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Advanced Nuclear Technology for a Carbon-Free Future
by Bob Leonard
Nuclear power is an important component of our clean, sustainable energy future. Wind and solar are crucial and they will continue to be so. Nuclear power is also essential, and we need to get over knee jerk reactions related to Chernobyl, Three Mile Island and Fukushima.
I explained in detail how the burning of fossil fuels is demonstrably much more dangerous to human health than even legacy (old) nuclear technology. You can read my explanations at these links: Nuclear’s Role in Our Climate Emergency and Nuclear Energy’s Safety Record.
Like all energy sources, nuclear power has advantages and disadvantages. What are nuclear power’s benefits?
First, since it produces energy via nuclear fission rather than chemical burning, it generates baseload electricity with no GHG emissions.
Second, nuclear power plants operate at much higher capacity than renewable energy sources or fossil fuels. Capacity is a measure of what percentage of the time a power plant actually produces energy. It’s a problem for all intermittent energy sources. The sun doesn’t always shine, nor the wind always blow, nor water always flow through the turbines of a dam.
In the United States in 2016, nuclear power plants, which generated almost 20 percent of U.S. electricity, had an average capacity factor of 92.3%, meaning they operated at full power on 336 out of 365 days per year. (The other 29 days they were taken off the grid for maintenance.) In contrast, U.S. hydroelectric systems delivered power 38.2% of the time, wind turbines 34.5% of the time and solar electricity arrays only 25.1% of the time. Even plants powered with coal or natural gas only generate electricity about half the time. Nuclear is a clear winner on capacity. https://e360.yale.edu/features/why-nuclear-power-must-be-part-of-the-energy-solution-environmentalists-climate
Third, nuclear power releases less radiation into the environment than fossil fuels. It’s not commonly known that burning fossil fuels releases radiation. It does. The worst offender is coal, which contains a substantial volume of the radioactive elements uranium and thorium. Burning coal gasifies its organic materials, concentrating its mineral components into the remaining waste, called fly ash. So much coal is burned in the world and so much fly ash produced, that coal is actually the number one source of radioactive releases into the environment.
Nuclear waste disposal, although a continuing political problem in the U.S., is no longer a technological problem. Most U.S. spent fuel, more than 90% of which could be recycled to extend nuclear power production by hundreds of years, is currently stored safely in impenetrable concrete-and-steel dry casks on the grounds of operating reactors, its radiation slowly dwindling.
That’s the story for currently running nuclear reactors. New, advanced nuclear technology is even cleaner and safer. These new nuclear technologies are based on advanced physics, enabled by modern computing power that only became available in the last 10 to 15 years.
Third-generation reactors have:
- More standardized designs to expedite licensing, reduce capital cost and reduce construction time.
- Simpler and more rugged designs, making them easier to operate and less vulnerable to operational upsets.
- Higher availability and longer operating life – typically 60 years.
- Further reduced possibility of core melt accidents rated at calculated core damage frequency (CDF) of 1×10-5.
- Substantial grace period, so that following shutdown the plant requires no active intervention for (typically) 72 hours.
- Stronger reinforcement against aircraft impact than earlier designs, to resist radiological release.
- Higher burn-up rates to use fuel more fully and efficiently, and reduce the amount of waste.
There are a number of Generation IV nuclear technologies currently in development. These are overseen and coordinated by the Generation IV International Forum. They include:
- Very-High-Temperature Reactor (VHTR)
- Molten Salt Reactor (MSR)
- Supercritical-Water-Cooled Reactor (SCWR)
- Gas-Cooled Fast Reactor (GFR)
All of these types of Gen IV reactors are expected to be deployed by 2030. This work should be accelerated so that one or more of these technologies can begin deployment by 2025.
These advanced nuclear reactors use up much more of the fuel than present-day reactors – leaving less waste. Small modular reactors can better tailor energy use to demand. Molten salt reactors obtain up to ten times the energy from the same amount of uranium because the fission products and reaction poisons are removed as it goes. Fast reactors obtain at least ten times the energy from existing nuclear fuel by burning everything, not just U-235.
Thorium is an abundant, lightly radioactive metal (named by its Swedish discoverer after the Norse god, Thor) that can be used in certain types of nuclear reactors. It isn’t really fuel, because it can’t be split like uranium can. But when thorium is placed in a reactor, it absorbs some of the neutrons that are given off by fission. A thorium atom that picks up a neutron becomes a new element – uranium 233, which is a reactor fuel. So, a reactor can cook thorium into reactor fuel, and then consume the fuel to make electricity.
Thorium is about three times more abundant than uranium. It’s already produced by mining companies as a byproduct, and it has a variety of non-nuclear uses. Used fuel from thorium reactors contains minimal amounts of very long-lived radioactive materials compared to current uranium fuel, so disposing of waste is easier and safer.
Nuclear deserves better than the anti-nuclear prejudices and fears that have plagued it. It will be an integral technology on our journey to a Finite Earth Economy by 2030.
