way to do it.”
Finding another way of doing it could mean changing the design of the government’s 12-billion-dollar processing plant. Or it could mean building another treatment plant to handle the waste before it ever gets to the massive plant they’re constructing now.
It’s possible to make the toxic waste flow better by simply adding water. But scientists say the evaporation that would be required later would drag out a mission that’s already scheduled to run 60 years. The Defense Nuclear Facilities Safety Board is studying Hanford’s plans for getting radioactive waste to its new facility. The agency plans to offer up an opinion, but hasn’t said when.
Copyright 2011 Northwest Public Radio