This announcement hit the nuclear industry like a two-by-four to the back of the head. There was no way not to process plutonium out of nuclear fuel. It is a byproduct of all commercial power generation using uranium as fuel. The operating license for the plant was denied, on presidential order.[292] It turned out that the reason for this strange action, stopping an industrial plant from operating after a quarter of a billion dollars had been spent building it, was President Carter’s fear of nuclear-weapons proliferation via easy access to plutonium. He was not necessarily afraid that the United States would build weapons using plutonium, as we were running two large, federally owned plants to turn out bomb-grade plutonium by the ton. He was afraid of smaller countries using their own fuel reprocessing for this purpose, and he wanted to symbolically show them that if we did not do it, then they should follow our example and not touch their nuclear waste.
The rest of the world went on about their business, and there is no record of anyone giving a thought to the President’s symbolic gesture. The Barnwell plant suffered drastically from the lack of an operating license, and although the next president, Ronald Reagan, lifted the ban on commercial fuel reprocessing, the concept of the federal government being able to shut it down at its discretion discouraged any further idea of operating it as a business, and its major customer, the Clinch River Breeder Reactor, had also been cancelled by President Carter. If there could be no civilian fuel reprocessing, then there was no sense in building a civilian breeder reactor. A fast breeder reactor runs on plutonium, and it must be extracted from the breeding blanket. The Barnwell plant was decommissioned in 2000. It had been a fine, constructive idea, a large investment, and 300 workers’ jobs, all gone down the drain.
The premise of the Carter administration’s decision to shut down civilian fuel reprocessing was incorrect, and it shows that a little knowledge is dangerous. Yes, spent uranium fuel from a commercial power reactor does contain plutonium, but it is not “bomb-grade” plutonium. In a plutonium-production reactor, specifically built to make plutonium for nuclear weapons, the fuel is natural uranium, containing very little fissile uranium-235. It burns up quickly, in weeks of running at full power, and it is changed for fresh fuel on a regular basis. The plutonium is separated chemically from the spent fuel. The plutonium is primarily the nuclide Pu-239, with a small amount of Pu-240. Pu-240 is made when a neutron is captured by Pu-239, presumably after it has been made by neutron capture by U-238. U-238 becomes U-239, and it does two quick beta-minus decays into Pu-239, using neptunium-239 as the bridge nuclide.
It is important to minimize the Pu-240 contamination, which is why the fuel is not allowed to linger in the neutron-rich environment of an operating reactor core. Pu-240 fissions spontaneously, not waiting for a neutron trigger, and in a bomb it would cause the device to engage in runaway fission and melt before it ever had a chance to explode. The presence of a Pu-240 contaminant, which cannot be separated from the desired Pu-239, is what forced the original design of the complex, difficult implosion method of setting off an atomic bomb in World War II. Minimizing the Pu-240 content is the reason for quick turnaround in the refueling of a plutonium production reactor.
A civilian power reactor does not turn around fuel quickly. It is usually changed out on a three-year schedule. Refueling requires the reactor to be taken offline, cooled down, and dismantled. You are not making electricity and the money from selling it when the reactor is down, so the time between refuelings is drawn out as long as is practical. Because it stays in the neutron environment for so long, the plutonium-239 is heavily invested with plutonium-240.[293] Its only application is for reactor fuel.[294] Nobody has ever built a nuclear explosive device using plutonium taken from a civilian power reactor.[295]
So, the current status of commercial nuclear power in the United States sums up bleakly as this:
1. America’s 100 operating nuclear power reactors are bloated examples of Rickover’s celebrated submarine power plants, increased in size to the point where the core structures are the weak point.
2. There is not a single reactor fuel reprocessing plant in the United States, making us unique in the nuclear-powered world, causing our reactor waste to be mostly inert filler, and discarding unused fuel.
3. That does not matter, because we presently have no place to bury the waste, even if to do so would be grotesquely inefficient. The waste is being stored in dry casks on the property of every nuclear power plant in the United States, waiting to be hauled away.
But all is not lost, and nuclear engineers and scientists, or what is left of them, are not sitting idle. There are currently in design or test at least five new power reactors, and they are all small, modular units, as was carefully planned for the Direct Connection Reactor back in 1960. It was a brilliant concept, to install from two to twenty tiny reactors at a power plant instead of four huge ones. Small reactors have small problems, small explosions, small coolant drips, and small investments. An entire reactor can be built in a production-line factory, loaded onto a truck, and taken to a pre-made hole in the ground. The difference in efficiency of building a small reactor out of standardized parts in a factory instead of welding together a unique mountain of plumbing in the field is mind-boggling.
This important concept, of minimally sized simple power units had been exploited by the U.S. Army in its Engineer Reactors Group beginning in 1954.[296] Its reactors provided reliable power for Army installations from the Panama Canal Zone to McMurdo Station in Antarctica. After a stunning list of accomplishments, including a nuclear power plant that could fit on the back of a truck, the program was laid to rest in 1977, due to budget cuts.
The companies that are planning to make modular reactors available in the competitive market are all private companies, and not any government or military organization. Three of them are in the United States. The NuScale Power Company in Corvallis, Oregon, is working on a 45-megawatt power reactor enclosed in a steel tube. Gen4 Energy, Inc. in Santa Fe, New Mexico, has designed a 25-megawatt modular reactor. Generation mPower LLC in Bedford County, Virginia, is planning to put six very small reactors in the ground in Tennessee where the Clinch River Breeder Reactor was supposed to have been.
Toshiba of Tokyo, Japan, is planning to install one of their tiny 4S reactors in Alberta, Canada, in 2020, and in France a consortium consisting mainly of AREVA is working on an interesting plan to use a nuclear submarine without a propeller as an off-shore, underwater mini-reactor power plant, the Flexblue. It will be controlled remotely by a person having a laptop computer, and if it should melt down they will simply unplug it. Being sealed up in a submarine hull underwater, it could be abandoned in place without causing environmental harm.[297]
292
Not exactly a presidential order. Barnwell and the Clinch River Breeder Reactor were shut down by presidential veto of S. 1811, the ERDA Authorization Act of 1978, preventing the legislative authorization necessary for constructing a breeder reactor and a reprocessing facility.
293
“Bomb-grade” plutonium is defined as 92 % Pu-239. Commercial reactor-derived plutonium is 60 % Pu-239. The United States, just to show off, once tested a plutonium-based bomb made of 85 % Pu-239 having an explosive yield of less than 20 kilotons.
294
Uranium fuel mixed with recovered plutonium is called “MOX.” MOX fuel was being used in reactor units 3, 5, and 6 at Fukushima I when it was hit by the Tohoku earthquake and tsunami, and this caused a great concern of several milligrams of plutonium dust possibly escaping into the atmosphere. (With 550 plutonium-based bombs having been tested above ground or underwater, there were probably already several tons of plutonium in the atmosphere.) MOX is commonly used in European power reactors.
295
The President’s heart was in the right place, but his nuclear waste isotope was wrong. What he should have been worried about was not plutonium, but neptunium. Neptunium-237 shows up in spent fuel, and it can be extracted using published chemical processes. No tedious isotope extraction is necessary, because it is all Np-137, which is just as fissile as Pu-239, U-235, or U-233. Np-137 makes a very low neutron background, so it can be used in a simple assembly bomb, just like U-235. There is evidence of an Np-137 atomic bomb test in the U.S., but it is, of course, classified SECRET. The neptunium bomb is something to worry about.
296
Right in the middle of the development program, the Army’s SL-1 reactor exploded in Idaho. The Army took this accident to mean that their reactor was
297
I applaud them for their various efforts and I wish these companies well, but, realistically, Toshiba and probably mPower have a chance of success. The Toshiba 4S design raised some licensing concern at the USNRC. It uses one central control rod, the part of the oversimplified SL-1 reactor that caused its destruction in a fatal steam explosion. We had pledged to never do that again. Toshiba will prove that its 4S reactor will not suffer from the single-control problem, but the other small companies are somewhat underfunded, and all are competing for what may be an initially limited market.