Nuclear Fusion No Waste? Not That Simple.

I came across this sentence:

Unlike nuclear fission reactions, our present source of nuclear power and weaponry, nuclear fusion leaves behind no nuclear waste and no other product besides helium.

Sorry, but it is not that simple.

The most feasible fuels for a fusion reactor are D (Deuterium) and T (Tritium):

1D2 + 1T3 -> 2He4 (3.5 MeV) + 0n1 (14.1 MeV) + 17.6 MeV
 (deuterium + tritium -> helium-4 + a neutron + energy)

The direct waste products are helium-4 and the DT neutron. The helium is just stable helium. Not a problem. The problem is the 14.1 MeV neutron. It has energy, and will induce radioactivity. What type and how harmful depends on what the walls of the reactor are made of.

The 14.1 MeV neutrons irradiate the surrounding structure, and when the neutron is ultimately absorbed, the absorbing nuclide becomes radioactive. So, fusion does produce waste products in the form of irradiated (and activated) structural materials, which ultimately have to be disposed of in some appropriate facility.

And likely, in a DT (deuterium + titrium) plasma, there will not only be D + T reactions, but also some D + D reactions, half of which produce p + T and the other half produce n + He3. The neutron produced in this case is called a DD neutron. The T in DD burning is radioactive, and it must be kept out of the environment.

The DD/DT burning ratio, which can be estimated by the DD/DT neutron ratio in the burning plasma, is considered essential for burn control, alpha particle emission rate monitoring and tritium fuel cycle estimation, and is currently still under research.

Saying that there will be no nuclear waste besides helium is simply not true.

  3 comments for “Nuclear Fusion No Waste? Not That Simple.

  1. Simon
    December 18, 2013 at 20:58

    Have you read about the fusion between Helium-3 and Deuterium? Because what i have gotten out of it there should not be any radioactive waste from that process.

    • anonymiss
      December 19, 2013 at 02:08

      Oh dear, a Space Race! We have to go plunder Earth immediately for building the spacecrafts required!

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