4 ms·

Re reactors: you're kidding yourself. The reacors that shut down regularly will be restarted, sure. But those where cooling failed will NOT run in a month or 3.

by brazzy 16y ago

Re reactors: you're kidding yourself. The reacors that shut down regularly will be restarted, sure. But those where cooling failed will NOT run in a month or 3. Those where the core melted are gone beyond salvage. And patio11 is talking bullshit as well: the situation at Fukushiuma may not be a Apocalyptic Nightmare Scenarios yet, but the systems did not work "exactly as designed", the situation it's not under control, and may still turn into a ANS if containment fails and the wind turns towards Tokyo (which is forecast to happen around Tuesday). Flooding the building with sea water is a desparate measure, not SOP.

mantas 16y ago
Just to clarify - I meant reactors that are OK. Failed ones won't be restarted for sure.
radu_floricica 16y ago
Since AFAIK they were designed to withstand a 8.2 earthquake, they pretty much exceeded expectation. And we can reasonably count on the standards being upgraded significantly after this. I like a lot the comparison of nuclear energy with airplane safety: when you look at the statistics, it's a lot safer. But when it fails, it makes the headlines.
- brazzy 16y ago
  The richter scale is pretty meaningless in that regard because it measures the total energy released by a quake, not the destructive power at a given point. To use it for a design spec, you'd have to specify the depth of the quake, the length and frequency of the shockwaves and, most importantly, the distance from the epicenter. I'd be very interested to learn what those specs actually said. If it really was a Richter scale value, it would logically have to be at point blank, which this quake wasn't. If so, the energy that hit the reactors may well have been considerably less than what they were designed for,
neutronicus 16y ago
Desperate, but not unforeseen. I guarantee you that there is something on file at Japan's nuclear regulatory agency describing exactly what they're doing now and the circumstances under which to do it. Nuclear engineering is imagining the worst case, every reload, and coming up with a plan for what to do to contain radioactive material if it happens.
stoney 16y ago
I don't know about these particular reactors, but I've worked at nuclear power plants in the past and the final cooling backup plan was generally a variation of "fill the building with sea water". The reactors I knew (I assume it's similar in Japan) each had a LOT of options for cooling them. Some options would allow regular operation (which requires very fine control of cooling), some options would harmlessly shut a reactor down (where "harmlessly" means without causing any damage to the reactor). The filling-with-sea-water option was "standard operating procedure" in the sense that it was in the manual as a standard procedure, but it's the kind of thing you only get to do once because after you've done it your reactor is permanently broken and won't be restarted.
lukevdp 16y ago
Worse case scenario is core meltdown, which poses no risk to humans. The reactor melts into a concrete pit made specifically for that purpose. Flooding the building with sea water is not something they came up with on the spur of the moment during this crisis. All of their options are well planned. More info: https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/ https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-w...
kahawe 16y ago
There is quite a difference in the way the situation of the nuclear reactors are describe in patio's article and the way the media here presents it. patio basically says everything is under control, nothing to worry about, no harmful radiation levels - not more than eating a banana or taking a long distance flight. The media is talking about meltdown, nuclear catastrophe and there have been at least two explosions by now. US forces moved away from the shores due to radiation, Russia is worried about the wind carrying radioactive caesium and iod all the way over to them. As far as I can tell from news coverage, radiation levels did exceed 500 mikro-sievert, at times were as high as 1500. It is just hard to understand what all this really means in terms of risk and how bad the situation really is. Meltdown and explosions at a nuclear plant just generally does not sound very safe and "standard procedure" to me. Anyone can shed some light on what is going on there, from a technical and engineering and maybe even physicist point of view?
- patio11 16y ago
  100 micro-sieverts is approximately equal to the radioactive exposure you'd get from one trip between Japan and Chicago.

by brazzy 16y ago

mantas 16y ago

Just to clarify - I meant reactors that are OK. Failed ones won't be restarted for sure.

radu_floricica 16y ago

Since AFAIK they were designed to withstand a 8.2 earthquake, they pretty much exceeded expectation. And we can reasonably count on the standards being upgraded significantly after this. I like a lot the comparison of nuclear energy with airplane safety: when you look at the statistics, it's a lot safer. But when it fails, it makes the headlines.

brazzy 16y ago
The richter scale is pretty meaningless in that regard because it measures the total energy released by a quake, not the destructive power at a given point. To use it for a design spec, you'd have to specify the depth of the quake, the length and frequency of the shockwaves and, most importantly, the distance from the epicenter. I'd be very interested to learn what those specs actually said. If it really was a Richter scale value, it would logically have to be at point blank, which this quake wasn't. If so, the energy that hit the reactors may well have been considerably less than what they were designed for,

neutronicus 16y ago

Desperate, but not unforeseen. I guarantee you that there is something on file at Japan's nuclear regulatory agency describing exactly what they're doing now and the circumstances under which to do it. Nuclear engineering is imagining the worst case, every reload, and coming up with a plan for what to do to contain radioactive material if it happens.

stoney 16y ago

I don't know about these particular reactors, but I've worked at nuclear power plants in the past and the final cooling backup plan was generally a variation of "fill the building with sea water". The reactors I knew (I assume it's similar in Japan) each had a LOT of options for cooling them. Some options would allow regular operation (which requires very fine control of cooling), some options would harmlessly shut a reactor down (where "harmlessly" means without causing any damage to the reactor). The filling-with-sea-water option was "standard operating procedure" in the sense that it was in the manual as a standard procedure, but it's the kind of thing you only get to do once because after you've done it your reactor is permanently broken and won't be restarted.

lukevdp 16y ago

Worse case scenario is core meltdown, which poses no risk to humans. The reactor melts into a concrete pit made specifically for that purpose. Flooding the building with sea water is not something they came up with on the spur of the moment during this crisis. All of their options are well planned. More info: https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/ https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-w...

kahawe 16y ago

There is quite a difference in the way the situation of the nuclear reactors are describe in patio's article and the way the media here presents it. patio basically says everything is under control, nothing to worry about, no harmful radiation levels - not more than eating a banana or taking a long distance flight. The media is talking about meltdown, nuclear catastrophe and there have been at least two explosions by now. US forces moved away from the shores due to radiation, Russia is worried about the wind carrying radioactive caesium and iod all the way over to them. As far as I can tell from news coverage, radiation levels did exceed 500 mikro-sievert, at times were as high as 1500. It is just hard to understand what all this really means in terms of risk and how bad the situation really is. Meltdown and explosions at a nuclear plant just generally does not sound very safe and "standard procedure" to me. Anyone can shed some light on what is going on there, from a technical and engineering and maybe even physicist point of view?

patio11 16y ago
100 micro-sieverts is approximately equal to the radioactive exposure you'd get from one trip between Japan and Chicago.