Earthquake/Tsunami in Japan

[Mintmaster]

A modern 1GWe reactor develops around 3GW heat. Eight hours after shutdown, residual heat production has fallen to 30MW (1%).

Water's specific heat of evaporation is slightly above 2MJ/kg, so you're boiling off 15 litres/second or 50 tons/hour.

Cheers

How ? Convective circulation in the primary cooling loop ? They cannot do without active cooling indefinitely.

Don't you see the disconnect between these two posts?

First of all, 15L/second is a piece of cake. You can buy a $200 gas pump that'll do 12000 GPH, or 0.3L/s. A hundred of these or 10 bigger ones would do the job just fine. I seriously doubt that lack of pumping power is the problem. I suspect that they can't get proper access to the pipes that need pumping.

Secondly, what don't you like about convective circulation? Ever watch a pot of water boil? Steam moves up through water quite well.

 

[Mendel]

I suspect that the water pumps they have been using aren't hand pumps.

yet someone has to add fuel to the diesel generator

 

[Kaotik]

What sucks most in the reporting is that nothing is put to any real perspective.

Finnish radiation safety center reported now that the levels of radiation in surrounding areas is "50-100 times higher than normal" at 5-10 microSieverts per hour.
That would bring it at worst to 87.6 milliSieverts per year, and for example in Rasham they've measured up to 260 milliSieverts per year of background radiation, and it causes no issues for the locals, the cancer levels aren't higher than elsewhere, if anything, they're lower.

 

[Gubbi]

Don't you see the disconnect between these two posts?

One was an estimate of the loss of water in the Fukushima reactors. The second was a honest question to Chalnoth saying that modern designs can do without pumps.

First of all, 15L/second is a piece of cake. You can buy a $200 gas pump that'll do 12000 GPH, or 0.3L/s. A hundred of these or 10 bigger ones would do the job just fine. I seriously doubt that lack of pumping power is the problem. I suspect that they can't get proper access to the pipes that need pumping.

Since normal operation invloves sinking 1.5 to 2.2GW heat, 30MW should be no problem at all. The problem is clearly not pump capacity, but that the pumps aren't working at all.

Secondly, what don't you like about convective circulation? Ever watch a pot of water boil? Steam moves up through water quite well.

Ever seen a 200MW pot? (residual heat production right after shutdown of a 1GWe reactor)

Cheers

 

[cjo]

yet someone has to add fuel to the diesel generator

Yes, the staff evacuating and not ever going back would be a problem, but at the moment they are only evacuating when the radiation spikes particularly high.

 

[hoho]

Water's specific heat of evaporation is slightly above 2MJ/kg, so you're boiling off 15 litres/second or 50 tons/hour.

Did you take into account the amount of energy it takes to heat the water to boiling point as well or did you only gave numbers for evaporating water that is already at 100C?

 

[Kaotik]

Some good news for a change, new powerline to the site is almost complete, after it's done, they should be able to use the backup pumps of the plants themselves

 

[liolio]

I wonder if Japanese gorvernment should not have called for help earlier. I got a bit disguted by the talk on some French news papers. There was a chat and people were asking various stuff about the risks. It was both morbid and selfish. In regard to the nature of the event the only one that are under a serious risk are Japanese. A lot of people were wondering about the potential risk for them self which is zero or had a morbid fascination about what could happened. People should be concerned of Japanese. Tokio is a crazy huge city, even the third economy in the world can't move in acceptable conditions 20 millions people. Not to mention the other problems in the country.
I find it a bit disgusting because the victims of the tsunami are not enough, it's not spectacular enough now the media are all out about the nuclear risks. But damned Japanese didn't ask for help in the first place and this "potential worst" is distracting people that could help of the terrible pain the country is already confronted to.

I really hope media of the world will tone down about this threat as they is not that much that can be done buy the look of it and show a more complete picture of the problem Japan is facing with outstanding dignity. May be I'm wrong but I feel like we (our states) under react to the problem as we though Japan is a rich country they can cope with it. It's winter there are plenty of homeless already, I can't even think if the worse were to happen in two weeks and we would not have send what it takes to help tenth millions of homeless but not even what it takes for the Japanese already suffering.

 

[tongue_of_colicab]

I can understand why people are concerned about their own safety first and don't think much about the safety of the Japanese. It's too far away for people to be able to really care. For the exact same reason probably non of us is losing any sleep over all the people starving and dying of diseases in Africa. Even I find it hard to say I honestly care for those people and I got friends there, study Japanese, and will go there in 10 days so I got more of a relationship to the country than most people have. Ofcourse I care, but it's very different than when something bad happens to your direct relatives. To be honest, the thing I care about the most by far is the nuclear plant. The situation for the homeless people is hard but I don't believe that the Japanese government is so incompetent that the situation will turn from difficult to people really dying from starvation etc. I will probably takes some time to set up supply routes but after that it should be relative fine I think.

I do think this disaster shows why atleast in Holland traditional media is totally worthless and your much better off looking on the internet. All you hear on the news is RADIATION!! DEATH!!! CANCER!!! CANCER!!! DEATH!!! NUCLEAR DISASTER!!! and than they always end up finding some expert to tell us how bad things are etc but forget to mention the dipshit has been anti nuclear for the past three deacades etc.

Just turn on the NHK world stream or the bcc. Even coming to this topic I find more useful information than the news provices me with. No people screaming stupid stuff but just normal thinking.

 

[Silent_Buddha]

I wonder if Japanese gorvernment should not have called for help earlier.

Well, they reached out to the US fairly quickly, probably due to the US having a significant presence in Japan. And that in itself is quite astonishing considering how reluctant Japan is to ask for help of any kind. I think this is the first time they've ever asked for help without first being bombarded with offers of help for days and weeks.

Regards,
SB

 

[GZ007]

First of all, 15L/second is a piece of cake. You can buy a $200 gas pump that'll do 12000 GPH, or 0.3L/s. A hundred of these or 10 bigger ones would do the job just fine. I seriously doubt that lack of pumping power is the problem. I suspect that they can't get proper access to the pipes that need pumping.

The BWR reactor vessel operates at pressures over 7MPa so the water boils at around 280 °C. The water is hot, at high pressure and radioactive. The pumps there are not ordinary shop pumps that u just replace.
They need electricity to start those pumps.

 

[MfA]

What sucks most in the reporting is that nothing is put to any real perspective.

On our local news they had reporters in Tokyo saying that the levels there were not dangerous ... how is that not perspective?

I think you are losing perspective though, the problem is not the present level of release. The problem is that they probably have a pool with spent MOX fuel with cooling problems (the cooling problems are definite, but we don't know if the storage pool has MOX or only the reactor, but chances are the pool has as well). Also they suspect this stuff has the potential to go critical if it melts down.

Is a significant chance of a burning pool of critical MOX in the open air enough to justify some fear? Between the fact that it's MOX, the fire and the increased temperature of a critical reaction I'd say that wouldn't really be comparable to the relatively harmless releases up till now.

 

[Kaotik]

On our local news they had reporters in Tokyo saying that the levels there were not dangerous ... how is that not perspective?

I think you are losing perspective though, the problem is not the present level of release. The problem is that they probably have a pool with spent MOX fuel with cooling problems (the cooling problems are definite, but we don't know if the storage pool has MOX or only the reactor, but chances are the pool has as well). Also they suspect this stuff has the potential to go critical if it melts down.

Is a significant chance of a burning pool of critical MOX in the open air enough to justify some fear? Between the fact that it's MOX, the fire and the increased temperature of a critical reaction I'd say that wouldn't really be comparable to the relatively harmless releases up till now.

Exception confirming the rule

I know, I generalized too much on the perspective thing, but most isn't put to perspective anyway when reported, because radical headlines sell better.

According to some nuclear/radiation specialists, even if everything continues to go wrong and worst possible scenarios happen and even the wind does nothing but blow towards Tokyo, all the people in Tokyo don't need to worry about anything as long as they keep indoors.

For good news, they've got apparently some new specialized firetrucks or something in the area finally to help on getting water in to cool things, as well as the powerline getting finally completed soon, which should enable them to use the plants own backup cooling which was knocked off when tsunami broke all the powerlines to the grid

 

[Mendel]

What looks like a brave but desperate operation, they are using helicopters to spray water on the reactors.

Live stream here: http://www3.nhk.or.jp/nhkworld/

Doesn´t look really effective to me but what do I know...

Edit: They made a grand total of 4 flights over the reactors, dropping with two choppers, twice each, before they apparently decided that it was ineffective. Next step: Fire trucks.

 

[Mendel]

Quoting some radiation level info from NHK

Higher radiation levels continue around Fukushima
Radiation levels at municipalities around the quake-damaged nuclear power plant in Fukushima Prefecture continue to be higher than normal. But authorities say the detected levels pose no harm to human health.

As of 9 AM Thursday, at Fukushima City, 65 kilometers northwest 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 located 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.

At the Onagawa nuclear power plant 120 kilometers northeast of the Fukushima plant, radiation levels measured 3.2 microseiverts, 32 times the usual amount.

In Kitaibaraki City south of the Fukushima plant, radiation found to be 1.19 microseiverts, 23 times the normal figure.

But health authorities say one-hour of exposure to radiation at any of the observed levels would range between one 500th to one 40th of the amount of radiation the body would receive in a single stomach X-ray.
Thursday, March 17, 2011 13:57 +0900 (JST)

I have to say I don´t think taking a stomach x-ray once every other day would be too healthy in the long run. Why wouldn´t they evacuate from wider radius seeing as things seem to be getting more and more out of hand.

 

[Arwin]

What looks like a brave but desperate operation, they are using helicopters to spray water on the reactors.

Live stream here: http://www3.nhk.or.jp/nhkworld/

Doesn´t look really effective to me but what do I know...

Edit: They made a grand total of 4 flights over the reactors, dropping with two choppers, twice each, before they apparently decided that it was ineffective. Next step: Fire trucks.

The way I understood it, they were doing 4 flights and then stopped to make sure the crew wouldn't be exposed too much, the biggest worry they had for this. Next, they would evaluate whether or not this operation is effective. That was last night though, and they are getting various other ways in to be able to get water in there, including apparently a US water cannon/mortar type thing? Also, they appear to be close to restoring powerlines to the plant which could get the pumps back up, if they're not too broken (likely at least some of them still work).

 

[Kaotik]

Quoting some radiation level info from NHK



I have to say I don´t think taking a stomach x-ray once every other day would be too healthy in the long run. Why wouldn´t they evacuate from wider radius seeing as things seem to be getting more and more out of hand.

While higher than normal for the area, there's still areas in the world where the natural background radiation is ten times more than Koriyama Citys reported radiation levels are now. And no, there's no signs of extra cancers or anything similar in those areas.

What looks like a brave but desperate operation, they are using helicopters to spray water on the reactors.

Live stream here: http://www3.nhk.or.jp/nhkworld/

Doesn´t look really effective to me but what do I know...

Edit: They made a grand total of 4 flights over the reactors, dropping with two choppers, twice each, before they apparently decided that it was ineffective. Next step: Fire trucks.

They would need 500 perfect hits where all of the water goes to the pool to fill it, so yes, kinda ineffective.

 

[MfA]

According to some nuclear/radiation specialists, even if everything continues to go wrong and worst possible scenarios happen and even the wind does nothing but blow towards Tokyo, all the people in Tokyo don't need to worry about anything as long as they keep indoors.

Making huge tracts of land unfit for use and making working on site a one way trip to cancer (someone will have to cover everything in sand and cement if things go really wrong) is a big enough catastrophe in and of itself.

 

[Mendel]

too much time has passed since the failed chopper operation with no new news. I suppose they cant tell people the truth because they want to save face and prevent panic. They cant tell people that the chopper operation was a failure and there is way too much radiation on site for anything else.

 

[Kaotik]

too much time has passed since the failed chopper operation with no new news. I suppose they cant tell people the truth because they want to save face and prevent panic. They cant tell people that the chopper operation was a failure and there is way too much radiation on site for anything else.

They've got Tokyo Police departments water cannon trucks coming in or in already to cooldown the building 4's pool (which was tried to cooldown with choppers)