The Nuclear Fusion Delusion (Part One)
It seems like only yesterday that the senior author of this article (Dr. Lehr) was walking past Albert Einstein on the streets of Princeton, New Jersey, nodding to the great man and receiving a nod in return. It was not exactly yesterday, of course, but a frequent occurrence from 1953 to 1955 when I (Dr. Lehr) was a student at the university there.
In those days, Dr. Einstein spoke frequently about the forthcoming wonders of nuclear fusion energy. He predicted that its grand benefits would arrive about 50 years hence. Unfortunately, 50 years later, long after Dr. Einstein’s passing, most physicists still predicted that we would have to wait yet another 50 years before the generation of electricity through controlled nuclear fusion may be possible. That prediction has not changed much in the past decade.
We think it is time to back off on the highly costly research currently being conducted on fusion. In deference to Einstein, in the mid-1950s, we had yet to learn through experimentation about the huge obstacles that we now recognize. While 100s of billions of dollars have now been spent in the effort to prove Einstein correct, success is now unlikely.
While in all current nuclear reactors, which have operated since the 1950s, atoms are split to produce energy, nuclear fusion normally requires two hydrogen nuclei to fuse together leaving excess energy behind to harness. Our Sun is a massive nuclear fusion reactor. It works because it offers a tremendous gravitational force to apply pressure to the nuclei within, while they bombard each other in attempts to overcome the huge electrostatic repulsion resulting from their identical positive charges. Only when they do overcome this repulsion does the fusion occur that gives off excess energy.
On Earth, we are unable to replicate the pressure at the core of the Sun where fusion occurs, and so we must create temperatures of at least 100 million degrees Celsius, far hotter than in the Sun, to encourage fusion to occur. But the required confinement of the fusion has not been created economically. And, thus far, while a tiny amount of energy has been produced in a donut-shaped magnetic fusion container, called a tokamak, in CERN, Switzerland, years ago, the energy required to produce this energy has been vastly greater.
More than a dozen experiments are going on around the world. The largest tokamak in the world is in Oxfordshire, UK but the best funded has been ongoing for many years at the International Thermonuclear Experimental Reactor (ITER) at Saint Paul-lez-Durance, France funded by the US, Russia, China, Japan, the European Union, South Korea, and India.
Dr. Daniel Jassby, writing in The Bulletin of the Atomic Scientists on April 19, 2017 said that, after 25 years working on nuclear fusion experiments at the Princeton Plasma Physics Lab, “I began to look at the fusion enterprise more dispassionately in my retirement, concluding that a fusion reactor would be far from perfect, and in some ways close to the opposite.”
The real problem is attempting to scale down the reactions in the Sun which burns hydrogen at enormous temperature and density, sustained with unlimited time, creating benign reaction products, primarily helium. On Earth we have none of these conditions so, besides having to generate temperatures even hotter than the Sun, we must use heavier neutron-rich isotopes of hydrogen which are deuterium and tritium. While the former is readily available in sea water, the latter is only found in minute quantities in nature and so must be manufactured in a nuclear reactor.
The proponents of fusion reactors believe that their byproducts are totally harmless. However, fusion reactors that must burn neutron-rich isotopes have byproducts that, in Jassby’s words, are “anything but harmless.” The neutron stream generated in a fusion reactor leads to four problems including:
- radioactive waste,
- radiation damage to structures,
- the need for biological shielding,
- the potential for creating weapons grader plutonium.
Jassby says that the latter problem adds to “the threat of nuclear weapons proliferation, not lessening it, as fusion proponents would have it.”
But these reactors, if ever brought on line, would also have many of the problems that have beset fission reactors, which include high coolant demands, large operating costs, and on-site power demands that would lessen the output of power made for sale.
In magnetic confinement fusion, the only practical solution available so far, electrical and magnetic fields are used to control the high temperature fusion fuel known as “plasma,” a difficult-to-control material consisting of free nuclei and electrons. Inertial confinement in a circular tunnel is required with laser beams used to squeeze and heat the plasma to the extreme temperatures mentioned earlier.
If we have your attention now, wait, there is more, much more that we will deal with on America Out Loud next week. The thought that fusion reactors will become an economical power source any time in the foreseeable future is a pipe dream.
NOTE: Technological advances may someday make the generation of electricity through controlled nuclear fusion possible. Through the use of high-speed computer technology, we are better able to control the magnetic field to hold the plasma for longer time frames, for example. Nevertheless, there are a myriad list of problems that make it improbable that fusion will ever be economic. We discuss these problems in part 2 of this article.