FUKUSHIMA earthquake and tsunami thread and aftermath

[TimeTraveller]

No.

If you live in a poorly vented house on a fairly radioactive part of Dartmoor you get a dose of about 50mSv a year (source: http://hansard.millbanksystems.com/written_answers/1987/feb/05/radiation). Divide that by 365*24 to get your average hourly dose and you get 5707 nSv per hour. A nSv is roughly equivalent to a nGy (actually it's a bit more but about the same order of magnitude - see http://en.wikipedia.org/wiki/Sievert) so you'd be getting about the same levels of radiation sitting in your living room in Princetown.

I've come from the future to ask you to: Show Your Working...

1. Absorbed dose in Sieverts = Absorbed Dose in Grays x radiation weighting factor (WR).

2. The lowest radiation weighting factor is for gamma or beta radiation, you don't want to be ingesting an alpha emitter, the weighting factor would end up being 20 rather than 1.

3. Absorbed dose is 0.7 times airborne dose.

4. 1 milli-Gray == 1000 nano-Grays.

With this in mind... not including the airborne dosage factor:

1. 50mSv/y == 50 mGy/y

2. Exposure in nGy/h is 50000 / ( 365 * 24 ) == 5.707 nGy/h

3. Accounting for airborne/absorbed difference 5.707 * 1.428 == 8.152 nGy/h.

Unfortunately you're a factor of 1000 out. If I had a NaI dosemeter that picked up 5000 nGy/h I would be running away very quickly. If it stayed at that level its a yearly dose of around 43 Sv... the annual dose for a radiological worker is 20 mSv...

<Edited to add original quoted post, and not BogBrush's post...>

Edited March 15, 2011 by TimeTraveller

[sparko]

wind is 15kts to the south

they have lost two potential days worth of evacuation

I take it the site is too contaminated to approach at this point. So that whatever is left to meltdown will do so at its own leisure?

[Tankus]

I take it the site is too contaminated to approach at this point. So that whatever is left to meltdown will do so at its own leisure?

not yet......... there is still a control crew and a water pump (fire engine )

The radiation reading at 08:31am local time (2331 GMT) climbed to 8,217 microsieverts an hour from 1,941 about 40 minutes earlier

this is the reading at the gate

Edited March 15, 2011 by Tankus

[ChumpusRex]

[*]1 milli-Gray == 1000 nano-Grays.

It seems that important units are shortly to be redefined.

In the present, 1 milli-gray = 1,000,000 nano-Gray

The original calculation is correct. 5000 nGy/h of radon exposure is about 1 mSv/y using a radiation quality factor of 20 (Rn is an alpha emitter)

[TimeTraveller]

It seems that important units are shortly to be redefined.

In the present, 1 milli-gray = 1,000,000 nano-Gray

The original calculation is correct. 5000 nGy/h of radon exposure is about 1 mSv/y using a radiation quality factor of 20 (Rn is an alpha emitter)

Just picked that up myself when I realised that all of my calculations were generating normal hourly dosages that would kill in yearly amounts... ah well looks like I can go back to the future a happy robot... i'llgetmecoat...

Edited March 15, 2011 by TimeTraveller

[Riedquat]

Before getting too excited about radiation levels you need to consider what the source is. From short-lived stuff - horribly unpleasant in the short term, no long term problem. If you've got bits of core causing it on the other hand then that's the sign that things are really screwed.

[mfp123]

japan cabinet minister has just anounced on TV.

reactor 4 is on fire.

a hole has been observed on reactor 2, presumed to be leaking.

the most salient comment - workers at the plant (number 2) who were pumping seawater into the reactors to keep them cool were putting themselves in a very dangerous situation.

there are 50 people there and the radiation levels there must be massive...

Edited March 15, 2011 by mfp123

[Kyoto]

japan cabinet minister has just anounced on TV.

reactor 4 is on fire.

a hole has been observed on reactor 2, presumed to be leaking.

the most salient comment - workers at the plant (number 2) who were pumping seawater into the reactors to keep them cool were putting themselves in a very dangerous situation.

there are 50 people there and the radiation levels there must be massive...

This is just dreadful. Those poor & brave people.

[SaintJay]

No sign of Max Clifford. Yet.

this is more Mandelson territory.

[Damik]

It can burn the container , and the control rods , the assembly , the sea water its in contact with , once you have partial core melt , the steam does not just contain n16 anymore .......its lethal ,, that's why they vented into containment risking an explosion and not to atmosphere

the reactor is full of salt water , which means that sodium, magnesium , potassium and all sorts of chemicals have gone in

the reason why de-mineralized water is normally used is to prevent unwanted and uncontrolled "chemistry " going on

they are already venting unfiltered steam out for last few days ...therefore the higher radiation levels

[mentholist]

The Japanese had better hope that the designers are as clever as they are often given credit for. Firstly this is not to denigrate the bravery or the general competence of those trying to save the plant. However, it appears the human systems are now failing to cope with the information available to them (or worse not available). The fire at reactor 4 is an indication of missing potential catastrophes whilst focusing on known ones.

I get the feeling this is now about luck rather than judgement. Which given the stakes isn't a good outcome. For all the remedial measured taken it still seems that an explosive dispersal of radioactive material is possible.

[Tankus]

20 km is nothing

perfect circles of evacuation is a bit of a placebo

,but it can be used to avoid major population if the density is too high

it needs to be elongated down wind

http://www.spiegel.de/international/world/bild-750773-191828.html

Edited March 15, 2011 by Tankus

[fluffy666]

20 km is nothing

perfect circles of evacuation is a bit of a placebo

,but it can be used to avoid major population if the density is too high

it needs to be elongated down wind

http://www.spiegel.de/international/world/bild-750773-191828.html

You realize that this is not Chernobyl, it does not have a graphite core which is liable to burn for weeks.

[Odakyu-sen]

From the Asahi Newspaper Japanese website http://www.asahi.com/national/update/0315/TKY201103150234.html , 13:46 Japan Time today.

福島第一原発４号機の使用済み燃料プールの火災はこれまでの爆発事故より深刻だ。プールは原子炉圧力容器や格納容器の外にあり、外部と隔てるのは鉄筋コンクリート製の建屋しかない。１、３号機と同様に水素爆発が起きて建屋が吹き飛び、高濃度の放射性物質が大気中に大量に放出される恐れがある。

使用済み燃料は原子炉で燃やした核燃料を貯蔵しておくプールで、原子炉の隣にある。しかし、使用済みでも燃料は熱を帯びており、１時間あたり数トンの水が蒸発している。このため、常に水を補充して冷まさなければならない。今回、電源切れで水の補充が止まり水が蒸発したとみられる。このため使用済み燃料がむき出しになり、燃料を覆う合金から水素が発生し、酸素と反応して爆発したとみられる。

(The Japanese text in the paragraph above may not come through, but I have translated it for you, below.)

The fire at the Fukushima Daiichi Nuclear Power Station's No. 4 reactor spent fuel pool is a more serious problem than the previous explosions at the facility. The pool is located outside the nuclear reactor pressure vessel and containment vessel, and is only isolated from the outside world by a steel-reinforced concrete building. There are concerns that a hydrogen gas explosion, like the ones that occured at the Nos. 1 and 3 reactors, would destroy the pool building and allow large amounts of highly concentrated radioactive materials to escape into the atmosphere.

The article goes on to note that ...the spent fuel rods in the pool give off a lot of heat (even though they are "spent") and normally boil several tons of water per hour, so they always have to be cooled by supplies of cooling water. With the power cut, the water levels in the pool have fallen and the spent rods are exposed. The alloy fuel rod covers generate hydrogen gas, which may explode.

There's your problem...

Edited March 15, 2011 by Odakyu-sen

[OnlyMe]

You realize that this is not Chernobyl, it does not have a graphite core which is liable to burn for weeks.

Chernobyl site did not store spent fuel rods in the roof above the reactor, another difference.

[corevalue]

People between 20 and 30 kM being told to stay indoors.

[SarahBell]

What always annoys me is that for whatever reason, a Nuclear accident killing 10 or even 1000 people is somehow much much worse than any other accident killing the same number of people.

If when someone got stabbed by a falling knife, the knife hung about and kept stabbing people ... but was invisible and was really hard to catch then it's be a similar situation.

[trekking]

the Chernobyl core had much more energy and it did not melt through ... our core is running only on 3% of the normal power

From you post 1124

"The third stage followed, when lamination of the fuel occurred and the melt broke through into the floors below and solidified there."

Chernobyl did melt through.

[fluffy666]

If when someone got stabbed by a falling knife, the knife hung about and kept stabbing people ... but was invisible and was really hard to catch then it's be a similar situation.

No, you are still not getting it.

Compared to a perfect, pollution- and risk-free energy source, Nuclear is expensive, unsafe and unreliable.

Compared to any real-world energy options, Nuclear is cheap, safe and reliable.

I'd point out in addition that particulate pollution from the burning of fossil fuels is virtually invisible, hard to do anything about once released and kills hundreds of thousands (i.e. several Chernobyls worth) per year, whilst the extraction of said fuels renders huge areas practically uninhabitable. But this is all fine, apparently, whereas a single death from nuclear power is echoed around the world..

[Left the UK 2009]

Oh dear. Radiation levels are now rising in Tokyo.

http://www.marketwatch.com/story/tokyo-radiation-levels-23-times-normal-officials-2011-03-15-04540

As I understand those levels are not dangerous but it is ominous. An evacuation of Tokyo would be impossible.

[Oh Well :(]

If the radiation levels rise so that it is potentially unsafe in Tokyo would the government tell the truth or lie to stop panic?

I think I know what the UK government would do in similar circumstances.

[Left the UK 2009]

There is a long history of cover ups from the Japanese nuclear industry, I think that they would lie. Tokyo comes to an absolute gridlock in Golden Week, a week long national holiday so there is no chance of any orderly evacuation. Imagine three Londons trying to evacuate to cornwall. Absolutely horrifying.

That said, these levels of radiation are not dangerous.

[Hyperduck Quack Quack]

A week ago, there had been 2 major disasters in the history of nuclear power generation. Now there have been 6, even if 4 of them have been on the same site - three explosions in reactor buildings and one fuel storage tank fire - all leading to radiation leaks.

Sorry for the metaphor but the nuclear power industry itself will go into meltdown now. Germany has cancelled the life extension plans for its older nuclear stations, in the USA plans have been dropped for two new nuclear power stations in Texas. The EU is to consider phasing out nuclear power throughout its member nations.

Here in Britain we should immediately scrap any plans for new nuclear power stations and then look to early decommissioning of existing ones.

Before this the Fukushima disaster, although I'm in the anti-nuclear camp, I was prepared to accept that the existing nuclear power stations should continue, and that possibly replacement ones could be built adjacent to existing ones to replace the capacity of redundant ones. I have now changed my mind.

Edited March 15, 2011 by Hyperduck Quack Quack

[fluffy666]

It's because it doesn't tend to happen like that. Just that an aeroplane crash is newsworthy but a hundred car crashes not.

In which case the only accident ever worth reporting was Chernobyl, and even that was a much smaller incident than, for instance, Bhopal.

[Doctor Gloom]

That really was a major explosion . To get some perspective those dynamo rooms (The square buildings) along side the reactor are at least 100metres high. There would have been a loss of life at the plant from the blast.

One 'expert' said that the explosion only blew the cladding off!

Seems to be bit more serious than that, but i'm no 'expert'.

Had to laugh, just like the financial crisis, there are only experts after the event has happened.