Cost-Benefit Analysis of Nuclear Power

My argument is not that nuclear power can’t be done wrong, but rather, that it can be done right. The obstacles are primarily social and economic rather than physical or technological.

My stance on the environment can be taken to be in line with that described by CitizensEarth at

https://citizensearth.wordpress.com/visions-of-earth/

Big picture

These are long term nuclear goals, which can be achieved piecemeal, while also expanding solar and wind power.

If the premise that nuclear power can be done safely and cost-effectively without generating harmful waste that is difficult to dispose of is correct, several important things follow from this:

  • Electricity can be non-polluting and carbon-neutral. This allows:
    • Reduction of need for fossil fuels stops worsening climate change, and pollution
    • Current home and industrial uses of fossil fuel power can be replaced with electric power even in situations where currently the carbon and pollution released by producing the electricity would outweigh the benefits of switching away from fossil fuel usage
      • For example: gas heating and cooking elements could be replaced with electric ones.
    • Freight transport can be done via electric train and large nuclear-powered shipping vessels
    • Industrial operations can mostly be converted to use primarily electricity / electric motors
      • Mining operations for uranium and thorium can be done with electric-powered mining equipment, thus making the fission fuel gathering carbon neutral
      • Mining operations for other things, such as building materials
      • Factory operations can use electrical power, for producing basic high-energy-requirement goods such as aluminum, concrete and glass
      • Factory operations for producing solar panels and wind power generators can be run on electricity, making solar and wind power more completely carbon-neutral from the outset
    • Powering production of carbon-neutral biodiesel (for use in industrial applications where direct electrical power would be impractical, such as freight trucks and some mining/construction operations)
      • One way this can be accomplished is by using greenhouses with electric lighting to grow high-oil-yield algae
    • Large-scale carbon sequestration can be powered by electricity including:
      • Pumping collected carbon dioxide into underground reservoirs
      • Powering machines/greenhouse lighting for growing or gathering plant materials for conversion to inorganic carbon (charcoal) which can be used as a fertilizer additive (biochar) to sequester carbon in topsoil while improving topsoil quality and crop yields (this is complementary with biodiesel production)

Bonus benefit: Reduced x-risk from loss of sunlight due to particulate matter in the atmosphere. This applies to comet impacts, supervolcano explosions, and nuclear war (in which the phenomenon is known as nuclear winter).

Downsides

-Centralized power in the hands of large corporations or governments

-Risk of dramatic dangerous failures

-Uranium and Thorium mining will initially not be carbon neutral

 

Why now?

Key changes that have occurred since early days of nuclear power development

  • Recognizing Thorium as a valid energy source (more abundant in earth’s crust, less costly to mine, total fissionable materials should be considered as easily mineable uranium plus easily mineable thorium)
  • Improvements in robotics making it easier to safely reprocess fissionable materials with less cost and risk to workers
  • Fusion has been explored thoroughly over the past 40 years, and can now be more confidently assessed as not near-term viable
  • We are now more certain than ever that fossil fuels are a really bad plan
  • Energy demands have continued to increase, and can be expected to increase even more (at least if we want to bring the entire population of the world up to 1st world consumption levels)
  • Solar and Wind have had substantial research and development and yet retain some apparently unavoidable drawbacks:
    • primarily: poor production/replacement cost to lifetime energy output ratios
    • other costs/limitations such as substantial land use, rare mineral requirements, high variability of power supply, etc. which make them undesirable as the primary source of energy for humanity
  • Long term experience with molten salts as a primary thermal conductor / coolant instead of water for high temperature systems have shown proven safety and reliability of this method. This experience has been in part with early alternative fission reactor design explorations, but mostly with industrial solar applications (parabolic mirror arrays). This means that fission reactors can be made much safer and more efficient, cheaper to build, and can cost effectively be built smaller and in more locations, and (where appropriate) even buried partially or completely underground to greatly increase safety.
  • Another former downside of reprocessing nuclear waste/breeder reactors was the increased availability of weapons-grade plutonium as a result. Now this is less of an issue because of widespread nuclear development around the world. China, India, Iraq, and even North Korea have made nuclear weapons on their own. As far as proliferation is concerned, the bird has flown the coop.
  • If more energy is utilized from the fissionable material through reprocessing, vastly less initial fusionable material will be necessary, thus greatly reducing mining costs.
  • The most dangerous portion of the nuclear waste is the actinides, which reprocessing/breeder reactors not only can eliminate but can actually harvest the substantial energy from, turning a huge negative into a positive
  • The current method of dealing with nuclear waste is encasing it in glass, encasing the resulting radioactive glass in metal, and burying the metal containers deep in seismically stable bedrock. If molten glass is used in the reactor as the initial coolant, and all the reprocessing is done as part of the normal function of the reactor, the waste will be prepackaged for disposal.

Gut Response that I suspect needs a bolded heading: “What about Fukushima and Chernobyl?”

What about Fukushima and Chernobyl?

A key factor about Fukushima and Chernobyl (and indeed, all currently active nuclear power plants) is that they are water cooled. They use water as the primary coolant, the medium by which heat is conveyed from the fissionable material to the heat-concentration-based generators which convert the heat energy to mechanical energy to electrical energy.

Unfortunately, water at a useful temperature for generating heat is very near its boiling point. If it does boil, it rapidly and dramatically increases in pressure as it becomes gaseous water (steam), followed by a rapid decrease in pressure if it then cools back to liquid water. This fluctuation in pressure is very difficult to deal with. Not only because of the difficulty of physically containing it, but because you are losing your (radiation-polluted) coolant if you vent the gaseous water away, thus potentially allowing the fissionable material to overheat causing a catastrophic meltdown. This is what happened to Chernobyl. A failure to monitor water temperature and pressure due to faulty gauges allowed steam pressure to accumulate to dangerous levels. This resulted in steam explosions, which in turn meant that the reactor lost its coolant. Which led to the graphite moderator (that which keeps the fissionable fuel source from reacting too quickly and exploding) to catch fire. This fire spread radiation polluted ash from the burning graphite into the atmosphere, where it spread widely and contaminated a wide region.

The big difference with using a molten rock cooled reactor is that the molten rock is nowhere near its boiling point. Thus, operating the reactor is not a dangerous balancing act, but a relatively very safe affair. Even more safe, is the fact that a molten rock cooled reactor will “fail safe”. Instead of the coolant boiling away (as water does), the overheated rock would melt the armatures which keep the moderator from completely stopping the fission reaction. The moderator would fall into place, the reaction would stop, and the molt rock would cool to a solid lump, trapping the radioactive material inside. This is a tricky situation in which to restart the reactor, but offers no risk of coolant loss, reactor meltdown, or radioactive material being released in anyway to the outside. No boiling coolant risk, thus no coolant loss risk, no air-exposed-moderator fire risk, no Chernobyl-style disasters.

 

What about Fukushima?

Again, Fukushima is a water-cooled reactor. Which means it fails-dangerous if anything goes wrong. A big earthquake and flooding went wrong. It failed-dangerous, as could be expected from a system set up in such a way that fail-dangerous is the default. Fortunately, it only failed a little bit, and thus was only a little bit dangerous compared to Chernobyl. Still bad. Still not how we should design a potentially dangerous system such a nuclear reactor. Again, this would not be the case for a fail-safe design where lack of operator control would result in the reactor ceasing fission automatically and safely sealing all the fissionable materials (surrounded by their fully-engaged moderator) in solid rock.

Furthermore, using molten rock as a coolant means you can build the reactor in safer places to begin with, such as deep underground. In this case, it would make more sense to consider the reactor to be a sort of “artificial geothermal source” rather than what we envision as a nuclear reactor of the water-cooled style. The reactor could be a mostly passive device which would fail-safe if overheated, and we would pump water onto/across the surface of the molten rock heat exchanger to generate steam to turn the electrical generators. Again, if for whatever reason this secondary coolant supply was cut off, the reactor would overheat (with no risk of phase change of the primary coolant!) and fail-safe by automatically shutting itself down.

 

Do we know this would work?

Yes, we can be pretty sure it would (I estimate about as sure as knowing that a jet plane is safe to use as a method of travel, which is pretty darn sure). The United States has already built and operated such a molten rock cooled reactor, and it worked fine. When they decided to shut it down and stick to water-cooled reactors (because of political reasons), the reactor was allowed to shut-down by putting the moderator fully into place. The molten rock cooled reactor shutdown safely just as anticipated. So we already have a historical example of a successful trial run with a successful shutdown. “Not only can we expect this will work, this did work.”

 

Why aren’t people talking about this already?

Well, they are, but it hasn’t gotten a lot of press. One of the ideas being talked about is a specific category of molten rock cooled reactors called a LFTR (Liquid Fluoride Thorium Reactor). As you can guess by the name, the designers of the reactors that fit into this category propose using fluoride salt as the molten rock to cool the reactor, and using thorium as the primary fuel source. There are multiple different reactor designs in this category, and different possible categories as well, such as a category which used a different molten rock as a coolant and/or uranium as the fuel source. What I’ve described about fail-safes and safer operating constraints (not having the balancing act of almost-boiling coolant) apply to molten-rock-cooled reactors in general, not just Liquid Fluoride Thorium reactors.

Both China and India have  has announced large research projects exploring thorium as a nuclear power fuel source, although it appears the India is focusing mainly on trying to adapt water-cooled reactors to be able to use Thorium as a fuel source (because India has a whole bunch of easily available Thorium). This relatively conservative take on it, rather than going for the safer-but-stranger option of molten-rock-cooled reactors has many of the same drawbacks (fail-dangerous) as current Uranium-fueled water-cooled reactors.

For more on LFTR technology, check out the wikipedia page, these youtube links, or look them up on google scholar.

https://en.wikipedia.org/wiki/Liquid_fluoride_thorium_reactor

https://youtu.be/nYxlpeJEKmw

 

Show me the Money

So, does the math work out? Is the cost of mining and refining (with electrical power) uranium and thorium, plus the cost of carefully disposing of the waste, plus the cost of all the infrastructure needed to support this, really worth the amount of power produced?

How does this compare to other expandable non-fossil-fuel sources such as wind and solar?

 

(spreadsheet in progress)

 

Getting there from here

The big problem is that fossil fuel industries are currently not being held to account for their externalities (air pollution, greenhouse gasses). Nuclear power plants are (more or less), and we want that to be even more the case. If the full externalities of waste control and harm prevention are on the producing industry, then the cleanest sources will also be the cheapest!

Holding fossil fuel industries to account for the complete cost of preventing or cleaning up all the pollutants released, including fully sequestering as much CO2 and CO as they release, will solve this problem. Wind, solar, and clean nuclear will seem like very good investments when compared to fossil fuels and old wasteful nuclear.

Part of the resistance to adopting the idea of waste-responsibility has been the (accurate!) fear that wind and solar would not be sufficient to power their own production and all of society’s needs (residential, freight, and industrial). With the additional option of clean nuclear, the math works out and society can continue to grow and flourish without destroying the environment or ourselves. Yay!

When cost effective Fusion power comes along, we can replace the moderately clean Fission plants with the even cleaner Fusion plants and have access to even more energy. Fission is a key bridge to get us there, though.

 

Sources or GTFO!

Alright, if you’ve gotten this far you may be thinking, “Nice pie in the sky dreams there, bucko, but this doesn’t match up with anything I’ve heard before. The logic sounds nice, the math seems promising, but I don’t believe the premises!”

To this I would reply, “What exactly don’t you believe?”

I would expect to get a list back (please feel free to suggest more!) that sounds something like this: I don’t believe molten fuel reactors are a real functional thing, I don’t believe the nuclear waste produced will be safe enough to dispose of by encasing in glass and burying, I don’t believe we can use thorium as a fuel, I don’t believe we can cost effectively mine thorium and uranium with electrical power, I don’t believe we can cost effectively run industrial scale factories on electrical power rather than fossil fuels, etc

 

(This part is boring so I’ve put off working on it, but I’ll get here.)

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