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Fukushima

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Re: Fukushima

#141

Post by jahewson »

jscheel wrote: post #105
speleding wrote: post #92

Earlier quoted context omitted.

Are you really not sensing an anti-nuclear sentiment? For example, take this paragraph where he talks about Chernobyl? "Silence, lack of cries, laughter, tears and only the wind answers... Have we learnt anything since then?" I would say the framing of that question makes his stance pretty clear.

I felt a bit of that sentiment, but it didn't seem ham-handed. If you are interested in reading about nuclear accidents and the things we can learn from them, I highly suggest Atomic Accidents by James Mahaffey ( https://www.goodreads.com/book/show/20820098-atomic-accident... ). He's pro-nuclear, but acknowledges that there are still things to learn about safe containment. His focus is mainly, and rightly, on the unr…

Is "ham-handed" a cross between being "heavy-handed" and "ham-fisted"? :)

Re: Fukushima

#142

Post by magila »

dfox wrote: post #117
struct wrote: post #14

One thing that grabs my attention is that the radiation levels in the contaminated zones are much lower than I thought they'd be. For context, the limit for a radiation worker in the US is 50 mSv. Obviously, I guess it depends on the radioactive isotopes released and what kind of radiation they release, but I'm still impressed.

The limit is 50mSv per year, not per hour. Sievert is cumulative unit that has to be either qualified by time or measured over entire lifespan to be meaningfully comparable. But on the other hand quantitatively measuring and comparing radiation effects is hard problem as there is essentially nothing that can be precisely measured and at the same time has any meaning as to biological effects, in practice the conversio…

All of the radiation figures in the article are in mSv per year, not per hour.

Re: Fukushima

#143

Post by e28eta »

orik wrote: post #29
ggreer wrote: post #17

I found the pictures fascinating, but the accompanying text marred my enjoyment. Considering the circumstances of the Fukushima disaster, the anti-nuclear sentiment really irked me. The Tōhoku earthquake & tsunami killed close to 20,000 people. The author completely ignored those victims. Instead, he focused on Fukushima, which will cause around 150 deaths from cancers. For every tragedy created by Fukushima, there a…

You are seeing a sentiment that isn't there. The author doesn't take a political stance on Nuclear Power. He's just documenting the contamination zone. He talks briefly about how the disaster could have been avoided if the plant was designed better. He gives factual and statistical information about how the residents don't want to return there. This is a primary source that offers an first-hand account of the Fukushi…

I see the sentiment too

"...I could assess the effects of the power station failure and understand the scale of the tragedy, especially the tragedy of the evacuated residents, in a better way. This was a way of drawing my own conclusions without being influenced by any media sensation, government propaganda, or nuclear lobbyists who are trying to play down the effects of the disaster..."

Re: Fukushima

#144

Post by dfox »

magila wrote: post #142
dfox wrote: post #117

Earlier quoted context omitted.

The limit is 50mSv per year, not per hour. Sievert is cumulative unit that has to be either qualified by time or measured over entire lifespan to be meaningfully comparable. But on the other hand quantitatively measuring and comparing radiation effects is hard problem as there is essentially nothing that can be precisely measured and at the same time has any meaning as to biological effects, in practice the conversio…

All of the radiation figures in the article are in mSv per year, not per hour.

Photos of various signs in the article are in uSv/hour.

Re: Fukushima

#145

Post by gknoy »

mikekchar wrote: post #128
Kankuro wrote: post #120

Earlier quoted context omitted.

I guess he was talking about higher walls around the (few) nuclear plants, not the whole country. That would not make the country "a jail where the only place I can see the ocean is from on top of a mountain".

The water will just go around the wall. I think people don't quite understand the logistics involved. You have this massive wave travelling at 300 km/h. The seawall will break up the wave, but you have to have it long enough to prevent the water from reaching the bits that you want to protect before it retreats (often 20-30 minutes later). Do a google search for "tetrapod japan images" to see what the beaches around…

Thank you for suggesting the image search -- I had been imagining a castle-like wall, and seeing the stacked tetrapods [0] was really eye-opening. (Apparently it helps dissipate the wave energy.)

0: https://en.wikipedia.org/wiki/Tetrapod_(structure)

Re: Fukushima

#146

Post by ju-st »

simoncion wrote: post #112
afterburner wrote: post #104

Earlier quoted context omitted.

> it's very hard and not cheap That also describes nuclear power.

1) Infrastructure projects always appear expensive to the layman. The correct way to price power generation projects is to look at the expected actual cost per MW over the lifetime of the generation facility, and to factor in -as best you can- actual externalities related to the operation of the facility. 2) As I understand it, the hard part of nuclear power isn't the engineering and construction; that's a solved pro…

I think the engineering and construction is not a solved problem (+nuclear waste). All new plants have construction delays and cost overruns.

Of course, one could argue that overly strict regulations (which may only exist because of public concerns) are the reason for these problems. But the reason for the safety of the existing reactors are these strict regulations, so I think loosening these rules is not a good idea.

Re: Fukushima

#147

Post by dfox »

e12e wrote: post #140
dfox wrote: post #117

Earlier quoted context omitted.

The limit is 50mSv per year, not per hour. Sievert is cumulative unit that has to be either qualified by time or measured over entire lifespan to be meaningfully comparable. But on the other hand quantitatively measuring and comparing radiation effects is hard problem as there is essentially nothing that can be precisely measured and at the same time has any meaning as to biological effects, in practice the conversio…

Would appear that the limit is similar - the "red zone" is for "(> 50 mSv/y)" (note "more than") -- and the sign at the end "Leaving the zone" reads 4.9 mSV/h. That'd be about 42.000 mSV/year -- if we assume constant dose. Or put it another way -- stay an hour and you're at the (safe) limit of exposure for a year. As for all the comments on how nuclear isn't all that dangerous -- how much do we really know about peop…

The main radiation hazard is not in the actual exposure to radiation, but in ingestion (in the broad sense, including inhalation) of radioactive isotopes. Such contaminants are able to remain inside the body for long times and have various long time effects that are more severe than acute radiation exposure. That is one reason why radiation (even measured in sieverts) is not really meaningful measure.

Re: Fukushima

#148

Post by mackwic »

mikekchar wrote: post #128
Kankuro wrote: post #120

Earlier quoted context omitted.

I guess he was talking about higher walls around the (few) nuclear plants, not the whole country. That would not make the country "a jail where the only place I can see the ocean is from on top of a mountain".

The water will just go around the wall. I think people don't quite understand the logistics involved. You have this massive wave travelling at 300 km/h. The seawall will break up the wave, but you have to have it long enough to prevent the water from reaching the bits that you want to protect before it retreats (often 20-30 minutes later). Do a google search for "tetrapod japan images" to see what the beaches around…

Thanks for your reply. I now think I don't understand the logistic involved and will look further.

Re: Fukushima

#149

Post by jessaustin »

tptacek wrote: post #114
coldtea wrote: post #111

It's a classic spin -- trying to blind people concerned with nuclear plants in their area etc, by using science selectively.

It's impolite to accuse people on an HN thread of being deceptive. It also doesn't add anything to thread itself, so why bother?

[EDIT] Nuclear power supporters believe themselves correct, so pointing out the spin isn't an accusation of deception per se. [EDIT] They're not trying to fool us, just to advocate their position. It is still useful for undecided parties to notice the spin and take it into account.

EDIT: Admittedly, "trying to blind people" is not a charitable characterization.

Re: Fukushima

#150

Post by pdonis »

dfox wrote: post #136
pdonis wrote: post #124

Earlier quoted context omitted.

> the correct response to such a major loss of cooling on BWR is just to evacuate premises and do nothing The problem at Fukushima wasn't a short-term loss of coolant; it was the long-term lack of backup cooling after the tsunami hit (by which point the reactor had already been shut down for about 45 minutes), because of poor siting of the backup generators and switchgear. The operators couldn't do anything about tha…

And that is exactly my point. In such situation just leaving the reactor be would cause destruction of the reactor and no major environmental impact, yet they misguidedly tried to save the situation and thus exacerbated the environmental impact. Poor placement of backup systems is critical to process continuity, but in case of BWR mostly irrelevant to actual nuclear safety as long as you are willing to just write off…

> In such situation just leaving the reactor be would cause destruction of the reactor and no major environmental impact

I'm not sure the last part is true; as I understand it, there was a significant risk of a containment breach if decay heat removal was insufficient--not from the reactor cores themselves, but from the spent fuel pools.

I agree with you, though, that any attempt to save the reactor itself was doomed to failure once the tsunami hit and the backup cooling was taken out, so any actions taken toward that end were misguided.

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