Meltdown Likely Under Way At Japan Nuclear Reactor

[bulmercke]

Kyodo News:

Radiation twice the maximum seen so far detected at nuke plant Monday: TEPCO

Fuel rods fully exposed again as of 11 p.m.

00:42 15 March 2011 JST

Isn't this a big problem? Fully exposed rods? I keep watching for a post from you guys.....

Isn't 11pm very recent? The posting times confuse me.

This is a huge - huge - problem. Sorry for sounding alarmist but that's how I see the situation now.

[Lopburi99]

I think our experts JFC, elcent and others have gone to get some sleep. Sure miss not getting their step by step take on things especially now that the crap may be ready to hit the fan....

[jfchandler]

I'm going to bed now... remember...I'm on Thailand time...

Yes...exposed rods are a huge problem.. No cooling means the reactor casing enclosing the fuel rods begins to melt and potentially expose the nuclear fuel, which can fall out of the enclosure and start doing all kinds of bad things...

The reactor no. 2 reactor rods were totally uncovered two different times Monday...including one time for at least two hours....

And those babies get HOT!!!!!

Worst case scenario in that kind of situation is an explosion caused by the melting fuel...the impact of which could spread the contamination far and wide....if it's not contained by the reactor's external enclosure...

But that's the doomsday stuff... Not there... hopefully ever...and certainly not yet. That's why it's so crucial the Japanese keep those reactors cooled down at least until the fission process subsides.'

[balo]

No cooling means disaster for Japan and the world.

The next 24 hours will be very important. Lets pray.

[Jdietz]

Explosion heard at Daiichi reactor #2 around 08:05.

That'll be the third one, as expected.

Edited March 14, 2011 by Jdietz

[Lopburi99]

Breaking news. Explosion at unit #2!

Glad Jdietz is up. I know he'll keep us informed. Thank you sir.

Edited March 14, 2011 by Lopburi99

[Jdietz]

Explosion at the Daiichi #2 plant.

This one seems to be a bit more serious though, as it seems to have happened within the outer containing vessel (the structure between the steel reactor vat and the outer building)

Streaming on NHK world: http://www3.nhk.or.jp/nhkworld/

- Right after the explosion a radiation level of 965.5 μSv was reported, now lowered to 882.7μSv. Still reasonably low levels.

- Plant operators not directly involved in this operation are being evacuated to prevent long-term exposure.

- Wind direction at the plant is NNE shifting to N

- Suppression pool (the donut-shaped structure at the very bottom of the reactor) may have been damaged, which may lead to contaminated water leaking into the environment.

Edited March 14, 2011 by Jdietz

[Jdietz]

The explosion apparently took place in the torus at the bottom of the reactor, inside the containment structure, but outside the steel reactor vat.

[Jdietz]

- Water level before and after the explosion constant at 2700mm exposed (means the fuel rods are still partially under water and nothing seems to be leaking out right now)

- Around 50 staff remain on site, rest is evacuated.

Edited March 14, 2011 by Jdietz

[canuckamuck]

Holy Fukishima!

[Jdietz]

Status update Daiichi #2 reactor:

- Water injection is still continuing

- Damage to structure not confirmed, though pressure dropped, water level constant. Only really known fact is the sound of an explosion

- No significant change in the reactors parameters after the explosion

Status update Daiichi #3 reactor:

- Steam-like substance is accumulating in the top of the reactor, unknown consistence.

Status update Daiichi #4 reactor:

- Temperature dropped below 100C, and is now in cold shutdown

Meteorological data at the site is unavailable since the quake

Northerly wind reported at MET site 50km south

Current radiation level at the site border: 871uSv/hour

Translator seems to have some problems with radiation units, looks like the earlier numbers are correct.

After the blast at #2 the pressure in the suppression chamber went down from 3 atmosphere to 1, indicating some kind of damage.

Edited March 15, 2011 by Jdietz

[LaoPo]

New Blast Reported at Nuclear Plant as Japan Struggles to Cool Reactor

By HIROKO TABUCHI, KEITH BRADSHER and MATT WALD

Published: March 14, 2011

TOKYO — An explosion early Tuesday morning may have damaged the inner steel containment vessel of the No. 2 reactor at Japan's Fukushima Daiichi Nuclear Power Station, leading to the wide release of radioactive materials there and forcing the evacuation of some emergency workers, the plant's operator said.

The blast appeared to be different — and more severe — than those that at two other troubled reactor at the same nuclear complex because this one, reported to have occurred at 6:14 a.m., happened in the "pressure suppression room" in the cooling area of the reactor, raising the possibility to damage to the reactor's containment vessel.

Any damage to the steel containment vessel of a nuclear reactor is considered critical because it raises the prospect of an uncontrolled release of radioactive material and full meltdown of the nuclear fuel inside. To date, even during the four-day crisis in Japan that amounts to the worst nuclear accident since Chernobyl, workers had managed to avoid a breach of a containment vessel and had limited releases of radioactive steam to relatively low levels.

Details of what happened remain unclear, with executives of Tokyo Electric Power, the plant's operator, giving only preliminary reports of damage to the suppression pool but declining to provide a full explanation of what that meant.

But the new blast came after emergency operations to pump seawater into the same reactor failed, leaving the nuclear fuel in that reactor dangerously exposed late Monday into early Tuesday morning.

Continues:

http://www.nytimes.c...tml?_r=1&emc=na

LaoPo

[Jdietz]

An extra pump vehicle is on the way to reactor #2 to help cool it, will arrive this morning.

This seems to be the latest real radiation information:

The radiation level at the troubled nuclear plant in Fukushima Prefecture shot up to 8,217 micro sievert per hour temporarily Tuesday morning after an explosion was heard at its No. 2 reactor, Tokyo Electric Power Co. said.

Perspective:

natural background radiation exposes people to about 0.35 micro Sievert per hour.

cosmic radiation during commercial flight exposes fliers to about 10 micro Sievert per hour.

After the incident the numbers dropped off again quickly.

965.5 uSv at 7am

882.7 uSv at 8am

387.3 uSv now.

Edited March 15, 2011 by Jdietz

[Jdietz]

As the situation seems not to be worsening now, I'm going to have a shower and breakfast, I'll keep monitoring the situation.

[jfchandler]

Jdietz... thanks for providing the morning updates here while I was blissfully sleeping...

Please do, however, provide the source and links for that kind of info, so everyone knows the source/sources it's coming from. That's SOP. A-OK!

As the situation seems not to be worsening now, I'm going to have a shower and breakfast, I'll keep monitoring the situation.

[jfchandler]

Explosion heard at Fukushima No2. reactor

Japan's Nuclear and Industrial Safety Agency says an explosion was heard early Tuesday morning at the No.2 reactor of the disaster-hit Fukushima No.1 nuclear power plant.

Agency officials told reporters that the blast was heard at 6:10 AM local time on Tuesday.

Chief Cabinet Secretary Yukio Edano earlier told a news conference that a reactor facility, called the suppression pool, has been damaged.

But agency officials said they have no detailed information yet about the report.

They said that depending on where the damage is done, either liquid or air could leak out of the suppression pool.

The suppression pool is linked to the reactor containment vessel and is designed to prevent radioactive material from leaking outside.

Experts say a breach to this crucial facility has raised the possibility of a radioactive leak.

The Nuclear and Industrial Safety Agency also said that nuclear fuel rods inside the No.2 reactor are exposed above water by about 2.7 meters. That's about half the length of the fuel rods.

Agency officials said that radiation levels around the nuclear power plant reached 965.5 microsieverts following the explosive sound.

They say the figure later dropped slightly to 882 microsieverts.

The officials said they believe the rise in radiation level is due to the breach in the suppression pool, but that they cannot say for sure. They said they are monitoring the situation closely.

The officials added that the monitored level of radiation would not immediately pose a health threat.

Tokyo Electric Power Company that operates the power station briefly evacuated workers from the facility following the sound of the blast.

Tuesday, March 15, 2011 09:26 +0900 (JST)

[jfchandler]

This is bad, by far the worst numbers thus far in this crisis... And this number is at the plant gate...farther away from the reactors themselves.

TEPCO: 8,200 microsieverts recorded at plant

Tokyo Electric Power Company says radiation levels reached 8,217 microsieverts per hour near the front gate of the Fukushima No.1 nuclear power station at 8:31 AM Tuesday.

Anyone in this kind of environment would be exposed to more than 3 years' worth of naturally occurring radiation within a single hour.

Tuesday, March 15, 2011 09:29 +0900 (JST)

http://www3.nhk.or.j...lish/15_17.html

Edited March 15, 2011 by jfchandler

[canuckamuck]

I wouldn't be surprised to see the incident level rise to 5 now.

Edited March 15, 2011 by canuckamuck

[jfchandler]

This a report from earlier today...prior to the latest explosion

TEPCO: Nuclear fuel may be melting

The Tokyo Electric Power Company says there is a possibility of fuel rods melting in the Number Two reactor at its Fukushima Number One plant.

A company official said at a news conference on Tuesday that the level of cooling water is now too low to measure.

He indicated that the fuel rods may have overheated and begun melting.

Tuesday, March 15, 2011 04:27 +0900 (JST)

http://www3.nhk.or.jp/daily/english/15_06.html

[Jdietz]

Source was mentioned in first post, NHK World.

I am still very doubtful about the radiation levels being thrown around, translators seems to regularly miss a decimal point here and there.

[jfchandler]

Japan stock market down an additional 6% today... below 9000 level in trading.

AND

Kyodo News

PM Kan to address message to public, Edano to meet press around 11 a.m. ( 9 am Thai time)

[jfchandler]

BULLETIN: Container damaged, radioactive materials feared to leak at Fukushima plant

TOKYO, March 15, Kyodo News

Radiation is feared to have leaked after the container vessel was damaged at the No. 2 reactor of the Fukushima nuke plant Tuesday morning, Tokyo Electric Power Co. said.

[jfchandler]

Blast heard at Fukushima's No.2 reactor, radiation shoots up

TOKYO, March 15, Kyodo News

Radiation is feared to have leaked after the container vessel suffered damage at the No. 2 reactor of the quake-hit Fukushima No. 1 nuclear power plant Tuesday morning, Tokyo Electric Power Co. said.

The utility also admitted that a critical situation called ''meltdown'' in which fuel rods melt and are destroyed is possible at the plant where three reactor cores are believed to have partially melted following Friday's magnitude 9.0 earthquake that hit northeastern and eastern Japan.

An explosion was heard early Tuesday morning at the reactor and the radiation level temporarily shot up later, the firm said as it continued efforts to prevent overheating of exposed fuel rods.

Shortly after the apparent blast at 6:10 a.m., which appears to have damaged the reactor's pressure-suppression system, the radiation level exceeded the legal limit to reach 965.5 micro sievert per hour before jumping to 8,217 micro sievert at 8:31 p.m., it said.

The maximum level is more than eight times the 1,000 micro sievert level to which people can be exposed in one year.

The utility said it is evacuating workers from the plant, except for those necessary for work to cool the reactor.

The reactor's fuel rods were fully exposed for around two and a half hours Monday evening after water levels rapidly fell, and again late Monday night although seawater was being injected, prompting the utility to open some steam valves at 1:10 a.m. Tuesday in order to resume pumping seawater.

The water level recovered somewhat later in the morning to cover about 1.2 meters of the fuel rods, about one-third of their height, the firm said.

Prime Minister Naoto Kan said earlier in the morning that the government and TEPCO will set up an integrated headquarters, headed by himself, to address issues at the Fukushima No. 1 plant.

With radiation levels around the facility up, TEPCO suspects the core of the No. 2 reactor has partially melted, a critical nuclear safety situation.

The development follows hydrogen blasts at both of the plant's two other reactors whose cores are also believed to have partially melted, occurring Saturday at the No. 1 reactor and Monday at the No. 3 reactor.

''A worrisome situation remains but I hope to take the lead in overcoming this crisis,'' Kan said of the nuclear power plant. ''I will take all measures so that damage will not expand.''

At the headquarters set up at the TEPCO head office, with TEPCO president and the economy, trade and industry minister serving as its deputy chiefs, Kan confronted TEPCO officials about their delay in reporting the initial blast.

Japan has asked the United States to provide more cooling equipment to help stabilize the plant, Gregory Jaczko, chairman of the U.S. Nuclear Regulatory Commission, said in Washington. The NRC has already sent two technological experts and is fully supporting Japanese efforts, he said.

The No. 2 reactor automatically shut down after the magnitude 9.0 earthquake hit the region on Friday. Its reactor cooling function was lost on Monday and water levels rapidly dropped, fully exposing fuel rods for around two and a half hours from 6:30 p.m.

Seawater was injected and water levels were increased temporarily but late Monday night they started dropping, leading to full exposure of the rods again.

At 1:10 a.m. Tuesday, TEPCO opened some steam valves and resumed work to pump seawater and was considering opening more valves, according to the company.

http://english.kyodo...1/03/78021.html

Edited March 15, 2011 by jfchandler

[webfact]

Officials: Latest blast at Fukushima plant may havedamaged reactor container, fear radiation leak - AP /RT @BreakingNews:

[jfchandler]

NISA says plant staff not directly involved in injecting sea water operations evacuated away from reactors.

[jfchandler]

NHK reporting winds blowing southward from plant area at about 15 Km per hour, at least thru midday Japan time.

Radiation levels reported at about 2400 mSv about five minutes after this morning's reactor explosion and peak readings above 8000 mSv then.

[brahmburgers]

Japanese officials acknowledged that the fuel rods appear to be melting inside all three of the reactors at the Fukashima plant. "Although we cannot directly check it, it's highly likely happening," Chief Cabinet Secretary Yukio Edano told the Associated Press.

Well, one silver lining in these reports, is it will put the brakes on Thailand's (EGAT's) nuclear ambitions. I don't say it will snuff out EGAT's dreams for a nuclear Thailand, but it will dampen them. And today's Post has a feature article mentioning PM Abhisit is also against Thailand going nuclear.

All this talk about hydrogen mixing with oxygen and causing explosions. I'm not a chemist, but last time I checked, H + O = water. As for breaching the containment vessel to release pressure, why not have a tank shoot an off-center shot?

This could also put additional worry on countries, particularly in the Middle East, who have nuke plants. A plant in Iraq was bombed by Israeli jets a number of years ago. We all know that all those countries have enemies, and what better way to screw your enemy than to cause a radioactive explosion in their midst? Along with all the other manifold safety measures already required for N plants, there will be a need to add a ring of anti-aircraft and anti-missile defenses to the equation.

[jfchandler]

deleted.

Edited March 15, 2011 by jfchandler

[Jdietz]

Radiation levels reported at about 2400 mSv about five minutes after this morning's reactor explosion and peak readings above 8000 mSv then.

Let's change that to 2,400μSv and 8,000μSv

Radiation level reporting has been very inconsistent, but let's try to keep the units right.

Sievert (Sv), Millisievert (mSv), Microsievert (μSv)

Edit: Since your previous post gives doses in milliSievert, this is equivalent to 2.4mSv and 8mSv.

Edited March 15, 2011 by Jdietz

[jfchandler]

So the peak readings this morning from the plant of 8000+ microSievert are, I believe, equal to 8 milliSievert... That's how they're getting the figure of that one hour exposure at that level being equal to three years worth... See comparisons below

An assortment of typical radiation doses (in milliSievert) (mSv)

Used to destroy the bone marrow in preparation for a marrow transplant (given over several days) 10,000

Approximate lethal dose ("LD₅₀") if no treatment and given to the entire body in a short period 4,500

Causes radiation sickness (when absorbed in a short period) >1,000

Increase in lifetime dose to most heavily exposed people living near Chernobyl 430

Average annual dose (excluding natural background) for medical X-ray technicians 3.2

Maximum permissible annual dose (excluding natural background and medical exposure) to general public 1.7

Natural background, Boston, MA, USA (per year)(excluding radon) 1.02

Natural background, Denver, CO, USA (per year)(excluding radon) 1.8

Dose from a single full-body computed tomography (CT) scan 45

http://users.rcn.com.../Radiation.html

Edited March 15, 2011 by jfchandler