Nuclear recycling has risks and benefits

Yomiuri Yomiuri / Reuters

There was another explosion at a Japanese nuclear power plant today. Same power plant, same cause, different reactor. (Also, same outcome: The outer layer of the buildings surrounding the reactor was blown apart, but, again, there was no increase in radiation following the blast. The reactor, itself, is still contained.)

This particular reactor—Fukushima Daiichi #3—is a little bit different, though, and the Wall Street Journal does a good job of explaining why.

Nuclear experts are particularly worried about the No. 3 unit, supplied by Toshiba Corp., because it uses an unconventional fuel called MOX fuel, short for mixed oxide.

It is made by mixing low-enriched uranium with plutonium that has been recycled from a global stockpile of defunct nuclear weapons. This recycling is part of an international effort to decrease the number of nuclear weapons and move from "megatons to megawatts."

MOX fuel has greater concentrations of "actinides," or radioactive elements and runs hotter than conventional fuel, so a shut down plant would have to deal with more "decay" or residual heat from fuel rods.

There are at least two dozen MOX-burning nuclear plants globally. But some experts believe that an accident at a nuclear power plant utilizing MOX fuel could be more dangerous than one that uses conventional uranium-based fuel.

It's worth noting that this is one of the reasons why an interdisciplinary faculty group from MIT advised against the United States adopting a nuclear fuel recycling program. Primarily, the group was worried about proliferation—the process of recycling the fuel leaves more opportunities for potentially dangerous materials to fall into the wrong hands.

MIT didn't rule out recycling completely—just advised against it in the near term. But reading their report took me from thinking of nuclear recycling as simply common sense, to having a much more nuanced understanding of both the rewards and the risks.

I'd recommend this report as a relatively readable primer on the nuances of nuclear energy, in general. The full thing is 12 chapters long, but the executive summary is a quick read, and it's all available for free online.

• [David A]

  Where exactly are the “benefits” here?

  http://www.fissilematerials.org/ipfm/site_down/rr03.pdf

  http://www.fissilematerials.org/ipfm/pages_us_en/documents/documents/documents.php

• [Anonymous]

  TheAntipodean is onto something good. There are even thorium reactors that operate subcritically, like this: http://www.acceltech.us/

• [Anonymous]

  Sorry Maggie, but the MIT report for me has lost any credibility just on the first pages, when stating that

  “We believe the nuclear option should be retained, precisely because it is an important carbon-free source of power”.

  This is wrong. Nuclear energy generation is not carbon free, and is by no ways ‘clean’ in whatever sense. Construction, fuel supply, and waste management / storage do have a considerable impact also carbon-wise. A short primer on fuel supply, which is a part of the nuclear energy generation process that is often not considered when issues are discussed:

  Producing nuclear fuel is an energy-intensive process, as the ores that are mined, e.g., in the US contain 0.05 to 0.3% uranium oxide. This amount of uranium oxide has to be extracted by chemical processes that, as a side effect, also extract other heavy metals present in the ores which pose a considerable health hazard. The resulting triuranium octoxide (U3O8) is then converted to uranium hexafluoride, UF6. This is due to the fact that only about 0.7% of the natural uranium is of the fissionable isotope U-235, the fraction of which must be elevated to ~3.5% for the uranium to be usable as nuclear fuel in light-water reactors (which is the most common form for commercial reactors). This process is called ‘enrichment’, and it is done by separating the different uranium isotopes in the gaseous UF6 in gas centrifuges. So only a tiny fraction of the uranium can be turned to fuel (‘enriched uranium’), while most of it becomes ‘depleted uranium’, which is quite probably toxical and is sitting around in storage in huge quantities as there are few other uses for it. (So this must be added to the spent fuel as the waste that nuclear energy generation produces.) Finally, the enriched UF6 is converted to uranium dioxide (UO2) which is then further processed to fill the fuel rods. A typical commercial reactor has 100-150t of UO2 as a fuel load.

  Sources:

  http://en.wikipedia.org/wiki/Nuclear_fuel_cycle#Front_end
  http://www.ati.ac.at/fileadmin/files/research_areas/ssnm/nmkt/06_BWR.pdf
  http://classes.engr.oregonstate.edu/ne/fall2001/ne116/Bwr.ppt

• [Anonymous]

  Strange to see MIT hectoring others about proliferation issues, since their research reactor uses uranium that is more highly enriched and therefore more of a proliferation hazard than typical research or power rreactors.

• [Uniquack]

  I don’t get the second part of your title… what benefits, exactly? Perhaps the real question is who benefits? Nuclear power is like a fake perpetual motion machine– if you look under the table, you’ll see a wire running to the wall where it’s plugged in.

  Really, nuclear power is a very profitable industry for a bunch of arms manufacturers like GE, etc. They live high off the government hog of countries like Japan, France, the US, etc. Nuclear power is a net energy loser– add up the energetic costs of all the mining, refining, building and maintaining the reactor, and the millenia of waste handling, and there is nothing to be gained from it but sorrow. The industry has only continued to exist because of government subsidies, and those subsidies are largely because the governments have been running large debts, which have allowed them to play the game of pulling in more fossil fuel energy than would otherwise be given, which what really allows a country to have nuclear power.

  When oil peaks, and the industrial debt based, oil fed economies crash, the unsustainable reality of nuclear will be easy to see. Because then, it will be hard to maintain these goliath machines, and we’ll probably be facing more core meltdowns, sadly, as well as leakage of nuclear waste material as the companies go bankrupt. Consider this even in Japan as presaging our future.

  Sadly, Obama wasted so much in subsidies to nuclear– and just imagine what those billions would have done for domestic solar, wind, tidal, and microhydro industries had he been less corrupt and smarter?

  • [AnthonyC]

    Your claim about net lifecycle energy costs is completely unsubstantiated, and runs counter to every study I’ve ever seen on the subject. The energy released by the fuel vastly exceeds that needed to build the reactor, make the fuel, and deconstruct the reactor.

    And one of the benefits of nuclear *recycling* specifically is that when you reprocess the fuel, then burn it in a properly designed reactor, the spent fuel ends up with much more highly radioactive actinides, less uranium and plutonium. That means shorter half-lives, and thus less time for which it needs to be stored. For some breeder reactor designs, I’ve seen estimates that the fuel will only be dangerous for a few centuries, as compared to the tens of thousands of years discussed for current once-through fuel cycles in use in the US. We’ve already demonstrated that we can store 50 years’ worth of spent fuel on-site at the plant.

    • [David A]

      @AnthonyC
      What makes you think commercial-grade fast neutron reactors exist?
      Or are the least bit practical even in their experimental stages?

      http://www.fissilematerials.org/ipfm/site_down/rr08.pdf

• [firstbakingbook]

  I’m seeing multiple reports now that the fuel rods have been fully exposed.

• [TheAntipodean]

  I was only recently made aware of the potential for thorium reactors http://energyfromthorium.com/.
  Unfortunately uranium reactors were the choice de jour during the Cold War as one wanted lots of lovely plutonium that one needed to build up one’s nuclear arsenal http://www.telegraph.co.uk/finance/comment/7970619/Obama-could-kill-fossil-fuels-overnight-with-a-nuclear-dash-for-thorium.html.
  Now we are left with these dirty relics of geopolitical brinkmanship, and neglect the possibility of much safer thorium reactors, something that would integrate with with renewables to manage peak load and get us off fossil fuels once and for all.