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Comment by paganel | Hacker News Reader

> That a nuclear power station situation in a major earthquake zone next to the coast could magically survive a 9.0 earthquake and a tsunami?

The un-posed question is "what happens if a group of terrorists fly an A380 directly into one of these plants"? Someone on reddit was mentioning that a nuclear plant in Texas was built to "withstand a direct hit from an F-16 traveling at supersonic speeds", but I guess an A380 is so much heavier and larger than a F-16. Because right now terrorists don't even need to get access to the US aerial space, they can hit a nuclear plant in Mexic (let's say this one http://en.wikipedia.org/wiki/Laguna_Verde_Nuclear_Power_Stat...) and still be able to cause important damage to the US population.

Here's the reddit comment I was talking about: http://www.reddit.com/r/pics/comments/g3tfr/and_you_are_tell...

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K=1/2*mv^2?

My intuition (as a mechanical engineer, desinging military systems as my day job) is that the F16 going supersonic is far worse. Either way, there is no possible way you have enough information to make any of the claims you just made.

A better question to ask yourself how safe your highway transportation is, because within an hour of my house we've had 15 people killed in bus accidents in the last 72 hours. And that doesn't even begin to count car accidents. I live within 5 miles of over 10 nuclear reactors and they have never and will never scare me because I actually understand the engineering behind them. Nuclear power is not magic. Small doses of radiation scare me far less than the concussions I get from sports I play.

> Either way, there is no possible way you have enough information to make any of the claims you just made.

I took out this from this report (http://www.euronuclear.org/reflections/nuclear-facilities.ht...), which I think was also mentioned by jgrahamc:

> The studies showed that even if knowledgeable insiders could disable key safety equipment, redundant systems would provide backup protection. In scenarios where all engineered safety systems were ruined, there was still a period of hours to take corrective actions before onset of core damage.

Now, you may argue that what indeed went wrong in the case of the Fukushima plant was that the "redundant systems" didn't provide the "backup protection" the experts relied on. I see this report is confident this would not be the case were the terrorists to hit a nuclear plant, but based on what happened in the last few days I'd say the confidence level for that scenario is bellow 100%.

Anyway, thx for those downvotting me, and I hope I'll never be proven right.

The backup generators that they bought on site had the wrong types of plugs on them.

When this is all done, I am sure that most of the problems at Fukishima will be found to be administrative rather than design.

As an aside, that plant was designed to withstand an 8.4 earthquake. Design requirements and actual strength are two different issues. Even a complete meltdown, such as at Three Mile Island, should be contained.

'had the wrong types of plugs on them'

I have seen this as one of the biggest failures so far.

Huh? The mass of the A380 is at least 100 (and perhaps 1000) times the mass of the F16 (just picture them flying side-by-side and note the area of sky obscured by the A380 versus the F16 and note that although the mass density of the F16 might be higher than the A380 because much more of the mass is engine, it is not twice as dense as the A380).

And no way can the F16 go 10 times as fast as the A380.

So the kinetic energy of the A380 is definitely higher, probably by a considerable amount.

Weight (Maximum take off)

  A380 = 569000 kg [1]

  F-16 = 19200 kg [2]

Top Speed

  A380 = 945 km/h = 262.5 m / s

  F-16 =  2410 km/h = 669.444444 m / s

Kinetic Energy

  E = 0.5 * m * (v^2)

  E380 = 0.5 * 569000* (262.5^2) = 19 603 828 125

  EF16 = 0.5 * 19200 * (669.444444^2) = 4.30229629 × 10^9

[1] http://en.wikipedia.org/wiki/A380

[2] http://en.wikipedia.org/wiki/F-16_Fighting_Falcon

That said I think it probably doesn't matter. On impact the plane would breakup and you probably wouldn't get full force from either and also I bet it was built with more then a factor of 10 safety factor.

My intuition says you are wrong. But I am just a person who liked his high school physics class 10 years ago.

http://en.wikipedia.org/wiki/Airbus_A380

http://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_...

A380 typical operating weight: 600,000 lb

F16 Loaded weight: 26,500 lb

A380 Max Speed: 580 MPH

F 16 Max Speed: 1500 MPH

Airbus weight advantage ~= factor of 30

F 16 speed advantage ~= factor of 3

3 ^ 2 < 30

Maybe there is some destructive value in having the kinetic energy more concentrated in the F16, but a full speed A380 has a lot more kinetic energy than a full speed F16.

Say you were to use a pebble bed reactor (Modern aircraft, modern reactor).

The reactor is designed in such a way that in case of coolant failure/containment failure/etc. the pebbles equilibrate at a stable containable temperature, and as such even if you could obliterate the reactor itself, the pebbles wouldn't melt down and as such wouldn't contaminate the environment with radioactive waste. Similarly as the coolant is helium, it is less radioactive in normal use and as such the coolant leak wouldn't be a critical disaster.

The pebbles themselves are coated in silicon carbide and as such are probably hard enough that you could use them as impactors against softer targets like, say, tanks. Due to this hardness it is thus unlikely that you would damage a large number of pebbles and hence release a large amount of core material.

Disclaimer: I'm not a nuclear scientist, I just think it's freaking cool.

You might enjoy reading "Deterring Terrorism: Aircraft Crash Impact Analyses Demonstrate Nuclear Power Plant’s Structural Strength"

http://www.nei.org/filefolder/EPRI_Nuclear_Plant_Structural_...

KE = 1/2mv^2, so depending on how supersonic they're talking about, it could very well withstand an A380 impact as well as a supersonic F16.

Supposedly an A380 carries much more fuel, whose explosive power might make up for the difference in impact speed.

The fuel is a fire risk, not an explosion risk. To get a decent explosion you would need to mix the fuel with a lot of air in the right ratio. Real life is not like the movies/TV; sealed tanks of gas are unlikely to explode if punctured by flaming debris. As an example, the fuel in the planes is what eventually killed the WTC buildings, but this was because the fuel burned, not because it exploded.

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