Japan earthquake + tsunami + nuclear problems

[Kuko 4000]

http://www.bbc.co.uk/news/world-asia-pacific-12720219

Huge blast at Japan nuclear power plant

Japan's nuclear agency said on Saturday that radioactive caesium and iodine had been detected near the number one reactor of the Fukushima 1 plant.

The agency said this may indicate that containers of uranium fuel inside the reactor may have begun melting.

Air has been released from several of the reactors at both plants in an effort to relieve the huge amount of pressure building up inside.

Mr Kan said the amount of radiation released was "tiny".

Thousands of people have been ordered to evacuate the area near the plants. BBC correspondent Nick Ravenscroft said police stopped him 60km from the Fukushima 1 plant.

How about keeping a track of the nuclear power plant proceedings here.

I do have to wonder why the Japanese were not prepared for this when other countries have warned them about this and know how to build better precautionary measures. What do you guys think would be the worst that could realistically come from this?

 

[JihadJane]

World Nuclear News:

'Battle to stabilise earthquake reactors'



'Japan nuclear alert and earthquake - live coverage' :

http://www.guardian.co.uk/world/2011/mar/12/japan-earthquake-tsunami-aftermath-live

 

[cgaduck]

Took this small extract from Sky news where they interviewed Ian Hore-Lacey of the WNA.

Ian Hore-Lacey, of the World Nuclear Association, said he believed the blast had been caused by a hydrogen build-up.

"If the hydrogen has ignited, then it is gone, it doesn't pose any further threat," he said.

He added the explosion may not necessarily have caused radiation leakage and told Sky News safety measures at modern nuclear plants should prevent harm to surrounding residents.

"If there were any meltdown in those reactors, it would be largely, if not entirely, contained," he said.


WNA Spokesman Ian Hore-Lacy On Nuclear Plant

"Any western reactor is built inside a containment structure, which is normally about 1.2 metres thick of reinforced concrete. They are designed to contain the worse conceivable accident.

"You can't get a nuclear explosion at a nuclear power plant. That's quite impossible, because they're run with fuel that's only enriched to about 5% at the most."

Sky News' Holly Williams, in Japan, said: "The government are saying they are prepared for any eventuality.

"But it seems like the authorities themselves are not entirely sure what happened."

Radioactive steam has been released to reduce rising pressure in the plants and the country's prime minister has ordered thousands of people living within six miles to leave the area.

Ryohei Shiomi, of Japan's nuclear safety commission, said officials were checking whether a meltdown had taken place at the Daiichi power plant.


Japan's Nuclear Power Stations Explained

But he said even if there was a meltdown, it would not affect humans within a six-mile radius.

 

[Kuko 4000]

Interesting piece of information from the second link that JJ posted:

"To reduce the pressure, you would have to release some steam into the atmosphere from the system. In that steam, there will be small but measurable amounts of radioactive nitrogen - nitrogen 16 (produced when neutrons hit water). This remains radioactive for only about 5 seconds, after which it decays to natural oxygen.

Here's a link to the Japanese Nuclear and Industrial Safety Agency (NISA):

http://www.nisa.meti.go.jp/english/index.html

 

[MG1962]

How about keeping a track of the nuclear power plant proceedings here.

I do have to wonder why the Japanese were not prepared for this when other countries have warned them about this and know how to build better precautionary measures. What do you guys think would be the worst that could realistically come from this?

Wow tough crowd - One of the largest earthquakes ever to hit the planet, the island the reactors are on moved 8 feet the planet moved 4 inches on its axis

I am no real fan of nuclear energy but I defy anyone to explain to me how engineers could have built these things any better. Sometime events are of a magnitude no engineer can design against

 

[jayh]

Wow tough crowd - One of the largest earthquakes ever to hit the planet, the island the reactors are on moved 8 feet the planet moved 4 inches on its axis

I am no real fan of nuclear energy but I defy anyone to explain to me how engineers could have built these things any better. Sometime events are of a magnitude no engineer can design against

Agreed.

What you have here is the strongest earthquake in Japan's recorded history, which would STILL not have caused the reactor problem except that it occurred in a spot causing a tsunami that hit the plant at the same time. This was an almost unbelievable combination of bad luck.

Even as it is, the nuclear aspect is much dwarfed the incredibly massive amount of destruction caused by the other effects (the Chernobyl blow up --not possible here-- did much much less surrounding damage than this quake ).

 

[Kuko 4000]

I agree with you guys, but at least here in Finland the experts say that the scientific community has long wondered about the insufficient protective measures in this and similar nuclear plants in Japan and of course in Russia. To me this incidence could show that even a nuclear plant that is critisised by the scientific community can survive major catasrtophes pretty well.

I hear stuff about some radiation cloud that was leaked from the reactor, but that we were only lucky that the wind direction was towards the sea and not where people live. Is there more info on this?

 

[Dr.Sid]

This is boiling water reactor. It means there is lot of steam in the primary circuit. Is the water gets irradiated in the reactor, some of the oxygen transforms into nitrogen 16, which has very short decay, halftime is 7 seconds. So if this steam leaves the plant, there is for a short moment some radiation uprising .. but it vanishes in seconds.
There are also some other elements in the steam, depending on the amount of the fuel rods damage, like cadmium and iodine. These are the real thread.
So .. the explosion is not important. Radiation increase is not important (as it mostly comes from nitrogen 16).
Damage to the reactor and fuel rods, and resulting amount of slower decaying elements, that is important. Unfortunately there is little info about these in the news so far.

 

[geni]

Wow tough crowd - One of the largest earthquakes ever to hit the planet, the island the reactors are on moved 8 feet the planet moved 4 inches on its axis

I am no real fan of nuclear energy but I defy anyone to explain to me how engineers could have built these things any better. Sometime events are of a magnitude no engineer can design against

Going by the problems described the structure did pretty well yes. The design flaw appears to be not having the people and equipment around to cope with the damage that did occure.

 

[Hindmost]

It is difficult to find out much information yet...however, it seems the diesels have failed on one unit and that is bad as they are relied upon to provide cooling water for older style plants. Without the capability to flood the reactor vessel, decay heat will cause the fuel to fall apart and possibly have some melting. It seems they are trying to use fire protection water to cool the plant. If the reports of radioactive cesium and iodine are correct, then some fuel damage has occured. How far and how much are important.

Typically, the diesels startup and provide cooling within 30 seconds if there is an accident in the plant...in this case the "accident" was external and there would be much more time. However, the diesel do need to start for everything to be OK.

As far as the explosion is concerned...I can't really tell what it is, but it may be the large transformers. It just seems a bit too big for that. There isn't much that can explode in a nuclear plant. If the reactor had caused a steam explosion, it would be inside containment and not visible--but there is no evidence of that occuring yet.

Information: For the latest passive reactor designs, the diesels are not needed and this type of problem wouldn't be as much of an issue as the core melt would not occur because the core would be flooded with passive safety water systems. The previous generation plants, however, the diesels are definitely needed to supply power to safety systems.

glenn

 

[geni]

As far as the explosion is concerned...I can't really tell what it is, but it may be the large transformers. It just seems a bit too big for that. There isn't much that can explode in a nuclear plant. If the reactor had caused a steam explosion, it would be inside containment and not visible--but there is no evidence of that occuring yet.

They had been venting steam from the innner to outer containment.

 

[MG1962]

Going by the problems described the structure did pretty well yes. The design flaw appears to be not having the people and equipment around to cope with the damage that did occure.

Agree - so the lesson to be learned, were people evacuted at the wrong time. Someone made a judgement call, something an engineer can not design against

 

[Hindmost]

They had been venting steam from the innner to outer containment.

The steam venting would be to keep containment pressure down...add fire protection water and vent steam...they are probably trying to flood the exterior of the vessel. Venting the steam is probably the cause of the radiation levels being higher--but the steam would not look dusty would come from a vent near containment. However, I don't know the details of this design to be sure.

The video of the explosion with the grey dust is what I was talking about. If the transformer(s) blew up, coupled with a failure of both diesels, it would be difficult to get power to safety systems. I am guessing that is part of the problem, but I really can't be sure. Temporary fire trucks can be used to help alleviate some of the problems, but it won't solve the core melt issue as large pumps are needed to push water into the reactor vessel as the pressure can remain fairly high.

glenn

 

[Chaos]

Agreed.

What you have here is the strongest earthquake in Japan's recorded history, which would STILL not have caused the reactor problem except that it occurred in a spot causing a tsunami that hit the plant at the same time. This was an almost unbelievable combination of bad luck.

Even as it is, the nuclear aspect is much dwarfed the incredibly massive amount of destruction caused by the other effects (the Chernobyl blow up --not possible here-- did much much less surrounding damage than this quake ).

The problem with this particular reactor, as far as I understand it, was that it used seawater for cooling.

The Japanese know about earthquakes. They also know abot tsunamis - after all they (bleep)ing INVENTED the term "tsunami". So how did it not occur to them that a tsunami would cut off the coolant supply for this reactor?

 

[JoeTheJuggler]

I'll play devil's advocate, though I have no particular opinion on this:

What you have here is the strongest earthquake in Japan's recorded history, which would STILL not have caused the reactor problem except that it occurred in a spot causing a tsunami that hit the plant at the same time. This was an almost unbelievable combination of bad luck.

Those are still all foreseeable circumstances. Japan is probably on nearly the hottest spot of the Pacific Ring of Fire, just about at the intersection of 4 tectonic plates. Tsunamis are certainly expected to happen in Japan (the source of the word is Japanese, isn't it?).

Risk is usually calculated as severity times probability, so even low probability things that are hugely catastrophic (such as a meltdown in such a populous part of the world) are considered high risk.

ETA: When they say the strongest earthquake in recorded history, I think that only means since we've had accurate seismographs, not in all of recorded history. A quake of this magnitude 500 or 1000 years ago wouldn't be counted, right?

 

[JoeTheJuggler]

The Japanese know about earthquakes.

Indeed. From the Wikipedia list of Earthquakes in Japan, it looks to me like one of magnitude 8.4 or higher happens about every 100 years. (See again the problem of comparing modern measurements to older ones. Since 1977, we generally use the Moment Magnitude scale, but prior to that it was the Richter Scale, and I have to believe the numbers given for older quakes are pretty subjective estimates based largely on damage to buildings--perhaps in the days of lower population density.)

 

[jayh]

...
ETA: When they say the strongest earthquake in recorded history, I think that only means since we've had accurate seismographs, not in all of recorded history. A quake of this magnitude 500 or 1000 years ago wouldn't be counted, right?

That was the explanation I have read.

 

[Hindmost]

The problem with this particular reactor, as far as I understand it, was that it used seawater for cooling.

The Japanese know about earthquakes. They also know abot tsunamis - after all they (bleep)ing INVENTED the term "tsunami". So how did it not occur to them that a tsunami would cut off the coolant supply for this reactor?

All nuclear (and fossil thermal plants) will use either seawater or a lake or hugh cooling tower to cool the condenser and plant components. Typically, the lake or the ocean is not safety related and it need not be available for an accident. (I worked at a plant on the missisippi river which was used for condenser cooling...a design basis accident was to survive the levy breaking and the river flooding the plant.) There would be a safety related cooling tower which would be designed to cool the reactor during accident conditions. I really can't say for this design, but if the ocean were part of safety systems, that would be a poor design considering the location--a tsunami should be a design basis event.

glenn

 

[JihadJane]

"The trouble is, says Katsuhiko, that Japan began building up its atomic energy system 40 years ago, when seismic activity in the country was comparatively low. This affected the designs of plants which were not built to robust enough standards, the seismologist argues."

Japan ministers ignored safety warnings over nuclear reactors
Seismologist Ishibashi Katsuhiko claimed that an accident was likely and that plants have 'fundamental vulnerability'



"According to CNN, the explosion at an earthquake-damaged nuclear plant was not caused by damage to the nuclear reactor but by a pumping system that failed as crews tried to bring the reactor's temperature down, Chief Cabinet Secretary Yukio Edano said Saturday."


Fukushima Explosion Update: Core Presumed Intact As Sea Water Used To Bring Temperature Down, Radiation Level At 1015 Microsieverts/Hour



Interesting analysis of explosion:

'Japan's Evolving Nuclear Accident'

 

[Chaos]

All nuclear (and fossil thermal plants) will use either seawater or a lake or hugh cooling tower to cool the condenser and plant components. Typically, the lake or the ocean is not safety related and it need not be available for an accident. (I worked at a plant on the missisippi river which was used for condenser cooling...a design basis accident was to survive the levy breaking and the river flooding the plant.) There would be a safety related cooling tower which would be designed to cool the reactor during accident conditions. I really can't say for this design, but if the ocean were part of safety systems, that would be a poor design considering the location--a tsunami should be a design basis event.

glenn

For clarification... a "design basis event" or "design basis accident" is something the thing is supposed to weather without suffering untoward consequences, correct?