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I was sent an email with a copied/pasted version of this NaturalNews article which contains the following quote (emphasis original):

Concerned about the 2012 U.S. presidential election? Worried about GMOs? Fluoride? Vaccines? Secret prisons? None of that even matters if we don't solve the problem of Fukushima reactor No. 4, which is on the verge of a catastrophic failure that could unleash enough radiation to end human civilization on our planet.

"It is no exaggeration to say that the fate of Japan and the whole world depends on No.4 reactor." - Mitsuhei Murata, Former Japanese Ambassador to Switzerland and Senegal, Executive Director, the Japan Society for Global System and Ethics

...

To better understand the severity of this situation, read these facts about Fukushima reactor No. 4 which I have assembled from available news sources:

  • Reactor #4 contains 1,535 spent fuel rods which remain highly radioactive.
  • These fuel rods currently hold the potential to emit 37 million curies of radiation.
  • Those fuel rods are stored in a concrete pool located 100 feet above the ground, inside the structurally compromised reactor building, effectively making the pool open to the air.
  • The pool holding these fuel rods is "structurally damaged."
  • "If an earthquake or other event were to cause this pool to drain this could result in a catastrophic radiological fire involving nearly 10 times the amount of Cs-137 released by the Chernobyl accident." - Mr. Robert Alvarez, former Senior Policy Adviser to the Secretary and Deputy Assistant Secretary for National Security and the Environment at the U.S. Department of Energy.

The opening statement says, "on the verge of a catastrophic failure," however subsequent statements say, "If an earthquake or other event were to..." These seem to be at odds. Couldn't one say my house is "on the verge of a catastrophic failure if an earthquake or other event were to destroy it"?

Just how likely is the failure of Fukushima Reactor Number 4, and what would the impact of such a failure be?

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Here's some collaborating evidence that the Mitsuhei Murata quote is accurate and in context. –  Oddthinking May 22 '12 at 4:32
    
I think you are misunderstanding the meaning of "catastrophic failure". –  Sklivvz May 22 '12 at 7:22
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There is a LOT of misinformation out there when it comes to Fukushima. Check out neutroneconomy.blogspot.com for real information from real nuclear engineers. –  David Boike May 22 '12 at 12:06
    
@Sklivvz 1) "You" == "me"? 2) How and where? I don't understand the comment. Was it my statement about my house? –  Hendy May 22 '12 at 22:23
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Oh man, some of the other points he makes are equally ridiculous. One is that the fuel should be moved into dry casks, but that the equipment to do that was destroyed. Fuel needs to be stored underwater for up to 20 years before it can be stored in dry casks, so I'd say there's plenty of time for repairs. –  jozzas May 22 '12 at 23:12
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2 Answers

No.

The assembled facts are all fairly inflammatory, and include a few common misconceptions.

  • Reactor #4 contains 1,535 spent fuel rods which remain highly radioactive. These fuel rods currently hold the potential to emit 37 million curies of radiation.

Firstly, definitions: Reactor 4 was shut down for maintenance(PDF, p35) when the earthquake struck, and all of the fuel assemblies had been removed from the reactor. There is a spent fuel pool which comprises part of the reactor 4 building, but these are absolutely not the same thing.

The spent fuel pool is literally a pool filled with water for holding spent fuel rods (in their assemblies) which allows them to cool (a years-long process once they are deemed "spent" and removed from the reactor core). All of the fuel assemblies that were removed from reactor 4 prior to the earthquake were placed into this pool in the reactor 4 building.

The spent fuel pool contained 1535 spent fuel assemblies at the time of the earthquake. As spent fuel assemblies are kept underwater, under normal conditions it is perfectly safe to walk around near the surface of the pool (see below), as no or very little radiation is emitted. Each fuel assembly contains 50-70 fuel rods.

Fuel Pool Image

Image Credit


  • Those fuel rods are stored in a concrete pool located 100 feet above the ground, inside the structurally compromised reactor building, effectively making the pool open to the air.

There are a few points here. Firstly, the concrete pool is located 4-5 storeys above ground level and is part of the structure of the reactor building itself. See the image below, where the spent fuel pool is labelled (5) and the spent fuel rods (27). It is not inherently more dangerous to have the spent fuel pool high above ground level - in fact the opposite is the case. The reactor is designed this way in order to eliminate any risk of any part of a damaged fuel pool's contents reaching the water table, allowing for redundant containment systems to be built beneath it.

enter image description here

Secondly, that the reactor building is structurally compromised. This is more or less restated in the next bullet point, which I address below.

Thirdly, that the spent fuel pool is open to the air. The upper surface of the pool is normally enclosed by a sheet metal structure (see picture above), which was blown off by a hydrogen explosion (the hydrogen may have come from reactor 3 via a pipe, but there have been subsequent contradictory reports) after the earthquake. The sheet metal structure is not meant for containment of radiation, so the pool being "open to the air" is not considerably more dangerous than if the sheet metal structure was intact. The fuel pool is currently covered with plastic sheeting to minimise evaporation.


  • The pool holding these fuel rods is "structurally damaged."

The reactor building and the pool were damaged, yes. A lot of things happened, so this is a massive oversimplification.

  1. The upper reactor building (sheet metal structure) was badly damaged by a hydrogen explosion (the pool is "open to the air"). I am unsure as to whether repairs have been made to this portion of the structure, as it is not critical for structurally or for safety I assume its repair would have been a lower priority.
  2. The pool was structurally compromised. This has been defined as a "4cm bulge" in one of the walls of the fuel pool. It has supposedly since been reinforced(PDF) with steel beams and concrete pours. It should be noted that at no time during the earthquake, tsunami or explosion did the fuel pool leak.
  3. The reactor itself or other parts of the reactor building may have been structurally compromised. I can't find much information on this, but the reactor was not running, has not been restarted and it is unlikely that it ever will be.

  • "If an earthquake or other event were to cause this pool to drain this could result in a catastrophic radiological fire involving nearly 10 times the amount of Cs-137 released by the Chernobyl accident."

The points leading up to this last one are worded so as to make you more and more fearful, culminating in this scary quote. However, since the earthquake:

  • All ability to circulate cooling water through the fuel pool was lost
  • Water injection was used to keep the levels high until the ability to pump was restored
  • Circulation cooling (rather than injection) has since been resumed
  • The pool has been structurally reinforced
  • The fuel rods in the pool show no signs of damage when observed with overhead photography, from both the low water levels and the earthquake itself.

The fuel pool has proven itself as remarkably resilient, withstanding a magnitude 9 earthquake, a tsunami, a loss of power, a loss of cooling, an explosion, low water levels partially exposing fuel rods, and minimal damage was sustained. I consider that pretty damn impressive. Given the repairs made to it, the likelihood of an earthquake causing the pool to drain is low. If it did occur, workers would follow the same procedure to keep the pool partially filled until cooling could be restored.

The quote sounds like a response to a question like "What if the spare fuel pool drained completely?", and there are a number of unlikely events required in order for such a situation to arise:

  1. Another earthquake of an intensity causing structural failure of the (repaired, structurally sound) fuel pool. This would have to be of a similar magnitude to the last one.
  2. That this structural failure itself is so severe that the fuel rods for some reason cannot be cooled by topping up the leaking fuel pool ("emergency cooling" like was performed last time), causing a radiological fire
  3. That the radiological fire could not be contained by any other means (dumping boric acid / sand / any number of other potential options) and is allowed to burn all of the available fuel
  4. That a radiological fire could and would release all of the Cs-137 contained in the fuel rods into the atmosphere.

The likelihood of all four of these things happening is just not very high. I haven't even looked at the consequence if these things were to happen, I may add something later.

I would assess the situation with the reactor 4 spent pool fuel as "stable, but obviously not ideal". It is not "on the verge of catastrophic failure". The end of the world is not nigh. This seems to be a fairly honest assessment of the situation.


In terms of potential consequence, I have been scouring the internet for any kind of modelling performed for expected outcomes for radiological fires in fuel pools. I can't find a thing. Please comment if you know of anything.

As far as I'm aware, the statement that all of the potentially radioactive material in the fuel rods could be released by a cladding fire is completely unfounded.

From what little I have been able to find, it appears that runaway zirconium cladding fires are an area of active research, and there aren't any definitive answers. For one to have any chance of happening, there would need to be relatively "fresh" (hot) fuel rods that had recently been moved to storage, and for them to become completely uncovered due to another loss of cooling/water.

Whether or not the zirconium "fire front" could spread from those initial assemblies to other, cooler assemblies is unknown. It also commonly stated that this event occurring may also require a physical failure in containment (dropped assembly / falling debris) causing two rods/assemblies to come into contact causing a criticality/excursion.


30th June 2012 Update: It also appears that the cooling system for the fuel pool in reactor building 4 has failed and is set to be restarted within a couple of days.

Tepco has been unable to activate a backup cooling system for the pool and is looking into the cause of the trouble, officials of the plant operator said later in the day, adding it is unlikely the temperature will rise rapidly.

The water temperature of the pool was 31 C at the time of the suspension at around 6.25 a.m. local time and no leakage of water with radioactive materials has been found, Tepco said.

The temperature of the pool rose 0.26 C per hour by late Saturday afternoon, according to the utility.

If Tepco continues to be unable to cool the pool, the temperature could reach 65 C, which is the upper limit designated in the safety regulations, on Tuesday morning. The cooling system at the No. 4 reactor was previously suspended on June 4.

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You missed the part where the pool is inside a containment barrier that is seperate from the containment of the spent fuel rods. The entire design of which is intended to be entombed with concrete in a worst case scenario. –  Chad May 22 '12 at 18:07
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Not to mention the silliness that "10x as much Cs-137 as Chernobyl" == "The whole world will die"... the author's been playing too much Stalker: Shadow of Chernobyl. –  Ben Brocka May 22 '12 at 20:55
    
@Chad I thought that was one of the flaws of this reactor design - There is no backup fuel pool cooling, no backup water storage for the pool, and the hydrogen explosion did make the pool open to the air. Steam was observed coming from the building days after the earthquake, which was assumed to be the water in the fuel pool boiling off, the response was to pump seawater into the pool (as there was no power and no fresh water available). Do you have a link about these containment barriers? –  jozzas May 22 '12 at 22:49
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Random anecdote: When I worked at a CANDU reactor, I never went into the spent fuel rod pool room, but just after the jettisoned the rods from the core into the pool you could see the pool glowing through the windows. It reminded me of the movie cocoon. –  Brian M. Hunt Dec 18 '12 at 1:59
    
and even if there were catastrophic failure (which is next to impossible), and that failure would cause a nuclear detonation by the fissionable material on site (which is impossible), that would not be powerful enough to destroy the planet. It might cause a great big hole in the ground on site, and serious contamination over an area with a radius of a few dozen kilometers, light contamination over a larger area, maybe a plume a few hundred kilometers wide and a few thousand long that would rapidly dissipate to below detectable levels, but that's it. –  jwenting Jul 15 '13 at 13:51
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Through my research, it's clear that such an event would indeed effect the entire world (much like Mount St. Helens), but it wouldn't be enough "to end human civilization on our planet."

I'm using Chernobyl as a baseline, since it was mentioned in the article. It says that 10 times the amount of Cs-137 will be released. Taken from the Chernobyl Wiki:

An area extending 19 miles (31 km) in all directions from the plant is known as the "zone of alienation."

I'm not a mathematician, but 10 times 19 miles is 190 miles (Or ~310 km). That's hardly a planet-wide apocalypse.

Also from the International Nuclear Event Scale, and the Fukushima disaster earned the highest rating (Level 7) right underneath Chernobyl.

Fukushima Daiichi nuclear disaster, a series of events beginning on 11 March 2011 ... Major damage to the backup power and containment systems caused by the 2011 Tōhoku earthquake and tsunami resulted in overheating and leaking from some of the Fukushima I nuclear plant's reactors. Each reactor accident was rated separately; out of the six reactors, three were rated level 5, one was rated at a level 3, and the situation as a whole was rated level 7. A temporary exclusion zone of 20 km was established around the plant as well as a 30 km voluntary evacuation zone.

Another excerpt from the Comparison of the Fukushima and Chernobyl nuclear accidents;

Maximum level of radiation detected

FUKUSHIMA: 72,900 mSv/h (inside reactor 2)

CHERNOBYL: 200,000 mSv

The point I'm trying to make is that all of the observations about both Level 7 Nuclear incidents says that Fukushima isn't as large as Chernobyl, and Chernobyl wasn't exactly a civilization-ending event.


EDIT for @Jozzas:

Of all of the studies I have found of various nuclear disasters, it seems that scientists are just now coming out with the long-term effects of small-scale events.

I have found numerous predictions about the effects of this, concentrating on the Pacific Ocean. Here,

Al Jazeera claimed “prevailing winds are likely to carry any contaminated smoke or steam away from the densely populated Tokyo area to dissipate over the Pacific Ocean.”

This image, as claimed official by a commenter (Doc Holiday, comment #2), shows the Pacific Ocean effects;

US-NRC Pacific Ocean prediction

Most of the predictions come from conspiracy-theorist sites, and I'd hardly call them accurate by any means.


Another Edit for @jozzas

I'm on a restricted network pretty much 100% of the time, so research on the subject has been hit and miss as far as graphics and being able to access certain pages. Here's a graphic posted on 03/18/2011 (Reference, Reference):

Fallout map

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This answer says nothing about the current status of the spent fuel pool, which is what the question is about. –  jozzas May 22 '12 at 5:00
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"I'm not a mathematician, but 10 times 19 miles is 190 miles (Or ~310 km)." Radiation doesn't work that way. Just because 10 times as much is released, it doesn't mean that 10 times as much land will become uninhabitable. If the fire were to occur on a still day, there could be a smaller area affected with much higher concentrations of radiation in that area. It could drift over Tokyo and make the city uninhabitable, killing millions. It could drift out to sea, ruining marine populations. It's not possible to make concrete predictions, but maybe someone has modeled some of these scenarios? –  jozzas May 22 '12 at 6:19
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@jozzas - I AM a mathematician, and we've already had MANY scenarios tested, modeled, in REAL life that were far more extreme than the scenario envisioned here. Do some reading. Its just wiki, but this site points out that more than 300 million curies remain in this one part of Nevada. And the last time I checked, the world has not ended. In fact, this would be an unpleasant event for many, but world ending? No. And the recovery of life around Chernobyl says that life is quite resilient. en.wikipedia.org/wiki/Nevada_National_Security_Site –  user3344 May 22 '12 at 8:59
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There is something deeply goofy about the lower-left panel of the map. The damaged reactors were all at one site between Tokyo and Sendai. Why does the map label four separate sites (one not even on the same island) as "meltdown"? –  dmckee May 22 '12 at 16:00
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What on Earth is this saying "This image, as claimed official by a commenter (Doc Holiday, comment #2), shows the Pacific Ocean effects;"? We've established almost everything about the image is complete junk science, and I don't see how that's reflected in your wording. It almost reads like you're endorsing it. Again, the image is a complete disaster, literally made up. –  AlanSE May 25 '12 at 14:46
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