FUKUSHIMA earthquake and tsunami thread and aftermath

[Damik]

Chernobyl exploded completely out of the containment.

Chernobyl is not the sub critical design. it is a military design to produce plutonium ...

[fellow]

once again just for you:

it is designed to keep the meltdown inside and it does indeed keep the melted core inside ....

it is a very simple concept ...

it is not ideal and the reactor is written off but it does not effect the environment as such ...

Fair enough, if that is what is was designed to do. It makes you wonder though, why they built this in the first place if it was always going to be rendered useless, and end up costing far more than the energy was worth.

[ChumpusRex]

Fair enough, if that is what is was designed to do. It makes you wonder though, why they built this in the first place if it was always going to be rendered useless, and end up costing far more than the energy was worth.

It is not designed to do that every time.

A meltdown with core contained within the reactor vessel is the design goal of worst possible case accident scenario. In other words, if everything possible that could go wrong does, the worst result will be a pile of slag at the bottom of the reactor vessel.

It looks like that is what is going to be the end-result here.

The problem is that the plant was designed to require actively functioning processes to prevent meltdown In other words, once all the power sources failed simultaneously and for more than several hours, the reactor was essentially guaranteed to meltdown without some form of radical intervention. This earthquake/tsunami was larger than that planned for in the design stage.

This type of design is no longer considered acceptable for new builds.

[Bloo Loo]

It is not designed to do that every time.

A meltdown with core contained within the reactor vessel is the design goal of worst possible case accident scenario. In other words, if everything possible that could go wrong does, the worst result will be a pile of slag at the bottom of the reactor vessel.

It looks like that is what is going to be the end-result here.

The problem is that the plant was designed to require actively functioning processes to prevent meltdown In other words, once all the power sources failed simultaneously and for more than several hours, the reactor was essentially guaranteed to meltdown without some form of radical intervention. This earthquake/tsunami was larger than that planned for in the design stage.

This type of design is no longer considered acceptable for new builds.

forgive me, but 5 mins ago, the thing was designed to failsafe..and now its not...Im getting the impression that reality is just a guess away.

[fellow]

Expert on Sky just now said that radiation readings 150km to the North had risen by a factor of 4. He said, it signified in his mind that a significant radiological event was underway.

They must be mistaken because the HPC experts said it couldn't happen.

[Scott Sando]

Expert on Sky just now said that radiation readings 150km to the North had risen by a factor of 4. He said, it signified in his mind that a significant radiological event was underway.

Are we about to hear the truth now. Don't move now you'll become radioactive, stay indoors.

[corevalue]

forgive me, but 5 mins ago, the thing was designed to failsafe..and now its not...Im getting the impression that reality is just a guess away.

I had a work colleague who later became a quality control manager on a nuclear weapons project. He resigned because it was not possible to test the system in any meaningful way because the safety/containment issues could not be addressed. I guess it's similar here, the last-stop systems can never be tested, because how can you? If they don't work as designed, you have a major disaster. If they DO work as designed, you've still got an expensive disaster.

[Liquid Goldfish]

Can anyone advise on the significance of them using seawater? I thought the problem was that they didn't have the power to pump any type of water around the cooling circuit rather than they were short of water.

[trekking]

it cant explode like a nuclear bomb, due to the different way they are designed.

however the radiation from a nuclear reactor is far greater than a nuclear bomb and more widespread anyway.

a nuclear plant doesnt even need to explode. all it needs to do is melt, melt through the container, and then it is free to contamininate the atmosphere. its as simple as that.

I am familiar with the different design re fission bomb/nuclear reactor. One is designed to go bang, while the other is designed to produce heat in a controlled manner.

However, when the Chernobyl reactor melted with the fuel burning it's way through the floor, it was no longer a reactor, but a mass of fissile material many orders of magnitude larger than any atomic bomb, although the fissile material was not as highly enriched U235 as used in a bomb.

I'm not a nuclear physicist, but the Russian chap, Vassili Nesterenko in the second source that I listed was. I assume that he knew what he was talking about when he said the the resulting explosion would have been equivalent to 3 to 5 megatons.

Now the explosion may not have been a 'bomb' as such (no neutron trigger or initiator & creating a critical mass in a few uS), but the

explosion of 3 to 5 megatons would have been caused by fission. I believe that would have made a big bang.

[rxe]

There is no worry of a nuclear explosion, but plutonium gives out more energy than uranium (hence why it is used in bombs), which makes it more likely that the container may be breached, as temperatures and pressure increase.

Both uranium and plutonium release something of the order of 200 MeV during fission, I recall that Pu-239 releases slightly less.

The fear during the Chernobyl disaster was the nuclear material burning through the containment building floor and landing in the water underneath. I assume that the water would act as a moderator, slowing down the neutrons which would enable them to be captured by the U235 causing a chain reaction. The Russian scientists calculated that only 1,400 kg of the uranium and graphite mixture falling into the water, would have been necessary to cause a chain reaction. They also calculated that the resulting explosion would have been equivalent to a three to five megaton nuclear weapon, and level 200 square kilometres.

It would have also vaporised the nuclear fuel in the other three reactors.

Even if all of the fuel at melted into a big blob under the reactor, at 2% enrichment, it could not possibly explode in a nuclear reaction. You could stack as many fuel elements as you like, but at 2%, they aren't going to go bang. What could have happened at Chernobyl is the hot "core" could have hit water, which would have made a big bang, but not a nuclear explosion.

[trekking]

Chernobyl exploded completely out of the containment.

+1

And the fissile material melted through the bottom of the containment, heading towards water.

[trekking]

They must be mistaken because the HPC experts said it couldn't happen.

[MrPin]

I think we should just pour yoghurt on it! It works with curries!

[ChumpusRex]

Even if all of the fuel at melted into a big blob under the reactor, at 2% enrichment, it could not possibly explode in a nuclear reaction. You could stack as many fuel elements as you like, but at 2%, they aren't going to go bang. What could have happened at Chernobyl is the hot "core" could have hit water, which would have made a big bang, but not a nuclear explosion.

The idea that the core melt could have reached prompt criticality in a graphite/water combination is not unreasonable.

To dismiss such a possibility without having seen, or having performed your own, calculations is foolish.

[_w_]

Sky: French embassy has advised its citizens to leave Tokyo because of fear of a radiation cloud.

Well well...

[Bloo Loo]

Maybe we shouldn't 'slashdot' their site servers.

Calling perverts...the Osaka monitoring station is the Kinki University.

http://www.kindai.ac.jp/english/

hot stuff, this radiation business.

[Scott Sando]

Sky: French embassy has advised its citizens to leave Tokyo because of fear of a radiation cloud.

another source for that info, must be serious if the french embassy releases this info link

French embassy urges citizens to leave Tokyo area in case radiation reaches city

Amid nuke crisis, French urged to leave Tokyo

A man holds his baby as they are scanned for levels of radiation in Koriyama, Fukushima Prefecture, Japan, Sunday, March 13, 2011. Friday's quake and tsunami damaged two nuclear reactors at a power plant... (Associated Press)

A man is scanned for levels of radiation in Koriyama, Fukushima Prefecture, Japan, Sunday, March 13, 2011. Friday's quake and tsunami damaged two nuclear reactors at a power plant in the prefecture, and... (Associated Press)

Fukushima Daiichi power plant's Unit 1 is seen in Okumamachi, Fukushima prefecture, Japan, Friday, March 11, 2011. The nuclear power plant affected by a massive earthquake is facing a possible meltdown,... (Associated Press)

An elderly man taken by wheelchair to be scanned for levels of radiation in Koriyama, Fukushima Prefecture, Japan, Sunday, March 13, 2011. Friday's quake and tsunami damaged two nuclear reactors at a... (Associated Press)

An official scans a man for radiation at an emergency center Sunday, March 13, 2011, in Koriyama, northeastern Japan, two days after a giant quake and tsunami struck the country's northeastern coast.(AP... (Associated Press)

An official scans a man for radiation at an emergency center Sunday, March 13, 2011, in Koriyama, northeastern Japan, two days after a giant quake and tsunami struck the country's northeastern coast.(AP... (Associated Press)

In this photo taken on Oct. 3, 2008, the Fukushima Daiichi Nuclear Power Plant in Okumamachi, Fukushima Prefecture, is seen. A strong earthquake on March 11, 2011 knocked out power at the plant, and because... (Associated Press)

Police officers wearing gas masks patrol in the area of the Fukushima power plant's Unit 1 in Okumamachi, Fukushima Prefecture (state), northern Japan, Saturday, March 12, 2011, amid fears that a part... (Associated Press)

A man holds his dog as they are scanned for levels of radiation in Koriyama, Fukushima Prefecture, Japan, Sunday, March 13, 2011. Friday's quake and tsunami damaged two nuclear reactors at a power plant... (Associated Press)

An official wears protective clothing while waiting to scan people for radiation an emergency center on Sunday, March 13, 2011, in Koriyama, northeastern Japan, two days after a giant quake and tsunami... (Associated Press)

Yo.After a devastating earthquake and tsunami, multiple nuclear reactors are facing possible meltdowns at plants more than a hundred miles (200 kilometers) from Tokyo.

The embassy's Sunday message said scientists were indicating that the crisis would be managed and pose little risk to Tokyo.

But it urged those who did not have to be in Tokyo to leave for several days, in case the worst happened and a "radioactive plume" headed for the area.

Up to 160 people in the immediate vicinity of the troubled plants may have been exposed to radiation.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

KORIYAMA, Japan (AP) _ Japan's nuclear crisis intensified Sunday as authorities raced to combat the threat of multiple reactor meltdowns and more than 170,000 people evacuated the quake- and tsunami-savaged northeastern coast where fears spread over possible radioactive contamination.

Nuclear plant operators were frantically trying to keep temperatures down in a series of nuclear reactors _ including one where officials feared a partial meltdown could be happening Sunday _ to prevent the disaster from growing worse.

Chief Cabinet Secretary Yukio Edano also said Sunday that a hydrogen explosion could occur at Unit 3 of the Fukushima Dai-ichi nuclear complex, the latest reactor to face a possible meltdown. That follows a blast the day before in the power plant's Unit 1, and operators attempted to prevent a meltdown there by injecting sea water into it.

"At the risk of raising further public concern, we cannot rule out the possibility of an explosion," Edano said. "If there is an explosion, however, there would be no significant impact on human health."

More than 170,000 people had been evacuated as a precaution, though Edano said the radioactivity released into the environment so far was so small it didn't pose any health threats.

"First I was worried about the quake," Kenji Koshiba, a construction worker who lives near the plant. "Now I'm worried about radiation." He spoke at an emergency center in Koriyama town near the power plant in Fukushima.

Edano said none of the Fukushima Dai-ichi reactors was near the point of complete meltdown, and he was confident of escaping the worst scenarios.

A complete meltdown _ the collapse of a power plant's ability to keep temperatures under control _ could release uranium and dangerous contaminants into the environment and pose major, widespread health risks.

Up to 160 people, including 60 elderly patients and medical staff who had been waiting for evacuation in the nearby town of Futabe, and 100 others evacuating by bus, might have been exposed to radiation, said Ryo Miyake, a spokesman from Japan's nuclear agency. The severity of their exposure, or if it had reached dangerous levels, was not clear. They were being taken to hospitals.

Edano said operators were trying to cool and decrease the pressure in the Unit 3 reactor, just as they had the day before at Unit 1.

"We're taking measures on Unit 3 based on a similar possibility" of a partial meltdown, Edano said.

Japan struggled with the nuclear crisis as it tried to determine the scale of the Friday disasters, when an 8.9-magnitude earthquake, the most powerful in the country's recorded history, was followed by a tsunami that savaged its northeastern coast with breathtaking speed and power.

More than 1,400 people were killed and hundreds more were missing, according to officials, but police in one of the worst-hit areas estimated the toll there alone could eventually top 10,000.

The scale of the multiple disasters appeared to be outpacing the efforts of Japanese authorities to bring the situation under control more than two days after the initial quake.

Rescue teams were struggling to search hundreds of miles (kilometers) of devastated coastline, and hundreds of thousands of hungry survivors huddled in darkened emergency centers cut off from rescuers and aid. At least 1.4 million households had gone without water since the quake, and food and gasoline were quickly running out across the region. Large areas of the countryside were surrounded by water and unreachable. Some 2 million households were without electricity.

Japanese Trade Minister Banri Kaieda warned that the region was likely to face further blackouts, and power would be rationed to ensure supplies to essential facilities.

The government doubled the number of troops pressed into rescue and recovery operations to about 100,000 from 51,000, as powerful aftershocks continued to rock the country. Hundreds have hit since the initial temblor.

Unit 3 at the Fukushima plant is one of three reactors there that had automatically shut down and lost cooling functions necessary to keep fuel rods working properly due to a power outage from the quake. The facility's Unit 1 is also in trouble, but Unit 2 has been less affected.

On Saturday, an explosion destroyed the walls of Unit 1 as operators desperately tried to prevent it from overheating and melting down.

Without power, and with its valves and pumps damaged by the tsunami, authorities resorted to drawing sea water mixed with boron in an attempt to cool the unit's overheated uranium fuel rods. Boron disrupts nuclear chain reactions.

The move likely renders the 40-year-old reactor unusable, said a foreign ministry official briefing reporters. Officials said the sea water will remain inside the unit, possibly for several months.

Robert Alvarez, senior scholar at the Institute for Policy Studies and former senior policy adviser to the U.S. secretary of energy, told reporters that the sea water was a desperate measure.

"It's a Hail Mary pass," he said.

He said that the success of using sea water and boron to cool the reactor will depend on the volume and rate of their distribution. He said the dousing would need to continue nonstop for days.

Another key, he said, was the restoration of electrical power, so that normal cooling systems can operate.

Edano said the cooling operation at Unit 1 was going smoothly after the sea water was pumped in.

Operators released slightly radioactive air from Unit 3 on Sunday, while injecting water into it hoping to reduce pressure and temperature to prevent a possible meltdown, Edano said.

He said radiation levels just outside the plant briefly rose above legal limits, but since had declined significantly. Also, fuel rods were exposed briefly, he said, indicating that coolant water didn't cover the rods for some time. That would have contributed further to raising the temperature in the reactor vessel.

At an evacuation center in Koriyama, about 40 miles (60 kilometers) from the troubled reactors and 125 miles (190 kilometers) north of Tokyo, medical experts had checked about 1,500 people for radiation exposure in an emergency testing center, an official said.

On Sunday, a few dozen people waited to be checked in a collection of blue tents set up in a parking lot outside a local gymnasium. Fire engines surrounded the scene, with their lights flashing.

Many of the gym's windows were shattered by the quake, and glass shards littered the ground.

A steady flow of people _ the elderly, schoolchildren and families with babies _ arrived at the center, where they were checked by officials wearing helmets, surgical masks and goggles.

Officials placed five reactors, including Units 1 and 3 at Dai-ichi, under states of emergency Friday after operators lost the ability to cool the reactors using usual procedures.

An additional reactor was added to the list early Sunday, for a total of six _ three at the Dai-ichi complex and three at another nearby complex. Local evacuations have been ordered at each location. Japan has a total of 55 reactors spread across 17 complexes nationwide.

Officials began venting radioactive steam at Fukushima Dai-ichi's Unit 1 to relieve pressure inside the reactor vessel, which houses the overheated uranium fuel.

Concerns escalated dramatically Saturday when that unit's containment building exploded.

Officials were aware that the steam contained hydrogen and were risking an explosion by venting it, acknowledged Shinji Kinjo, spokesman for the government's Nuclear and Industrial Safety Agency, but chose to do so because they needed to keep circulating cool water on the fuel rods to prevent a meltdown.

Officials insisted there was no significant radioactive leak after the explosion.

If a full-scale meltdown were to occur, experts interviewed by The Associated Press said melted fuel would eat through the bottom of the reactor vessel, then through the floor of the containment building. At that point, the uranium and dangerous byproducts would start escaping into the environment.

Eventually, the walls of the reactor vessel _ six inches (15 centimeters) of stainless steel _ would melt into a lava-like pile, slump into any remaining water on the floor, and potentially cause an explosion that would enhance the spread of radioactive contaminants.

If the reactor core became exposed to the outside, officials would likely began pouring cement and sand over the entire facility, as was done at the 1986 Chernobyl nuclear accident in the Ukraine, Peter Bradford, a former commissioner of the U.S. Nuclear Regulatory Commission, told reporters.

Another expert, physicist Ken Bergeron, told reporters that as a result of such a meltdown the surrounding land would be off-limits for a long time and "a lot of first responders would die."

___

Edited March 13, 2011 by Scott Sando

[Optobear]

Can anyone advise on the significance of them using seawater? I thought the problem was that they didn't have the power to pump any type of water around the cooling circuit rather than they were short of water.

It is odd isn't it, must be last resort. We're used to water being pretty innocuous stuff (we evolved that way), but it is a very agressive chemical especially at high temperature. So for example, if you heat silicon wafers in oxygen it forms an oxide layer, but only slowly, if you add some steam then the rate of oxide growth is considerably increased...

So hot water is pretty agressive, and hot water with salt added sounds very nasty in a system made of steel.

[stormymonday_2011]

ha

Russia has a power cable connected to Japan, talks were under way yesterday to switch this on and provide juice along with other fossil fuels to help them out.

All that LNG is gas that won't be finding its way onto the world market. The amount of electricity supplied will depend on the capacity of the cable. It will all have a knock on effect somewhere.

[Errol]

French official policy is now to warn French nationals to leave the Tokyo area. I think the Nuclear/radiation story is being hidden from the news.

[acidreign]

Latest:

10:36pm

More on that press conference from Japan's nuclear safety commmittee on the No.3 reactor at Fukushima:

- Water level has been increased, temperature lowered within the reactor

- Trouble occurred with the pump so they switched the water source to sea water

- This injection of sea water was unstable in the beginning, which initially caused the water level to be lowered significantly, but was eventually raised after a thorough investigation

- A high level of hydrogen was generated when the core of the reactor was not fully cooled down

- The hydrogen level is being monitored at the upper level of the reactor so it could be likely that hydrogen is being stored there

- Measures are being taken to prevent No.3 reactor from exploding

Taken from http://blogs.aljazeera.net/live/asia/japans-twin-disasters-march-13-live-blog

[Scott Sando]

Sky news now ,state of emergency declared at second nuclear reactor.

Edited March 13, 2011 by Scott Sando

[fellow]

Sky news now ,state of emergency declared at second nuclear reactor.

It's at Onagawa, a separate nuclear facility entirey, north of Fukushima. 'Excessive radiation levels have been detected'

http://www.channelnewsasia.com/stories/afp_asiapacific/view/1116240/1/.html

Edited March 13, 2011 by fellow

[cyprinus]

And to add to their woes, a volcano has just erupted in the southwest of the country.

[stormymonday_2011]

French official policy is now to warn French nationals to leave the Tokyo area. I think the Nuclear/radiation story is being hidden from the news.

How far are these things from Tokyo ?

Could we end up with a capital city being seiously contaminated?

What direction are the prevailing winds in this part of the world?