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Comment by badloginagain | Hacker News Reader

Doesn't Plutonium-238 occurs naturally along the Thorium decay chain? I believe that it's fairly easy (relatively speaking) to capture 238 from the Thorium nuclear reactor process.

A Thorium-based nuclear reactor prototype has already been successfully run for years at Oakridge National Laboratory- seeing the value of Plutonium-238, it might justify the cost of building a full grade Pu238-extraction nuclear reactor.

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I've consistently heard the following two claims about thorium reactors:

1. They offer a number of advantages in safety, efficiency, input materials, byproducts. No comparative disadvantages.

2. The United States is not actively pursuing any plans to implement thorium reactors.

Is the above really true, or are there some comparative disadvantages to a Thorium reactor vs a traditional nuclear reactor? If the above is true, there must be some conflict of interest (imagine that, a conflict of interest in the domain of energy!) causing #2. Is there a legal issue?

A mix of politics, historical nuclear industry in-fighting, 9/11-terrorism-godzilla paranoia and oil industry lobbying make nuclear development very difficult.

It's also made nuclear power one of the safest and cleanest sources of power in the States.

China and India are very aggressively pursuing Thorium reactors though, which risks putting the West at another energy competitive disadvantage within decades.

From what I've read it's not a legal issue, it's a "huge amount of money needed to get thorium reactors to where they need to be" issue. Nobody is really interest in putting up that money because current modern reactors are "good enough" - all the problems with nuclear plants tend to come from old, bad ones that are decades behind the state of the art.

From what I have read, the best traditional fission plant designs are very safe, efficient, and produce few byproducts. It's the older plants that have problems but we have learned from them and made improvements.

Compared to the most state-of-the-art plant, thorium reactors are not significantly better and we have years of first-hand experience with traditional uranium reactors and very little with liquid fluoride thorium reactors so the incentives to start at square 1 with an new technology are small.

So the good news is if we ever got over our irrational fear of nuclear power, we have time-tested plans for safe, clean and efficient power plants ready to be built.

From what I've read, the reason for #2 is historical. You cannot make bombs with thorium reactors, and when bombs were being made is when most of the advances in nuclear power were made. Since then a number of accidents at nuclear power plants have rendered any advancements in nuclear power taboo in the US so there is no development, especially not in anything new nuclear-wise.

My understanding is that thorium reactors have a bit of a chicken and the egg problem.

We've got plenty of experience building more traditional nuclear designs - considering how conservative and concerned the masses tend to be when it comes to nuclear technology (not entirely unreasonably), do you want to be the one "risking" it on an "unproven" reactor design? It's politically tricky, in an age when several countries are phasing out nuclear power entirely in a knee-jerk reaction to Fukushima.

Even ignoring political risk, I'd imagine there's some budgetary risk for investing in the "cutting edge" of nuclear tech - more room for new mistakes to be made, additional complications to be discovered, resulting in budget overruns.

I believe China is investing in building thorium reactors. It wouldn't surprise me if at some point in the future, the US is left in the position of poaching nuclear talent from China to play catch up in the thorium reactor department.

Wikipedia lists a lot of possible disadvantages:

http://en.wikipedia.org/wiki/Thorium-based_nuclear_power#Pos...

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

No, the naturally abundant isotope of Thorium has 6 fewer nucleons. Why would building a special reactor for a program that has so little funding be justifiable?

Because along with a steady source of Pu238, you also get the benefit of a safer, smaller nuclear reactor using a fuel that is significantly more common and less weaponizable than uranium/plutonium.

Please provide evidence that a Thorium reactor is safer. We have the means to make all the 238Pu we want. NASA just needs to pay commercial reactor operators to irradiate 237Np targets. This is a big problem, because NASA has very little funding to accomplish this, and the target material comes in a purified form suitable for direct use in nuclear weapons.

Is it practical to irradiate the target in units of mass that are smaller than the critical mass?

(The thought being that you can then only allow one unit to be in transit from storage to a reactor at any given time, pretty much entirely mitigating the risk of someone gathering enough of it to make a bomb)

You can make a bomb out of a little of this, and a little of that. A bomb requires much more than a critical mass anyhow.

On the safety: http://en.wikipedia.org/wiki/Liquid_fluoride_thorium_reactor...

Economic feasibility: http://www.thoriumenergyalliance.com/downloads/plutonium-238...

I'm a nuclear safety analyst. I need more than a powerpoint to convince me that an untested technology is safer than a technology that has seen billions of dollars of investment in enhanced technology, engineering, modeling, etc; along with decades of lessons learned. I'm not saying it couldn't be, but I think there are better ways to spend money on nuclear energy technologies right now, in terms of carbon offset and prevention of radioactivity release.

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