In the 1980s, many municipalities built facilities to convert garbage into energy. Some of those plants, in order to keep the garbage burning at a high temperature, also burned natural gas or oil. The machines were designed to solve a problem in providing adequate facilities for garbage disposal by burning it to produce electricity.
The same idea is possible in nuclear power, except that the potential gain is far greater. What is now known as “spent” nuclear fuel can be useful fuel in a reactor that also converts former weapons material into short lived fission products and electricity. This combination takes a little creativity and a sound knowledge of nuclear technology.
Converting Energy
The Shippingport reactor, the first “commercial” nuclear power plant in the United States, used a core configuration known as a “seed and blanket.”
This configuration used a blanket of natural uranium surrounding a replaceable seed of highly enriched uranium to keep the core reactivity high enough for operation. The blanket material produced more than 50 percent of the energy output of the plant. It lasted for the life of three to four seeds.
The seed and blanket design was not adopted by private industry, partially because highly enriched uranium was not readily available. At the time, most of the material was needed for defense programs.
Times and technology change, and we are now presented with a timely opportunity to use the seed and blanket design to reduce the volume of two existing waste streams.
The fuel that has been removed from our current generation of reactors is somewhat more reactive than natural uranium. The elements are generally in excellent physical condition. The government has announced that it possesses a large store of highly enriched uranium and plutonium, both of which could readily be converted into seed-type fuel elements.
If 200 tonnes of highly enriched material (plutonium and uranium) were available, that would be enough to manufacture approximately 2000 seeds each with 100 kilograms of fissile material. If those seeds could achieve burn-ups similar to naval reactors, they would be able to produce as much energy as 200 million tons of oil. They would also be able to stimulate the production of a matching amount of energy from “spent” nuclear fuel. Following the first generation of such reactors, the seed could be recycled into about 1000 additional seeds to continue the process.
Simple and Efficient
This design could very easily be adapted to existing plants. There would, of course, be some up-front costs for the conversion, but the fuel should be available at garage sale prices since it is currently scheduled for permanent storage.
Using the former weapons material in the seed, both provides a secure place for temporary storage and provides a means by which the material can be rendered less useful for building bombs. There are few places in the world more resistent to forced entry than an operating nuclear reactor.
In the reactor, the highly enriched material is converted into a complex mix of fission products and transuranic isotopes that interfere with the complex machining required to produce a usable weapon.
There is currently a world-wide glut of nuclear fuel, since the infrastructure was constructed to support a reactor population that was projected to be far larger by now. Nuclear fuel costs are currently quite low because of the supply and demand imbalance. It might be difficult to economically justify the costs of the conversion to an accountant responsible for the finances of a single plant, but for the industry as a whole, it would give a terrific boost.
The main impact would be to defuse the argument that the industry does not know what to do with its waste. If the waste is recognized for its value as a fuel resource, the urgent need for a huge project to construct a nuclear waste storage site and the transportation infrastructure required to support it disappears.
There might even be a renewed interest in building new reactors. The nuclear companies that have been comfortable with their service and fuel supply business might suddenly have power plant customers beating down their doors. As shown by the movie industry’s boom after the widespread introduction of the VCR, a potential competitor often proves to be a lifesaver for a creaky old business.
As the management gurus would say, this seems to be a win-win situation (unless you happen to have an interest in selling coal, oil or natural gas).
