Dmitri Prieto

Nuclear fusion.  Image: wikipedia.org
Nuclear fusion. Image: wikipedia.org

HAVANA TIMES — It seems to me that we are not sufficiently aware of the risks surrounding a new, emerging technology. Producing energy through the fusion of light nuclei (such as deuterium and tritium, which are heavy, radioactive isotopes of hydrogen) is the dream of many physicists and technologists.

This is the process which takes place inside the sun, the stars and hydrogen bombs. The aim is to “domesticate” the thermonuclear reaction so that, on the one hand, it does not produce an explosion (like the 50-megaton hydrogen bomb detonated by the Soviets in the Arctic in 1961), and, on the other, the process stabilizes at a temperature in which the atomic nuclei can fuse and generate energy.

No fusion thermonuclear plant yet exists.

Existing complexes are fission plants. I am referring to those that work on uranium and plutonium (like the Chernobyl and Fukushima nuclear power plants).

Since I was a child, I, the son of electrical engineers and physics lovers, have been hearing that we will “soon” see the first fusion reactor. I’ve read stories about complex Tokamak machines that use a magnetic field to control the ultra-hot plasma where the thermonuclear reaction is supposed to take place, and about reactors that heat up and weld radioactive isotopes with lasers.

In the 80s, there were even those who claimed they could achieve “cold fusion”, something which turned out to be a hoax.

I was about to get bored from the long wait (I’ve had plenty of people tell me that the “sun on earth” is just “around the corner”) when, this past October 18, Cuba’s Granma newspaper published an article quoting a BBC piece (Paul Rincon’s “Nuclear fusion milestone passed at US lab”) which reported that, under strictly controlled conditions and using 192 lasers, scientists at California’s National Ignition Facility managed to have a hydrogen pellet produce more energy by nuclear fusion than that supplied by the lasers.

That is to say, for the first time in history, controlled fusion has become a fact. It’s been proven: a facility that produces energy through the fusion of hydrogen nuclei can be constructed.

Of course, we’re not talking about a functioning thermonuclear plant, but about the possibility, in principle, of building one in the future.

In this connection, Granma repeats what has become a commonplace for those who write (or read) about the study of nuclear fusion:

 “They call it ‘The Holy Grail’ of energy, for it is clean, cheaper and practically inexhaustible…for it can meet the world’s energy needs without the threat of nuclear proliferation or environmental damage. [While] fission produces highly destructive and long-lasting residues that are difficult to eliminate, the residue produced by fusion is helium, a harmless and economically valuable gas.”

From this, we get the idea that fusion is so good that, in addition to solving humanity’s energy problems once and for all, it can be used to produce helium, a gas with which balloons at sweet-fifteen birthday parties can be filled up. It all sounds very clean and safe.

I feel, however, that we are (once again) giving in to dangerous hyperbole. Nuclear fusion produces neutrons.

Neutrons, as their name indicates, are neutral particles. As such, it isn’t hard for them to interact with positively-charged atomic nuclei. Neutronic radiation, thus, is capable of transforming a given nucleus into a heavier isotope, which tends to be radioactive.

This leads us to the problem of “the first wall”: any nuclear fusion facilities must be fitted with an internal container made up by a “first wall” that faces the space where the reaction takes place.

This wall will be exposed to neutronic radiation. It won’t take long for it to become radioactive and begin to erode. In time, it will have to be replaced by another wall if the fusion reactor is to remain in operation.

Where will the discarded containers end up? These “first walls” will be loaded with radioactivity. As fusion technology develops, this can become a problem.

Scientists may claim that the levels of radioactivity produced are low and the risks minor when compared to the advantages of this energy generating technology. But they said the same thing when fission reactors started to be used, and we know what happened later. I wonder if scientists have any concrete proposal in this regard.


Dimitri Prieto-Samsonov

Dmitri Prieto-Samsonov: I define myself as being either Cuban-Russian or Russian-Cuban, indiscriminately. I was born in Moscow in 1972 of a Russian mother and a Cuban father. I lived in the USSR until I was 13, although I was already familiar with Cuba-- where we would take our vacation almost every year. I currently live on the fifth floor of an apartment building in Santa Cruz del Norte, near the sea. I’ve studied biochemistry and law in Havana and anthropology in London. I’ve written about molecular biology, philosophy and anarchism, although I enjoy reading more than writing. I am currently teaching in the Agrarian University of Havana. I believe in God and in the possibility of a free society. Together with other people, that’s what we’re into: breaking down walls and routines.

20 thoughts on “Nuclear Fusion: Is it as Safe as We Think?

  • The walls will be constructed out of the isotope lithium-6. When lithium-6 is bombarded with neutrons it will either split in to one helium-4 and one hydrogen-3 (tritium).
    Now and then (in rare occasions) it will turn in to lithium-7. Lithium-7 is the most common form of lithium so nothing to worry about.
    If one lithium-7 then gets bombarded with a neutron and becomes lithium-8 then it will decay in to the very unstable beryllium-8, one free electron and a lot of energy (about 16 MeV).
    The very unstable berylium-8 will then fission in to two helium-4 and even more energy (about 2 MeV).
    The first lithium-6 to lithium-7 reaction will also release about 7 MeV.

    So the conclusion goes like this: Most of the neutrons will form one new hydrogen-3 for fuel and one helium-4. In the rare case that the neutrons forms lithium-7 it will only produce more energy. In the extremely rare case when one of those new lithium-7 atoms gets bombarded 18 MeV will be released and two new helium-4.

    This asumes you are using a DT fuel.

  • Lithium 6 bombarded with a neutron splits in to one hydrogen-3 and one helium-4. Tritium is the fuel used in the reactor. In very few cases it will turn in to lithium 7.
    Lithium 7 bombarded with a neutron turns in to the very unstable berylium-8 and one beta particle. The halflife of berylium-8 is 6.8×10^17 of a seconds and splits in to two helium-4. This allso releases something like 18 MeV if I remember it right.

    If there will be any radioactive waste then it would be from the reactor it self and not the cooling system.

  • It’s only the reactor components, and they will degrade due to neutron bombardment. That and the lithium metal coolant will get very radioactive. But, like you said, not for 1000 centuries.

    http://energizenw.com/wp-content/uploads/2013/05/Trojan-ISFSI-aerial.png

    These storage tanks are all that’s left of Trojan. Every fuel rod ever used is still there. It looks like these are good for centuries.

  • In the article, the only commercial fission reactors mentioned are Chernobyl, Fukushima, and 3-mile island. All three of which are most known to the general public for their issues. I also noticed the author’s attempt to relate all types of fission maybe even fusion reactors to these 3 reactors that experienced problems. To me it discredits the article as a fear-fanning media article aimed at a misinformed public that doesn’t understand the actual safety of fusion and fission plants.

  • I agree with the first response. A catastrophic failure, such as Chernobyl, is extremely unlikely with nuclear fusion. In most foreseeable cases of failure for a fusion reactor, the laws of physics aren’t obeyed. Also, for a fusion reactor, fuel can be cut to the reactor core and the fusion process would stop within a matter of milliseconds or even microseconds.

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