[LINK] Nuclear winter: a reminder

Also, while civilization is on the ropes, humanity could be taken out by a large asteroid, supervolcano, or other natural disaster.

1: One does not simply turn the reactor all the way off (picture of Aragorn, err, Boromir, or who ever). There's the decay heat, several megawatts of it even after months of shutdown (google decay heat), that can't be turned off, and virtually all reactors require intervention to keep that cooled. Likewise for spent fuel pools, that boil itself out over course of a week or two. That's what happened in Fukushima - the reactors did shut down correctly but all powered decay heat removal systems failed when tsunami water flooded the basements (in which they kept the switchgear and emergency generators). The spent fuel pools were an immense problem and at least one - in the reactor building #4 where reactor was not loaded with fuel - did boil off to the point of partially uncovering the fuel, at which point they got the concrete pump to pump water in. That's Japanese, a nation of 127 millions, responding in the tsunami that killed about 16 000 people and displaced perhaps a million (excluding those displaced due to reactor). The spent fuel pool was allowed to boil itself off to the level of fuel.

AP1000 is advanced safe reactor design. It raised the no-intervention time to the whooping 72... hours.

http://en.wikipedia.org/wiki/AP1000#Design_specifications

http://www.ne.doe.gov/pdfFiles/AP1000_Plant_Description.pdf

Major safety systems are passive; they require no operator action for 72 hours after an acci-dent, and maintain core and containment cooling for a protracted time without ac power.

Which is typical hard to parse statement which translates to: after 72 hours, the cooling water reserve evaporates off, and you get yourself regular meltdown like in any other design. The protracted time without water is 72 hours. The operator action is getting a lot of water on top of 10 story building somehow. Note that most reactors in use require AC power, that's why it is so awesome AP-1000 doesn't need AC power. Also, note risk estimates at one in 10 millions years. WTF are they even doing at NRC, some sort of circle of self delusion wrt what sort of stuff happens in 10 millions years. Mankind survival is unlikely to have that sort of reliability, and that's counting the recoveries from stone age.

2: Mostly yes, i'm only speaking of radioactive pollution there.

In general, if a bomb is powerful enough to result in a major radiation release from a nuclear power plant, then it would probably do more damage if used on a major population center. There are measures you can take to prevent people from getting too irradiated by a dirty bomb, from evacuation to simply staying indoors and wearing a face mask to reduce particulate inhalation. Straightforward explosions, in contrast, do not offer quite as many second chances.

(BTW, on the subject of surviving a nuclear blast: duck and cover. It works. There were some crazy-badass scientific investigations into the effects of nuclear weapons, back in the days when we would actually set off a nuclear bomb in the desert somewhere to get experimental data, and the results were clear: in a fairly large range of radii around a nuclear bomb, you can increase your chance of survival a lot if you can just get a wall between yourself and the flash, and a table or something over you to protect you from falling debris. At the time they were also very concerned about buildings collapsing, but they discovered that some simple changes to typical construction methods could make buildings much more durable, and those have been mandatory in most places ever since.)

I know. But how this compares to big wildfires, yearly coal and oil burnings and a volcano or two?

We are told, that the Giga tones of burnt coal and oil per year, warms the planet. About the same amount of plastics, wood and so on would trigger the so called Nuclear Winter?

I am a NW skeptic.

Never take it out of context.

As I've said. All the atom bombs we have, have combined less energy than a big wildfire. So the energy is not a problem.

Then, the amount of "black smoke", which would those bombs emits, compared to a volcano is small. There is nowhere one ton of a black smoke emitting plastics per person alive, not to mention that everything will not be burned.

I don't see where they are getting their numbers. One of those scenarist was Carl Sagan. He made quite a panic when Saddam Hussein ignited those Kuwait oil pumps. He was wrong.

Look it now either from the energy point of view, either from the soot lifting point of view - it is not such a big event in the geological terms at all.

Billion of people may die, maybe more, maybe less. An unspeakable evil, it would be, yes.

But a nuclear winter from an event comparable with no such a big wildfire? One million square kilometers of the Australian bush burnt. One trillion square meters. One kilogram of grass and wood per square meter burnt. One million J of energy released. This is a very conservative calculation, but it gives you 10 times more energy than the combined nuclear stock pile would. And the biggest wild fire covered 5 times more land. So, maybe 50 times more energy released - caused no nuclear winter.

Every year we have enough wildfires to release more energy than there is in those bombs.

You have to put everything in a perspective.