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Merged nuclear power safe?

From what I've seen on WNN all reactors seem to be shut down:

http://www.world-nuclear-news.org/indtalk.aspx

All four units at the Fukushima Daini nuclear power plant have now achieved cold shutdown - where coolant water is at less than 100ºC - with full operation of cooling systems, Tepco reported. All the reactors shut down automatically during last week’s earthquake and have remained safe. While unit 3’s shutdown went as expected, damage to the emergency core cooling systems of units 1, 2 and 4 led to the announcement of emergency status. These three reactors were prepared for potential pressure release, but this was never required. Unit 1 announced cold shutdown at 1.24 am on 14 March and unit 2 followed at 3.52 am. Tepco has now announced that unit 4 achieved cold shutdown at 7.15 pm on 15 March. Water levels are now stable in all four reactors and offsite power is available, the company said.
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Confirmation ?
 
BenBurch said:
Well, radionuclide nobel gas effluent does levels DO decay with distance in a function that includes wind speed and mixing.

First, they are very short in half-life. If the wind is ten miles per hour, the gas carried on the wind will be at half-strength 100 miles away.

Second, there is a LOT of mixing.

This gas volume is very small. Concentrated, the dose is very high. But mixed well with the air, the dose level falls off pretty quickly. Ten miles out with a moderate wind, even a worst-case scenario is not an alarming body dose.
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That is diffusion, not decay.

{/semantic nit pick}
 
MarkCorrigan said:
For the lurkers, since DC appears to be trollin' away to the hills now:

The problem at Fukushima is a serious one. No one doubts that, and no one expects anyone to ignore it like it's a small car crash. Nuclear facilities going into meltdown is a big thing, and if the worst case scenario happens, will be a dangerous thing too. However, as has been pointed out time and time again, meltdown doesn't mean nuclear waste/fuel/radiation being pumped into the atmosphere. Nuclear meltdown doesn't mean the ground will be poisoned for decades. Nuclear meltdown with intact and fairly stable containment means a big mess and a lot of expensive cleaning up.

If the containment was absent as it was in Chernobyl, yes, we would be seeing radiation entering the air at a fairly alarming rate, and if the containment is destroyed we might also see some smallscale but highly dangerous leakage. As it happens though, at worst one reactor containment area has been mildly damaged. This sounds alarming as hell, but all it means is a small amount of radiation is being leaked. So far this has peaked at a level that is not dangerous for small scale exposure, but prolonged and continuous exposure could well be harmful. However, it is notable that this peak was short lived, as far as I am aware, although if anyone wants to contradict me, show your sources.

All this means is that in order to be in any danger whatsoever, you would have to stand in the affected area (between two reactors mark you, so not somewhere John Q Public is likely to be) for a prolonged time without a protective suit.

Further to this, as it stands the radiation levels are dropping and plant cooling is occurring. A couple of the reactors have already gone into cold shut-down, meaning that they are now safe, and only one other reactor, Fukushima reactor 2, is still being cooled. This procedure seems to be going as smoothly as it can given the devastation wrought upon the area by the natural disasters that occurred. The same can not be said for the petrochemical plants in the area.
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That is not the way I udnerstand what is happening.

The current issue now is not so much the reactors themselves, which are still at risk, but the spent fuel pools.

The last explosion was caused by one of those pools in a reactor building where the reactor was not even in operation.

They don't even know the status of the pools at reactor's 1 and 2.

Those pools are NOT in containment like the reactors are.
 
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H'ethetheth said:
About the 400 mSv/hr figure:

The JAIF reports 400 mSv "beside Unit 3" and about 500 μSv/hr at the NPS (I assume nuclear power station) border.

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300189582P.pdf

On the other hand, they quote the "chief cabinet secretary" as saying "400 mSv/hr in the vicinity of unit-3"

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300191989P.pdf

I'm not sure, but my guess is that the cabinet secretary misquoted the numbers.
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That could well be. The media here is confusing milli- and microsieverts all the time; it's not fear-mongering (the errors go both ways), it's just scientific illiteracy plain and simple.
 
DC said:
well i am not so sure if i would want to be living death sick or rather death.
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An in-depth IAEA study, described as a "three-volume, 600-page report and incorporating the work of hundreds of scientists, economists and health experts, assesses the 20-year impact of the largest nuclear accident in history" had this to say about the health effects on humans:

  • Approximately 1 000 on-site reactor staff and emergency workers were heavily exposed to high-level radiation on the first day of the accident; among the more than 200,000 emergency and recovery operation workers exposed during the period from 1986-1987, an estimated 2,200 radiation-caused deaths can be expected during their lifetime.

  • An estimated five million people currently live in areas of Belarus, Russia and Ukraine that are contaminated with radionuclides due to the accident; about 100,000 of them live in areas classified in the past by government authorities as areas of "strict control". The existing "zoning" definitions need to be revisited and relaxed in light of the new findings. About 4,000 cases of thyroid cancer, mainly in children and adolescents at the time of the accident, have resulted from the accident's contamination and at least nine children died of thyroid cancer; however the survival rate among such cancer victims, judging from experience in Belarus, has been almost 99%.

  • Most emergency workers and people living in contaminated areas received relatively low whole body radiation doses, comparable to natural background levels. As a consequence, no evidence or likelihood of decreased fertility among the affected population has been found, nor has there been any evidence of increases in congenital malformations that can be attributed to radiation exposure.

  • Poverty, "lifestyle" diseases now rampant in the former Soviet Union and mental health problems pose a far greater threat to local communities than does radiation exposure.
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Not quite the radiological disaster on human health as one might have thought given the seriousness of the accident.
 
Belz... said:
Then why were they saying it was level 6 ?
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The only "they" I know of who was saying it's a 6 was Wikipedia a while ago. Their sole source was a Telegraph article citing unnamed "French experts". Even Wikipedia has Fukushima back at 4.

I could also give you a Finnish-language reference of a Swedish "expert" who says it's a 7, as bad as Chernobyl. Nuclear experts seem to be a dime a dozen nowadays, and naturally the extreme ones get more than their due share of publicity. This is fear-mongering (again helped by an alarming level of scientific illiteracy among journalists).

ETA: Oops, sorry. Wikipedia now says that the rating of the Fukushima incident is disputed. They still have no other source but the Telegraph article linked to above.
 
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timhau said:
That could well be. The media here is confusing milli- and microsieverts all the time; it's not fear-mongering (the errors go both ways), it's just scientific illiteracy plain and simple.
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The terms confuse me, and I'm not even in the media. :D

It might be helpful if a consistent measurement standard was used, even if it results in a number with lots of decimal places from time to time.
 
timhau said:
The only "they" I know of who was saying it's a 6 was Wikipedia a while ago. Their sole source was a Telegraph article citing unnamed "French experts". Even Wikipedia has Fukushima back at 4.

I could also give you a Finnish-language reference of a Swedish "expert" who says it's a 7, as bad as Chernobyl. Nuclear experts seem to be a dime a dozen nowadays, and naturally the extreme ones get more than their due share of publicity. This is fear-mongering (again helped by an alarming level of scientific illiteracy among journalists).

ETA: Oops, sorry. Wikipedia now says that the rating of the Fukushima incident is disputed. They still have no other source but the Telegraph article linked to above.
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And way overpriced at that.......
 
MarkCorrigan said:
Further to this, as it stands the radiation levels are dropping and plant cooling is occurring. A couple of the reactors have already gone into cold shut-down, meaning that they are now safe, and only one other reactor, Fukushima reactor 2, is still being cooled. This procedure seems to be going as smoothly as it can given the devastation wrought upon the area by the natural disasters that occurred. The same can not be said for the petrochemical plants in the area.
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After the reactors are rubbished, what are the Japanese going to do with the nuke waste?
 
Nosi said:
After the reactors are rubbished, what are the Japanese going to do with the nuke waste?
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Don't know. Probably barrel and bury, but if the waste is useful they could use it in a breeder reactor maybe?
 
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