Monday, September 19, 2011

Why a solar flare won't kill you

In response to a comment on the previous post, I thought it would be good to explain why a solar flare won't cause the end of the world (it's going to take more space than just a comment to clear this mess!). Let's see if I can put some sense into this doomsday discussion.

"To date, Fukushima has already released 168 times the total radiation released from the Hiroshima nuclear bomb detonated in 1945, and the Fukushima catastrophe is now undeniably the worst nuclear disaster in the history of human civilization."
According to the International Atomic Energy Agency (IAEA), radiation levels at the Fukushima Daiichi site are constantly monitored, and display a "general decreasing trend." As for the claim that the Fukushima plants have released 168 times the total radiation released from the Hiroshima bomb, we have to specify a couple things. One thing that must be kept in mind is that radiation, radioactivity and radioactive material are different things. Radiation is the energetic particles which are emitted, via radioactivity (which is the process), by radioactive materials (the "parent"). Radiation affects us in a different way to radioactive materials, because while radiation is gone in an instant, radioactive materials can hang around. So if we're talking about radiation, we're talking about the "instantaneous" dose rate (the dose you'd get from the actual particles of radiation hitting you). At the Fukushima plant, the highest confirmed radiation dose rates recorded (and as I said, they're constantly getting better) were about 80 microsieverts per hour (about 8 mrem in US terminology). This was very near the plant and thus no one was actually exposed to it long-term; if a nuclear plant worker stood there for an hour, he or she would get only 2% of the annual dose we get from natural background radiation. As for radioactive materials, which are a bit more insidious because they can linger, the ongoing monitoring in Japan has picked up trace amounts of materials like iodine-131 and cesium-137. The IAEA reports that very near (under half a mile) from the plant, the highest concentrations in air for these radioactive materials was 3 Becquerel per cubic meter and 9 Becquerel per cubic meter, respectively. No ground contamination of iodine was detected; the ground contamination levels for cesium varied from very little to almost 100 Becquerel per square meter. One becquerel is one radioactive decay in a second - so 100 Becquerel (Bq) is the same as 100 decays per second. That may sound like a lot, but it isn't - at the Rocky Flats nuclear weapon building facility in Colorado, contaminations of 500,000 Bq were detected during the 1970s. (In case you're wondering, the area is now a nature preserve!)
Now, to compare these numbers to other instances of nuclear contamination. The United Nations scientific committee which investigates nuclear incidents produced a map of the cesium-137 depositions in Europe following the Chernobyl accident (and I've already touched several times on why Chernobyl was a "freak accident"). Notice the legend: that's a maximum of nearly 1500 kBq/sq m... or 1,500,000 Bq per square meter. In no way is Fukushima worse than this. And yet, even Chernobyl wasn't that bad. So let's last touch on the comparison to the Hiroshima bomb. The Telegraph ran a story last month claiming that the Fukushima incident was equivalent to 168 nuclear bombs (it's uncertain whether they were the first to do so), without really taking time to clarify what that actually means. The Japanese government has estimated the total amount of cesium-137 released so far (it's been about six months) is 15,000 teraBecquerels (TBq), or 15 followed by fifteen zeros. Governments have been known to overestimate the severity of a disaster in order to receive more international aid, and it is understood that when lives are potentially at stake, underestimating severity is more dangerous. So we know with reasonable certainty that this estimation is in actuality too large (pretend, for the sake of argument, that the 100 Bq per square meter measurement quoted earlier is deposited each day - that would mean you'd get a total deposition of ~150 TBq in the whole of Miyagi prefecture since the accident, about a hundred times less than the government estimate). Now the Telegraph writer is connecting this number - the possible upper limit on the total amount of radioactive cesium-137 released in 6 months' time (notice how specific that is) - with the amount of cesium-137 released by the detonation of Little Boy above Hiroshima in 1945. The report claims that Little Boy released 89 TBq (they actually don't specify if this is just cesium, or total), 168 times less than the Japanese claim. Making this kind of inflammatory comparison is nothing new. But, as it even says in the article, "government experts" continue to argue that the comparison is simply not valid, and for good reason. Nuclear weapons produce different radioactive materials than do nuclear reactors (the entire field of nuclear forensics is based on this fact), and the time scales are vastly different. Bombs are dispersive instruments by design, whereas nuclear reactors are made to be contained. Most importantly, from a public relations point of view, people (wrongly) associate the radiation of a nuclear weapon with the deaths the bomb causes (the vast majority of which are due to the explosion itself: heat, pressure, fire), so the inference drawn from the comparison is that release of radioactivity from a nuclear plant is equivalent to detonation of a nuclear weapon, which is the same as assuming it's the pickle that kills everyone born before 1865. And even so, it's worth noting that the radiation/radioactivity released by the nuclear weapons during WWII have - still - had minimal long-term effects on people in the area.
Long story short, I hardly believe that Fukushima represents the "worst nuclear disaster in the history of human civilization." Chernobyl was worse, and in that instance the plant operators didn't have a magnitude 9.0 earthquake and 30-foot-tall tsunami waves to deal with.

"All nuclear power plants are operated in a near-meltdown status. They operate at very high heat, relying on nuclear fission to boil water that produces steam to drive the turbines that generate electricity. Critically, the nuclear fuel is prevented from melting down through the steady circulation of coolants which are pushed through the cooling system using very high powered electric pumps."
The claim that nuclear plants are operated in "near-meltdown status" is absolutely ludicrous, and gives away a complete lack of understanding as to how a nuclear reactor actually operates. Nuclear fuel - typically uranium-235 enriched to a few percent (naturally it comprises under 1% of uranium ore) - is one of a few materials which is fissionable (it can undergo "induced fission"). Left to its own devices, uranium-235 prefers to alpha decay: it emits an alpha particle, which is the same as the nucleus of a helium atom, made up of two protons and two neutrons. Sometimes (less than 0.00000001% of the time, actually), uranium-235 will undergo "spontaneous fission," where instead of an alpha particle, it will break up into two large chunks, plus a bit of energy and a few neutrons. Inside of a reactor, where a lot of uranium-235 is packed into a small space, these neutrons (after being slowed down by water) can hit other uranium-235 nuclei and cause them to fission also (that's "induced fission"). These also produce a few neutrons, which then hit other uranium nuclei, and the process begins what's called a chain reaction, or criticality: the nuclear reaction is self-sustaining. All that energy being released each time a uranium nucleus fissions is being collected in the form of heat to make steam. But this shouldn't be confused with being "near meltdown." Here's why.
Inside of a reactor, there are several things which impede this criticality. First is the water itself: water is a neutron moderator as well as a coolant. A moderator is something which slows the neutrons down. When they first are kicked out of the fissioning nucleus, the original neutrons are actually too high in energy to efficiently set off another fission reaction. If they travel through water first, they lose some of that energy and become "thermalized," making them far more likely to cause another uranium nucleus to fission. Thus, if the cooling water is lost (in the nuclear industry, this is known as "LOCA" - loss of cooling accident), the moderator is lost as well, and the neutrons speed up - and this (ironically) makes criticality even more difficult to attain. In addition to the water, control rods are used to (as the name suggests) control the nuclear reactions. Control rods are made out of materials which absorb neutrons (things like boron and graphite), so they have the effect of removing neutrons from the reactor core, meaning fewer neutrons are available to cause fission.
Now here's an important point which is overlooked by the Natural News author: if the coolant stops, the fuel rods do not necessarily "go critical." This is what happened in Chernobyl, but for a very obvious and unfortunate reason - the operators there, while conducting a test, turned off the safety system interlocks. While a LOCA can cause the uranium fuel to overheat, it does not suddenly go out of control in some sort of nuclear-bomb-like explosion. Nuclear reactor fuel CANNOT EXPLODE like a nuclear bomb. It simply isn't physically possible (water can't burn your skin the way sulfuric acid does - it's not physically possible). Reactors these days are designed with catastrophe in mind - they have to be, given the increasingly strict regulations surrounding them (chemical plants, industrial plants and coal burning plants have incredibly lax regulations by comparison) - so with each possibility of something going wrong, an additional layer of protection is built-in.
So imagine the scenario that the nuclear plant suffers from a loss of power (and nuclear plants, just like other power plants, do supply their own power; the Japanese struggled to reconnect the Fukushima plants to the grid because it would allow them to supply power from plants unaffected by the earthquake and tsunami). All hell breaks loose, right? Nope. In modern reactors (and older reactors in the US are required by law to be retrofitted to meet new safety standards), safety systems don't all depend on getting power. The control rods are gravity fed - meaning if something happens, they will simply drop into place, no power necessary. The cooling water may run on electric pumps, but these pumps have diesel or battery backup bumps, and these have gravity fed or thermodynamic backup systems (ie, systems which run on gravity, as the control rods, or which depend upon the natural circulation of air or liquid). Reactor safety systems which don't require power - or sometimes, don't even require an operator! - are called "redundant" and "passive" systems. They operate without power, without diesel, without batteries, without plant access, without people. They just work. Designs for modular nuclear plants exist even now that are completely meltdown proof.
Without getting too much more in-depth, it's fair to say the scenario isn't quite as dire as originally imagined. But let's take a couple more specific points.

"When the generators fail and the coolant pumps stop pumping, nuclear fuel rods begin to melt through their containment rods, unleashing ungodly amounts of life-destroying radiation directly into the atmosphere."
As we previously discussed, reactors have lots of redundant safety systems built-in. So it's not a guarantee that fuel rods will melt through their containment if the cooling water is lost (see above). It's also a horrible crime to claim that when nuclear fuel gets hot, it releases radiation "directly into the atmosphere." Secondary safety systems, such as containment, prevent this from happening. If the unlikely event of a LOCA occurred and the backup systems and backup-backup systems were to fail (with each layer of failure comes an even more decreased probability of it actually happening, like drawing four aces in a row from a deck of cards), the hot nuclear fuel is contained within a steel and concrete containment vessel which can withstand the heat and pressure the fuel creates (in fact, they can withstand earthquakes and airplane crashes and all manner of highly unlikely things). Physically, there are limitations as well: nuclear fuel is heavy, metallic stuff. If you took a chunk of steel, for example, and melted it, you'd be left with a lump of steel, and the same is true of nuclear fuel. Most of the material remains as a big, solid lump. Very little becomes gaseous or particulate, so very little even has the potential to become airborne in the first place. So even if the nuclear fuel were to melt, it wouldn't escape directly into the atmosphere. And we've already touched on the fact that nuclear material is not as frighteningly deadly as it's made out to be.

"As any sufficiently informed scientist will readily admit, solar flares have the potential to blow out the transformers throughout the national power grid. That's because solar flares induce geomagnetic currents (powerful electromagnetic impulses) which overload the transformers and cause them to explode.... But the real kicker in all this is that the power grid will be destroyed nearly everywhere."
Well, this is a half-truth. Transformers explode when they are overloaded; a power spike, usually caused by lightning or a sufficient power blip down the line (perhaps caused by another exploding transformer), melts the circuits inside the transformer and secondarily heats the oil used to cool the circuitry inside, causing an explosion. I doubt, however, any "sufficiently informed scientist" will admit that regular solar flares would wipe out the entire power grid (a good scientist will always admit that something is possible, but will also maintain that it need not be probable). Solar flares occur all the time - we wouldn't have the Aurora without them. Powerful solar flares do have the potential to interrupt satellite communications and cause temporary surges in the power grid, as has been seen previously, and the Sun is coming up to the peak of its 11-year cycle (due in about 2013). But this cycle is set to produce fewer sunspots than normal, and fewer sunspots means fewer possibilities for massive solar flares.
We can't discount the potential for large solar flares, however, at some point in the future. The chances of a flare being a massively disruptive one are low, but not zero. It's not that we haven't known about the potential for years. But because of this, we have systems now to tell us when something is going to happen. NASA satellites which float constantly in the space between us and the Sun are monitoring at every moment, ready to give us hours of notice should a large solar flare occur. If we have hours to know a solar storm is coming, doesn't that mean we have hours to shut down any sensitive systems?

"Did I also mention that half the people who work at nuclear power facilities have no idea what they're doing in the first place? Most of the veterans who really know the facilities inside and out have been forced into retirement due to reaching their lifetime limits of on-the-job radiation exposure, so most of the workers at nuclear facilities right now are newbies who really have no clue what they're doing."
This is a common misunderstanding. While there are lifetime limits for work-related radiation exposure, it doesn't mean the expertise of someone retiring from the nuclear industry is lost (think, how many consultants do you know?). And to claim that new employees have no idea what they're doing is to ignore the years of technical training required by law for any nuclear operator.

"Imagine a world without electricity. Even for just a week. Imagine New York City with no electricity, or Los Angeles, or Sao Paulo. Within 72 hours, most cities around the world will devolve into total chaos, complete with looting, violent crime, and runaway fires."
We don't have to. We've already seen what happens, and it wasn't so bad.

"Now imagine the scenario: You've got a massive solar flare that knocks out the world power grid and destroys the majority of the power grid transformers, thrusting the world into darkness. Cities collapse into chaos and rioting, martial law is quickly declared (but it hardly matters), and every nation in the world is on full emergency. But that doesn't solve the really big problem, which is that you've got 700 nuclear reactors that can't feed power into the grid (because all the transformers are blown up) and yet simultaneously have to be fed a steady stream of emergency fuels to run the generators the keep the coolant pumps functioning."
I've already spent some time explaining why the response need not be so frantic (passive safety systems, etc), and I've also already spent quite a bit of time ranting about worst case scenarios. So imagining this scenario is at once easy and absurd.

"Let's be outrageously optimistic and suppose that a third of those somehow don't go into a total meltdown by some miracle of God, or some bizarre twist in the laws of physics. So we're still left with 115 nuclear power plants that 'go Chernobyl.' Fukushima was one power plant. Imagine the devastation of 100+ nuclear power plants, all going into meltdown all at once across the planet. It's not the loss of electricity that's the real problem; it's the global tidal wave of invisible radiation that blankets the planet, permeates the topsoil, irradiates everything that breathes and delivers the final crushing blow to human civilization as we know it today."
Again, let's be realistic. Even if all of the 440 power-generating nuclear reactors in operation today were to lose power (we can't count the research reactors, because they are purposely designed to be small and harmless and not designed to create power, nor can we count the nuclear navy ships and submarines, which would be impervious to any problems with the national power grid), that doesn't imply nuclear holocaust. Since the Chernobyl incident, safety standards have been raised such that containment is required; only the old Soviet style reactors lack a containment vessel, and these have been outfitted. In order to see any radioactivity leak from a nuclear plant, we'd have to have a breach of containment, and we have estimates of that potential through Probabilistic Risk Assessment (the mathematical way to calculate the potential for an accident to occur in a highly technical system, like a reactor). A Sandia Labs report estimates that a typical containment vessel might fail at a rate of roughly 1x10^-7 per year (that's 0.0000001 failures per operating year), and that's IF THE CORE HAS ALREADY FAILED (in other words, if all of the nuclear fuel has already melted). So we have 440 nuclear reactors, and we'll assume they've all lost power, and we'll assume even further that they've all lost cooling water, and we'll assume even further that they've all lost their passive safety systems, and we'll assume even further that their nuclear fuel has overheated. 440 plants with core damage times a containment vessel failure rate of 0.0000001 gives a probability of ~0.005% that any radioactive material is released into the atmosphere. In order to get one incident (in other words, in order to achieve a likelihood of 100%), you'd have to wait over twenty thousand years. And like I said, that's already assuming the reactor core is damaged.

"The world's reliance on nuclear power, you see, has doomed us to destroy our own civilization. Of course, this is all preventable if we would only dismantle and shut down ALL nuclear power plants on the planet. But what are the chances of that happening? Zero, of course. There are too many commercial and political interests invested in nuclear power."
I'm quite curious as to where he gets this idea. Nuclear power, because of all of the regulations surrounding it, is expensive and difficult to get started. I can think of not one instance of there being commercial or political investment in nuclear power in recent years. Oil and coal, on the other hand, is a huge lobby, and moneymaker, for politics and commerce. We won't even bother to go into that here (though I find it amusing that our author even admits in his own article that "most people don't realize it, but petroleum refineries run on electricity" - making the oil and gas infrastructure just as vulnerable, if not more so, to his outlandish doomsday scenario). Besides, it's ridiculous to assume that having 14% of the world's power supplied by nuclear counts as "reliance." We're far more reliant on other sources of power (coal produces nearly half the power in the US).

"What can you do about any of this? Build yourself an underground bunker and prepare to live in it for an extended period of time. (Just a few feet of soil protects you from most radiation.) The good news is that if you survive it all and one day return to the surface to plant your non-hybrid seeds and begin rebuilding human society, real estate will be really, really cheap."
Is it mean to say that I hope this is what he plans to do, so the rest of us can move on to something more productive?

8 comments:

  1. I admit, I skimmed through some of this...but it still made me want to express appreciation for your writing. (Again!) Very thorough, very grounded (you did let outrage shine a couple of times, but overall, it had a calm and rational tone), and in spite of the thoroughness, written in a way that I felt I (mostly) comprehended. Your capacity for writing about science so...effectively (if you understand what I mean by that) is an incredible talent.

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  2. Why, thanks! As always, if there are points I can clarify, please let me know.

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  3. How about this? The short version:
    1) Solar flares can (and do) occur. But NASA and others have been studying this phenomenon for decades, so we have some understanding and some advance warning.
    2) Blackouts can (and do) occur, but while our electrical infrastructure does need updating and safeguarding, we know from past experience how to handle technical difficulties. Also, these difficulties hardly result in instantaneous pandemonium, as suggested.
    3) Nuclear plants do not operate in "near-meltdown status," nor are they as prone to technical problems as suggested.
    4) The rarity of each of these events taking place - a large solar flare, a worldwide electrical blackout, simultaneous failure of all nuclear plants (which in itself involves dozens of "what ifs") - means that the possibility of them all occurring together is minimal.
    5) Fear-mongering is what the internet does best. ;-)

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  4. Very nice! :)

    Really, I actually do like the more detailed explanations. I think the lack of understanding in areas is due more to laziness on my part than anything else. In spite of your brilliant writing, this is still rather advanced science (at least in my realm - stuff I've not ever really learned before), which means it still takes a conscientious effort on my part to comprehend it all. And most of the time when I'm spending my "me time" on the internet, I'm just too lazy, or too impatient, to take the time to slowly work through the science. After all, this is supposed to be an indulgence for me, not work! ;) And there is still grocery shopping to be done...

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  5. It's kind of a systemic problem, I suppose. Human beings simply aren't capable of being expert at (or even interested in) everything. The fewer people who choose to become expert in a given topic, the more mysterious the topic appears to everyone else (did you know there are people who spend their whole lives trying to get golf course grass to be the perfect color and texture? ...and what's more, there are people who decide what constitutes "perfect" in relation to golf course turf?). In any case, I try to make it accessible, because I feel that it is accessible, and sometimes (cough, cough) people need to know a little bit in order to make informed decisions.

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  6. That's the beauty of it - that it does feel accessible. And that's empowering. Even when I choose to not spend the time to completely understand, I come away feeling a little bit smarter because I know I could understand, and isn't that incredible that this complex science is something I could figure out? Now PDEs, on the other hand, are a different matter...

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  7. Thanks Miss Bomb for the meaty response to the fear mongering olar lare article. It's easy to throw something out there with no documentation and little foundation in fact. Unfortunately many blindly accept pseudo science and jargony writing as science. Keep up the truthing. I enjoy everything you write.

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  8. Thanks everyone for the comments. Speaking of solar flares, check out today'sAPOD!

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