Basically it's really really safe as far as byproducts. And yeah, it's a teeny sun, that instantly goes out if you stop feeding it juice, which sounds bad, but it's all the tiny stable particles, not the big slowly decaying scary ones.
If a fusion reactor is breached, the plasma will likely dump it's thermal energy into the air (likely this will cause a minor detonation, it's strength depends on the energy in the reactor and the amount of fuel). Additionally it'll leak some short lived isotopes and maybe create a few long live ones.
All in all, a detonated fusion reactor is likely save to walk in the same year it exploded, if not significantly earlier.
As for some unexpected pathway, energies like this are reached in stars all the time, and they don't spontaneously explode on a regular basis. If you're talking about a basic science experiment being the Great Filter -- well, maybe. I'm skeptical.
Well, they kind of do…
But really, the only reason why stars manage to stay in hydrostatic equilibrium is because of gravity, which we really can’t do on Earth so we settle for fancy magnetic confinement vessels.
On global scale it negligibly increased ever-present background radiation. It's not a good thing, but far from poisoning.
The bomb tests did increase background radiation for us; irresponsibly so in my opinion. But so does burning coal. We have been lifting the level of background radiation over the natural level for centuries by now.
I don't see how sunk steel would be any more valuable than steel from freshly mined ore. But I like to be surprised about these things :-)
Steel production uses air from the atmosphere. Thus it picks up the increased background radiation while it is refined. It may be possible to scrub the radioactive components from the air to avoid contanimating the steel, but I expect the cost would be prohibitive (at the very least, more expensive than getting it from old battleships).
Try pointing a Geiger counter at a brick or ever better plaster wall and be surprised about the amount of radiation you get during the day.
Seawater is about 0.04% potassium, so this is about 5.35 * 10^14 ton of potassium.
Potassium contains naturally occurring radioactive isotope (40K): the radioactivity of potassium is 31 Bq/g. Hence the natural radioactivity of all potassium in seawater is 1.66 * 10^22 Bq.
For comparison, again according to Wikipedia:
> In May 2012, TEPCO reported that at least 900 PBq had been released "into the atmosphere in March last year [2011] alone"
...which is 9 * 10^17 Bq, or about 1/18,000 of naturally occurring radioactivity in the ocean due to potassium alone.
(We didn't even start on stuff that are commonly considered "radioactive", like all the uranium and thorium lying beneath where you are.)
* Meanwhile we're busy burning fossil fuels, increasing the amount of CO2 in the atmosphere by ~30%.
As a power source fusion is pretty good, which is why it’s such a target for research.
D-T fusion, which is the easiest to achieve and perhaps sustain, directly produces He nuclei (that is, alpha particles) and rather energetic neutrons at 14 MeV. Those neutrons, aside from being a form of ionizing radiation themselves, are bound to transmute some of the surrounding material into radioactive isotopes. So, I don't think that "no toxic or radioactive byproducts" is correct. However, the results are easier to handle than those of fission reactors.
You can't dismiss the technology based on that incident. Just like we don't ban cars because a lot of people don't operate them properly.
As far as I remember from the news at the time, the tsunami was terrible, but not unprecedented. If this obvious risk was ignored, what other risks are being ignored elsewhere?
I don't know the facts of the tsunami whether it was unprecedented or not, but considering the magnitude of the quake I'm guessing it was one of the largest tsunamis to ever hit Japan. This is speculation on my part.
They didn't ignore the risk of tsunamis, they had precautions against them but they weren't up to par. It was a series of malfunctioning safeties that caused the accident. The backup power generators conked out, and the backup to the backup was washed away by the floods. And the floods only managed to get that far because the protective walls weren't enough.
"Build better walls" seems like a trivial problem to solve, don't you think?
International regulatory bodies could also be more proactive in finding these flaws prior to accidents.
It's not a hard problem to solve in the long run. It'll be easier and quicker than finding a viable non-nuclear energy option anyway.
He was referring to the core meltdown, not the very specific fault mechanism. I should have made it clear. Otherwise, it would be an uninteresting technicality.
The entire Fukushima incident makes me suspect it's a result of defining an exact fault model and then optimizing to the model. This way, if the fault slightly exceeds the model, the result is not graceful degradation, but catastrophic failure.
Can we put the generators below sea level? sure, the sea wall is high enough, no need to worry about that at all.
> "Build better walls" seems like a trivial problem to solve, don't you think?
Yes, but is it a robust solution?
The earthquake itself killed over 15000 people.
Imo it's a massively overblown disaster. Yes, it's bad, especially the environmental effects, but it's absolutely nothing compared to the earthquake and tsunami itself.
It is also irrelevant to compare the earthquake and tsunami to the nuclear disaster. Earthquake and tsunamis are unavoidable natural disasters, but the Fukushima Daichi disaster could have been easily avoided.
You're also ignoring the massive costs of the disaster and the monumental scale of the cleanup. The official costs put it at $188B and counting.
The Japanese built Fukushima to standards that they felt were acceptable, and they were wrong and now the ocean is being polluted for the next thousands of years with the continuous risk of things getting worse at Fukushima.
In the same manner, they may be building this fusion reactor or LHC with what they feel is acceptable risk, but could they be wrong, with extremely catastrophic results? This is something I don't know but would love to know the answer to.
Then don't spread FUD?
With all the talk about the LHC possibly producing mini blackholes or magnetic monopoles that could potentially cause protons to decay spontaneously, I don't have enough nuclear physics background to know whether we are inherently safe, or if there is a real risk here.