Fukushima: Reactor 3 blast looks serious

After correct analysis ahead of concrete news from Japan on Saturday, more analysis from ex-nuclear physicist Kevin today.  While the media is speculating like crazy and ‘official sources’ are playing down the risks, to a former AGR designer, it looks serious.

[Update 23:30 – BBC is reporting a third explosion at Reactor 2]

Earthquake and Tsunami damage, Japan-March 14, 2011: This is a satellite image of Japan showing damage after an Earthquake and Tsunami at the Dai Ichi Power Plant, Japan. (credit: DigitalGlobe) http://www.digitalglobe.com

Firstly what really happened at Reactor 1?

There is too much speculation with regard to the state of the reactor core. The bottom line is the hydrogen must have come from somewhere and dissociation of the coolant is the obvious source. I think there has been a partial core melt with the production of some hydrogen from an interaction between the very hot (superheated) steam and the cladding and /or other steel component parts of the reactor vessel. I find it laughable when some of the LWR people posting refer to PWRs and BWRs being inherently safe because if the coolant boils away you can’t get a re-critically of the core. Maybe, maybe not, but I’m sorry what you have got is a core meltdown in this case.

Chernobyl (credit: http://www.stsci.edu)

This is because the power density of LWRs is much higher than say UK advanced gas-cooled reactors. High temperature steam and hot steel is not a good mix. CO2 and stainless steel as we have in UK AGRs is much more less chemically reactive. I’d never have the hubris to try to claim that because of this relative chemical inertness AGRs are ‘inherently safe’. If you lose all the CO2 coolant because of the containment depressurising then you will have a meltdown of some degree. I don’t think I’ve ever recounted my story of an experiment not dissimilar to what happened at Chernobyl – ah well sometime.”

And now the Reactor 3 explosion

There are reports coming out following the Reactor 3 explosion that we now have fuel melt in all 3 reactors at Fukushima. I get no pleasure whatsoever from turning out to be correct in my guess as to what was likely to be happening on Saturday morning.

This is more than just the roof cladding blowing off as happened in Reactor 1

The Reactor 3 explosion was much larger than the Reactor 1 explosion and this looks to be much more extensive damage to the R3 recator building, yet hey are claiming no significant radiation leaks and that all 3 reactor vessels are intact.

Looking at the explosion again and then the close-in damage after, I’d say they the force of the explosion didn’t come from hydrogen in the reactor hall as it did for R1 but rather below the level of the reactor hall,  i.e. at the level of the primary containment that surrounds the reactor pressure vessel.

Close up - as picture above, with notes (credit: DigitalGlobe)

Whereas Reactor 1 has little damage to the bottom half of its reactor building, Reactor 3 is showing extensive damage to the concrete walls, internal and external to the base of the Reactor 3 building.

BWR Design (credit: http://enr.construction.com)

If you look at that diagram, the toroidal coolant suppression pool system is below ground level but the primary containment with the reactor pressure vessel is inside it above ground and the footage is showing definite and extensive damage to that part of the building. I’m sorry but there must be damage to the penetrations (inlet and outlet pipes) to the reactor pressure vessel.

I know I’m speculating quite a bit but I’m just looking for evidence that the floor above – the roof above the primary containment and floor of the reactor hall above it have been blown up. And what has happened to that ‘refuelling bridge’ as its called?

The Register reports:

This structural damage is purely cosmetic, and the radioactive material released into the atmosphere poses a negligible threat to the population.

Well does the damage to R3 look cosmetic to you?

And the continuing concern over Reactor 2?

According to some reports Reactor 2’s core has twice been completely uncovered. If so then that could result in a complete fuel meltdown, and the control rods are inserted from the bottom of this type of reactor.  Earlier today they were talking open breaking into the R2 reactor roof to relieve pressure and prevent possible hydrogen build up so maybe it just hasn’t built up as much as it did for R1 and R3.  But I’d expect to have seem some steam coming out of the R2 reactor building roof if that had happened.

Earlier NHK-World-TV interviewed the designer of the Fukushima plants; he seemed to think the reactor vessel has a leak, which was reducing levels in the reactor.

According to The Guardian this evening, Reactors 1 & 3 are relatively stable for now, however Reactor 2, which had been using an emergency pump to keep the reactor cool was still of concern:

Speaking about the situation at Reactor 2, the government’s chief cabinet secretary Yukio Edano said: “The pump ran out of fuel, and the process of inserting water took longer than expected, so the fuel rods were exposed from the water for a while.”

The decision to pump salty, untreated seawater into the nuclear reactors – along with boric acid to dampen down radioactivity – is a vastly expensive last resort that effectively writes off the reactors. The plants are usually cooled by highly purified deionised water that does not damage the delicate components inside.

Engineers at the power plant face a difficult balancing act because the seawater being pumped into the reactors immediately boils and the steam is raising the pressure inside. This has to be vented before more water can be pumped in, but this releases small amounts of radioactive material into the air.

Update: from The Telegraph:

A huge explosion hit another reactor at an earthquake-damaged Japanese nuclear power plant early Tuesday, the third blast since Saturday, the plant operator said.

“There was a huge explosion” between 6:00 am (2100 GMT Monday) and 6:15 am at the number-two reactor of Fukushima No.1 nuclear power plant, a Tokyo Electric Power Co (TEPCO) spokesman said.


Chief Cabinet Secretary Yukio Edano told reporters the suppression pool of the number-two nuclear reactor appeared to have been damaged.

This is the bottom part of the container, which holds water used to cool it down and control air pressure inside.

This could be much more serious…

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12 Responses to Fukushima: Reactor 3 blast looks serious

  1. Brian Phipps says:

    NHK reports (per TEPCO) that the explosion in Unit 3 blew the roof off the spent fuel pool. This may explain some of the steam visible in the photo. It also means that the spent fuel (quantity?) is now a factor in any meltdown equation.

    NHK also reports (per TEPCO) that the explosion occurred in the lower containment/ suppression pool area, confirming your speculation.

  2. boballab says:

    Seems like a bad design to keep the spent fuel pool in the same building as the operating reactor (The plant I was at that was a separate facility), but if true, again as long as the containment vessel remains intact it isn’t the concern and if the things are stabilizing in 1 and 3 as reported then that would point to no damage to the containment vessel. Always keep in mind blast force follows the path of least resistance. It is much easier to blow out the outer building then it is to crack the containment vessel (or the below ground components) when an explosion happens between the two. Then again we are only speculating from what we can see in photos. Though between here and EM Smith’s site the speculation has been more accurate then MSM and more timely. Ralph B called Hydrogen Explosion on EM’s site at the same time Kevin called it on WUWT for Unit #1, 13 hours before the news reported it.

    Has anyone seen a video of the explosion at #2 yet? After eating and such I wasn’t watching updates and just seen a report that #2 had an explosion but they keep saying it was heard but I have seen no video/stills. Also what I have been hearing it sounds like #2 is much worse then the other 2. Like I stated in the other thread this one was the one I was worried about because of what TEPCO and NISA reported earlier about having problems venting #2 and not able to keep the water level up.

    Oh great, NHK is reporting that a fire has broken out from a hydrogen explosion at #4. They are reporting they think the Hydrogen came from the spent fuel pool there.

    • boballab says:

      Here is the best description I have heard about what happened to Unit 2 so far:

      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)

  3. gallopingcamel says:

    A key issue is area monitor readings. According to TEPCO the highest reading at the boundary of the Daiichi facility was 20 micro-Sieverts/hour yesterday, falling to 15 today. They report 0.038 micro-Sieverts/hour for the Daiini facility (background levels). See:

    Meanwhile government officials are talking about potentially lethal radiation levels:

  4. boballab says:

    I have been monitoring the TEPCO and NISA English websites and so far there hasn’t been a release about Unit #2 yet. On the NISA Site they got ones for units 1 and 3 only and on the TEPCO site they also have statements about 1 and 3, but also the minor problem they had at unit 4. To me that is mildly disturbing, especially when taken in concert with a NISA official on NHK stating the explosion at the #2 Unit was near the Suppression Ring and so far I haven’t seen a video of the explosion. As Kevin’s diagram shows that is below ground and a large Hydrogen Explosion in that enclosed space has a much larger potential to do serious damage then above ground where the blast effects can be dissipated taking out the relatively weak outer wall of the building.

    This is also the unit that NISA has stated on NHK that the core was completely uncovered for over 260 mins when the injection had to be halted and then only half covered after they were able to resume. It is also the Unit I believe one of designers of the Fukushima plant thinks might have a leak.

    All in all to me that spells this unit is the one to watch out for major problems.

  5. KevinUK says:


    “All in all to me that spells this unit is the one to watch out for major problems.”

    I agree. It’s always what you aren’t being told about that you should be worried about. From the start of these series of incidents we were reassured that all three reactors had be shutdown successfully and that all would be fine. Yet subsequent events have proven otherwise. There is clearly some degree of withholding of bad information going on. I can live with that and can understand why it is necessary inorder to avoid panicking the local population.

    What I can’t stand is the constant wheeling out of so called ‘nuclear experts’ on the different MSM TV channels who clearly don’t have much of a clue about what they are talking about. Each time someone new is wheeled out I immediately Google them and so far they have all been either PR hacks (like the first so called nuclear expert on BBC News I saw who turned out to be a former UKAEA ‘information officer’), members of anti-nuclear advocacy groups like Shaun Burnie or (worst of all IMO) bloody academics (like Paddy Regan) who’ve never been anywhere near a nuclear power plant let alone had to deal with a major incident at one. In Paddy regan’s case I let him off as he is a former Liverpool University Physics graduate (like myself) and he was (unlike al the others) actually quite accurate.

    We are all supposed to learn lessons from our previous history (like what happened post the Chernobyl disaster – lots of feeling of deja vu with this latest nuclear incident for me I’m afraid). As with climate change it appears that some would prefer not to learn what history has taught us time and time again. Instead so-called experts (who aren’t experts but only self proclaimed experts who in realit like us just don’t know whats happened) prefer to once again show their hubris and try to tell us that they are right and that because they know they are right that we must do what they are telling us to do.

    After all the dust has settled on this incident so to speak, appropriate inquiries will take place, recommendations will be made (and probably not implemented) and some lessons will be learned no doubt. We will most likely find out that the reactors were not in the best state of preparedness and that contingency plans were never particularly well exercised because this was never going to happen was it? Well it did! Will Japan and other countries still think it is a good idea to build reactors of this type (any type!) in a (relatively high) seismically active area on the coast of a very large ocean? I suspect as is all too often they case that inconvenient history will be fogotten and some point some scientist/nuclear safety consultant will be paid handsomely to announce that the next best generation of NPP made by XXX is ‘inherent safe’ and can withstand equakequake strength X followed by tsunami wave height Y.

    Given the situation they are in they’ll have to start up their other NPPs because they are desperate for reliable power at the moment. Power they will desperately need in order to deal with the after effects of the earthquake and tsunami. If they don’t then all they will be doing is prolonging the recovery period because of international politics and that IMO is bad, very bad.

    Talking parochially. How do I expect this incident to affect the UK’s nuclear plans? Well judging from the ‘Buff Huhne’s’ (buffoons) comments to date, our (with very few exceptions) incompetent. scientifically illiterate and self-serving politicians will cover their ears, and mouths and close their eyes and carry on regardless and do what they were always planning to do anyway. They (and their paymasters) care not one jot what the electorate thinks.

  6. boballab says:


    I lived for over two years in Japan and their mentality about disasters (or any type of mishandling of events) is completely different then the western one of playing the blame game and passing the buck. This is one of the reasons I went to the NHK direct feed.

    On it you saw NHK talking directly with one of the designers of the plant and he was giving frank answers. Would you see that from a guy that designed a plant for GE in the US or how about the UK? Not hardly, you would get a quick no comment and after that a PR hack and lawyer would be making all the statements.

    Also NHK had the guy on from Tokyo University that did the report for the Japanese government 10 years ago (after the 1995 Kyoto quake) on that fault line where he stated bluntly they never expected that fault to be able to produce a quake higher then in the low 8’s and that they expected a High 7 to Low 8 quake within 30 years. From there they ran models on what size Tsunami they would get and that came back with no bigger then 25 to 30 ft (less then 10 meters). From there they wen’t in put in those 10 meter high seawalls and re-did there buildings to withstand a quake of the size they predicted. They admitted they were wrong in the interview and with the new data about how the sea floor in that area is they re ran the computer models on how high a Tsunami would get from a 9.0. Turns out in the shallow bays and such the wave got well over 40 ft in height in the simulation, just like what really happened since it went over 10 meter walls. Now what was the last wave height the MSM reported 25ft? Again would an academic that did a report for the US or UK governments admit to the media they screwed up? Not a chance, again it would be no comment followed by the PR hacks and lawyers.

    You just wouldn’t see that type of stuff int he West, too afraid of the lawsuits and looking guilty.

    • Verity Jones says:

      Watching NHK thanks to you is actually something of a revelation. In the UK we are so used to speculation being pushed as news in the MSM and NHK is refreshingly devoid of this. As you say they report ‘what happened’ – facts, reasons, causes.

      I’m glad that the damage to R3 seems to be small, despite looking so bad. IIRC Kevin plays squash on Tuesday evenings, so isn’t around tonight.

      As you say the lack of news about R2 is concerning. There seems to be little new information today. Some here about R4: http://nei.cachefly.net/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/

      “Tokyo Electric Power Co. said that an oil leak in a cooling water pump at Unit 4 was the cause of a fire that burned for approximately 140 minutes. The fire was not in the spent fuel pool, as reported by several media outlets. Unit 4 was in a 105-day-long maintenance outage at the time of the earthquake and there is no fuel in the reactor.”

      • boballab says:

        Still nothing from NISA or TEPCO on their websites but NHK had NISA officials on and they said they thought Unit #2’s explosion was near the Suppression ring and might have damaged it. Still I haven’t found a single video of the Unit 2 explosion unlike with Unit 1 and 3. However I did find these two things from the IAEA (International Atomic Energy Agency) today:

        Japan Earthquake Update (15 March 2011, 18:00 UTC)

        The IAEA can confirm the following information about the status of the Fukushima Daiichi nuclear power plant:

        Unit 4 was shut down for a routine, planned maintenance outage on 30 November 2010. After the outage, all fuel from the reactor was transferred to the spent fuel pool.

        Units 5 and 6 were shut down at the time of the earthquake. Unit 5 was shut down as of 3 January 2011. Unit 6 was shut down as of 14 August 2010. Both reactors are currently loaded with fuel.

        As of 00:16 UTC on 15 March, plant operators were considering the removal of panels from Units 5 and 6 reactor buildings to prevent a possible build-up of hydrogen in the future. It was a build-up of hydrogen at Units 1, 2 and 3 that led to explosions at the Daiichi facilities in recent days.

        Japan Earthquake Update (15 March 2011, 14:10 UTC)

        The IAEA remains concerned over the status of the Fukushima Daiichi nuclear power plant, where sea water injections to cool the reactors in Units 1, 2 and 3 are continuing. Attempts to return power to the entire Daiichi site are also continuing.

        After explosions at both Units 1 and 3, the primary containment vessels of both Units are reported to be intact. However, the explosion that occurred at 21:14 UTC on 14 March at the Fukushima Daiichi Unit 2 may have affected the integrity of its primary containment vessel. All three explosions were due to an accumulation of hydrogen gas.


        Also in Japanese culture admitting you made a mistake is not the same as an admission of guilt, unlike in modern western culture. If for example the academic that made the report tens years ago that turned out to underestimate what that fault could do didn’t admit that error, in Japanese culture that would be a sign that he deliberately got the report wrong for whatever reason. Remember in Japan accepting and admitting your mistakes is culturally the honorable thing to do and is a huge mitigating factor in Japanese court when things like suits and damages get sorted out. Also you need to take into account the religion of Shinto. The BBC actually has a very good description of Shinto:


        Purity is at the heart of Shinto’s understanding of good and evil.

        Impurity in Shinto refers to anything which separates us from kami, and from musubi, the creative and harmonising power.

        The things which make us impure are tsumi – pollution or sin.


        The causes of impurity

        Pollution – tsumi – can be physical, moral or spiritual. ‘Tsumi’ means much the same as the English word ‘sin’, but it differs from sin in that it includes things which are beyond the control of individual human beings and are thought of as being caused by evil spirits. In ancient Shinto, tsumi also included disease, disaster and error. Anything connected with death or the dead is considered particularly polluting.


        There is many things a westerner wouldn’t think twice on that is considered at the minimum rude up to including mortal insult. Here is an example: You are sharing a a meal and eating with chopsticks and you are stuffed. You offer the rest of you meat to your significant other and they accept. You pick the meat up with your chopsticks and hand it over and they take it from you with their chopsticks.

        Seems pretty tame but that is a very big no no since it deals with the Shinto practice of passing on the ancestors bones, which is the only time you pass something from one person to another and both use chopsticks and never let the object touch down in between. So you are touching on the impure topic of death at the dinner table.

        Another one: You go to wave a Japanese person over to you from a distance away. The way we do it in the west with hand turned up and palm facing in towards you, with arm motion starting low and going high is a major insult. That is the way you call for a dog. The proper way is to put your arm out straight, palm down. Then move your hand and arm like you are a kid digging sand one handed at the beach.

        That is just two examples that shows that you can not look at how the Japanese react through the prism of western culture.

  7. Verity Jones says:

    Other cultures are fascinating, especially when you have the time and opportunity to explore the details through contact with friends or colleagues.

    I’ve always liked “the person who never made a mistake, never did anything”. The culture of culpability that has developed in the West can be very counterproductive.

  8. gallopingcamel says:

    Much has happened during the last two days, particularly with regard to the storage of spent fuel rods withing the reactor buildings. We have all seen the helicopters dropping water.

    What puzzles me is that even if radiation levels inside the building are high there must be some place in the supply piping that can be used to inject water into the storage pools without exposing workers to unacceptable levels of radiation. It would make sense to use the helicopters to bring in water tanks so that the contents can be pumped directly into the pipework without wasting most of the water as the air drops do.

    I am following the story via NHK and Brave New Climate:

    • boballab says:

      The problem is no longer “inside the building” since all 6 outer shells have either blown apart (Units 1 and 3) or have holes put into them either through explosions (Units 2 and 4) or deliberately (Units 5 and 6) to vent steam and hydrogen. So you get increased radioactivity every time they vent from one of the reactors containment or pressure vessels.

      Another of the problems is that people that haven’t been trained in the field/been in one of these facilities do not the actual scale involved with these pipes and pumps. The amount of water a firetruck pumper can move is a tiny fraction of the amount of water these pipes handle to the Containment and Pressure Vessels. To put it into perspective to power just one of the coolant pumps it will take 1 GE Gas Turbine Generator. The size of this generator is so big it takes 4 tractor trailers to hold the whole thing and 3 days to set up.

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      GE is sending 3 of these packages to Japan to help out, but it will still take awhile to get them to the site and set up. First it will take a about a dozen large cargo planes such as the C-17 to fly them to Yokota Air Force base. Then you will have to find a land route that isn’t clogged with debris or damaged to the point such heavy objects can’t transit through. The hearts of these monsters are just too big even for the CH53E Super Stallion Heavy Lift Helicopter to move.

      As to the Spent fuel pools, the firetruck pumpers can handle those but they have to get close enough to the buildings to hook up, which brings us back that the operators of those trucks have to fall back each time they vent the cores/containment vessels.

      Over on EM Smith’s site George (another old Nuke hand) has seen a report where the Japanese are running a land line to a fixed grid some distance away. Once that gets hooked up and tested that will at least provide enough juice to power at least one coolant pump. However keep this in mind just about every cable line that is less then about 7 to 10 meters above the ground has to be replaced because of them getting flooded by the Tsunami.

      [Reply – thank you – timely and pertinent comment once again – Verity]

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