Wednesday, June 19, 2013

The New Modern Nuclear Reactor

Non-Conventional Power


Chalk River Laboratories sits adjacent to the Ottawa River in Chalk River, Ontario, about
180 km (110 miles) from the nations’s capital, Ottawa; it has been existence since 1944,
constructed initially to help the Allies develop a nuclear bomb during the Second World War.
I worked there as a summer engineering student in 1980.
Photo Credit: CNA
Source: Canadian Nuclear Association

An article, by Gareth Cook, in The New Yorker looks at how two engineering students from M.I.T. have designed a nuclear reactor, which can conceivably and conceptually avoid the problems of traditional reactors, most notably a nuclear meltdown of the core and the need to replace spent uranium fuel rods.

Cook writes:
In February of 2010, Leslie Dewan and Mark Massie, two M.I.T. students, were sitting on a bench in a soaring marble lobby under the university’s iconic dome. They had just passed their Ph.D. qualifying exams in nuclear engineering, and were talking about what to do next. This being Cambridge, they began to muse about a start-up. By the end of their conversation, they’d decided to design their own nuclear reactor. Even as start-up concepts go, it was pretty weak. Constructing a nuclear power plant is not like tossing together a ninety-nine-cent app, and the industry is not an obvious one to try to disrupt. Nuclear engineering is a complex and potentially dangerous field that drives international conflicts. Dewan and Massie would need money and an abundant amount of patience. Another flaw in their scheme: they didn’t actually have an idea for a new and better nuclear power plant.
Three years later, Dewan and Massie have a company, called Transatomic, with a million dollars in funding, an impressive board of advisers, and a vote of confidence from the Department of Energy, which recently awarded the pair first prize in their Future Energy innovation contest. Russ Wilcox, a co-founder of E Ink, has joined as C.E.O. and resident grownup. In the months after their first conversation, Dewan and Massie drew up a design for a nuclear reactor that is small, relatively cheap, and “walk-away safe”: even if it loses all power, it cools on its own, avoiding a Fukushima-style meltdown. Theoretically, the reactor can put out as much electric power (five hundred megawatts) as a standard coal plant without belching carbon into the atmosphere. It can also run on nuclear waste, generating power even as it relieves another environmental burden. “We had this sense that there are so many unexplored aspects of nuclear technology,” Dewan said. “We knew that there would be something out there that would work, and would be better.”
To understand how a nuclear reactor works in to understand the basic process. It is in many ways a simple process to understand:
“A nuclear power reactor is just a fancy way of boiling water,” she began. Nuclear fuel typically contains uranium-235, a massive and slightly unstable atom famously capable of sustaining chain reactions. Under the right conditions, its nucleus can absorb an extra neutron, growing for an instant and then separating into two smaller elements, releasing heat and three neutrons. If, on average, at least one of these neutrons splits another uranium atom, the chain continues, and the fuel is said to be in a critical state. (Criticality has to do with the concentration of uranium, and whether the neutrons are bounced back toward the fuel. A Ph.D. in nuclear engineering is helpful for understanding the concept, as is this video of ping-pong balls mounted on mouse traps.) Water is pumped past the heat source and becomes steam, which then turns turbines, generating electricity.
The company has many obstacles to overcome before even getting the go-ahead to build a prototype of the modern reactor, the most important being receiving regulatory  approval from the U.S. government. This is never easy to gain, particularly since we are talking about nuclear energy and nuclear fuel, which can theoretically be enriched for nefarious non-energy producing  purposes. There are also a number of security issues that go with dealing with any type of nuclear fuel. Equally important is the initial resistance to any new, untried technology, no matter how brilliant are its innovators.

This brings back personal memories. In 1980, I worked for a summer at Chalk River Nuclear Laboratories (CRNL) in Chalk River, Ontario, about 180 kilometres (110 miles) north-west of Ottawa (note: it is now called Chalk River Laboratories). The research facility was a former military installation dating to the Second World War; when I was there it still retained the green-and-white-colour scheme common to military bases. The Petawawa military base was not to far off; we often saw fighter jets zoom by above us.

Even then the nuclear research facility was a secure one; I had to undergo security screening and clearance to work there; and even had to swear an oath to the Queen. There was a coterie of summer students, many in science and engineering, who underwent the same process, and being young we found it both amusing and not to be taken serious. Yet, the work carried out at this top-notch research facility was very serious.

Our group all underwent an extensive three-week orientation, where many leading scientists lectured us on the nuclear industry and on nuclear reactors; in a sense we were receiving a mini-education in nuclear engineering. During the summer as an engineering student I learned much about the process of harnessing nuclear energy, including how fairly stable Uranium-235 is bombarded to make more neutrons leading to what is called a “controlled a chain reaction.” We also learned about the dangers of plutonium and the experiments of Enrico Fermi at the University Of Chicago, which lead to the development of the first nuclear reactor.

The CRNL site contained two research reactors, which were used to make nuclear isotopes destined for medical use; spent nuclear fuel was sent to Oak Ridge National Labs in Tennessee. It was all very hush-hush, since I was there a year after the partial core meltdown at Three Mile Island, in Pennsylvania, in March 1979. Then I was an advocate of nuclear energy, even seriously considering becoming a nuclear engineer. I have not thought about the issue for decades, but this article brought back memories, and more.

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You can read the rest of the article at [New Yorker]

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