Nuclear accident follows Japanese earthqauke

[nexus]

Some apt comments on that video. I particularly like this one:

I believe it is only fair for top government officials and their families to live next to the nuclear power plant.

+1 and this rule should also be followed if any more stations are built in Britain.

[clv101]

The 2nd explosion is huge, bigger than the one at reactor 1. Also note the cooling ponds holding the spent fuel rods are located at the top of the pressure vessel, towards the top of the big square building. Hard to imagine them surviving the 2nd explosion.

[Aurora]

CTV News - 14/03/11

Japanese officials are reporting that a disaster-ravaged nuclear power plant has lost the ability to cool down another one of its reactors, hours after the same plant suffered its second explosion in three days.

Article continues ...

[2 As and a B]

That particular YouTube video has been removed. Here is the footage on the Bbc.

http://www.bbc.co.uk/news/world-asia-pacific-12729138

Soon afterwards, the government said a third reactor at the plant had lost its cooling system.

Water levels were now falling at reactor 2, which is to be doused with sea water, said government spokesman Yukio Edano.

A similar cooling system breakdown preceded the explosions at reactors 1 and 3.

[Aurora]

WSJ Market Watch - 14/03/11

The U.S. Seventh fleet said Monday it was pulling its ships and aircraft back from a stricken Japanese nuclear power plant after detecting low levels of airborne radioactivity, according to a military statement. The aircraft carrier USSS Ronald Reagan was about 100 miles offshore from the Fukushima Dai-Ichi Nuclear Power Plant when three returning helicopter crews detected radioactive elements. Seventeen crew members suffered low levels of exposure from a radioactive plume released from the Fukushima nuclear facility, the statement said. Personnel aboard the carrier and support ships passing through the area would at maximum have been exposed about one month's natural background radiation such as that from the sun and rocks, the military said.

Original Article

This tends to suggest that the Japanese authorities are telling the truth about the current levels of airborne radiation.

[sam_uk]

Not a view I share, but a coherent explanation of the situation

http://morgsatlarge.wordpress.com/

[2 As and a B]

Plan of the site...

[biffvernon]

The 2nd explosion is huge, bigger than the one at reactor 1. Also note the cooling ponds holding the spent fuel rods are located at the top of the pressure vessel, towards the top of the big square building. Hard to imagine them surviving the 2nd explosion.

Yes the 2nd was certainly a different sort of explosion. A lot of stuff went straight up in the air and then, looking at the left hand side of the cloud, you see very large pieces of solid stuff falling down. I guess that was the concrete roof going up hundreds a feet and down again. Even if the steel reactor vessel is intact there can't be much of the plumbing around it left.

Just where are these spent rods? That sounds like a significant vulnerability.

There's talk of radioactive caesium and iodine being detected, but that would be expected if steam from within the reactor had been vented and does not mean there has been a breach. All the reassuring stuff on the net talks about that. If there were spent fuel rods within the big square building but outside the reactor, waiting to be moved to the storage facilities up the road, that would be a very different kettle of fish.

[emordnilap]

So, what do we learn?

Fúck all.

[Aurora]

The Press Association - 14/03/11

The fuel rods in one of Japan's damaged nuclear reactors have been temporarily fully exposed from their coolant, raising the risk of overheating and a meltdown.

A spokesman at the Fukushima plant said that Unit 2's rods were briefly exposed.

Sea water has been channelled into the reactor to cover the rods again.

Article continues ...

[2 As and a B]

Aerial view now...

[adam2]

update.
Posted: Mon Mar 14, 2011 3:48 pm Post subject:

--------------------------------------------------------------------------------

From BBC:

1531: Japanese broadcaster NHK is saying that pressure inside reactor 2 at Fukushima rose suddenly when the air flow gauge was "accidentally" turned off. That blocked the flow of water into the reactor leading to full exposure of the rods, it says. That report has not been confirmed.

1535: Just to recap for you: We're getting reports that water levels in reactor 2 at Fukushima have fallen sharply, leaving the nuclear fuel rods fully exposed and raising fears of a meltdown. More as it comes in.

originaly posted in the earthqauke thread,by UE but moved here to keep the nuclear accident posts together.

[2 As and a B]

This from Reuters...

FACTBOX - What is happening inside Japan's nuclear reactors?

REUTERS - A second blast on Monday rocked the quake-stricken nuclear plant in Japan where authorities have been working desperately to avert a meltdown.

Japan's biggest recorded earthquake has knocked out back-up cooling at several stricken reactors at a nuclear power plant in Fukushima prefecture north of Tokyo, causing a build-up of heat and pressure.

What is happening now in the core of the nuclear reactors?

* The core of a nuclear reactor consists of a series of zirconium metal pipes or rods containing pellets of uranium fuel bundled into what engineers call fuel assemblies.

* Water is pumped between the pipes to keep them cool and create steam to drive an electricity-generating turbine.

* Back-up cooling has struggled at various times over the past three days at reactor units 1, 2 and 3 at the Fukushima plant.

* In the normal running of a reactor, high-energy neutrons from the uranium fuel bash atoms and break them into pieces in a chain reaction which creates heat, new radioactive elements such as strontium and caesium, and new neutrons which continue the process.

* The chain reaction halted within a few seconds of the earthquake at all the nuclear reactors in Japan, including those worst affected, as they automatically shut down: control rods made of boron were inserted into the fuel, absorbing the neutrons.

* However the natural decay of the radioactive materials in the reactor core continues to produce heat, called decay heat, which falls to a quarter of its original level in the first hour, and then disappears more slowly.

* Normally that heat is removed by coolant pumps whose back-up power supply was knocked out by the earthquake, tsunami or both at the Fukushima plant.

* Emergency workers are trying to cool the inner reactor cores and remove this decay heat by pumping seawater inside. They have added boric acid to the seawater to try and further halt nuclear reactions in a "belt and braces" measure.

* It is important to cool the reactor cores because even though the chain reactions have stopped, there is still enough heat to melt the metal sheaths surrounding the uranium fuel. If these are hot enough they react chemically with the surrounding water, producing an explosive gas hydrogen.

* It is that hydrogen gas which has caused the two explosions at the Fukushima plant, at unit 1 on Saturday and reactor unit 3 on Monday, experts and authorities say.

* Engineers have tried to vent the hydrogen into the atmosphere, which has also contributed to some local radiation because the gas contained small amounts of radioactive particles.

* The core of the reactor is inside a thick steel container called a reactor vessel, and around that there is a concrete containment shield. Around the whole there is a more open building with quite a thin covering not intended to be structurally important.

* The hydrogen explosions only damaged the outer building, which collapsed, not the inner shells, say authorities.

* If an inner reactor vessel were breached that would raise radiation levels. But there is no longer enough heat to blow these apart, experts say.

* The worst remaining risk is that the core melts, which would make it much more difficult and perhaps impossible to remove the fuel, which is what happened at Three Mile Island in Pennsylvania in 1979. The site would have to be sealed permanently.

* Chernobyl in 1986 was a different situation where the control rods failed to control the fission chain reaction, leading to blasts which blew the reactor apart, releasing radiation which contaminated Ukraine and Europe in the world's worst civil nuclear disaster.

http://in.reuters.com/article/2011/03/1 ... 4020110314

[mikepepler]

Aerial view now...

Number 3 reactor looks significantly more damaged than the Number 1...

[2 As and a B]

Bbc news channel - wind may change and blow from Fukushima towards Tokyo.