Accelerator Driven Treatment of Nuclear Waste 226
quax writes "In the wake of the Fukushima disaster the nuclear industry again faces massive opposition. Germany even decided to abandon nuclear energy altogether and the future of the industry is under a cloud of uncertainty in Japan. But one thing seems to be here to stay for a very, very long time: radioactive waste that has half-lives measured in thousands of years. But there is a technology under development in Belgium that could change all this: A sub-critical reactor design, driven by a particle accelerator can transmute the nuclear waste into something that goes away in about two hundred years. Could this lead to a revival of the nuclear industry and the reprocessing of spent reactor fuel?"
Developed in the US not Belgium (Score:5, Informative)
Back in the 1990s this was developed at Los Alamos and a few other accelerator centers. it's not new or unique to belgium.
http://www.lanl.gov/orgs/pa/science21/ATW.html [lanl.gov]
http://www.world-nuclear.org/sym/1999/venneri.htm [world-nuclear.org]
Re:Cue the hippies (Score:4, Informative)
Yes, everyone's so worried about the disposal of the spent nuclear fuel rods, while coal ash is scattered to the wind with reckless abandon: http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste [scientificamerican.com]
Re:Thorium reactors? (Score:5, Informative)
Primary reason is the many billions of dollars of development needed to figure it all out.
There is no design for a "working commercial thorium reactors". It's all just bits and pieces of theory, and experimental reactors that only answered some of the questions.
It's a possible technology, just not an actual technology. Kind of like the guy at NASA who recently got into the news for a pen and paper proposal of how warp speed might be possible. We are still a long way from building interstellar spaceships. Just like we are long way from building a Thorium salt reactor that works and is economically viable.
sounds too good to be true (Score:2, Informative)
The "transmutation" of nuclear waste into harmless substances, sounds too good to be true? That's because it is. This paper takes a more critical look at the theory: www.laka.org/docu/boeken/pdf/6-01-5-56-25.pdf
"Transmutation of all long-lived radionuclides into short lived ones to a degree sufficient to obviate the need for a geologic repository is practically impossible. In particular, the transmutation of separated uranium, which constitutes about 94 percent of the weight of light water reactor spent fuel and which is very long-lived and generally
contaminated with some fission products, would be counterproductive. The main transmutation route for almost all the uranium would be to convert uranium-238 (the dominant isotope) into plutonium-239. Hence, the complete transmutation of uranium-238 essentially requires the creation of a plutonium economy, which would be unsound
whether viewed from an economic, environmental, or non-proliferation standpoint. Almost all the uranium must therefore be disposed of without transmutation as a matter of practical necessity. Other long-lived fission products as well as residual transuranic actinides would also need disposal. Hence, a repository, as well as other waste
management and storage facilities would still be an essential part of transmutation schemes. "
Re:A step (Score:5, Informative)
Re:1,000 year? 200 year? Who cares. (Score:5, Informative)
They spend the money on bread and circuses while leaving the waste at the plants. Typical federal government.
Actually leaving the waste at the plant may in the long run prove to be the right decision.
After all, if this method works it is likely to be co-located with an existing generation plant, because it has the potential of transmuting the spent fuels into something useful again.
As TFA points out: In 2006 France changed its laws and regulations in anticipation of this new technology, and now requires that nuclear waste storage sites remain accessible for at least a hundred years so that the waste can be reclaimed.
Transporting, burying, and sealing waste up into vaults that may be too dangerous to open, could turn out to be exactly the wrong decision.
Obligatory "Is Nuclear Waste Really Waste?" (Score:5, Informative)
Is Nuclear Waste Really Waste? [youtube.com] The short answer, is "hell no"; while there is a very small part of spent fuel which could actually be considered waste, the vast bulk of it is a goldmine of energy and a source of other highly valuable fission products.
It is totally silly to talk of "waste treatment" or "destruction"--this is just another way of doing fission. It is equally silly to talk about destroying enormously vast reserves of energy, just because our antiquated reactors are terribly inefficient and make a mess of the partially burned fuel. It does not have to be that way, and modern molten salt reactors like LFTR [wikipedia.org] burn the fuel so completely that there is barely any waste left at all.
We need to take another look at spent fuel. Aside from burying it, which merely delays the problem, the only way to rid ourselves of it is by fissioning it. There are many ways of doing so, but the best would be to harness the energy contained within in safe and inexpensive LFTRs. Such reactors are capable of providing not only for our electrical needs, but also the production of liquid fuels, as well as process heat for water desalination, foundries, fertilizer, concrete, and more.
Certainly, fissile material like U235 and Pu239 should be disposed of, but it should be done so in a manner which maximizes its value, and fast reactors or other waste eaters are terrible in this respect. LFTRs require much less fissile material to start up, and if we were to use the fissile in this way, we could ramp up their production very quickly, and eliminate it just the same. Only this way would be safer, simpler, more efficient, and vastly cheaper.
Re:or, they could bombard it with neutrinos.. (Score:4, Informative)
Your initial supposition is basically wrong so the rest of your argument falls apart rather.
The materials in a nuclear reactor structure exposed to high levels of neutron and gamma flux are chosen so they don't activate easily or indeed at all. For example the steel alloys used for the reactor vessel don't contain cobalt as Co-59, the most common isotope plus a neutron produces the very radioactive isotope Co-60 with a short halflife of five years producing an intense gamma ray on decay. The fuel rods are jacketed with zirconium for similar reasons since it is pretty much transparent to neutrons. The result is that after a BWR or PWR has been opened for refuelling and the hot fuel rods removed the level of radioactivity within it is miniscule and people can work around and even inside the open reactor vessel (once it has been drained) with minimal protection.
Decommissioning a reactor is carried out either quite quickly after the reactor is shut down for the last time e.g. the Japanese Tokai 1 Magnox reactor which was reduced to brownfield status in about ten years or the alternative process employed by the British for its older Magnox reactors is to remove the fuel rods, demolish the rest of the site (turbine halls, control room etc.) and mothball the reactor building, leaving it for eighty years or so for residual radiation to decay to the point where the future demolition job has no radiation problem to deal with at all.
The long-term radiation problems with reactors really only accrue from the fission products and some of their daughters in the spent fuel rods. Separating them out for vitrification and geologic burial is a solved problem -- it costs money to carry out but it reduces the volume and mass of true waste quite substantially while returning 90%+ of the original fuel rod material to the fuel cycle. The US for political reasons does not reprocess fuel rods and the bulk and mass of the resulting stockpile is starting to become problematic hence the Yucca Mountain project and its political aftermath.
ADSR, aka the energy amplifier or EA (Score:2, Informative)
Search for stuff on ADSR's (accelerator driven subcritical reactor). Or the Energy Amplifier, which is patented by a CERN guy. The basic idea is (insert car analogy) a turbocharger. You have a barely subcritical reactor that by geometry of the tanks/reactor (if using molten fuels, which is a good thing by the way) can't go critical. You have a freeze plug in the tank bottom, so if it overheats, the thing drains the fuel into multiple dump tanks, which by geometry, prevent it from being critical. Now, you have an electrically driven (probably high temperature superconductor) particle accelerator at or above 1GeV firing at a (probably molten due to the particle stream) lead target in the middle of the tank, that spalls neutrons into the surrounding fuel. Fuel gets hot, heat exchangers take the heat to conventional steam generators to make electricity, some of which is fed back to the accelerator. For waste transmutation, either the waste is directly mixed into the fuel, is formed as a inner liner between the lead target and the fuel, or is in an outer liner around the fuel but before the neutron reflector. They've gotten to the point that the accelerator can use less than 10% of the gross electrical output of the generators, so it is practical. It also avoids needing highly enriched uranium or other stuff for starter fuels in a molten fuel (typically thorium).
For a molten fuel based design that is likely a pool based design, the freeze plug drain and the accelerator operation itself as a "virtual" control rod setup makes it pretty safe. You would a need a monumental disaster to cause the draining fuel to collect enough to go critical. Anything else cause the accelerator to trip, causing the reactor to essentially shutdown due to lack of neutrons, but the pool type molten reactor can stay molten long enough for the accelerator to be restarted in a reasonable amount of time (if you aren't using electric heaters to keep the thing liquid). Doesn't directly solve the remaining core heat problem of a sudden shutdown, but since it is molten by design, the dump tanks should be much more survivable compared to conventional reactors if shutdown cooling is lost.
For more
ADSR/ADS/ADTR/MSR/LFTR
https://en.wikipedia.org/wiki/Accelerator-driven_system
Professor Rubbia from CERN, now supported by Aker solutions, working on EA/ADSR
http://en.wikipedia.org/wiki/Energy_amplifier
http://cdsweb.cern.ch/record/297967?ln=pt
http://www.akersolutions.com/en/Global-menu/Media/Press-Releases/All/2010/Aker-Solutions-wins-Energy-Award-at-IChemE-for-its-innovative-ADTRTM-power-station/
GEM*STAR work at Virgina Tech
http://www.phys.vt.edu/~kimballton/gem-star/pub/w.shtml?home/overview.jpg
MYRRHA
http://myrrha.sckcen.be/
Re:A step (Score:5, Informative)
This is really neat. So is the current control software in Mol using your code?
Yes.
Will MYRRHA use the same code base or does it require a complete re-write?
Myrrha is only a concept so far: no development yet. It will most likely be a complete rewrite looking as to how far the code has diverged from the original specs.
Are you using a real-time kernel?
No. Everything that needs to be real-time is done on FPGAs and then transmitted to the kernel and user app via GPIOs.
What kind of quality control are you using to ensure the software performs exactly as designed?
Basically years of testing. Anyway, since it is a subcritical reactor, the security requirements are much less stringent. Some purely security stuff (read: not the control/command and or acquisition), is handled by other systems which have no interaction with mine. And as for the original 'design', well, it is research, meaning that specs start from a white sheet and build from there as we add pieces to the machine.
Are you using a functional programming paradigm?
All in C.
Are the reactors computer systems networked to the outside world? If so what kind of security measures do you have in place to safeguard access?
They are indirectly accessible (2 sets of firewalls). Like I said it is a research system with much less stringent security requirements, and quite a few researchers work on it and need remote access.
Is your software a critical component of the control feedback loop e,g. reduces beam intensity based on the measured neutron flux? If so what kind of redundancy is build into the system?
One set of software runs on the cards themselves: a minimalist BuildRoot install with a basic software that does as few things as possible (transferring acquired data to the network, reacting to commands from the Control/Command, sanity checks, basic security, going into security mode in case contact is lost, ...). One or more linux PCs run the C/C software and communicate with those cards and tell them what to do. If this soft crashes, nothing actually happens, the system keeps running for a while. You can actually shut down one PC and start another and everything keeps running like nothing happened.
But all the 'real' security is done in hardware: thermal shutdowns, beam intensity shutdowns, etc... It's actually difficult to turn the system on: everything has to be just right and there are plenty of little things that do stop the process.