Nuclear Fusion: Is it as Safe as We Think?

Dmitri Prieto

Nuclear fusion.  Image:
Nuclear fusion. Image:

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.

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.

    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.

  • A fusion reactor wouldn’t ‘Blow up’ because if the reaction touched the sides of the tokamak the heat from the reaction would dissipate and fusion would cease. Essentially it’s so difficult to get fusion going in the first place that it’s pretty damn easy to stop. So it can’t melt down like a fission plant can.

  • Thorium and molten salt reactors have been tested and can already produce the world’s yearly electricity demand with 5000T of the stuff according to Kirk Sorensen… ”Fuel costs. Thorium fuel is plentiful and inexpensive; one ton worth $300,000 can power a 1,000 megawatt LFTR for a year – enough power for a city. Just 500 tons would supply all US electric energy for a year. The US government has 3,752 tons stored in the desert. US Geological Survey estimates reserves of 300,000 tons, and Thorium Energy claims 1.8 million tons of ore on 1,400 acres of Lemhi Pass, Idaho. Fuel costs for thorium would be $0.00004/kWh, compared to coal at $0.03/kWh.” to put things in perspective Germany pays on average 0.38/kwh .Many ‘too big to fail’ corporations in energy and automobile might go bankrupt if they don’t adapt and i believe thats why its not out there already, but imagine the boost to the economy with such a lowering of the electricity and heat costs! We’re launching a democratic movement for the development and crowdfunding of Thorium and MSRs to tackle climate change and reduce the risk of a MAD war, if anybody cares to join, comment or simply inform themselves about Thorium and MSRs, your help is needed. 2015: 3 minutes to midnight… we must act. ps: This movement started yesterday by the way : )

  • My only issue with this is that we still wont get off fossil fuels. Sure, we could trade in all our petroleum cars for electric, but we still have our shipping industry- jet airliners, diesel trucks and trains, shipping.. Electric versions of these is just not a viable solution unless they carry spare batteries, which would just take up more weight. Yes, we will see a substantial drop in our fossil fuel use, but it still wont go away.
    Also of concern is just how small can fusion reactors be made? one mistake made at Chernobyl, Fukushima and 3-mile was that they built one big facility each rather than several smaller ones. In doing so, then when one blows up it causes less damage, one would think.
    I want to see this ITER project succeed, but it will be many years in the future before we see it start to actually do something beneficial.

  • What fusion produces depends on what fuel is used. For some fuel combinations there are practically no neutrons (search for “aneutronic” fusion and see). Fusion is self-limiting (it’s almost impossible to start, unlike fission that’s almost impossible to stop).

  • It appears that doesn’t matter if it safe or not….when it works …works…And consequently make money from it…

  • Thorium reactors are essentially breeder reactors. You need something fissile (uranium-235 or plutonium-239/244) to get them going. The way it keeps running is the change of thorium-232 to uranium-233, an entirely artificial and fissile element. The idea that the fuel will just burn on like a perpetual motion machine is a dream – just like the perpetual motion machine! Radioactive particles will not be “told what to do”, they don’t just hit the atoms fuel that you want them to hit. There will be other radioactive elements produced which will eventually “clog” the process. Meltdown is less likely but still possible. Radioactivity into the environment – probably no change. In any case, in spite of the global interest, there are no functioning thorium reactors at this time. They are theoretical.

  • I really believe
    that fusion will come in forms smaller, cheaper, and sooner than most energy
    analysts now anticipate.

    Some people like the idea of fusion and an abundant energy generator that
    produces non-radioactive helium as its nuclear waste. What is less exciting is
    the fact that only one type of nuclear fusion has ever produced net energy
    (more energy out of the fusion experiment than it takes to run the fusion
    experiment). That form of fusion is “impure fission-fusion” that uses
    the power of fission to create the conditions needed for fusion.

    There is real reason to be optimistic about fusion today (not just hype and
    rah-rah). Several small fusion experiments are getting genuinely close to
    achieving “break-even” and fusion ignition.

    Here is a link to an article at The Next Big Future Blog that does a good job
    reviewing the current status.

    Fusion has a real advantage over fission today as regards the current level of
    regulatory obstruction from NRC.

    While this may not seem significant, it could make a real difference in how
    quickly fusion will emerge as a commercial technology in forms people will want
    to build and own to produce power.

    Some of the small, low cost fusion approaches are getting genuinely close to
    fusion ignition and practical power generation [1].

    One of the keys to practical production of fusion power is to meet the basic
    conditions required for fusion (the famous Lawson criteria of temperature, plasma
    pressure, and confinement time). At least one small fusion experiment at
    Lawrenceville Plasma Physics headed up by Dr. Eric Lerner has at this point
    technically already met the minimal conditions for D-T fusion.

    D + T -> 2He-4 (3.5 MeV) + neutron (14.1 MeV)

    The Lawson criterion for fusion ignition and break-even with D-T fusion is
    about 4 x 10^15 keV s/cm^3.

    Eric Lerner of Lawrenceville Plasma Physics reports in peer reviewed literature
    that his experiment has achieved 5 x 10^15 keV s/cm^3

    This report makes things sound like LPP has achieved the long sought fusion
    goal of break-even energy already, but (as usual) things are more complex than
    a single number like Lawson criteria.

    First off, the temperatures LPP has achieved are actually too hot for ideal D-T
    fusion. At 150 keV they would need longer confinement times and/or higher
    densities than they have

    achieved (or so far announced) to reach break-even. So if they were actually
    looking to produce fusion ignition via D-T fusion they would aim to make their
    plasma a little cooler and a little denser.

    In theory, LPP should not be that far away, but they are not putting effort
    into D-T or D-D fusion at this time (although in the past they have made many
    runs using both D-T and D-D fusion). D-T fusion is the fusion reaction that is
    easiest to achieve – but LPP is not currently interested in going that

    That’s because LPP isn’t really interested in D-T type fusion. The
    “problem” with D-T fusion is that a lot of the energy in D-T comes in
    the form of 14.1 MeV high-energy neutrons, which tend to make reactor materials
    highly radioactive via neutron activation. In theory you can capture that
    energy the same way you do with a conventional nuclear reactor (that is, by
    using the radiation to get something like liquid Lithium hot and using it to
    boil water or heat molten salt to run a turbine). Part of the problem with D-T
    fusion is the tritium itself, which is radioactive unlike deuterium fusion
    fuel, and LPP doesn’t want to get into all those radioactive-materials handling
    issues. Tritium is also very expensive to purchase (about $30,000 per gram as
    estimated by Los Alamos National Lab).

    So LPP has chosen to set their sights just a bit higher. They plan to bypass
    easier to achieve D-T and the cheap and very sustainable D-D fusion reaction in
    favor of aneutronic fusion (for me, the is a questionable and perhaps
    unfortunate choice – neutronic fusion producing a huge number of high value
    neutrons is valuable and could be used for applications like nuclear waste
    burning, medical isotope production, and manufacture of fuel for fission
    reactors, as well as producing electricity from fusion).

    The fusion reaction LPP prefers is called p-B-11, which uses conventional
    hydrogen (which becomes a bare proton, p, when ionized) and boron-11, which is over 100X more difficult to ignite in a tokamak (and is about 20X as hard to
    ignite in a properly designed Inertial Confinement Fusion device).

    [1] – LPP at Google’s Solve for X Conference – still leading the field –

  • I’m surprised there is no mention of thorium. For Cuba, a thorium-powered electricity plant may be feasible. It is not dangerous and the “fuel” is ubiquitous. Fusion is too costly and dangerous. There is no possibility of meltdown or radioactivity being discharged into the environment with thorium reactors as I understand them.

  • The radioactive material in a fusion plant is short lived, i.e. 20-30 years half-time. For a fission plant the radioactive material has a half-time of >100000 years. I do believe it is possible to store something for 50-100 years safely, but not for more than 100.000 years….

  • Only safe nuclear power is the aneutronic nuclear fusion with which is possible to produce carbon-free electric power with no long-lived radioactive materials, no meltdowns and no enrichment of uranium and plutonium for nuclear weapons.

  • I’m not sure if I get that point. Chernobyl was 100% human error (actually, it was almost sabotage) and Fukushima was the result of a huge earthquake followed by a massive tsunami and even so, it was fairly intact (most of the damage was caused again by human error). Even with those two, nuclear plants have a damn good operational record in the last 50 years or so, at least compared with other sources of energy (68 direct deaths – 56 of them i Chernobyl, plus 4000 indirect deaths by cancer)

    Now, lets compare the numbers with “cleaner” sources of energy, like hydroelectric… 26000 direct deaths and 145000 indirect deaths caused by a single incident plus 79 additional deaths and several incomplete reports

    And we are not even analyzing the worst offender (coal generation) or direct and indirect accidents caused from the extraction of the components for “green” sources, like solar and wind turbines.

    The bottom line is, danger is all around the place and accidents happen, but nuclear power has a fairly clean operational record compared wit virtually any other power source.

    There are dangers? Of course, but safety have been continuously improving, and right now the greater risk comes from the irrational fear of nuclear power by people spreading FUD and preventing the construction of newer and safer plants without realizing that the only thing they have achieved is keeping older, unsafer plants in operation because despite of or the bit***ng, very few people are willing to REDUCE their own levels of power consumption and the other sources are either too expensive or too unreliable to replace nuclear power.

  • They are not the only two fission plants, but enough to make a point.

  • Obviously this article aims to excite and worry the reader rather than simply to inform. Interesting that the only two fission plants mentioned are Chernobyl and Fukushima ! This is second-rate journalism.

  • Just to correct.

    Cold Fusion is not a hoax (the hoax was to use free space scatterings statistic inside a solid, claim fraud in public 20 days after announce, sabotage experiment 40 days after, and refuse to stepback 3 years after when all was clearly proven, and then claim that any success was a fraud and any failure a reality).

    today Cold fusion , alias LENR is nearly industrial.

    It is supported by the swedish R&D consortium of Swedish electricity utilities, Elforsk, which publicly confirm it work, and write it in their corporate magazine

    National instruments publicly support , invite and sponsor LENR “Edisonians”.

    NASA, US Navy NRL (after SPAWAR), ST Micro, Toyota, Mitsubishi, currently support and work on it.

    I have made an executive summary.

    you can find links to article on the scientific question if you doubt that those corps have a brain, to oppose the consensus (corp can be stupid, but they are stupid WITH the consensus, not against it).

    why it is not public is a psychiatric problem, well described by groupthink theory of roland benabou, by Thomas Kuhn, and experienced clearly in finance as recent Subprime crisis have shown (like current debt and keynesian crisis).

    Very common in fact, especially in a globalized world where groupthink can cover the planet through international scientific journals.

    by the way not totally…
    Italian energy research center ENEA could work despite US dogma.
    Japanese corporates (Toyota, Mitsubishi), like journals (Japanese Journal of applied physics have peer-reviewed Toyota article replicating Mitsubishi LENR transmutation this month), like even wikipedia (japanese wikipedia administrator refused to obey the censorship orders of western wiki talibans)

    hots fusion is dead and still don’t know it… or do they ?
    I see them hastily publish advertizing, as fast as LENR get endorsed by new corps.

    most of physicists will discover LENR , like SciAm discovered Wright planes, in the finance newspapers.

  • LOL, you sound like those prudes demanding walls in the sides of the railways because trains moving at 30 km/h will induce motion sickness to observers.

    More to the point, until we get a working reactor all we can do is idle speculation, but I’ll humor you. If all that fusion reactors emits is NEUTRON radiation, there is no need for a first wall shielding, at least not in the same sense as for fission reactors needs it. We can either use boron to contain the radiation in the primary shield or we can simply remove it completely and surround the reactor in a pool of water.

    That second option would work because as opposed to other forms of ionizing radiation, neutrons interact at much lower rates with matter, so it is possible to build a thin primary shield “transparent” to neutrons and contain the radiation using the water of the pool. The effect in the water at worst is going to be the formation of deuterium (that is harmless) and tritium (that is radioactive, but has a half life of 12 years) isotopes which ironically are the theoretical fuel for fusion reactors, but even if it can’t be reused as fuel, it produces WAY less of ecological impact that the disposal of the waste created with the current fission technology.

    There are some additional caveats, like replacing whatever you use for the shield regularly as it still gong to degrade slowly over time, or performing maintenance tasks with robots instead of people (that I bet we do right now whenever possible) but even in a worst case scenario, the resulting waste will only emit low level radiation.

    So, if that are your only concerns, bring it on.

Comments are closed.