Meltdown Likely Under Way At Japan Nuclear Reactor

[OzMick]

Sunday night update from NHK, basically confirming what we reported above from Kyodo News:

Cooling system problems continue to plague two nuclear plants in earthquake-hit Fukushima Prefecture.

The level of coolant water in the Number Three reactor at the Fukushima Number One power plant dropped on Sunday, leaving the fuel rods exposed by two meters. The situation continued for at least until 3pm, possibly causing a partial melting of the rods.

As a result, masses of hydrogen gas have accumulated in the inside top of the reactor building. The gas may cause an explosion similar to that which occurred at the Number One reactor on Saturday.

Tokyo Electric Power Company, also known as TEPCO, is considering ways to remove the hydrogen from the structure.

The Number One reactor and its containment structure are being pumped with seawater in an effort to secure cooling.

This has been gone over before. Exposed rods will oxidise in the reactor by reacting with the steam (there is no oxygen gas in the atmosphere inside the reactor) releasing hydrogen (water minus oxygen). When the steam pressure reaches a level approaching the pressure limits of the reactor it is released, normally via a vent stack. If the stack or associated pipework have been damaged by the quake and the hydrogen/steam mix is vented inside the building it will rapidly form an explosive mix with the air in the enclosed space.

An explosion is highly likely to inevitable as the hydrogen will generate static electricity causing a spark. This happens even when vented via the stack, but with little effect as it is not contained.

[jfchandler]

Guys, once again, please try to keep the discussion here on the Japanese nuclear reactors, and save the energy-politics debates for some other place and time.

[StreetCowboy]

Reply to post in other thread:

Thanks, I understand this point of view, but cooling it with sea-water would have the same effect as boric acid. - The reactor would never be up again. This is talked about since more than 12 hours.

The problems seem to be with the injection of sea-water and boric acid.

Although Boric acid isn't a standard regulating compound in a BWR, it is just an additive to the coolant, and does no harm to the reactor. It regulates the reaction in much the same way as the control rods do. When flushed out again, reaction starts back up.

The boron in boric acid is a neutron modulator also known as a neutron absorber.

The core reaction produces neutrons, the neutrons hit another element and can release two neutrons which hit another element each releasing two neutrons...thus increasing core reaction and of course, heat. So the use of boric acid is an attempt to quench the ongoing nuclear reaction as well as cool the core. Sea water will cool the core but absent the boron modulater, will not act to slow the nuclear reaction.

That boric acid was used is another bit of evidence that at least part of the core (fuel rods) have melted. The problem is that once part melts, if the melted portions flow together (at about 5080 Fahrenheit) neutron flux increases, the reaction increases, and heat increases. If enough of the uranium/ceramic pellets melt and flow the molten mass can become critical. This would likely result in a physical explosion, not a thermonuclear explosion but would be catastrophic. This was the great fear at Chernobyl and luckily though the core melted, the molten mass never managed to come together in a critical mass and enough neutron absorbing material was piled on it to slow the reaction.

There is a bogus radiation map circulating, purportedly from the Australian government predicting deadly radiation exposure--it is BOGUS, don't believe a bit of it.

Still, the absence of quality reporting on the incident is quite worrisome to me.

To clarify a little:

Thermal reactors (like the Boiling Water Reactors in question) function thus:

a. unstable uranium or plutonium isotopes break up spontaneously, releasing several neutrons

b. These neutrons bounce around; if they are slowed down to 'thermal' speeds, they may be absorbed by other ploutonium or uranium atoms, causing them to become unstable and split, thus creating a self-sustaining chain reaction. This relies upon: (i) A moderator to slow the neutrons down (ii) adequate neutron economy i.e neutrons are not absorbed by other elements (absorbers). In a BWR or a PWR, the cooling water also acts as the moderator; if we lose all the cooling water, we also lose the moderator and stop the chain reaction; unfortunatrely, the very radioactive fuel will continue to give off a lot of 'decay heat' for several days to come...

Boron (in boric acid) is an absorber; it takes neutrons out of the nuclear reaction and thus stops the reaction.

WIthout a moderator, the fuel in the PWR or BWR CANNOT become critical; to do so, it would need to be enriched to 15 - 20% or higher, compared to about 5% in these reactors.

I really feel for the operators at the plants in question, who must be going through pretty stressful times at home, as well as some quite remarkable challenges at work; thank heavens for the diligence of the Japanese workers!

SC

[jfchandler]

Good morning Japan....

Fukushima nuke plant continues to be in 'alarming' state: Prime Minister Kan

AND

Radiation level again tops legal limit at Fukushima No. 1 nuke plant

TOKYO, March 14, Kyodo News The radiation level at a quake-hit nuclear power plant in Fukushima Prefecture has again exceeded the legal limit, Tokyo Electric Power Co. reported to the government Monday.

The Fukushima No. 1 [Daichi] nuclear plant has been shut down since a magnitude 9.0 quake struck northeastern and eastern Japan on Friday, but some of its reactors have lost their cooling functions, leading to brief rises in the radiation level over the weekend.

On Monday, radiation at the plant's premises rose over the benchmark limit of 500 micro sievert per hour at two locations, measuring 751 micro sievert at the first location at 2:20 a.m. and 650 at the second at 2:40 a.m., according to the report.

The hourly amounts are more than half the 1,000 micro sievert to which people are usually exposed in one year.

The maximum level detected so far around the plant is 1,557.5 micro sievert logged Sunday.

The utility has continued pouring seawater into the plant's No. 1 and No. 3 reactors to help cool their cores. The cores are believed to have partially melted after part of the fuel rods were no longer covered by coolant water when levels fell following the quake.

No changes have been observed with the water level and the pressure inside the reactor containers, it added.

Edited March 14, 2011 by jfchandler

[jfchandler]

Reuters Monday morning update:

Officials confirmed three nuclear reactors north of Tokyo were at risk of overheating, raising fears of an uncontrolled radiation leak.As [Prime Minister] Kan spoke [sunday], engineers worked desperately to cool the fuel rods in the damaged reactors. If they fail, the containers that house the core could melt, or even explode, releasing radioactive material into the atmosphere.

AND

Authorities have poured sea water in all three of the reactors at the complex, run by to cool them down.

Nuclear experts said it was probably the first time in the industry's 57-year history that sea water has been used in this way, a sign of how close Japan may be to a major accident.

"Injection of sea water into a core is an extreme measure," Mark Hibbs of the Carnegie Endowment for International Peace. "this is not according to the book."

Chief Cabinet Secretary Yukio Edano said there might have been a partial meltdown of the fuel rods at the No. 1 reactor, where Saturday's blast took place, and there was a risk of an explosion at the building housing the No. 3 reactor, but that it was unlikely to affect the reactor core container.

A Japanese official said 22 people have been confirmed to have suffered radiation contamination and up to 190 may have been exposed. Workers in protective clothing used handheld scanners to check people arriving at evacuation centers.

"NOT ANOTHER CHERNOBYL"

The nuclear accident, the worst since Chernobyl in Soviet Ukraine in 1986, sparked criticism that authorities were ill-prepared for such a massive quake and the threat that could pose to the country's nuclear power industry.

Prime Minister Kan sought to allay radiation fears:

"Radiation has been released in the air, but there are no reports that a large amount was released," Jiji news agency quoted him as saying. "This is fundamentally different from the Chernobyl accident."

Nevertheless, France recommended its citizens leave the Tokyo region, citing the risk of further earthquakes and uncertainty about the nuclear plants.

http://www.reuters.c...E72A0SS20110314

Edited March 14, 2011 by jfchandler

[jfchandler]

Factbox: Nuclear accidents: Fukushima vs Three Mile

Sun Mar 13, 2011 8:15pm EDT

(Reuters) - The Japanese Nuclear Safety Agency on Saturday rated the nuclear accident at Tokyo Electric Power Co's (TEPCO) Fukushima Daiichi plant in Japan at a four on a scale of one to seven, which is not quite as bad as the Three Mile Island accident in the United States in 1979, which was rated a five.

The agency hasn't provided an update of its assessment since Saturday despite further problems at the Daiichi plant.

So how were the events different?

MORE: http://www.reuters.c...E72D01O20110314

Edited March 14, 2011 by jfchandler

[jfchandler]

US senator: 'put the brakes' on nuclear power plants

Sun Mar 13, 2011 12:53pm EDT

* Lieberman says US must understand what happened in Japan

WASHINGTON, March 13 (Reuters) - The United States should "put the brakes on" new nuclear power plants until fully understanding what happened to the earthquake-crippled nuclear reactors in Japan, the chairman of the U.S. Senate's homeland security panel said on Sunday.

Engineers in Japan tried on Sunday to avert a meltdown at three nuclear reactors following Friday's huge earthquake by pumping in cooling seawater after authorities said they assumed that some damage had already occurred.

"I don't want to stop the building of nuclear power plants," independent Senator Joe Lieberman, chairman of the Senate Homeland Security and Governmental Affairs Committee, said on the CBS program "Face the Nation."

"But I think we've got to kind of quietly put, quickly put the brakes on until we can absorb what has happened in Japan as a result of the earthquake and the tsunami and then see what more, if anything, we can demand of the new power plants that are coming on line," Lieberman added.

MORE: http://www.reuters.c...329263820110313

Edited March 14, 2011 by jfchandler

[jfchandler]

U.S. agencies provide insight into how to prepare for, respond to nuclear disaster

Excerpted from CNN

There is no indication the U.S. has been or will be affected by Japan's nuclear troubles, but advice and regulations from U.S. government agencies provide insight into how Japan might respond to the damaged reactors.

Those told to evacuate should put as much distance as possible between themselves and the source of the radiation.

While evacuating, keep car windows closed and use recirculating air inside the car. Be sure to bring a flashlight, portable radio, batteries, first-aid kit, can opener, essential medicines, cash, credit cards and a supply of sealed food and water, the Centers for Disease Control and Prevention advises.

The U.S. Environmental Protection Agency also suggests purchasing a radiation detection meter and wearing a well-fitting mask, because inhaled and ingested radiation are the most damaging to living tissue.

"Radioactive particles may lodge in the lungs or digestive tract and release radiation directly to living tissue for a lifetime," the agency says.

MORE: http://news.blogs.cn...clear-disaster/

Edited March 14, 2011 by jfchandler

[jfchandler]

From CNN - [6:35 p.m. ET, 7:35 a.m. Tokyo]

The International Atomic Energy Agency says that - based on information the agency received from officials in Japan - investigators determined that radiation levels have returned to "normal" at one of the power plants previously flagged for concern.

The agency said that authorities have concluded that there were "no emissions of radioactivity" from the three reactors at the Onagawa nuclear plant.

"The current assumption of the Japanese authorities is that the increased level may have been due to a release of radioactive material from the Fukushima Daiichi nuclear power plant" located 135 kilometers (about 85 miles) north of Onagawa, the IAEA said.

Jfchandler note - That's a pretty interesting conclusion, in that it means that the supposedly minimal radiation releases from Fukushima traveled and could be detected to another location 135 Km away...

Here was the earlier report on Onagawa:

[10:39 a.m. ET, 11:39 p.m. Tokyo]

A state of emergency has been declared at a nuclear power plant in Onagawa, Japan, where excessive radiation levels have been recorded following Friday's massive earthquake, the United Nations' atomic watchdog agency said Sunday.

Authorities have told the agency that the three reactor units at the Onagawa plant "are under control."

Edited March 14, 2011 by jfchandler

[bulmercke]

Nuclear Plant Designer Says Japanese Government Suppressing Scale Of Crisis - BBC News - Sunday - March 13 2011

A former nuclear power plant designer has said Japan is facing an extremely grave crisis and called on the government to release more information, which he said was being suppressed. Masashi Goto told a news conference in Tokyo that one of the reactors at the Fukushima-Daiichi plant was “highly unstable”, and that if there was a meltdown the “consequences would be tremendous”. He said such an event might be very likely indeed. So far, the government has said a meltdown would not lead to a sizeable leak of radioactive materials.

[jfchandler]

Excerpted from Japan Times Online

Electric power companies in other regions, as well as Japan Nuclear Fuel Ltd., have dispatched 48 people to help Tepco deal with the crisis at the Fukushima power plants.

http://search.japantimes.co.jp/cgi-bin/nn20110314a1.html

[harrycallahan]

Must be like Armageddon for the people there.

What can individuals do to help?

Maybe stop the fear mongering?

Fear mongering?

After an earthquake with the strength of nine on the Richter-scale, a devastating tsunami that killed 10s of thousands of people, a volcano outbreak and the reactor catastrophies do you think it is suitable to say everything is alright?

Still there's is huge danger coming from one of the reactors that runs additionally with plutonium.

I think it's better to call a spade a spade.

Yes thousands killed by the tsunami. So far 1 reported killed in a nuclear reactor incident (crane driver).

But lets not lose sight of the threat those reactors pose, MELTDOWN MELTDOWN MELTDOWN....

If they suffer a full meltdown (less likely as time goes by) the likely scenario is they'll have a radioactive pool of muck sitting at the bottom of the sealed core housing and a very messy and expensive cleanup.

Once the rods are melting and when any of the radioactivity goes into the atmosphere or ground water the area is doomed.

Doomed I tells ya! Doooooomed!

[jfchandler]

The BBC's environmental correspondent wrote this assessment of the plutonium fuel component being used in Fukushima Daichi Reactor No. 3...

In the meantime, there have been suggestions that an incident at reactor 3 would inherently be more dangerous than at reactors 1 and 2 because it burns "mixed oxide fuel" (MOX) containing plutonium.

Plutonium is produced during nuclear fission, so is present in all reactor cores - the longer the fuel has been there, the more plutonium will be present, up to about 1%.

In some countries, spent fuel rods are re-processed and the plutonium set to one side.

However, Japan - in an attempt to be more frugal with a valuable resource - has a programme that mixes the plutonium coming out of the re-processing facility back into new fuel rods that also contain uranium. This is MOX fuel.

So, reactor 3 fuel rods will contain more plutonium than those in reactor 1.

But this would only become an issue if there were an explosion or a catastrophic meltdown. The radioactive release so far has been of much lighter fission products and of short-lived nuclei generated in cooling water, which are identical no matter which fuel is used.

[jfchandler]

Scale of nuclear accidents from the BBC

[Japan's nuclear agency thus far has rated the Fukushima reactors problem as a Level 4 incident]

• Level 7 - Major release of radioactive material. Example: Chernobyl, Ukraine, 1986
• Level 6 - Significant release of radioactive material. Example: Kyshtym, Russia, 1957
• Level 5 - Limited release of radioactive material. Example: Three Mile Island, US, 1979, and Windscale, UK, 1957
• Level 4 - Minor release of radioactive material with at least one death from radiation. Example: Tokaimura, Japan, 1999
• Level 3 - Exposure in excess of 10 times the statutory annual limit for workers
• Level 2 - Exposure of a member of the public in excess of 10mSv (average annual dose is 1mSv)
• Level 1 - Exposure of a member of public above statutory annual limit. Minor safety problems

(Source: UN nuclear agency, IAEA)

Edited March 14, 2011 by jfchandler

[jfchandler]

Struggle to Stabilize Japan's Fukushima Nuclear Plant

By Richard Black Environment correspondent, BBC News

13 March 2011 Last updated at 15:07 GMT

Two days after the alarm was first raised about safety at Fukushima Daiichi plant, uncertainty still surrounds the situation on the ground and the status of the three reactors that were functioning at the time of Friday's earthquake and tsunami. It appears that a partial meltdown did occur in reactor 1.

On Sunday, officials said the same thing was suspected in reactor 3 - although later, they appeared to retract this statement.

What is certain is that engineers are still struggling to pump enough water past the reactors to keep the cores cool.

MORE: http://www.bbc.co.uk/news/science-environment-12726628

[george]

BREAKING NEWS:

AFP: Estimated 3m (10ft) tsunami seen off Japan by helicopter.

Sound of explosion at Fukushima Reactor 3, NHK saying

[george]

More on Hachinohe: City says tide has receded 2 meters; residents urged to go to higher ground - @HachinoheCity

[george]

NHK warning people to get away from coast in Miyagi-ken and Fukushima-ken. Tsunami wave coming in 15 mins.

[george]

More on Hachinohe: City says tide has receded 2 meters; residents urged to go to higher ground - @HachinoheCity

AP: Gray smoke spotted at stricken Fukushima Dai-ichi reactor

Kyodo says Japan issued a 3-meter tsunami warning on east coast, including Fukushima. AP says gray smoke is seen on Fukushima reactor.

[bulmercke]

Monster aftershock could strike within days

Adam Morton - March 14 2011 - SYDNEY MORNING HERALD

QUOTE FROM STORY:"NORTH-EASTERN Japan can expect another monster earthquake large enough to trigger a tsunami within days, the head of the Australian Seismological Centre says.

The director, Kevin McCue, said there had been more than 100 smaller quakes since Friday, but a larger aftershock was likely."

http://www.smh.com.a...0313-1bt2p.html

[jfchandler]

This excerpt from a long Wall Street Journal Monday update on the nuclear situation:

Japanese officials released no new information overnight about the Fukushima situation. But a foreign observer briefed on the situation early in the Japanese morning said reactor No. 3 remained critical, with about three feet of the fuel exposed. "The fuel is getting hotter and hotter," this person said.

The more of the fuel that is exposed, the hotter the fuel gets, converting even more of the coolant into steam, and worsening the situation, by exposing even more fuel to the melting and heating process, this person said. He described the crisis as proceeding like a freight train, that gathers momentum as the crisis continues.

A similar crisis in reactor No. 1 at the same nuclear power station appeared to be slowing, he said, but it is unclear if the crisis in reactor one is completely past.

The full article is here:

http://online.wsj.com/article/SB10001424052748704893604576198232980341072.html?mod=asia_home

[bulmercke]

NHK:CNN reporting: Smoke rising from reactor #1 , blast in reactor #3

[jfchandler]

Kyodo News

BREAKING NEWS: Residents near nuke plants ordered to be inside buildings

BREAKING NEWS: Hydrogen blast occurs at Fukushima nuke plant's No. 3 reactor: Japan nuclear agency

[webfact]

Japan nuclear safety agency - Hydrogen explosion at Fukushima No. 3 reactor, cannot confirm blast caused radioactive leak /RT @REUTERSFLASH:

[webfact]

AP: Officials believe a hydrogen explosion has occurred at Fukushima Dai-ich plant /RT @BreakingNews:

[jfchandler]

NHK BREAKING NEWS: The Nuclear and Industrial Safety Agency says a hydrogen explosion occurred Monday morning at the No.3 reactor at a nuclear power plant in Fukushima prefecture.

[webfact]

Japanese PM Naoto Kan says situation at quake-damaged nuclear plant remained worrisome and that authorities are doing their utmost to prevent damage from spreading /MCOT

[jfchandler]

NHK showing this video of the Number 3 reactor, saying the exterior wall blown away...

Says 600 residents still in 20 Km evacuation area around the plant being ordered to stay indoors.

Reports the explosion occurred about 9:08 am Thai Thai, 11:09 am Japan time.

Edited March 14, 2011 by jfchandler

[animatic]

Let's wish them the best of luck and increased stamina and ability to get the jobs done, they are really needing it in a major way. It appears the hydrogen build ups are a byproduct of the type of control mechanisms they are being forced to use.

Hopefully this is, as was the earlier one, still an external containment building explosion and nothing internal. Though the destruction to framing of this one appears much worse than the first.

Edited March 14, 2011 by animatic

[jfchandler]

This is the image NHK says was taken just after the explosion with smoke rising: