Next-Generation Nuclear Energy Reactors: A Primer

Diagram of a boiling water nuclear reactor used in current nuclear plants/Credit: US NRC  

The next generation of nuclear power reactors promises to be safer, more fuel efficient and less water intensive — but the world must wait at least 20 years to see them in action.


Known as Generation IV reactors, the models are "revolutionary" in design, said David Lochbaum, director of the Nuclear Safety Project at the Union of Concerned Scientists. Ironically, though, the reactors' leading-edge features could end up being the greatest impediment to their initial adoption, he said.
Utilities are likely to be leery to shell out billions and billions without proof of operational success, Lochbaum told SolveClimate News, and that could "slow down the market" for the new designs.
The goal is to make the Gen IV fleet "competitive" on price with today's plants, said Robert Hill, a senior nuclear engineer at the Department of Energy's Argonne National Laboratory, though it's too early to tell if that's possible. A large nuclear reactor today costs between $4 and $10 billion.
For the moment, at least, the point is immaterial. Gen IV reactors still need a great deal of research and development, and the U.S. Department of Energy estimates they won't be commercially viable until 2030 at the earliest.
Development of the reactors is led by the Generation IV International Forum, a collaboration of 13 member nations, including the United States, Canada, Japan, China and the European Atomic Energy Community (Euratom). Each country contributes its own share of funding. In total, the forum's research and development work costs $400 million dollars a year.


Since its establishment in 2001, members have selected six basic designs of Gen IV technology.
Safety Improvements


Most of the world's existing reactors are Generation II plants designed in the 1970s. Over the past ten years, several countries have built Generation III reactors that are safer and simpler in design, supposedly reducing upfront capital costs.
Many Gen III reactors include "passive safety" mechanisms that get triggered by gravity or other natural forces in the event of trouble, said Hill. A reactor vessel, for instance, might have circulation systems that kick in even when electricity goes out to cool the facility through convection, making the plant less vulnerable to meltdown.
There's also a subset of reactors called Gen III-plus that can be hard to distinguish from Gen III designs, though generally they have safety enhancements.


Ted Quinn, former president of the American Nuclear Society, an industry group, said one of the Gen III-plus designs includes a "swimming pool," a reservoir of water positioned high up in the reactor. Since the water can be released through gravity there's no need to find power for water pumps during emergency situations, he said.


If Japan's Fukushima Daiichi reactor, a Gen II design, had such safety features, "we could have prevented some of the core damage," Quinn added.


The Gen III-plus plants also have backup batteries with a 72-hour lifespan, which gives emergency responders three days to restore power. It's an improvement over older reactors like Fukushima, whose batteries only last four to eight hours, he said.


Four Gen III-plus units are being licensed in the United States. Two are proposed for the Vogtle plant in Burke County, Georgia, and the other two for the V.C. Summer station near Jenkinsville, South Carolina.