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PostPosted: Aug 22, 2011 9:55 am 
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'The areas to be kept off-limits will likely include parts of Futabamachi and Okumamachi, both in Fukushima Prefecture. They are within three kilometers of the nuclear plant crippled by March 11 disaster.

The areas could be kept off-limits for "several decades," according to government sources.

In April, the government designated the 20-kilometer no-entry zone around the Fukushima No. 1 power plant. The government had planned to lift the no-entry zone after the reactors at the nuclear plant are brought to a stable condition known as cold shutdown by mid-January.

However, the Education, Culture, Sports, Science and Technology Ministry estimated that cumulative radiation levels during the year since the accidents at the plant would greatly exceed 20 millisieverts--the benchmark for designating an expanded evacuation zone--at 35 locations mainly in Okumamachi and Futabamachi in the no-entry zone.

The annual cumulative radiation level was calculated to reach 508.1 millisieverts in the Koirino district of Okumamachi, which is three kilometers west-southwest of the nuclear plant, and 393.7 millisieverts in Ottozawa in the town.

The ministry measured radiation levels at 50 locations in the no-entry zone. It estimated annual cumulative radiation levels on the assumption that residents are outside for eight hours a day and inside wooden homes for 16 hours a day.

The government decided that areas very close to the Fukushima No. 1 nuclear plant will be uninhabitable for an extended period because they are heavily contaminated with radioactive substances and could suffer further serious damage if another major problem occurs at the plant.'

http://www.yomiuri.co.jp/dy/national/T110821002920.htm

Yikes!


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PostPosted: Aug 22, 2011 11:37 am 
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Half a Sievert/year is about the radiation dose received by the highest cohort of the Taiwanese cobalt-60 contaminated appartments.

That group had a cancer incidence several times lower than the Taiwanese average.

Even more bizarre, is the standard the government of Japan has set for nuclear evacuations. According to the fallacious linear no threshold theory, 20 mSv/year would give you about a 0.2 percent higher chance of cancer of any type. That's the threshold the Japanese are using for evacuations. Many parts of my country are situated with particulate matter emissions that cause many times higher chance of cancer than that, yet we aren't evacuating my country. We'd have to evacuate all areas closer than a few miles to major roads, industrial areas, refineries etc. Basically half the country.

Should we start evacuating entire countries?


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PostPosted: Aug 22, 2011 12:14 pm 
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I'd agree that evacuation for areas at 20MSv/year is daft.
500MSv is pretty substantial though, and I had not realised that the background level outside the plant had increased to that level.
With the evidence we have, I would think that anything much over 20MSv/year is doubtful to live in.


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PostPosted: Aug 22, 2011 12:16 pm 
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Location: Charlottesville VA
Thanks Cyril,

I love information like this, it usually tips the scale in an argument about nuclear power.
At least for those with an open mind!


Andrew


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PostPosted: Aug 22, 2011 1:41 pm 
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ajm90 wrote:
Thanks Cyril,

I love information like this, it usually tips the scale in an argument about nuclear power.
At least for those with an open mind!

Andrew


Even if radioactive radiation is every bit as dangerous as claimed we should still use nuclear power. It's still less dangerous than the alternatives even for ancient reactors with questionable designs.


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PostPosted: Aug 22, 2011 3:06 pm 
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DaveMart wrote:
I'd agree that evacuation for areas at 20MSv/year is daft.
500MSv is pretty substantial though, and I had not realised that the background level outside the plant had increased to that level.
With the evidence we have, I would think that anything much over 20MSv/year is doubtful to live in.

Anything below 100MSv/year is statistically impossible to differentiate from any other dose. I'm not sure I have faith in any model over any other and so I wouldn't make any policy based on models that are themselves essentially only capable of being based on faith.


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PostPosted: Aug 22, 2011 3:10 pm 
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DaveMart wrote:
With the evidence we have, I would think that anything much over 20MSv/year is doubtful to live in.

The evidence would like to says otherwise.


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PostPosted: Aug 22, 2011 4:16 pm 
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Dudes, units!

20MSv/yr - 20 Mega Sievert/year - 20 10^6 Sv/year as in very deadly, deterministic range

20mSv/yr - 20 mili Sievert/year - 20 10^-3/year as in acceptable, probabilistic range, though the ALARA principle tells you to evade it when reasonably possible. Under the current circumstances, it isn't that unreasonable to close the area for the immediate future. Follow-up may then undo this decision. It is also important to notice that perhaps not all details about the contamination are collected and hence it is a wise decision, as contamination uptake results in a much higher dose.

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Liking All Nuclear Systems, But Looking At Them Through Dark And Critical Glasses.


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PostPosted: Aug 22, 2011 8:23 pm 
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STG wrote:
Dudes, units!

20MSv/yr - 20 Mega Sievert/year - 20 10^6 Sv/year as in very deadly, deterministic range.

Thank you, if we get our M's and our m's mixed up, that won't help the cause at all.

Not that the US general use of the prefix MM (for 1 million, 1,000 x 1,000, M x M in Roman numerals) does not help much either. (It took me years to work that one out being a slow learner)


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PostPosted: Aug 22, 2011 9:30 pm 
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STG wrote:
Dudes, units!

20MSv/yr - 20 Mega Sievert/year - 20 10^6 Sv/year as in very deadly, deterministic range

20mSv/yr - 20 mili Sievert/year - 20 10^-3/year as in acceptable, probabilistic range, though the ALARA principle tells you to evade it when reasonably possible. Under the current circumstances, it isn't that unreasonable to close the area for the immediate future. Follow-up may then undo this decision. It is also important to notice that perhaps not all details about the contamination are collected and hence it is a wise decision, as contamination uptake results in a much higher dose.

Right, apologies, running with quotes does some things to enhance my laziness sometimes.

However I still feel ALARA is bad policy, partly because it creates a climate of fear that leads us to ignore much more dangerous things. Like swimming pools for example. Further, its not like basing such policy entirely on the faith that maybe one model is potentially more dangerous than another in entirely unmeasurable ways is zero cost either.


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PostPosted: Aug 23, 2011 2:36 am 
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The science to evaluate risks does not seem to be too accurate, but as others have said there might be local hotspots.
If it were me and my family, then I would compare it with natural levels of radiation, to give a 'Cornwall equivalent'.
In places in Cornwall the dose is about 8mSv/year, so I would not be too worried about anything up to maybe 20 mSv/yr.
It is worth noting though that although in general the elevated levels of radiation in Cornwall do not pose excess risks, lung cancer does seem to be rather higher due it is thought to poorly ventilated houses letting radon hang around.
I am not sure how solid the science is for this, but in general I would be cautious about levels much higher than are normally found, and I would most certainly not be hanging around in areas with 508mSv/year radiation levels.
In practical terms it is clear that no-one is going to authorise re-population of areas with levels of above 20 mSv/year, and I would not take children into areas with 100 mSv/year although I might go there myself to live, as I am 60 and the enhanced risk if any would be minimal.
The uncertainties seem far too great to allow children with 80 years in front of them for damage to manifest to be exposed though.


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PostPosted: Aug 23, 2011 3:37 am 
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Yes, ALARA is flawed. Too myopic. It doesn’t consider all alternatives and consequences. In the case of Fukushima, permanently evacuating large areas has itself impacts not only on the economy, but also on health of the people. Stress is bad for your health. In the case of nuclear power in general, investing billions in upgrading nuclear plants to get down to the microsievert range, causes nuclear power to be less economically attractive which causes less of it to be built. Guess what’s going to take up its place – deadly fossil fuels.

What’s more, ALARA completely ignores hormetic effects, for which there is broad evidence in chemical as well as radiological exposures.


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PostPosted: Aug 23, 2011 2:57 pm 
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Rainstorms apparently played a role in washing out to sea much of the radiation that lingered after the Hiroshima and Nagasaki bomb blasts. Is it possible that such downpours could also have this effect in the Fukushima evacuation zone?


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PostPosted: Aug 23, 2011 3:53 pm 
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Cyril R wrote:
Yes, ALARA is flawed. Too myopic. It doesn’t consider all alternatives and consequences. In the case of Fukushima, permanently evacuating large areas has itself impacts not only on the economy, but also on health of the people. Stress is bad for your health. In the case of nuclear power in general, investing billions in upgrading nuclear plants to get down to the microsievert range, causes nuclear power to be less economically attractive which causes less of it to be built. Guess what’s going to take up its place – deadly fossil fuels.

What’s more, ALARA completely ignores hormetic effects, for which there is broad evidence in chemical as well as radiological exposures.


Investing billions to get to the microsievert range isn't reasonably achievable and hence is against ALARA. Furthermore it isn't done as far as I know! The impact on the economy of the Fukushima exclusion zone might be limited since those products wouldn't sell that well due to radiation fear...

Hormetic effects are still not quantified, so they can not be taken into account in any risk assessment...ALARA or not ALARA based.

Furthermore ALARA has nothing to do with the perception of radiation risk for the public, it is only a guideline in the nuclear industry...

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PostPosted: Aug 24, 2011 3:23 pm 
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STG wrote:
Hormetic effects are still not quantified, so they can not be taken into account in any risk assessment...ALARA or not ALARA based.

Furthermore ALARA has nothing to do with the perception of radiation risk for the public, it is only a guideline in the nuclear industry...

ALARA has problems because it shapes thinking about policy beyond the guideline in the nuclear industry, as well as perpetuates the myth of LNT. Statistically it is impossible to say anything about doses below 100mSv, so we shouldn't have any policy below what is measurable.

ALARA is flawed because it sets goals in the land of faith, and "reasonably achievable" is not zero cost.


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