A Safer Nuclear Future?

June 14th, 2012 by Joshua S Hill

Replacing uranium with thorium could see currently installed nuclear reactors recycling their nuclear waste indefinitely.

Since the development of nuclear power, many different strategies for the minimisation and disposal of nuclear waste have been considered. There are two types of nuclear waste: fission product waste and actinide waste. Fission product waste is generally easier to manage, because it has relatively short half-lives. By contrast, actinide waste has much longer half-lives; disposal strategies usually envisage that it will have to be stored in purpose-built facilities for thousands of years.

As a result, many researchers have begun to consider the actinides as a resource instead of a waste product, using the reactors themselves to recycle the actinide waste and then reuse it as nuclear fuel.

“The idea of taking actinide waste and getting rid of it in nuclear reactors rather than disposing of it in the ground is well-established, but this hasn’t been thought possible using current commercial reactor technology,” Dr Geoff Parks, of the Department of Engineering, said.

As well as the lack of suitable reactor technology, another issue with establishing an actinide recycling programme is the uranium which is used as fuel in nuclear power plants. The safety of nuclear reactors relies upon negative feedback coefficients, which stabilise the power level in the reactor if operating conditions change. What has been shown when recycling actinide waste in a uranium fuel cycle is that it can be recycled just once or twice before the recycled fuel develops a positive feedback coefficient, making it unsafe for use.

However, as one of Parks’ undergraduate students found, if uranium was replaced by thorium as a fuel source, current reactor technology could be used and the actinide waste could be safely recycled indefinitely.

The idea of using thorium as a fuel source is not new; prototype reactors using thorium were operated in the United States in the 1960s.

“The reason why thorium was never seriously pursued as an alternative to uranium is believed to be because the uranium fuel cycle generates much more plutonium, which is the raw material used for nuclear weapons,” said Parks.

In addition to its greater resistance to proliferation than uranium, thorium is also about four times more abundant.

Ben Lindley, at the time a fourth-year undergraduate student, discovered that when recycling actinide waste in a thorium-based fuel cycle, the feedback coefficients stay negative, meaning that it can be continuously recycled, leaving only the much shorter lived fission product waste to be disposed of.

Thorium could, in principle, be exploited immediately in existing nuclear reactors, but in order to maximise efficiency, Lindley is looking at ways of reconfiguring the design of such reactors. Now in the first year of his PhD under the supervision of Dr Parks, Lindley is working with Cambridge Enterprise to commercialise his research.

There are issues with using thorium, however. There is currently no thorium industry, so a great deal of infrastructure needs to be put in place before existing power plants can make the switch. However, in order to address the dual concerns of electricity supply for an exponentially growing population and global warming, many contend that a major investment needs to be made in nuclear power. While Parks says nuclear is only part of the solution to those twin problems, he believes it is a key component. With the advantages that thorium presents, and finite resources of uranium, thorium is now being seen as a viable alternative.

“The reasons for choosing thorium are its abundance in comparison to uranium, its greater proliferation resistance and the possibility of a fuel cycle where the only waste is fission product waste,” said Parks. “I think our vision of how nuclear power might work in the future addresses quite a lot of the concerns about it such as very long-lived radioactive waste which is a burden on future generations.”

With the 50% increase in global population which is expected over the next 50 years, in order just to maintain per capita electricity consumption, a major power station would need to go online every day somewhere in the world. “The electricity-generating infrastructure to meet global energy demands is staggering when you think about it in those terms,” said Parks. “And if it’s going to be low-carbon, then nuclear has to play a role in that.”

Source: University of Cambridge
Image Source: Brian Kong

Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.

Tags: nuclear recycling, nuclear waste, recycling nuclear waste, thorium, thorium nuclear, uranium

About the Author

Joshua S Hill I'm a Christian, a nerd, a geek, and I believe that we're pretty quickly directing planet-Earth into hell in a handbasket! I also write for Fantasy Book Review (.co.uk), and can be found writing articles for a variety of other sites. Check me out at about.me for more.

Tom Bammann

Hi Josh, great article. I’ve been very interested in why thorium hasn’t been used before, and in particular why Australia haven’t considered it for power generation considering we have so much of it. It makes sense for other countries not to consider it if they’d have to import their thorium due to poor energy security. Australia is accustomed to just being able to buy products off the shelf from other countries that have been forced to do it before us. I notice you’re a fellow Australian, so thought you may like to know that I’ve started thoriumaustralia.org as an attempt to centralise thorium power generation discussions for Australians. It’s not particularly busy at the moment although I hope it becomes of use. Just my way of contributing to education of Australians about the topic http://thoriumaustralia.org/forums/
Chris

There is alot of comments on here without much resarch, Thorium is going to happen weather we want it or not China and India are both doign it right now, Both of those countrys dont have anything to lose,
Personally I cant wait truck size reactors for your town at 250k each with the cost of free power for 100years for a few kg of Throium, I have $5 here that says in less than tens years china and india are producing power with thier reactors,
- http://ronaldbrak.blogspot.com.au/ Ronald Brak
  
  China and India have to lose is the difference between the cost of nuclear and the cost of other cheaper source of electricity. And more specifically they have the difference between the cost of developing thorium reactors and the cost of uranium, which is a very small part of the cost of nuclear power.
- Bob_Wallace
  
  Don’t hold your breath for those truck sized reactors.
  
  There’s a lot you don’t understand about economies of scale.
Morriarty

There’s no doubt about it; we need thorium based nuclear power to sustain civilization in the future. A point not made in the article is that all the thorium can be used as fuel as opposed to just 1% of uranium, the remaining 99% ending up as poisonous anti tank munitions or being buried as waste. A much better reactor design is the liquid fluoride thorium reactor (LFTR), invented by Prof. Alvin Weinberg. This uses a liquid anhydrous fuel thus operating at atmospheric pressure and eliminating the need for any actinide removal from the reactor. This invention was sadly shelved in the interests of cold war nuclear armament. Chernobyl, 3 mile island and Fukushima would not have happened had they been LFTR’s. Clean nuclear power DOES exist and for the sake of the planet we need to wake up to that fact.
- http://ronaldbrak.blogspot.com.au/ Ronald Brak
  
  My state has gone from all fossil fuel to getting one third of its electricity from wind and solar in seven years at much less than the cost of nuclear power. If all fossil fuel supply was suddenly cut off today it would be very annoying, but my state would still have enough electricity to sustain civilization. This makes me doubt that thorium reactors will be necessary to sustain civilization in the future.
- Bob_Wallace
  
  Actually it’s very clear that the world needs no nuclear reactors, regardless of the fuel, to power all its needs.
  
  Nuclear power, regardless of the fuel, is the most expensive way to power our grid and takes far too long to implement.
  
  A some point we simply have to recognize that the nuclear industry has made false promise after false promise. We need to stop paying attention to their claims that “Next time electricity will be too cheap to meter. Just trust us.”.
Pingback: 7 Arguments Against Nuclear Power (Why It Should Be a NoGo) - CleanTechnica
Henz

Joshua – what the F is this *#&@ ? Nuclear energy on a “clean” tech website!? Go inside the Chernobyl sarcophagus and call me up and let me know how “clean” it is. Go to the Fukushima reactors with no special protection and let me know how “clean” it is. You’ve obviously been sold some B.S. by the nuclear industry, and now you are selling it to us? If you are not here to write about renewable energy, get lost pal.
- Bob_Wallace
  
  Clean, in this case, means low greenhouse gas emissions. Nuclear does produce electricity with a lot GHG footprint.
  
  Nuclear fails because we have cheaper ways to make clean electricity and because, as you so clearly point out, nuclear brings a particular, very serious danger to our lives.
sambar

“With the 50% increase in global population which is expected over the next 50 years,” In 1950 there were 2.1 billion people, today 7 billion, how can the next 50 only bring 50% more?
- http://ronaldbrak.blogspot.com.au/ Ronald Brak
  
  The bulk of the human population has either passed through the demographic transition or is passing through it now. Once a country passes through this transition (basically becomes rich) its birth rate falls below the replacement rate. World population growth is now way below the maximum it reached about 30 years ago and it seems very unlikely that population will increase by 50% before it peaks. An increase of about a third seems more likely given current trends.
  - Bill_Woods
    
    Countries like China aren’t even waiting to become rich.
    - http://ronaldbrak.blogspot.com.au/ Ronald Brak
      
      China definitely started restriciting family size while it was still very poor, but it is now rich enough to have passed a long way through the demographic transition. By the time a country reaches China’s current level of development, birthrates are already far below their peak. Of course, just how far varies from country to country.
      - Bill_Woods
        
        China’s trajectory is fairly extreme. http://www.bit.ly/LSCPlc
        
        As a result, it’s ‘getting old before it becomes rich.’ http://www.bit.ly/LSDjHZ
      - Bob_Wallace
        
        It’s going to be very interesting to see how this plays out for China.
        
        China is already starting to move some of its low skilled labor manufacturing to other counties. They apparently are taking Japan’s strategy of hanging on to the better paying higher skilled jobs and letting the low paying jobs leave.
        
        China is also starting to install automated manufacturing, putting a lot of robots to work. They should be able to keep producing large amounts of goods even with a decreasing labor pool.
        
        China still has a huge portion of its population living in rural areas. They won’t have quite the burden of supporting an aging urban population as they downsize their population. The older folks in the countryside won’t retire, they’ll just farm/garden a bit slower. And I doubt that China has created any expectation on the part of those folks that they’ll get much medical care in their later years.
        
        I sure would love to read how the Chinese government is planning the transition to a lower population. I’m betting they are actively planning while in the West we’re just letting things run their course….
- Bob_Wallace
  
  Birthrates are rapidly falling in much of the world, especially the developed/industrialized world.
  
  https://www.cia.gov/library/publications/the-world-factbook/rankorder/2127rank.html
http://ronaldbrak.blogspot.com.au/ Ronald Brak

Thorium reactors don’t address nuclear power’s main drawback, cost. Or at least it was its main drawback before Fukushima. Now many people consider safety to be their main drawback. Fuel is not a significant portion of the cost of nuclear power, so any saving from using thorium over uranium is almost irrelevant. While nuclear plants can be built that can be “switched off” at short notice, this does nothing significant to reduce their costs because fuel is such a small portion of their total costs. Being able to quickly ramp a nuclear power plant up and down is useful for grid management, but it does next to nothing to lower the cost of nuclear electricity.
- Bob_Wallace
  
  How quickly can reactors switch on and off?
  
  Combined cycle gas takes a few hours (up to 3) for the steam gen to go from full off to full on.
  
  Coal plants can take eight hours to go from cold to full power.
  - http://ronaldbrak.blogspot.com.au/ Ronald Brak
    
    Well, switching off electricity production is one thing, switching off the nuclear reactor is another. Most reactors can’t be switched off entirely without melting a hole in the floor a la Fukushima. So the answer is somewhere between minutes and never.
    - http://www.facebook.com/profile.php?id=100000197577056 Daniel Moreno
      
      If you look at Flibe energy’s LFTR design, then you will see that the reactor can indeed be shut down without melting a hole in the floor. A frozen plug melts away and the fuel is drained to an underground storage tank, where it cools on its own. LFTR boasts passive safety where it maintains its temperature on its own, and without uranium as a pseudo catalyst, the chain reaction will eventually come to a halt on its own(hence it being drained, a la gravity, to a seperate tank in the even of a power failure).
  - http://ronaldbrak.blogspot.com.au/ Ronald Brak
    
    And I’ll just mention that while coal and combined cycle gas plants can take a long time to start up, depending on the plant they can generally get going in less than 8 or 3 hours. (Of course, if a plant is being started up after maintenance or a prolonged shutdown, it can be a good idea to take things slowly and make sure everything is in working order.)
    
    One thing that we might start doing in Australia now that our carbon price is taking effect on July the first and solar and wind are pushing down wholesale prices at times, is install electrical resistance heating in coal and combined cycle gas plants. This can be used when the price of electricity drops below the cost of coal or gas + carbon price to cheaply and cleanly maintain a head of steam so the fossil fuel plant can respond immediately when electricity prices increase.
  - Bill_Woods
    
    Steam turbines don’t care whether the water is heated by coal or uranium. Gas turbines don’t care whether the gas is heated by methane or thorium. So their ramp rates up and down will be essentially the same.
    - Bob_Wallace
      
      There’s considerable difference in the amount of time it takes to bring a mass of coal to full flame and the amount of time it takes to get a gas turbine fully ignited.
      
      That said, no one has yet provided any ramp up/down times for a reactors.
      
      My understanding is that reactors can be load-following to a degree. You can cool things down a bit and lower output. But if you totally shut down it can take days to come back to full output.
- Bill_Woods
  
  Molten salt reactors pretty clearly will reduce cost, and should reduce concerns about safety.
  
  The reactor core is unpressurized. That means there’s no need for a pressure vessel capable of withstanding 75 or 150 atmospheres, nor for a huge containment structure to deal with a boiler explosion.
  
  Since the fuel is liquid in normal operation, the reactor is incapable of a meltdown. In extremis, the fuel can simply be dumped, and allowed to cool at its own pace. That means there’s less need for multiply-redundant cooling systems.
  
  Volatile fission products (xenon, krypton, iodine) are easily removed during ordinary operation. So in the event of an accident, they’ve already been dealt with.
  
  http://www.aps.org/units/fps/newsletters/201101/hargraves.cfm
  - Bob_Wallace
    
    If that were the case don’t you think reactor construction companies would have stepped forward and submitted acceptable bids in Ontario, San Antonio and Turkey?
    
    Those were all opportunities for those who can build affordable reactors to show their stuff. Yet the bids received were very much over the top and thus discarded.
    
    I’m sorry, I’ve lived around nuclear reactors for many decades. I’ve heard the hedged promises that have fallen flat over and over.
    
    If reactors could be built cheaply don’t you think a company like GE would put <3% of their $230 Billion net worth on the line in order to demonstrate that they can produce for a reasonable price and open up a very lucrative income stream for themselves?
    - http://www.facebook.com/profile.php?id=100000197577056 Daniel Moreno
      
      GE doesn’t get it’s money in nuclear energy from installing plants, it comes from producing solid fuel.
      - Bob_Wallace
        
        I think you understand my point.
        
        If nuclear reactors were good investments then we’d have major corporations building them.
        
        The Fukushima reactors that melted down were designed and supplied by GE. It’s not like they are strangers to the business.
        
        Ask yourself why very large corporations are not investing even a tiny percentage of their capital in reactors.
        
        If you answer yourself honestly you’ll admit to yourself that nuclear reactors are not a good investment. Very high risk for something that will have great difficulty competing in a free market.
  - http://ronaldbrak.blogspot.com.au/ Ronald Brak
    
    Okay, let me know when my safe as wind power, cheaper than solar, molten salt nuclear plant is ready and I’ll install one near Adelaide.
- Wdobner
  
  Except that it does. The Liquid Fluoride Thorium Reactor as discussed in the article operates at atmospheric pressure, thereby greatly reducing the footprint and specialized metal forgings that must be created (and which account for much of the material cost of installation). The engineering costs to get the site operational remain, but then if Solar and Wind plants had to do full environmental impact studies on their installations we’d never have built a single one because both have rather steep ecological and environmental impacts we’ve ignored to this point.
  
  On the operational end the reactor isn’t burning through an isotope that is somewhat less common than gold, and the fuel requires no fuel rod fabrication. It doesn’t need to be taken offline to refuel, and it achieves a nearly complete burnup of the fertile fuel. As was noted, GE doesn’t sell reactors, they sell the fuel for the reactor because that’s where the profit is in nuclear power. Getting away from solid fuel will bring with it a tremendous reduction in cost.
  
  But mostly whatever cost reductions can be attributed to LFTR or other MSR designs will come through economies of scale and assembly-line like production facilities for large numbers of small to medium sized reactors. Modular reactors, particularly the nearly self-contained units FLiBe has proposed, with small, supercritical turbines can be built as drop-in, lower cost replacements for natural gas turbines, coal powerplants, and other GHG generating powerplants. Instead of designing a gigawatt reactor and a 250MW reactor for two installations, just string four 250MW plants together and accept the slight hit in thermal efficiency as a trade against the lower cost an assembly line construction system brings to the process.
  - Bob_Wallace
    
    “But mostly whatever cost reductions can be attributed to LFTR or other MSR designs will come through economies of scale and assembly-line like production facilities for large numbers of small to medium sized reactors. ”
    
    Please explain how this will work.
    
    What we see right now with electric vehicles such as the Nissan Leaf is that initial production is very expensive. Nissan points out that with adequate manufacturing volume that cost will drop significantly.
    
    Present Leaf volume is in the very low tens of thousands. That’s not enough to create economies of scale. Nissan states that the necessary volume needed to drastically lower prices is somewhere between 500,000 to 1,000,000 units per year.
    
    Now, how can MSRs be made cheap from day one when cars can’t?
    
    Let’s assume that they can’t (unless you can show otherwise) and let’s assume that governments might decide that is was worthwhile to buy some MSRs at a very high price in order to create volume (just like is now being done with EV subsidies).
    
    How would it be possible for MSRs to reach significant volume at only a few
    dozen or even few hundred units when it takes hundreds of thousands of
    units for EVs?
    - Wdobner
      
      That example has nothing to do with what I said. The Leaf is a product designed for mass production and its profitability is dependent upon the business decisions and assumptions made before the start of production. The current nuclear reactors are the construction equivalent of a Bugatti Veyron. They’re built, essentially, by hand with steel reactor vessels forged in Japan, occupy an inordinate amount of space, and burn a fuel which is charitably described as ‘premium’. There is nothing about the light water reactor that is well suited to ease of construction and operation, or safety.
      
      An LFTR need not achieve the economies of scale associated with the auto industry for mass production techniques to bring about an enormous reduction in cost. Merely being able to build them on the sort of production lines associated with Boeing, Caterpillar, or Litton Ingalls could be sufficient to bring about an order of magnitude reduction.
      - Bob_Wallace
        
        Sorry. That is not a convincing argument.
        
        If MSRs ever get built they are not going to get built at a scale which will produce significant savings. Meaningful economies of scale do not occur at the dozens/hundreds level.
Matt

I keep hearing TH, but if nuclear want a place at the table they need to be “turn off the power and walk away” safe. While there are “on paper” LIFTer design for this they are not the current plants. And why in the 60s a TH plant ran full power for a long time (year?), it was the design of current plants. And until someone puts up the billion dollars to build a prototype TH reactor today, all we have are unsafe design that make materiall for bombs.

Yes there if a lot of mined TH “stored” out west in a trench. So getting the feul isn’t the problem for a while. It is getting funds. Don’t count on a large scale TH reactor being running for at least 10 years.
- Bob_Wallace
  
  Not only
  “turn off the power and walk away” safe but also cheap enough to compete.
  
  You can’t build a new generation plant that must sell its power 24 hours a day for >15 cents per kWh and survive when wind is going to grab a lot of your nighttime market and solar is going to grab a lot of your daytime market.
  
  During wind up/Sun shining hours you are going to have to sell at a loss because you can’t turn your reactor off for short periods. And you can’t turn off the loan payments.
  
  Then you’re going to need to make up for those losses by cranking your selling costs up well over 20 cents per kWh during the other hours.
  
  Do that and other generation and storage comes into play, forcing you into bankruptcy.
  
  —
  
  By the time a new reactor could be built and brought on line the price of solar should be significantly lower than the current 15 cents per kWh price. Wind should be down to a nickle. Storage could easily be in the nickle range.
  - http://www.facebook.com/people/Mike-Carey/100003524380104 Mike Carey
    
    The wind water and solar argument comes up short when looked at carefully.
    See the detailed counter argument –
    http://bravenewclimate.com/2009/11/03/wws-2030-critique/
    - Ross
      
      That contrarian tract attacks a straw man of WWS (wind, water or sunlight) but Bob also predicts cheaper storage.
      - Bob_Wallace
        
        Aquion is going into production this year with sodium-ion grid storage batteries. An independent lab has confirmed >5,000 100% DoD cycles and Aquion is projecting a $300/kW or less price.
        
        5,000 cycles and $300/kWh = 6 cents per kW.
        
        Six cent wind stored for 6 cents < 15 cent nuclear. (Throw in another penny or so for battery inefficiency. Nuclear still looses its shorts.)
        
        Aquion is also stating that they expect to be able to exceed 20,000 cycles which would bring the cost of storage to 1.5 cents per kWh.
        
        I suspect that the MIT liquid metal battery is going to do as well or better. Cheap 'ingredients' which are not 'used up' with use.
        
        And those are only two of the players in the game.
      - Ross
        
        A prediction that is likely to be accurate so.
    - http://ronaldbrak.blogspot.com.au/ Ronald Brak
      
      Mike, has Barry worked out how to make nuclear electricity cheaper than other low emission alternatives? And has he worked out how nuclear can supply anything other than baseload without multipling the costs of nuclear power? Does he have any solutions to these problems or does he just avoid them or ignores basic economics to get around them? Please briefly tell us here right here how he is going to solve these problems.
    - Bob_Wallace
      
      If you’ve got a point, Mike, please make it.
      
      Don’t send us off to read something somewhere else.
      - http://www.facebook.com/people/Mike-Carey/100003524380104 Mike Carey
        
        Why not, Bob – too busy to look at the facts?
      - Bob_Wallace
        
        Bring it.
      - http://cleantechnica.com/ Zachary Shahan
        
        because the discussion is going on here. if there’s something relevant from that page for the discussion, put it in here.
- http://cleantechnica.com/ Zachary Shahan
  
  right, and while i don’t think the researchers and Thorium enthusiasts expect this, i think the talk of a beautiful, much safer thorium nuclear future is just used by those in the actual nuclear industry and politicians to further advance/install/subsidize conventional nuclear… the stuff that shouldn’t be moving anywhere…
http://soltesza.wordpress.com/ sola

This would be a very good way to keep our nuclear fleet in operation AND get rid off the nuclear wast we have already built up.