White House Chronicle

News Analysis With a Sense of Humor

The Birth of a New Reactor: Thorium Past and Present

by Leave a Comment

If you are designing a car from scratch, there are certain essentials to begin with. You need to start with the wheels on the corners, for example.

But when it comes to building a nuclear reactor, things are different. There are hundreds and maybe thousands of ways of doing it. The constant is that you need fissionable fuel and a moderator to collect the heat and manage the neutron flux.

That embarrassment of choice — now reflected in the number of small modular reactors (SMRs) vying for market acceptance — may be why thorium reactors, which began with promise, have been left on the shelf.

The nuclear establishment, goaded by the Nuclear Navy’s Adm. Hyman Rickover, wanted light water technology. That is what the first 100-plus U.S. civilian reactors employed.

At the dawn of the civilian nuclear age, it was a straight contest between two fuels: uranium and thorium. Thorium is fertile but not fissile: It can’t start a chain reaction unless it is triggered by a small amount of the isotope uranium-235.

Once this happens, thorium becomes uranium-232 and fizzes wonderfully with a steady stream of neutrons, producing heat in the moderator, which is where the first steps in making electricity are taken.

That heat is captured to create steam that turns a turbine.

Thorium was used in part in the first power-producing, commercial nuclear reactor: the 60-megawatt Shippingport Atomic Power Station in Beaver County, Pennsylvania. With three different fuel assemblies, it ran for 25 years, starting in 1957. It used solid fuel, which was to become the standard for civilian nuclear power.

Meanwhile, at the Oak Ridge National Laboratory in Tennessee, under its director, physicist Alvin Weinberg, work went ahead on what would become a legendary fast-breeder thorium reactor, using a liquid fuel embedded in molten salt. It went critical in 1965 and operated for five years before it was closed by the Atomic Energy Commission (forerunner of the Department of Energy) in a political move.

A fast reactor uses extra neutrons to create new fuel and burn up radioactive waste. The process is akin to perpetual motion — but isn’t, of course.

Now a charismatic nuclear engineer, Yash Patel, founder and CEO of AMReactor, is planning to bring thorium back as a viable future option for space exploration, power generation and, eventually, ship propulsion.

Patel told me that his reactors – he has designs for a microreactor (under 20 MW) and for a SMR (250 MW). The planned reactors are molten salt-moderated, thorium-fueled fast reactors.

He believes they will not only be cheaper, but will also operate better than the SMRs now entering the market.

Patel’s plan for Austin-registered AMReactor is to outsource as much of the fabrication as possible.

A fast reactor is called a breeder reactor because it generates more neutrons than are needed to produce fission, and these transmute waste into additional fuel.

Patel went to school in California and while looking for a career, a break came that changed the trajectory of his life. He got an internship with NASA at the Jet Propulsion Laboratory. There he worked on Curiosity, the plutonium-fueled Mars rover. His nuclear love affair, he told me, was “complete and instant.”

From NASA, he went to Texas A&M and graduated in nuclear engineering. He was well along with his PhD, when a family illness caused him to abandon it.

Patel lists two great blessings in his life. “The first was that I moved to America from India. The second was attending Texas A&M. That was another wonderful break.”

After a stint in biopharma, where he prospered, Patel started designing reactors in all his waking hours along with a friend, D’mitri Scott, now the chief technology officer at AMReactor.

Patel said the numbers didn’t work for their plans until they switched to thorium. It was a eureka moment.

There followed a period which he likened to Bill Gates and Steve Wozniak working on the first computer operating system. The two young men were obsessed and inspired by what they believed was extraordinary. “Our girlfriends, now our wives, saw very little of us. We sometimes worked all night,” Patel said.

With thorium, they found all they were looking for: a stable source of reliable power that was safe, couldn’t melt down, and was able to handle most of the fission products.

And it was proliferation-proof because of the presence of intense gamma radiation, which made it hard to process, steal or divert. “Thorium was the winner,” he said.

A new reactor is on the way.

 

The Scramble for a New Nuclear Reactor

by 1 Comment

You can build a car with three or four wheels. But mostly, you would want to do so with four for stability and marketplace acceptance. Basically, you need a wheel at each corner, after which you can do what you like. Flexibility comes in how you use the vehicle.
 
For nuclear power, the reverse of that truism applies. There are many, many ways of building a reactor and fueling it. But its purpose is singular: to make electricity. And making electricity is done in the time-honored way, using steam or gas to turn a turbine attached to a generator.
 
Around the world, some 460 reactors are electricity makers. Even allowing for events like the tsunami which struck Fukushima Daiichi, they are statistically the safest and most reliable electricity makers.
 
Yet they are large and built one at a time; one-offs, bespoke. They rely predominantly on two variations of a technology called “light water,” originally adapted from the U.S. Navy. This has left no room for other designs, fuels and materials.
 
Now there is a new movement to design and build smaller reactors that are not as wedded to the light water technology, although that is still in the game.
 
The U.S. Energy Information Administration calculates the demand for electricity will double by 2050, which means that the demand for nuclear-generated electricity with its carbon-free attributes should soar.
 
To understand the heft of a nuclear plant, which range from about 900 to 1,600 megawatts of electrical output (MWe), one needs a visual comparison. Most of the windmills that are now seen everywhere generate 1 MWe, or a little more when the wind is blowing. So it takes 1,000 or more windmills to do the job of just one nuclear power plant. That stark fact is why China, in environmental crisis, has the world’s largest nuclear construction program.
 
But the days of the behemoth light water reactor plants may be numbered.
 
The challenge comes from what are known as small modular reactors (SMRs), rated at under 300 MWe. Stimulated by a total of $452 million in matching funds from the U.S. Department of Energy, the race is on for these smaller reactors. Call them the new, improved, front-wheel drive reactors.
 
The future for these is so alluring that eight U.S.-based manufacturers are competing for seed funding from the DOE for reactors that range in size from 10 MWe up to 265 MWe. Other countries are also revved up including Argentina, China, India, Japan, Korea, Russia and South Africa.
 
Whatever the design, one of the big advantages the new entrants will have is that they will be wholly or partly built in factories, saving money and assuring quality. Some designs, like those of Babcock & Wilcox (which won the first round of funding) and Westinghouse, are sophisticated adaptations of light water technology.
 
Others, like General Atomics’ offering, called the Energy Multiplier Module, or EM2, are at the cutting-edge of nuclear energy. It relies on a high operating temperature of 850 degrees Centigrade to increase efficiency, reduce waste, and even to use nuclear waste as fuel. It is designed to work for 30 years without refueling, relying on a silicon carbide fiber ceramic that will hold the fuel pellets.
 
“The ceramic does not melt and if it is damaged, the material tends to heal itself,” says John Parmentola, senior vice president at General Atomics, which developed the Predator unmanned aerial vehicle and the electromagnetic launch system for aircraft carriers, which replaces the steam catapult.
 
Others designs include thorium fuel instead of uranium, the use of molten salt as a moderator and coolant. Three of them, including General Atomics' design, are so-called fast reactors, where a moderator is not used to slow down the neutrons as they collide with the target atoms. Think fission on steroids.
 
It is as though nuclear designers have thrown off the chains of legacy and are free to dream up wondrous new machines, similar to the start of the nuclear age. — For the Hearst-New York Times Syndicate

 

The Scramble for a New Nuclear Reactor

by 1 Comment

You can build a car with three or four wheels. But mostly, you would want to do so with four for stability and marketplace acceptance. Basically, you need a wheel at each corner, after which you can do what you like. Flexibility comes in how you use the vehicle.
 
For nuclear power, the reverse of that truism applies. There are many, many ways of building a reactor and fueling it. But its purpose is singular: to make electricity. And making electricity is done in the time-honored way, using steam or gas to turn a turbine attached to a generator.
 
Around the world, some 460 reactors are electricity makers. Even allowing for events like the tsunami which struck Fukushima Daiichi, they are statistically the safest and most reliable electricity makers.
 
Yet they are large and built one at a time; one-offs, bespoke. They rely predominantly on two variations of a technology called “light water,” originally adapted from the U.S. Navy. This has left no room for other designs, fuels and materials.
 
Now there is a new movement to design and build smaller reactors that are not as wedded to the light water technology, although that is still in the game.
 
The U.S. Energy Information Administration calculates the demand for electricity will double by 2050, which means that the demand for nuclear-generated electricity with its carbon-free attributes should soar.
 
To understand the heft of a nuclear plant, which range from about 900 to 1,600 megawatts of electrical output (MWe), one needs a visual comparison. Most of the windmills that are now seen everywhere generate 1 MWe, or a little more when the wind is blowing. So it takes 1,000 or more windmills to do the job of just one nuclear power plant. That stark fact is why China, in environmental crisis, has the world’s largest nuclear construction program.
 
But the days of the behemoth light water reactor plants may be numbered.
 
The challenge comes from what are known as small modular reactors (SMRs), rated at under 300 MWe. Stimulated by a total of $452 million in matching funds from the U.S. Department of Energy, the race is on for these smaller reactors. Call them the new, improved, front-wheel drive reactors.
 
The future for these is so alluring that eight U.S.-based manufacturers are competing for seed funding from the DOE for reactors that range in size from 10 MWe up to 265 MWe. Other countries are also revved up including Argentina, China, India, Japan, Korea, Russia and South Africa.
 
Whatever the design, one of the big advantages the new entrants will have is that they will be wholly or partly built in factories, saving money and assuring quality. Some designs, like those of Babcock & Wilcox (which won the first round of funding) and Westinghouse, are sophisticated adaptations of light water technology.
 
Others, like General Atomics’ offering, called the Energy Multiplier Module, or EM2, are at the cutting-edge of nuclear energy. It relies on a high operating temperature of 850 degrees Centigrade to increase efficiency, reduce waste, and even to use nuclear waste as fuel. It is designed to work for 30 years without refueling, relying on a silicon carbide fiber ceramic that will hold the fuel pellets.
 
“The ceramic does not melt and if it is damaged, the material tends to heal itself,” says John Parmentola, senior vice president at General Atomics, which developed the Predator unmanned aerial vehicle and the electromagnetic launch system for aircraft carriers, which replaces the steam catapult.
 
Others designs include thorium fuel instead of uranium, the use of molten salt as a moderator and coolant. Three of them, including General Atomics' design, are so-called fast reactors, where a moderator is not used to slow down the neutrons as they collide with the target atoms. Think fission on steroids.
 
It is as though nuclear designers have thrown off the chains of legacy and are free to dream up wondrous new machines, similar to the start of the nuclear age. — For the Hearst-New York Times Syndicate