Comment by potatolicious | Hacker News Reader

Comment by potatolicious | Hacker News Reader

Parent Full thread

... I'm not one of the "OMFG LOOK AT THE NUCLEAR ANGEL OF DEATH" people, but can we wait for this crisis to reach some resolution before we make loud proclamations either way?

The main information that concerns me right now is that there appears to be a consistent radiation leak of 400 mSv/h at the plant. While not Chernobyl by any measure, this is quite a bit of radiation, considering one's yearly dose limit is 1 mSv total.

This seems to contradict the extremely optimisitc reports that all is well, under control, and that no significant radiation leak has occurred.

[edit] One thing that optimistic reports consistently fail to address is the situation with the spent fuel pools. While not capable of melting down, from what I've read the pools are rapidly boiling dry and plant workers are struggling to maintain cooling on them. Left to its own devices the fuel will boil out the pool, light on fire, and then you have burning nuclear waste drifting directly into the atmosphere (after all, the buildings no longer have roofs). There is some speculation that the current radiation spike at the plant is not from any reactor but rather its spent fuel containment.

"considering one's yearly dose limit is 1 mSv total."

In Ramsar, Iran the background radition is around 200 mSv/Y (compared to a worldwide average of 2.4 mSv/Y) and _according to wikipedia_ this "high level of radiation does not seem to have caused ill effects on the residents of the area".

Call me confused.

Is the 1 mSv/Y total one of those made-up safety guidelines?

1 mSv is estimated to increase your odds of serious medical complications by 1/1,000,000. Not a significant amount, but one's regularly allowable dose should not be expected to cause health problems in the first place. Also, these limits are very conservatively set for various reasons - most of which I agree with (used to work in a nuclear facility).

So no, if you got blasted with 10 mSv all at once you shouldn't expect to vomit blood or fall over dead, but it's still a sizable amount of radiation.

Also, 400 mSv/h is 3,504,000 mSv/Y (aka 3504 Sv/Y, aka 17,000 times the radiation output in Ramsar, Iran). Of course, one doesn't expect this radiation leak to last for a whole year, but the dose rate does matter. Sucking in 400 mSv over an hour is many, many times worse than getting it over a matter of years or decades.

A typical CT scan will expose you to 10-15mSv. A dose of 100mSv infers a 1% lifetime cancer risk. The effects of doses as small as 1mSv are not known and are inferred by models.

The 1 mSv/Y guideline is based on a hypothesis that extrapolating downward from higher dosages that have well understood health effects we can infer the effects of lower dosages. They call this the Linear no-threshold model. It was chosen because it's the most conservative, safest option.

Scientists suspect that it's wrong though. We have DNA repair mechanisms that may catch many errors.

The wikipedia article (http://en.wikipedia.org/wiki/Linear_no-threshold_model) is pretty good.

Well, it's prudent to low-ball the dosages in safety guidelines.

Possibly. The largest human study ever done on the effects of chronic low-level radiation found them to be beneficial.

The researcher involved proposed a radiation hormesis model, in which the body adapts to the destructive effects of radiation by upgrading its self-repair response. US regulatory groups adhere to a linear no-threshold model in which all radiation, regardless of how weak it may be, leads to cumulative damage. It's not a resolved issue however. The French Academy of Sciences & National Academy of Medicine, for one, cited the study linked below in an argument against the LNT model.

http://www.scienceboard.net/community/perspectives.122.html

The physics and physiology of radiation exposure seem to be quite complicated. I can't really answer your question, I'm very far from qualified to do so, but again _according to Wikipedia_ the short term effect of 0.2 Sv per day, let alone a year, seems to fall into the "no effect" category[1]. And according to this[2] post on Boingboing, the long term effect may not be as bad as one might think either.

[1] http://en.wikipedia.org/wiki/Sievert#Symptom_Benchmarks [2] http://www.boingboing.net/2011/03/14/radiation-dose-and-r.ht...

The effects listed in the Wikipedia article refer to acute radioation poisoning, i.e. what happens when radiation is so intense that it directly kills so many of your cells that your body can't cope.

Even if at 0.2 Sv/d none of that happens, you still have a very actual, massively increased risk of cancer and genetic defects in future children. To declare "no health issues", you most definitely want to stay several orders of magnitude below that

200 mSv/Y : so that is 20 R/Y in the old language? That can not cause any ill effects only in the very specific countries, like Soviet Union, North Korea, Iran, Libya... I guess people there are just more radiation resistant.

>... I'm not one of the "OMFG LOOK AT THE NUCLEAR ANGEL OF DEATH" people, but can we wait for this crisis to reach some resolution before we make loud proclamations either way?

Well you could see this as a calm article to balance those with cries of the nuclear angel because lets face it, they sure are making something of this.

It's not a calm article though - it's as bad as the ones proclaiming the death of nuclear and the upcoming atomic apocalypse... just in the complete opposite extreme.

Where one side is "fire! brimstone! death!" this side is "lalalalala NO PROBLEMS KEEP CALM CARRY ON". Both are unnecessary, unproductive, and dogmatic.

But the question isn't who is being extreme in which direction. The question is, who's right? If the facts in this article are accurate, then they're not being extreme, they're just plain right. If the facts aren't accurate, then they are wrong.

This isn't a "(D) say -10, (R) says 10, the truth is probably somewhere in the middle" situation. This is engineering and reality. If the worst "nuclear" injury that has occurred is a dose equivalent to a year of background radiation and another of 1/10th of a year, the right answer is that nothing resembling disaster has happened, heck nothing you could even notice without sensitive instruments has happened, and it's not an "extreme" to say so if it's true.

Applying the political template to the story is immediately a fail, at least in terms of understanding the truth.

The 400 mSv figure was a spike measured at one of the reactors, not ambient radiation in populated areas. In Shinjuku in Tokyo for example they measured 0.809µSv (note the µ) between 10 and 11 this morning, although the average for that period was about half that.

If there are no further blasts or fires I think things will be fine, but I don't know how much more damage the facility can take. Some of my friends and coworkers are evacuating Tokyo and I'm not sure they don't have the right idea...

Yes, the 400 mSv figure is at the plant - the front gates to be specific IIRC. If 400 mSv/h is measured in a populated area this would be a complete and absolute disaster - within a few hours people would be falling sick from radiation sickness, some will die in the short term from it, and you're now dealing with an incredibly large long tail of cancers in the future.

Even just measuring that level at the plant is alarming, though it currently poses little threat to the public. It does raise the question of whether or not they have it under as much control as we'd hope.

It was 11 mSv/hr at the front gate. The 400 mSv/hr figure was from literally right next to or inside the reactor. And this was a spike, mind you, not sustained for even an hour (as with the 0.809µSv/hr figure).

http://search.japantimes.co.jp/cgi-bin/nn20110315z2.html

http://search.japantimes.co.jp/cgi-bin/nn20110315z1.html

Reply on news.ycombinator.com