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Fukushima Daiichi nuclear disaster

bi0boy said:
Actually, this is the dogma, but it's theoretically the case that low doses should reduce cancer risk by activating DNA repair enzymes. However there isn't enough data to show how this works in practice so "there is no safe dose" is the default assumption, but actually that's likely to be wrong, though we don't know for sure.
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I think I'll stick with the default assumption for now ta very much, not quite convinced enough to visit a Radium spa yet. ;)
E2A also I was speaking more from a regulatory POV, as I mentioned the maximum allowable levels vary according to occupation, mine being as much as 50mS/a.
 
Guardian (sorry lost link)

On NHK, Professor Akira Yamaguchi of Osaka University has offered a somewhat gloomy analysis of the attempts to douse the fuel pool with water using helicopters. The images suggested it was "highly likely" the effort was insufficient, he said, because the spent fuel pool is believed to have been almost empty and when water is dropped from above a lot of it gets lost en route. He added:


"7.5 tonnes of water has been dumped [it seems]. We do not know the size of the pool, but judging from other examples it probably holds 2000 tonnes. It does not mean the pool needs to be completely full, but maybe a third of the tank's capacity is needed.
It [the water dumping] needs to be done continuously."
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Guardian

Japanese government spokesman Yukio Edano has denied the authorities are withholding information on the situation around the nuclear facilities: "The information that we're collecting on the Japanese side, we naturally pass to authorities in the United States. But there is a time delay in delivering this information. This was especially the case with information regarding reactor No.4. However, we have heard that the situation in the cooling pool of reactor No.3 is more of a priority, and so we are dropping water on that first. We are also concentrating on the situation in the cooling pool of reactor No.4, but we still haven't come to a firm conclusion about its situation."
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Guardian,

Kyodo says Japanese officials are "baffled" by the warning from the chair of the US nuclear regulatory commission that there was no water in the spent fuel pool in reactor 4, which we reported earlier. The NRC has dispatched experts to assist Japan as it battles the crisis at the nuclear plant.
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rover07 said:
This is the end for Nuclear fission.

No one in their right mind would build anymore power plants
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Of course there are a fuckload of elderly plants still in operation around the world, and unless people start reducing consumption immediately these will stay online. Can't see California (or indeed France) shutting it all down for a start.
 
Guardian

10.11am (7.11pm JST): NHK has a round-up of radiation levels in towns around the stricken Fukushima plant. While the report insists there is, as yet, no danger to human health the figures are somewhat disquieting:

As of 9am Thursday, at Fukushima City, 65 kilometres north-west of the Fukushima Daiichi plant, radiation level was 13.9 microsieverts per hour. This is more than 340 times the usual background level.

At Koriyama City west of the plant, the reading was 2.71 microseiverts, 45 times the normal level.

South of the plant, in Iwaki City, radiation levels were as high as 20 times the usual level at 1.25 microseiverts.

But health authorities say one-hour of exposure to radiation at any of the observed levels would range between 1/500th to 1/40th of the amount of radiation the body would receive in a single stomach X-ray.
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Wind directions in next few days can be seen here

Tuesday as of this post looks like blowing from the NE, which is roughly the direction of the reactor.
 
rover07 said:
No one in their right mind would build anymore power plants
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Hardly anybody did during the 90s...

And no-one would now in the UK if it weren't for the subsidies concealed by the government's claim that there must be no, er, subsidies.

Economically, the crucial subsidy is us bearing most of the cost of waste disposal and decommissioning. That makes little sense to those who don't understand the role of the discount rate in economics, though. Where they're politically dead now is the claim that nuclear is entitled to market guarantees for being "green".
 
Reuters live blog has this comment from someone pertaining to be a doctor...

....the real-world comparison [to radiation levels measured] is quite disquieting, the measurement in the city 65km away, outside the exclusion zone, would expose one to the equivalent of one stomach x-ray per hour, 24 hours per day. Exposing a patient to that amount of radiation would be considered dangerously unacceptable and outrageous in my profession.
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He then realised he had made a mistake with the levels however:

I was mistaken, it indeed would be equivalent to one stomach x-ray every 40 hours for residents of Fukushima City, 65 kilometres from the plant. That would be one x-ray every two days which is still totally unacceptable. How can the residents of this city, especially children and pregnant women be asked to live for extended periods of time with this level of exposure that would be considered dangerous under normal circumstances. Do not forget that the US gov't reccomends an 80 km evacuation zone while Japan continues to insist on only 20km.
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rover07 said:
This is the end for Nuclear fission.

No one in their right mind would build anymore power plants
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Well, if that is the case, there are going to be several countries soon where people have to spend long periods sitting in the dark, especially when it isn't windy or sunny.

Or we could just re-open those coal mines..... no environmental problems there at all!

Giles..
 
Some info on Zirconium, the metal use to clad the rods.

Solid metal will not ignite. High surface area material such as 10 micron powder may autoignite at room temperature. Fine chips, turnings, or grinding dust produced from this metal are flammable. Ignition point for powder varies from 200 oC to above 500 oC depending on particle size.

Minimum Explosible Concentration (g/m3): Less than 100. Varies with particle size.

Extinguishing Media: Dry table salt. Type D fire extinguisher. DO NOT USE water, carbon dioxide or halocarbon extinguishing agent.

Special Firefighting Procedures: If metal fines become ignited it is advisable to allow the material to burnout. Fire can be controlled by smothering with dry table salt or using Type D dry-powder fire extinguisher material. Wear reflective heat-resistant suit.

Unusual Fire & Explosion Hazard: Do not spray water on burning zirconium. Carbon dioxide is not effective in extinguishing burning zirconium.

If a fire starts in a mass of wet metal fines, the initial fire may be followed by an explosion. Therefore, when in doubt, personnel should retire and not attempt to extinguish the fire. The explosive characteristic of such material is caused by the steam and hydrogen generated within the burning mass.

Spontaneously combustible in dry powder form. Flammable and explosive as dust or powder, also in the form of borings and shavings. Zirconium metal is a very dangerous fire hazard in the form of dust when exposed to heat, flame or by chemical reaction with oxidizing agents. May be an explosion hazard in the form of dust by chemical reaction with air, alkali hydroxides, alkali metal chromates, dichromates, molybdates, sulfates, tungstates, borax, CCl4, copper oxide, lead, lead oxide, phosphorous, KClO3, KNO3, nitryl fluoride. May be extremely sensitive to shock, and static electricity may cause spontaneous ignition.
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PDF giving information on the used fuel pools. worth a read.
 
It is suggested that the meltdown disaster was caused by the failure of auxiliary power supply systems operating the cooling water pumps.

The external power supply was cutoff by the earthquake damage. Standby diesel generators were disabled by the tsunami. Batteries were exhausted.

How long does it take to restore the earthquake damaged external power supply looming a radiation disaster?

What prevented bringing any number of mobile generators/ pumps from Tokyo or anywhere in Japan?

What risk assessments have they carried out, building nuclear plants on a megathrust earthquake belt? Will they ever learn and respond accordingly?
 
AnandLeo said:
How long does it take to restore the earthquake damaged external power supply looming a radiation disaster?

What prevented bringing any number of mobile generators/ pumps from Tokyo or anywhere in Japan?
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A huge problem is that the circuits that they would connect the power to have been damaged. in last 18 hours they have been trying to make good news by talking as though reactor 3 is nearly ready to be reconnected to electric supply. But even when they manage this, lots of stuff has been damaged as we can see from the state of the buildings, so its unclear quite how much help this will be.
 
How come it's so dangerous for the helicopter crews? Aren't they wearing NBC suits? They're only in the area for a minute or two. What about the workers who are still at the plant? They must be wearing similar suits - but they're in the plant for hours on end. Have they already had a lethal dose?
 
nick h. said:
How come it's so dangerous for the helicopter crews? Aren't they wearing NBC suits? They're only in the area for a minute or two. What about the workers who are still at the plant? They must be wearing similar suits - but they're in the plant for hours on end. Have they already had a lethal dose?
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Protective clothing is very limited in what it can protect against. Details on radiation levels at the plant itself and in the air directly above have not been very forthcoming in last 24 hours, so hard to get a full picture but it likely isnt good.

None of the levels mentioned so far would cause immediate death, but could cause longer term health problems, or more immediate problems if people lingered in the area for a sizeable amount of time.

As for workers on the ground, they evacuated the majority of them for good reason. Normally we would expect those that are left to be rotated in shifts to try to minimise exposure, but they have still had to increase the legally permissable exposure levels somewhat in order to maintain staff.
 
Guardian live blog:

A Tepco official has told a press conference in Japan that radiation levels at the site soon after 9.30 am were at 3,750 millisieverts per hour, Ian Sample has just told me. "These are absolutely dangerous levels," Ian said.
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Fuck me.
 
Guardian:

A Tepco official has told a press conference in Japan that radiation levels at the site soon after 9.30 am were at 3,750 millisieverts per hour, Ian Sample has just told me. "These are absolutely dangerous levels," Ian said.
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Well that explains why I havent seen more data from around the site recently. I will take a few minutes to think about these levels but man, off the top of my head those are very bad numbers.
 
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