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TEPCO reactor by reactor status report at Fukushima

Current status of reactors, from TEPCO (will update as required, click to enlarge)


By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

93 replies on “TEPCO reactor by reactor status report at Fukushima”

If that is in JST, it is nearly 12h old. We know that situation at block 2 has changed significantly since:

RCIC has failed, containment has been vented, sea water is tried to be injected, water level is unknown atm (latest reports?) but it is believed to have been near zero at times, fuel integrity is believed to be (partly) damaged.

all from Tepco and gov pressers, but since Tepco website is still down it is sometimes difficult to assess what they really said.


The radiation level quoted at the boundary of the #1 complex is 20 micro-Sieverts/hour. For those of you who are used to the older units, I think that equates to 2 milli-Rem/hour.

While that is well above “background” you can expect more radiation on a commercial flight.

For unit #2 the radiation level is quoted as 0.038 micro-Sieverts/hour. That has to be pretty close to “background”.

Anyone know what the background radiation level is?


While unit 1, the first reactor to explode at the plant, appears to be stable, unit 3, which exploded early Monday morning in Japan, reportedly has a leak in its bottom.

“We’ve never encountered this type of situation in history before,” Joe Cirincione, a nuclear policy expert, said. “We are beyond a reactor crisis at this point, this is a nuclear system crisis. The entire northern part of the Japanese nuclear power system has been delivered a body blow.”

The leak is making it difficult to keep the core of the reactor covered with sea water, Dr. Michio Kaku, a physicist, said.

“The situation is getting worse by the hour. We haven’t hit bottom yet… We now have reports that unit 3 suffered perhaps a 90 percent uncovering of the core — this is unprecedented since Chernobyl,” Kaku said.



2 mrem/hr is about 10-20X greater than the exposure rate on a cross-continental flight. The total EXPOSURE, not the rate, for a flight is ~2-5 mrem.

0.038 microsievert/hr is certainly a background level (and a low one at that).


From the Guardian some apparently good news:

“Justin McCurry, the Guardian’s Tokyo correspondent, emails to say the water level inside the No. 2 reactor at Fukushima Daiichi nuclear power plant has recovered to a level of about two metres, according to Kyodo News. The rods were fully exposed for about two and a half hours, according to Japan’s Nuclear and Industrial Safety Agency.”


It is also notable that the seawater/boron injection will trash a reactor core irrecoverably. Can’t even sell the stuff as scrap metal.

I also find it quite nonchalant by TEPCO to claim “no containment damage”. Would that not require up-close visual inspection? Did they do that? I heard them say this was too unhealthy at present.
We *know* there has not been a full containment breach.

In addition: how can the USS Ronald Reagan squadron detect radiation levels 700 times the background level 100 nautical miles offshore, if this is still INES-4? How can elevated radiation levels at Onaga (almost 100 land miles from Fukushima) be blown over from Fukushima and this still be an INES-4 event?

100 km+, IAEA has an interesting definition of “local”.


Re containment breach: if they had performed an up-close inspection, they would be able to give an explanation from which pipe or other peripheral system the Cs-137 and I-141(IIRC) did leak.

They assume it was not the containment, meaning that containment integrity is not even compromised (as their report states). But they have not provided another explanation. They simply ask us to swallow this fact, despite the fact that a lot of their past reports were simply summed up with 4 words: “complete and utter fiction”.

But some people will trust blindly in stakeholders harming themselves voluntarily… .


Thanks for the input but you appear to have lost a decimal point somewhere.

Check out the following web site:

Flying from Orlando to Tokyo today, this site says one should expect a dose of 70 micro-Sieverts or roughly 7 micro-Sieverts/hour.

Radiation levels at high altitude can be orders of magnitude greater during CMEs (coronal mass ejections).



you need to update the link to the TEPCO pdf, it’s still pointing to the earlier version and thus showing outdated information

Click to access 110314fukushima_event-status-2.pdf

(@ everybody) can substitute a 3 at the end in case there’s a new version available (+can reasonably expect the last part to change to /110315fukushima_event-status-1.pdf after Japan’s midnight)


I’m still wondering about the effect of 3000F seawater on the stainless steel containment vessel:

“The NRC recently notified licensees that chlorides – usually from the air at nuclear plants near the ocean, worker sweat or adhesives – have caused cracking on stainless steel piping in pressurized-water reactors.”



bks, I doubt the relatively slow mechanism of streess-corrosion cracking will be an issue – the corrosion will kill off the potential for restart, even if the damaged core rods can be removed. I don’t see these three reactors ever generating again.


Joffan, won’t they need to maintain containment on the Unit 3 MOX fuel for some years in that same vessel?



bks, nothing is leaving either reactor 1 or reactor 3 until the crane stages are rebuilt, so the question is a little academic; but my understanding is that any spent fuel, U or MOX, is much the same in terms of handling out of the reactor. I doubt they would leave the seawater in any longer than they have to, and the whole assembly will be cold and depressurized within a few weeks – eliminating the “stress” part of SCC.


Mr. Brook, I pray that you will extend your analyses to the current and most updated status of Fukushima no.2. You mentioned about the most important priority of cooling down and controling of internal nuclear reaction. What would happen now if they fail to cool down (by not able to pump in water in due time)? They say the ventilation openings were by some unknown causes closed, leading to exceedingly high internal pressure (which disabled any additional cooling sea water entry)


The libs and left are going to use this is an excuse to stall nuclear power efforts for decades. This disaster is going to set us back far longer than it will take the Japanese to clean up the situation.


William, this isn’t about left vs right. This isn’t about stalling. Reducing the discussion to Pro vs Anti stalls progress and clouds the real issues.

This is about how to provide the world with relatively safe power. Disasters like this uncover the truth behind the assumptions and propaganda.

“I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crises. The great point is to bring them the real facts.”
–Abraham Lincoln


The state of the ruined nuclear power plants is probably among the least of the worries of folks hit by this tragedy. While pollution by radionuclides is hardly a trivial issue, the threat to human life posed by this is no greater than threats due to mundane, uncelebrated harms like soot rising from poorly ventilated cooking fires in poor parts of the world.

The disaster in Sendai, and up and down the Japanese coast, looks truly horrific now, something you would never wish even upon your worst enemies. It’s funny how one realizes that parts of the world once thought to harbor creatures akin to Martians are actually the homes of human beings, mothers with children, and an enterprising young man washed 20 km to oceanward aboard the roof of what had been his house. It just takes Mother Nature in a bit of an irritated mood to force cognizance of our fellows upon us. The helplessness of an ex-homeless galaxian to relieve immense human suffering is immediately apparent, though I have sent a brief note of condolence. Best of luck.


Please publish the place where one can find out the readings on radiation levels at the gate of the plant. No one can use the quoted levels to inform other people if there is not a web link provided.


@William “The libs and left are going to use this is an excuse to stall nuclear power efforts for decades.”

Isn’t that nice. I hate the way nuke lobby has been pushing Gen 3 reactors instead of working on LFTR and other Gen 4. They have been doing a bait & switch – leaving tax payers on the hook if anything were to go wrong (like the present problems).


Can someone with a BWR background explain why the water level in the vessels is unknown? I thought BWRs had vessel monitors in the control room (but admittedly I know much more about PWRs).


The Punch is linking being tested for radiation with full thickness burns from napalm …

and when the story first appeared this morning, they even ran the original picture of naked Vietnamese children … they got enough flak that
they at least dumped the picture, but kept the
textual linkage.

My comment on said story hasn’t appeared … but some after it have, so I presume I’ve been cut.


All this is academic while the containment vessels remain unbreached.
To all those still scaremongering and gleefully promoting their anti-nuclear stance – where is your humanity. Thousands of people have died as a result of the earthquake and tsunami and you are trying to whip up hysteria. Galaxian has it right – let’s concentrate on what has happened in Japan not what might happen. All we should discuss here are the facts that are currently available, to assist people living in Japan and their family and friends elsewhere to guage the situation accurately. That is the purpose of this blog at this time and I suggest that everyone respects that. If you can’t do that -stay away!

Like lists the current radiation levels as:

MP3 (Monitoring at North West of Site Boundary for Unit 2) : 231.1 micro Sv/h (14:30 March 14)
MP4 (Monitoring at north- west of Site Boundary for Unit 2 : 56.4 micro Sv/h(04:08 March 14)
2 →29.8 micro Sv/h(14:14 March 14)

(Other monitoring stations are much less.)

This is pretty bad news. I think the INES level will be upgraded soon.



As I understand it, “unknown water level” means they are pumping water in, but the level is not rising [1]… Earlier it was reportedly thought to be a faulty meter, since other indicators (pressure etc) hinted to higher water level than indicated by the water level meter. Later the governement reported fuel rods having indeed been exposed.

Now turns out there has been another explosion around tow hours ago, possibility of rupture/leak in the containment vessel/suppression pool.



German TV is also reporting the confirmation of third explosion via telephone. the journalist also reported a very pessimistic feeling among press after a press conference early morning.

the complex can not withstand constant explosions.


Tv is still reporting, there is steam rising from the plant, about one hour after the explosion. they are measuring high values south and north of the plant.


Jason, plant 2, and it would mean containment is breached, stuff will soup out, and will further complicate cooling efforts.

This won’t stay on INES 4 much longer.


An article on the Web site of The Union of Concerned Scientists explains that a reactor’s suppression pool plays a central role in the event of a nuclear accident.

The water condenses the steam and cools down the air bubbling to surface of the suppression pool. The suppression pool water serves as an “energy sponge” to soak up energy (heat) released into primary containment during an accident. It heats up to nearly 200ºF during the course of an accident….

“The suppression pool water has another equally important job. The emergency core cooling system (ECCS) pumps take water from the suppression pool and supply it to the reactor vessel to prevent overheating (melting).”


Chris Warren, on 15 March 2011 at 11:21 AM — This is a highly focused thread for a particular topic. Take your general remarks to Open Thread 9, please. Thank you.


Surely the spent fuel is one of the most pressing problems at the moment? Looking at the cutaway diagrams, there isn’t really much protection for the pools, and both second and third explosions were massive.

Can someone reassure me that the uncontained spent fuel catching fire is not the most dangerous issue at the moment? Would the sea water pumping also include the spent fuel pool??


Was it the reactor with the plutonium that was breached? Is it possible that it was the plutonium itself that caused the breach? I’m asking because the Army ‘tips’ some of its tank rounds with plutionium right?

It would really suck if it was the most toxic fuel (plutonium) that was also the most likely to breach a reactor. Even more reason to never use that stuff again.

Nuke plant operator: reactor seal intact March 15, 2011 – 12:09PM


The seal around a reactor at a quake-damaged Japanese nuclear power plant does not appear to have been holed, the plant operator says, following an explosion at the plant.

Chief Cabinet Secretary Yukio Edano told reporters earlier on Tuesday that the suppression pool of the No.2 reactor at the Fukushima No.1 plant appeared to have been damaged.

The pool forms the base of the container vessel which seals the fuel rods.

Advertisement: Story continues below Plant operator Tokyo Electric Power Co (TEPCO) “said it believes the container vessel has not sustained damage such as a hole, judging from the fact that the radiation level has not jumped,” a spokesman for the country’s nuclear safety said.

A huge explosion hit the building housing the number-two reactor early on Tuesday, the third blast at the plant since Saturday – hydrogen explosions at Unit 1 and Unit 3.


To help allay people’s fears about radiation
“The psychological effects were the biggest health effects of all – by far,” said Fred Mettler, a University of New Mexico professor emeritus and one of the world’s leading authorities on radiation, who studied Chernobyl for the World Health Organization. “In the end, that’s really what affected the most people.”

In fact, radiation is a far less potent carcinogen than other toxic substances. Studies of more than 80,000 survivors of the Hiroshima and Nagasaki blasts have found that about 9,000 people subsequently died of some form of cancer. But only about 500 of those cases could be attributed to the radiation exposure the people experienced.

The average amount of radiation that victims in Hiroshima and Nagasaki were exposed to would increase the risk of dying from lung cancer by about 40 percent, Boice said. Smoking a pack of cigarettes a day increases the risk of dying of lung cancer by about 400 percent.

“Radiation is a universal carcinogen, but it’s a very weak carcinogen compared to other carcinogens,” Boice said. “Even when you are exposed, it’s very unlikely you will get an adverse effect. But fear of radiation is very strong.”


My god, the perps behind this site continue to ignore reasonable worst case scenarios.

If the containment vessel on Unit 2 is breached, the ability to control Unit 3 is being lost. The reasonable worst case scenario now is loss of containment on both Units 2 and 3, (and still maybe Unit 1). Unit 3 has the plutonium fuel, so if the containment vessel on Unit 3 explodes, the radioactive fuel (containing plutonium) can rain out on the terrain around the plant, and into the ocean.

The reasonable worst case is an increasing amount of radioactive material into the environment, and the dispersion of the radioactive contamination through the ocean and air.

The odds of losing the containment on both Units 2 and 3 are likely higher than 50%.


Can anyone explain why the difference in unit #2 – compared to 1 & 3. Why dd the blast occur within the secondary containment ? This sounds more serious than the other 2. Just heard from a Japanese colleague – they are really worried about this.


> half life of the released radioactive gases … short
> … why is the US Navy repositioning

Half life means average time until half decays into something else — not all of the results are stable; some decay into other isotopes that are also radioactive. The plume will be mostly volatiles — stuff that boils out easily, like iodine and ‘noble gases’; some part of those (not all, remember) will be radioactive isotopes. Look at their decay paths.

When a radioactive gas decays into a solid or chemically reactive element, that can quickly get heavy enough to fall out of the atmosphere, or could stick to something (like a helicopter). And those are what they could wash off with soap and water. (Also, rain can wash out both solids and gases).

It was helicopters delivering relief supplies that flew through a radioactive plume and came back with some contamination; they will be moving the ships so the helicopters don’t fly through airspace downwind of the source.


PaulK2 says

“If the containment vessel on Unit 2 is breached…”

As reported above the latest news

“TEPCO said it believes the container vessel has not sustained damage such as a hole, judging from the fact that the radiation level has not jumped,” a spokesman for the country’s nuclear safety said.


quokka, on 15 March 2011 at 12:32 PM — Thanks, but I don’t do telly. Could you kidly report a summary?


Interesting that the Japanese PM spokesman says there is a hole in Unit 2 pressure vessel, while TEPCO says radiation isn’t high enough (yet) to confirm a hole in Unit 3.


Sorry… correction:

TEPCO says radiation isn’t high enough to confirm a hole in Unit 2, while PM office says there is a hole.


Reactor 4 is on fire, apparently due to debris falling onto the building from the other explosions. Radiation levels due to that fire are in millisieverts, not microsieverts, and are in the range dangerous to human health. All but 50 of the 800 workers are being evacuated. Between 20 and 30 km away from the plant shelter in place, close windows, do not use ventilation.

I’ve typed some transcripts into the older general thread as I heard them on the live stream:


@David B. Benson

Summary: Not Good.

High radiation readings – can’t remember exact figures. Think it was up to hundreds of mSv/hr (?)

Probably a rupture in #2 pressure vessel.

Fire in #4 reactor. No fuel in reactor but there is spent fuel stored and apparently radiation release.

Continuing to pump water into 1,2, 3.

No further evacuations – advice is to stay inside for people 20km – 30km from plant.

Hope I’ve got this broadly correct.

There is a lot of fear. Nikkei futures down ~12%



At my work place our maximum allowable annual dose is 0.05 Sv i.e. 50 milliSievert, so 38 comes close but definitely not background. Here is the detailed breakdown allowed by the Nuclear regulatory commission:

The Nuclear Regulatory Commission (NRC) has set standard maximum permissible doses. These limits are as follows:

Adult (Non-pregnant Workers)
18 years and above
Organ Yearly Limit
Whole Body (uniform exposure) 5,000 mRem / 0.05 Sv

Extremities (upper & lower) 50,000 mRem / 0.50 Sv
Skin 50,000 mRem / 0.50 Sv
Thyroid 30,000 mRem / 0.30 Sv
Lens of the Eye 15,000 mRem / 0.15 Sv


The Japanese PM recently gave a press conference where he emphasized that radiation levels near the reactors were now hundreds of mSv (eg 100 mSv near reactor 4.) The chief cabinet secretary spoke at more length and reiterated that levels were currently hundreds of mSv. Presumably they mean mSv/hr.
The press conference was on

Whether or not this represents a significant worsening of the situation, it explains why they have evacuated all but 50 essential personnel (those doing the pumping). A day’s work at those levels would leave you pretty sick without good protection. Let’s just hope the winds stay low and the fire in reactor 4 hasn’t spread too much radiation.


If unit #4 has “no fuel rods” how can there by “damage to the rods suspected” seems people would rather give their opinion than actually understand what they are reading.. hack bloggers, talking about things they know little about, reading the same information everyone else is on google news. Looks like a fair amount of time went into creating that image.. Too Bad its inaccurate, Making it as useless as anchor on a airplane


I don’t think this is a proper place to tell any idea to cool down reactor at Fukushima but may be some proper guy will get through it.
Well idea is all about that a huge team can work from out side of 30KM area with normal tools to cool down the reactor.Ask How ?
The Under sea fiber optic cable has the continues length of 50KM or more and with 1000lb weight hold capacity.
ships-undersea-fiber-optic-cable stand out side the radiation area.and helicopters take the fiber-optic-cable and tie them on tower near the reactor.the fiber optic cable hold water piper or bukets.
the number of fiber cables tie between ship and tower and supply sea water continuely to the reactors to fill the tank.
The ship has three work to do.
1- unroll the fiberoptic to long distance with 50% water floots tie on it.
2-tie the fiber optic to any other mount on ship after achiving the reqired distance.
3- pump water into the pipe attached with fiber optic.
the simple helicopter has three works to do-
1- take the fiberOpticCables attached waterpipe to the other side of the plan without passing through radiation area.
2- Specil helicopeters Anker the fiberOptic-cable on same tower near the reactors or simple helicopters can Tie it on any other tower outside radiation area but can put water over the reactor area’s
3- hold the cable in Air in case of no tower avaible.

So all idea is about to work from out side of radiation area with a large team and equipment which is not specially designed for radiation safty.


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