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Comment: Re:The space race isn't over... (Score 1) 297

by sketerpot (#29920161) Attached to: Russia Develops Spaceship With Nuclear Engine

The article isn't forthcoming about details, but radioactive material falling to earth is only a concern if this uses nuclear power to reach orbit. If they're just talking about a small nuclear reactor as a power source for electronics and an ion engine (or something like that) then the fuel does not become significantly radioactive until it's safely out of earth's atmosphere. Until the reactor is turned on, you can handle the fuel with bare hands.

Comment: Re:I'm surprised.... (Score 2, Insightful) 315

by sketerpot (#28877661) Attached to: Funds Dwindle To Dismantle Old Nuclear Plants

Nuclear power is a great cash cow once you've paid off the amortized cost of building the plant. The cost of operations and maintenance, including the complete fuel cycle and the regulatory paranoia, is so small that electricity from the US fleet of nuclear plants is now cheaper than electricity from coal on a per-kWh basis. The problem is building the plants: you need to raise billions of dollars for licensing, politicking, and the construction of one of the modern gigawatt behemoths. The financial risk is so large that few investors are willing to finance construction of a plant that would be very lucrative in the long run. After all, nuclear plants last at least 60 years, and you only have to build them once.

As for government subsidies, the nuclear industry is actually getting a negative subsidy if you include all the billions of dollars they have to pay the US government to "put their waste in Yucca Mountain", which of course hasn't happened and probably won't happen ever.

Comment: Re:Weird (Score 3, Insightful) 315

by sketerpot (#28877619) Attached to: Funds Dwindle To Dismantle Old Nuclear Plants

The problems with Chernobyl go way past that. Here are a few:

1. Positive void coefficient of reactivity. Once bubbles started forming in the reactor coolant, it sped up the reaction, causing a positive feedback loop. This is, of course, not the case with light water reactors.

2. The SCRAM rods actually sped up the reaction because of their graphite tips. There's a pretty crazy design defect.

3. It was physically possible for those morons to disable the safety systems.

Compare this with a truly modern design like China's HTR-DB modular pebble bed reactors, and the difference is striking. The HTR-DB has a strong negative temperature coefficient of reactivity, so all the feedback loops are very negative. They can actually shut off the cooling systems and the reactor will simply shut off because it's not able to sustain a reaction without active cooling. Overheating inherently kills the reaction. Nice, isn't it?

Comment: Re:You don't get better by not doing (Score 5, Interesting) 315

by sketerpot (#28877487) Attached to: Funds Dwindle To Dismantle Old Nuclear Plants
I've got news for you, buddy: someone has come up with a solution to the waste problem. It's called a liquid fluoride thorium reactor (PDF warning!) and it's not being embraced with open arms despite its elegance and practicality. It's a reactor that takes thorium (more abundant than uranium) as fuel, continuously refuels and reprocesses its fuel, and is about 100 times more fuel-efficient than existing nuclear reactors. Here's the really fun part: the waste, of which it produces very little, becomes exponentially less radioactive over time, becoming safe to handle with bare hands in about 300 years -- not hundreds of thousands of years. And it produces medical isotopes continuously, which is a nice bonus. And it's passively safe and self-regulating, so the reactor core itself doesn't really even need human supervision. Prototypes were tested successfully. (There are other reactors with similar advantages, by the way, so we don't necessarily have to use this particular solution. There's more.)

Energy companies won't develop them because of the large financial risk and paranoid regulatory environment and lack of a clear payoff. Governments won't step in because any nuclear reactor is seen as evil by the green fanatics and seen as threatening by the coal companies.

Comment: Re:You don't get better by not doing (Score 3, Informative) 315

by sketerpot (#28877361) Attached to: Funds Dwindle To Dismantle Old Nuclear Plants
What's more, the melted fuel barely even scratched the surface of the pressure vessel. The pressure vessel acted as a heat sink, and a puddle of melted fuel is a subcritical configuration so the reaction stopped, and all that was left to deal with was decay heat. It simply was not physically possible for a meltdown in a TMI-style reactor to melt through the pressure vessel (it got almost 13% of the way through the PV), let alone get through the containment structure. There just wasn't enough energy in the system. Things have improved a lot since then, too, which is why we haven't seen any more of these weaksauce "disasters" at light water reactors.

Comment: Re:Minimal? (Score 1) 50

by sketerpot (#28201755) Attached to: An Inside Look At the SpaceX Rocket Factory

Wrong. Nuclear thermal rockets use a reactor to heat propellant. It's also possible to have a nuclear reactor producing electricity which is used in an ion drive, which you have unfairly written off; it gets very high specific impulse in space, albeit with small thrust.

Also, there are countries where people aren't irrationally paranoid about anything with "nuclear" in the name. China, for example, is set to start kicking a lot of ass with their HTR-DB mass-produced high-temperature gas-core pebble bed modular reactors. I think when you say "nowhere on earth" you actually mean "nowhere in the United States or Europe".

"The pyramid is opening!" "Which one?" "The one with the ever-widening hole in it!" -- The Firesign Theatre

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