Scientific American claims Nuclear Fission Confirmed as Source of More than Half of Earth’s Heat
Nuclear fission powers the movement of Earth’s continents and crust, a consortium of physicists and other scientists is now reporting, confirming long-standing thinking on this topic.
But … there’s a problem. The paper’s abstract says nothing of the sort.
[U]ranium-238 and thorium-232 together contribute 20 (±error) TW to Earth’s heat flux. The neutrinos emitted from the decay of potassium-40 are below the limits of detection in our experiments, but are known to contribute 4 TW. Taken together, our observations indicate that heat from radioactive decay contributes about half of Earth’s total heat flux.
That’s radioactive decay, not fission. While they are both nuclear interactions, they are very different, and any science journalist writing on the topic should know the difference. David Biello and Scientific American screwed the pooch on this, and need to issue a mea culpa.
edit: maybe the body of the paper says something different, but it would be strange to not include it in the abstract
I don’t think it’s fair to say that decay and fission are “very different”. After all, uranium does undergo spontaneous fission – which is a type of radioactive decay.
However, I believe uranium is much more likely to decay via the creation of an alpha particle, so the vast majority of the heat is not produced by fission.
…but wait a minute, isn’t alpha decay — whereby a nucleus cleaves into a helium nucleus and a larger nucleus — just a special case of nuclear fission?
Maybe David Biello was right all along?
Hamish
No, alpha decay is alpha decay, not fission, in much the way that superconductors are not semiconductors This is sloppiness with the terminology.
I agree with the sloppiness, but I still don’t understand why alpha decay isn’t just a special case of spontaneous fission.
Any nuclear physicists out there?
Hamish
Fission implies the fragments are of comparable mass, certainly within a factor of two. Alpha-fission is perfectly reasonable: Add a neutron to boron-10, 3840 barns, obtain fission to He-4 and Li-7.
http://en.wikipedia.org/wiki/Boron_neutron_capture_therapy
http://en.wikipedia.org/wiki/Fission_product_yield
graph 1/3 down
Cosmic rays impacting the atmosphere and blasting atoms to bits is spallation. Spallation neutrons convert N-14 (n,p) C-14.