The 'why I am not worried' article, edited by MIT nuclear scientists | Hacker News Reader

The 'why I am not worried' article, edited by MIT nuclear scientists

mitnse.com

128 pointsRyanMcGreal131 comments

This is BULLSHIT, the guy (Oehmen) is a mechanical engineer with a management focus. He worked at my alma mater (ETHZ). His field of experties is supply chain risk management. Look up his papers, he isn't a nuclear physicist.

I'd say he's about as qualified to make a comment on the situation as I am.

The "essay" by Oehmen was first published by a notorious nuclear lobbyist, Jason Morgan. Look at this: http://nuclearfissionary.com/about/

  Nuclear Energy suffers from a poor public image. We’re here to change all that.

  For decades the nuclear energy industry has been under attack 
  by antinuclear activists both organized and unorganized. 
  Fear and panic have been their call signs and with little 
  regard for science or the impact on civilization, they   
  have remained unchecked for years

And more, from that page:

  Jason Morgan

  A corporate finance and accounting professional 
  who has great personal interest in the future of 
  the world’s energy crisis. Jason is looking forward 
  to utilizing his financial and economic data 
  analysis skills to shed light on nuclear energy.

In short: FUD by nuclear energy lobbyists.

> In short: FUD by nuclear energy lobbyists.

So mechanical engineer cannot possibly say anything truthful about nuclear energy?

The fact still remains: nuclear energy is the safest and cleanest we have for now.

So far we had what, three serious incidents with total number of causalities of 35, all in Chernobyl. Sure it affected much more people but still: the single incident at Sayano-Sushenskoye hydroelectric power plant claimed 75 lives. How about Banqiao Dam?

  According to the Hydrology Department of Henan Province,[5] in the
  province, approximately 26,000 people died from flooding and another
  145,000 died during subsequent epidemics and famine. In addition, about
  5,960,000 buildings collapsed, and 11 million residents were affected.

And thats not counting all the incidents in coal and oil industry (and the fact that burning coal releases more radiation for the same amount of energy produced than nuclear power plants).

Sure it affected much more people but still

indeed. who cares about them...

total number of causalities of 35, all in Chernobyl

Wrong, according to http://en.wikipedia.org/wiki/Chernobyl_disaster

- 31 dead from acute radiation poisoning within months - 216 non-cancer deaths until 1998 - Between 9,000 (official government report) and 60,000 (TORCH report) cancer deaths overall

60,000 (TORCH report) cancer deaths overall

Thanks for pointing that out one more time. I'm not an anti-nuclear zealot but I'm getting extremely tired of supposedly intelligent people citing the "35 deaths" bullshit-figure on HN in each japan-thread.

If there had been only 35 or 4000 deaths then Chernobyl would not be considered a catastrophic event up to this day. Instead it would be considered a testament to the safety of the technology.

I wonder if the part that these people have trouble wrapping their head around is the latency?

This is what happens during a nuclear accident: Nothing. At the very worst we may see a few hundred immediate deaths. Other than that, life goes on.

The real aftermath kicks in 10-20 years later, when people start developing cancer and birth defects. Different sources report different figures for Chernobyl, partly due to political bias, and partly because it's just really hard to track >600k people over such a long timeframe.

However, the estimates from most sources other than the IAEA and the russian government range in the tens of thousands - quite a long shot from "35".

I was watching a documentary about Chernobyl a while ago and some of the birth defects are extremely severe.

>If there had been only 35 or 4000 deaths then Chernobyl would not be considered a catastrophic event up to this day. Instead it would be considered a testament to the safety of the technology.

Doubt it. Nobody says Three Mile Island was a testament to the safety of nuclear power, and the harm was pretty small, unambiguously less harm than 35 dead: http://en.wikipedia.org/wiki/Three_Mile_Island_accident#Heal....

> If there had been only 35 or 4000 deaths then Chernobyl > would not be considered a catastrophic event up to this > day.

It wouldn't. Oil and coal industry killed waaay more people. Heck, take Banqiao Dam alone. Nobody cares. Water is safe, nuclear is scaaaaaary.

> The fact still remains: nuclear energy is the safest and cleanest we have for now.

Burning natural gas is both cleaner is safer, and it is a power source for much of Europe. I wonder why all nuclear advocates always bring in coal into the comparison.

I imagine this is why: http://upload.wikimedia.org/wikipedia/en/8/83/2008_US_electr...

And in China they indeed burn even more coal. However, why build nuclear stations to displace coal, when it's possible to burn gas instead?

I imagine it has something to do with the quantity of power a nuclear power plant can generate compared to a gas based power station (given equivelent time/amounts of fuel)?? But I don't really know.

Having said that, though I don't remember the name/type ofdhand and am too lazy to look it up, there are new types of power plant in development/trials that 1) physically cannot meltdown, 2) produce much less (and less hazardous) waste and 3) use a plentiful form of nuclear fuel. If/when those nuclear power plants become production ready, then the choice between nuclear and fossil fuels is an easy one. For now, though, I agree with you and don't know the answer.

It reads very much like a last-ditch effort by nuclear energy lobbyists to convince us that nuclear energy is really safe. This brings back memories of the Iraqi information minister.

In 15 years, if there are no further disasters, they might crawl out of their holes and start preaching about the wonders of nuclear energy again. Until then, just give up.

> a last-ditch effort by nuclear energy lobbyists to convince us that nuclear energy is really safe.

Well, let's see. In this case we've had a bunch of nuclear power stations very close to the site of a historically-large earthquake and the ensuing tsunami, large enough that even with Japan's outstanding disaster-preparedness thousands or tens of thousands of people have died. That would seem to be pretty much a worst-case scenario.

And, so far, all the troubles at the nuclear reactors have produced a grand total of zero deaths. Now, for sure, it's too early to know what the final outcome will be. Maybe there will be a Vast Nuclear Holocaust that obliterates Japan. (No, the laws of physics do not in fact permit this, but that objection applies equally to a number of other nightmare scenarios people have been proposing.) But so far as anyone can tell, the worst outcome that's at all likely is: a few people die, a few square km of land become unusable for a while, and they need to rebuild from scratch somewhere else. Well, that's pretty bad, for sure. But if that's the worst-case outcome from such a major natural disaster, it seems to me that -- so far as what we know right now goes -- nuclear energy is still looking pretty safe overall.

(Note: I am not a nuclear energy lobbyist.)

And, so far, all the troubles at the nuclear reactors have produced a grand total of zero deaths.

Make that one death. One worker died as a result of the the crane he was working in becoming unbalanced and falling over.

Lets see: genetic fallacy[1], circumstantial ad hominem[2], appeal to spite[3], and well-poisoning[4].

All in all, a very good compendium of logical fallacies, but as such, not a terribly good argument against the assertions made.

1:http://www.nizkor.org/features/fallacies/genetic-fallacy.htm...

2:http://www.nizkor.org/features/fallacies/circumstantial-ad-h...

3:http://www.nizkor.org/features/fallacies/appeal-to-spite.htm...

4:http://www.nizkor.org/features/fallacies/poisoning-the-well....

To be fair, the unworried proponents of this piece used equally fallacious rhetorical tricks, and did so with the intent to deceive.

What is your point?

Presumably the correct response to bullshit is to call it out as such rather than producing your own.

I don't think the grandparent poster was aware of the fallacies in his argument; more importantly, it throws the reliability of the original information supplied into question.

For example, the 'not worried' writer explains that 'the nuclear fuel is uranium oxide.' But that is not true of the whole plant: http://www.tepco.co.jp/en/challenge/csr/nuclear/cycle-e.html

Plutonium complicates things rather significantly. Accuracy should not be sacrificed to fearmongering, but nor should it be sacrificed for mere reassurance.

Edit: downvoted for supplying more accurate information with a citation? Classy.

I don't think all examination of qualifications constitutes a genetic fallacy. If anything it's closer to an argument from authority plus a closed-world assumption (i.e. I only accept arguments from authorities). But expertise and authority has a significant role in science, and not entirely an improper one imo. If I say that I prefer to hear expert analysis of nuclear reactors from someone with a PhD in nuclear physics, rather than from someone with a PhD in another field, that seems like a decent epistemological heuristic. The qualifications don't prove anything about the argument, but in general I expect people with relevant qualifications to know more of the relevant facts, so am more willing to defer to their judgment.

It's doubly the case when the original article author promoted the article as being by an "MIT PhD". If someone is explicitly invoking their credentials to add weight to an argument, investigating whether the credentials are relevant seems reasonable.

I disagree. The logic of the post clearly states that the source of the information is a reason to reject it rather than a problem with the information itself. This is a common problem with a vast majority of the negative responses to the "why I am not worried" article.

Remember, the poster says that the origin of the facts makes those facts bullshit. Textbook genetic fallacy.

What I'm discussing is evidential weighting and critical source analysis, not logical inference (I do happen to research logic in my day job, so I'm familiar with what constitutes valid deduction).

Since this isn't a scientific paper that presents data sufficient to support its conclusions, we can't judge it purely objectively. It presents itself as an engineering safety analysis. The first step in judging an engineering safety analysis is usually: was it performed by someone qualified to perform such an analysis? We typically want them to be performed by people who are both domain experts (in this case, nuclear engineers), and specifically people who are experts in assessing the risks in that domain, as well as in the general science of risk analysis. If a safety analysis is done by someone who isn't such an expert, it's quite rational to give it lower weight, because we aren't confident that they're familiar with all the relevant science and possible risks.

I mean, would you argue it's also a genetic fallacy that I take articles in Nature more seriously than I take articles in the Daily Mail? That I believe what Richard Feyman's lectures have to say about physics more than I believe what some random person on Geocities has to say? It just seems like good sense to me; considering the source of a claim is a good first step when deciding how much weight to give it. Bayesians would agree! It's possible that the Daily Mail will publish an insightful new analysis of global warming, but it's not very likely, and I would probably want to hear confirmation from a more reliable source before I believed it. Same here; this analysis is interesting, but I'd have more confidence in an analysis performed by someone who's actually an expert in the field, so until I hear one of them say that it's correct, I treat it with skepticism.

I'm arguing about the original post that I responded to, which makes the argument "this is not from an engineer, but a lobbyist and is therefore bullshit". That is a genetic fallacy.

If he had made the entirely reasonable point that you did-- that this might not be as trustworthy a source compared to another, or engaged the actual evidence used, I wouldn't have taken the time to critique it.

In other words, my disagreement with you has nothing to do with the weighing of credible sources, but the fact that the original post didn't do that.

Note that I haven't even brought up the fact that the post he actually responded to was a revised version of the article by nuclear engineers, thus invalidating much of his claims about it anyway.

In short: FUD by nuclear energy lobbyists.

Um... Kinda the opposite of FUD, wouldn't you say?

kitsune_, wrong choice of words, IMHO!

The article is full of facts that make absolute sense and shed light on a large number of things that the news do not get right. My thanks to the author especially for a clear interpretation of the explosions. We need a clear head and should rely on facts in these situations. We also should not assume that nuclear reactors are not well constructed. I am sure they are. So it does not come as a surprise to me, that someone who knows the details is able to explain them in a way that it makes sense.

This does not excuse the fact that the reactors failed. This is a different story. But it helps to understand what really happens now. What the author did not stress is the fact that, as the Zircaloy structure may have failed, all subsequent pressure releases will be highly contaminated.

BTW, engineers are the ones who know best how safety is constructed, not scientists (I write this as someone who got his phd in atomic physics. So I am not an engineer).

Some supporting background information here. http://www.ritholtz.com/blog/2011/03/the-strange-case-of-jos...

I'm not touting the veracity of this link. I'm only trying to show that the intent of the original article should be questioned.

Nuclear engineering is a sub-discipline of mechanical engineering at many schools that offer it... Mechanical engineers do LOTS of thermodynamics.

I'm really kind of sick of listening to people talk about how everything is hunky-dory. I heard one supposed expert on CNN basically state that a nuclear meltdown is no big deal. The lesson to learn here is when a government tells you everything is ok regarding an event with potential regional impact, get the hell out of town.

I'm assuming the reactors are melting down and are out of control. Pumping seawater in may be keeping the thing from blowing up, but obviously isn't cooling the reactors down. So what happens now? Do they keep melting down indefinitely, or do the reactions eventually fizzle out?

That particular lesson was actually learned decades ago (see my comment 3 days ago http://news.ycombinator.com/item?id=2316593)

The worst case scenarios are bad:

If one reactor gets so bad (meltdown) forcing permanent evacuation - all the remaining reactors won't be maintainable/saveable and thus in a domino effect - if one goes, all go (meltdown).

It is unlikely that a meltdown through the core will occur but if that happens - the scary term China Syndrome - the melted radioactive fuel will melt through steel, concrete, rock, maybe even bedrock.

For the USA and rest of the world: Irradiated food supplies will be a real concern if hundreds of tons of radioactive melted fuel merge with the outside environment

To put it in perspective: If you were in Japan near Tokyo or closer to the affected nuclear plant, would you be more skeptical of the seemingly contradictory news coming out.

Why would one meltdown cause evacuation?

The meltdown would still be contained

Why would one meltdown cause evacuation?

Because of fire, explosions, and excessive radiation exposure to workers.

The meltdown would still be contained

Containment is believed to have failed in reactor 2 and likely 3 at this point. Smoke or steam has been billowing from number 3 for hours now and its fuel is in the reactor, not the spent fuel pool.

I heard one supposed expert on CNN basically state that a nuclear meltdown is no big deal.

He's right, in a sense. Modern nuclear reactors are designed so that if the fuel melts it will end up in a wide concrete tray which sits under the reactor, where -- thanks to the fact that the tray is very wide and not at all deep -- it will cool down to a safe temperature.

All good engineering works on the principle of defence in depth. This is the last step to safely contain the hot fuel, after the many redundant cooling systems fail, and it's certainly not ideal -- but it's nothing like the mythical "China syndrome". (Or like Chernobyl, which involved a graphite fire causing fuel to go up rather than down.)

I suspect your parent did not realize a nuclear meltdown simply means the melting of the fuel, and instead (like most people) simply directly associates the words with "huge disaster".

(From that frame of reference of course- "a huge disaster would not be a big deal!"- it DOES sound ridiculous)

A few short days ago, we were told that everything was a-ok, no worries. Then the buildings started exploding -- still, everything is under control. On Monday we hear that fuel rods are fully exposed, but that is ok too.

Now we're talking about the staff evacuating the site to avoid acute radiation poisoning and dropping seawater from helicopters. At what point do you stop accepting the best-case scenario as the most likely one?

Well, I imagine when people are dying. The quake and resulting waves killed a lot of people. This hasn't, yet. Excuse me for thinking the most about those.

"All good engineering works on the principle of defence in depth."

That line is as much a sound-bite at this point as anything you'll hear on cable television. Yes, good engineering has many levels of fall-backs and redundancies. But when you've reached the point that you've evacuated the last fifty people from your site because it's no longer safe for them to be there, then you've exhausted your defenses. There's no more depth.

Let's stop whistling past the graveyard: a meltdown is, in fact, a really big deal. Maybe the "wide concrete tray" will capture the waste. Maybe it won't. But in the meantime, you're hoping that there's not a secondary fire from the heat, or a steam explosion, or some other kind of explosion that flings radioactive particulate for miles around. You're hoping that the fuel won't melt, form a critical mass in the bottom of the reactor, and re-initiate a reaction that's hard to stop. You're hoping that the containment doesn't breach, and that vast quantities of radioactive waste aren't exposed to the elements before the whole system calms down again. You're hoping that the whole system calms down again.

The point is: they've lost control. The 'engineering' that they're doing right now is desperate and hacky, and they're very nearly out of options. It might be comforting to pretend that this whole thing is scripted out on some intricate Japanese checklist somewhere, but that's really nothing more than a fantasy. I certainly hope that things aren't as bad as they sound, but this isn't just a matter of bad PR by some pessimistic, nuclear-energy skeptics. These guys are actually in trouble.

Maybe the "wide concrete tray" will capture the waste. Maybe it won't.

Maybe the laws of physics will change, but I'd be willing to bet that they won't.

But in the meantime, you're hoping that there's not a secondary fire from the heat

Concrete doesn't burn.

or a steam explosion

At the point when the nuclear fuel melts, all the water has boiled off 1000 degrees ago.

or some other kind of explosion that flings radioactive particulate for miles around.

Explosions don't just happen for no reason.

You're hoping that the fuel won't melt, form a critical mass in the bottom of the reactor, and re-initiate a reaction that's hard to stop.

Nuclear reactors don't hold enough fuel to form a critical mass. In order to become critical, they need a moderator (usually water) which thermalizes neutrons.

Sure the laws of physics don't change. But the state of this complex system is way way out of understood and explored space at this point.

http://www.digitalglobe.com/downloads/featured_images/japan_...

This game was out of the playbook from the beginning, as soon as all the batteries and backup generators failed.

"Maybe the laws of physics will change, but I'd be willing to bet that they won't."

There's absolutely nothing about the "laws of physics" that guarantees that this particular reactor design is going to be able to contain a full meltdown, because it's never happened before. Nobody knows.

"Concrete doesn't burn."

No one said it did. There's plenty of other stuff around that does burn readily, which is why the plant is currently on fire. A lot of that stuff is radioactive.

"Explosions don't just happen for no reason."

Indeed. But red-hot piles of radioactive waste are a good way of making explosions happen, particularly when there's lots of hydrogen gas floating around from the breakdown of the cooling water and the fuel. That's why there have been several explosions at the plant.

"Nuclear reactors don't hold enough fuel to form a critical mass. In order to become critical, they need a moderator (usually water) which thermalizes neutrons."

You're assuming an intact core. Criticality is a function of density, shape and temperature, in addition to mass. Melt the fuel rods, and the guarantees of that nice, well-moderated behavior are off.

In general, you're making lots of simplistic assumptions about a nicely behaved, engineered, controlled system. What they've got now is far messier. Moreover, a lot of the stuff that you're saying can't happen, is actually happening right now. The reality of the situation trumps your theories of the situation, however confident.

It's a shame that cperciva's nonsense is being modded up.

> "Nuclear reactors don't hold enough fuel to form a critical mass."

Come on. Each reactor core holds over 100 tons of uranium, of which about 3-5 tons is U-235. Critical mass under perfect conditions is 50 kilograms. Conditions are not perfect for forming a critical mass, but you've got 100 times as much U-235 as is strictly necessary, and there is no fucking way of knowing what will happen when an entire reactor core melts and flows together, because no one has ever been stupid enough to try it. Chernobyl experienced a criticality event, and there is absolutely no guarantee that Fukushima will not.

Moreover, each reactor has a spent fuel pool with five times as much fuel in it as the reactor itself has. And no containment vessel. And no water being supplied. And when the water boils away from those pools, and that fuel melts and flows together...

Each reactor core holds over 100 tons of uranium, of which about 3-5 tons is U-235. Critical mass under perfect conditions is 50 kilograms.

Critical masses don't work that way: the additional U-238 absorbs neutrons making more difficult to achieve criticality. In fact, even an infinite amount of unmoderated natural uranium cannot sustain a chain reaction. See the figure 3.1 in [1] for more information about unmoderated critical masses for enriched uranium.

[1] http://www.ornl.gov/sci/radiation_transport_criticality/Hopp...

Chernobyl used UNENRICHED uranium, containing only .7% of U235, and went kablooey. Which you just said can't happen, so I suppose Chernobyl didn't actually happen. /thread

This thread has brought out the worst aspects of Hacker News - reasonably bright people who feel compelled to opine, in their usual arrogant "I am always right" manner, about subjects where they have no clue.

What the FUCKKKKKKKK? You DO know Chernobyl wasn't a nuclear explosion right? It was a STEAM explosion.

Please read carefully before making absurd accusations. I said: "even an infinite amount of unmoderated natural uranium cannot sustain a chain reaction". The nuclear excursion at Chernobyl occurred in a graphite-moderated reactor core.

I don't claim any special expertise in nuclear power but, as you don't seem to know the importance of moderation in criticality, I think you should refrain from accusing others of cluelessness in this topic.

There's absolutely nothing about the "laws of physics" that guarantees that this particular reactor design is going to be able to contain a full meltdown, because it's never happened before. Nobody knows.

Physics isn't biology/medicine. The laws of physics are not discovered by running experiments to enumerate every possible combination or permutation of configurations.

You're assuming an intact core. Criticality is a function of density, shape and temperature, in addition to mass. Melt the fuel rods, and the guarantees of that nice, well-moderated behavior are off.

The optimal shape for criticality is a sphere - surface/volume is the key factor here. A wide, shallow puddle at the bottom of the containment chamber is the least dangerous shape.

Temperature affects things because higher density makes achieving criticality easier. I.e., the colder things get, the more likely criticality is to be achieved.

"Physics isn't biology/medicine. The laws of physics are not discovered by running experiments to enumerate every possible combination or permutation of configurations."

Wanna bet? Guess how we know most of what we know about criticality and neutron cross-sections? People like Louis Slotkin, who spent hundreds of hours poking at piles of radioactive material in the lab, to derive those mathematical models that you're leaning upon. Critical mass calculations, in particular, are so fiendishly complicated that the entire field of stochastic simulation (i.e. monte carlo methods) were invented to address them. So tell me again about the "laws of physics", and how they're not tested through pemutation.

"The optimal shape for criticality is a sphere....a wide, shallow puddle at the bottom of the containment chamber is the least dangerous shape."

Prove it. It's pretty amazing how everyone wants to cite "physics" to prove that there's no problem with a meltdown (in the face of overwhelming empirical evidence to the contrary), but nobody is doing much more than hand-waving allusions toward their undergrad physics textbook in defense of their assertions.

A sphere is definitely a shape where we have good calculations to model critical mass. Otherwise, we don't really know much that wasn't determined empirically. We know that criticality depends strongly on density. We've assumed that the structure of this reactor will prevent that density change from occurring. We don't actually know what will happen.

I can almost understand why a community of nerds is so strongly interested in maintaining the self-delusion that the world is a fully knowable, controllable place, but I don't understand how so many people can ignore so much real-world evidence for so long. If you're seriously telling yourself that a meltdown isn't a big deal, you need to go back and re-examine what you know about the situation, and why you think you know it.

The physical principles behind criticality calculations are not fiendishly complicated. The computations are computationally intensive, yes (Slotin was around in a time where experiments were cheaper and easier than simulations), and (maybe -- I don't know) the exact nature of physical materials involved was not well known, and needed to be measured.

Prove it.

Why don't you prove it? It's not other people's job to do all the work for you. It is provable that a sphere is the optimal shape. If somebody on the internet suggests that you're wrong, you don't win the argument by saying it's their responsibility to do all the hard work of convincing you you're right. You're still the one who is wrong.

"Why don't you prove it?"

Because I'm not the one making extraordinary claims. I'm also arguing that you can't 'prove' anything in this situation; there are too many unknowns.

> > "Why don't you prove it?"

> Because I'm not the one making extraordinary claims.

You are, though. You're the one suggesting a nuclear catastrophe, contrary to apparent scientific evidence.

So tell me again about the "laws of physics", and how they're not tested through pemutation.

Ok. You generally perform a sequence of experiments, construct a low entropy theory, and then apply that theory in the future. Kind of like what Louis Slotkin did.

He doesn't need to redo them on a train, a plane, in a car, at the bar. The fundamental principles discovered tend to be pretty solid.

Prove it.

Not that hard. Take a fixed volume, convolve it with the 1/r kernel of the neutron diffusion equation. If the volume of uranium is a sphere, you get the spot neutron density at the center is [(3V)^{2/3}]/2. If the volume is a disk of height dz, radius R, you find the the local density is 2(pi V dz)^{1/2}. The smaller dz gets, the smaller the local density of neutrons is, and the further from criticality you are.

(Computing the volume at someplace other than the center is left as an exercise for the reader. However, the maximum principle shows that it always goes down.)

Now plug this into the standard soliton machinery (i.e., use Duhamel's principle, L^p-L^q estimates, etc) and you'll always need a bigger source for a flat soliton than a spherical one.

Yes, I'm skipping a few steps. You can find them in Cazenave's book on solitons (that's where I learned it) and most likely any book on nuclear engineering (but with much less of a mathematical bent). No, it's not the "undergrad physics textbook" you seem to think I'm referring to.

It's pretty amazing how everyone wants to cite "physics" to prove that there's no problem with a meltdown (in the face of overwhelming empirical evidence to the contrary), but nobody is doing much more than hand-waving allusions toward their undergrad physics textbook in defense of their assertions.

What is the "overwhelming empirical evidence" that criticality will be achieved?

You're assuming an intact core.

No, I'm not.

Criticality is a function of density, shape and temperature, in addition to mass. Melt the fuel rods, and the guarantees of that nice, well-moderated behavior are off.

It is impossible for the uranium in a nuclear power plant to become critical in the absence of a moderator. Even if it's shaped into a sphere and supercooled. Add heat, and it gets further away from criticality (mostly due to doppler broadening; partly due to thermal expansion). Change the shape, and it gets further away from criticality (because there's more surface area to lose neutrons).

I may ask you about the spent fuel disposals that seem to be on fire.

Are they within the containment? This picture doesn't clear things up for me (http://en.wikipedia.org/wiki/File:BWR_Mark_I_Containment_ske...)? And if so and if they are on fire, does the containment still work?

And if they are not within the containment, aren't we f..ked? Isn't the greatest risk of nuclear plants not the reactor but the proper waste disposal? Storing it near a nuclear plant seems to be idiotic.

EDIT: Most news articles read like there was a waste disposal next to the plants and outside of the containment

EDIT 2: http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300...

Your argument would hold a lot more water if all the other things that 'couldn't possibly' go wrong hadn't already gone wrong.

Concrete doesn't burn.

No. But concrete can crack during, say, an earthquake.

And I assume concrete can also lose integrity (melt? vaporize?) under very high temperatures.

Wikipedia has some details on the typical interactions here: http://en.wikipedia.org/wiki/Corium_(nuclear_reactor)#Corium...

The summary is that yes, typically concrete would melt at temperatures anywhere in the range that you'd expected a molten core to be at.

My understanding is that newer designs have a "core catcher" under the reactor made of something more resistant than concrete, but this unit doesn't.

Totally agree with this, it reminds me of impenetrable software and unsinkable ships.

Exactly, the bottom line is were playing with nuclear reactions and hoping everything goes as planned. It's arrogance.

As is every technological and scientific achievement humankind has ever reached and is relying upon. Replace nuclear reactions with, say, human flight and your statement remains just as valid. I don't see many people crying out for abolishment of planes, though.

I don't see many people crying out for abolishment of planes, though.

I think there's a tiny difference between a plane falling out of the sky and a nuclear reactor melting down. I'm sure you can spot it, too, if you think long and hard.

The plane falling happens a lot more often?

Are you serious?

According to [1] roughly 15k people died in plane accidents over the past decade. It doesn't seem unreasonable to assume that Chernobyl killed many more than that.

Furthermore a nuke meltdown renders a large area uninhabitable and leaves an economic footprint "slightly" bigger than a few planes coming down every year.

Quote from [2] (page 33):

  Coping with the impact of the disaster has placed a huge burden on national   
  budgets. In Ukraine, 5–7 percent of government spending each year is still 
  devoted to Chernobyl-related benefits and programmes. In Belarus,
  government spending on Chernobyl amounted to 22.3 percent of the
  national budget in 1991, declining gradually to 6.1 percent in 2002.
  Total spending by Belarus on Chernobyl between 1991 and 2003 is estimated 
  at more than US $13 billion.

Other Quote (same page):

  Belarus, for instance, has estimated the losses over 30 years at US $235 
  billion.

[1] http://en.wikipedia.org/wiki/Aviation_accidents_and_incident...

[2] http://www.iaea.org/Publications/Booklets/Chernobyl/chernoby...

Yes, I am serious. I said the plane falling happens more often, not that it is worse as a singular event.

Unfortunately it is a problem with human psychology that we respond more strongly to a singular large event than to consistent low-level events.

Some of the discussion on this page has suggested Chernobyl killed around 60k, directly and indirectly. Certainly a tragedy, and a huge one at that, but it is also the only major nuclear disaster. The second worst (until we fully understand the current Japanese incident at least) remains Three-mile island, where there are no confirmed deaths I am aware of.

So, we're comparing approx 60k deaths, over the course of approximately 60 years, which works out as about 10k deaths a decade, against aviation accidents of, as you said yourself, approximately 15k a decade.

By those numbers, approximately 50% more people die each year from aviation accidents than from nuclear-power-related injuries. It's just that Chernobyl is a big story, but we hear about plane crashes all the time.

Unfortunately it is a problem with human psychology that we respond more strongly to a singular large event than to consistent low-level events.

I agree with that in general, although my opinion on this particular comparison differs.

we're comparing approx 60k deaths, over the course of approximately 60 years

Sorry to be nitpicking, but I'm not sure where the 60 years are coming from. However, since there's no hard data to rely on I'll even concede that plane accidents may have accounted for the same or slightly more "directly related" deaths in the same timeframe.

But: This is only a single datapoint. And a relatively "lucky" one.

The surrounding area around Chernobyl was sparsely populated and quickly evacuated. This is not representative for the locations of the majority of nuke plants, and certainly not for the Fukushima area.

If we imagine a worst-case scenario in Japan, with Tokyo right around the corner, then the second data-point could already change the equation in a drastic way.

This is why I think analogies to plane-crashes or traffic-accidents are invalid.

60 years is approximately how long we've had nuclear power for, I believe.

I looked at your first source, and immediately noticed that the 2001 death toll does not count those who died in the WTC collapse (article states for 2001, 200 accidents, 1534 dead, so it doesn't include ground zero casualties). In order to make an apples-to-apples comparison, you really need to include the deaths of those in the buildings, those in the planes, the rescue workers with respiratory problems, and anyone else exposed to pollutants at ground zero.

After all, we're counting the fallout from Chernobyl, so we have to count the fallout from 9/11. Both are huge, (hopefully) once-in-a-lifetime occurrences with massive secondary casualty counts.

And as far as economic costs, I believe you have to address the 9/11 costs.

Yes, I already regret jumping in on the math-game, when the real point I wanted to make was that this is an invalid comparison (apples/oranges) - sorry for that.

Plane crashes are created relatively equal in rate and magnitude.

Nuke crashes are nothing like that. We have only a single datapoint to draw from, and one that in hindsight almost seems like a relatively lucky one.

No worries. I still think you are incorrect, based on this:

>Plane crashes are created relatively equal in rate and magnitude.

Not all of them are... 9/11 was a plane crash that wasn't like any other before it.

9/11 was a plane crash that wasn't like any other before it.

Yes, but think of the scales.

How many 9/11's does it take to match a worst-case scenario involving Tokyo (~35 million people)?

When I say "relatively equal" then I mean somewhere between 500 and perhaps a few thousand deaths from a plane crash. Whereas a nuke accident may range from 600k exposed to.. well, let's hope Fukushima gets its act together.

I don't see many people crying out for abolishment of planes, though.

But a lot of people, especially those who know anything about planes are always crying out for more safety. Both in mechanical terms, more plane inspections, and in human terms, more rest for pilots.

And I don't think many people here are arguing for the abolishment of nuclear power. That is a straw man.

I think what we all want is the safest possible nuclear power.

And this argument is between the people who willing admit knowing little to nothing and think things can always get worse, versus the people who keep arguing things are peachy and there's no way they can get worse, even as the situation has continued to deteriorate.

I think this boils down to an argument of "Shit happens!" vs. "Nah uh, engineering is magic!"

EDIT: nvm, found the answer by re-reading the article.

In short, even without chain reaction, substantial (7% of normal output early after shutdown) heat is produced, so some cooling is needed.

The original post:

Why are (or were) they pumping water in anyway? Wasn't the whole point of reactors moderated by water that once the moderating water escapes (evaporates or flows out), the unmoderated neutrons don't sustain chain reaction anymore and it basically ceases to produce heat?

There's already no chain reaction - the control rods, plus the boron in the water they're pumping in absorb too many neutrons to sustain a reaction. The heat is not from uranium fission, but rather from the fission products made while the reactor was running undergoing spontaneous decay. This process cannot be stopped; you can only wait for it to slow down and cool to a reasonable level.

The reason they want to keep it cool is to prevent the fuel rods from melting. While melting won't immediately mean a release, it would mean the loss of two of the five barriers to a radioactive release, as well as quite a lot of heat for the remaining barriers. It would also significantly complicate later cleanup. As such, it is preferable that the fuel rods remain intact if at all possible, and this means attempting to cool them.

I respect your faith in good engineering, but I haven't seen alot of evidence of good engineering here.

There is no evidence to support your assertion that this is nothing like a "China syndrome" type issue. This facility is located a few miles from the eqicenter of the 4th largest earthquake in recorded history. None of the safety systems worked, and the power company and Japanese government has no clue about what to do.

So the future of (at a minimum) an entire region of Japan is dependent on a slab of concrete after a massive earthquake. It is a facility built in a known earthquake and flood hazard zone that requires continuous access to the utility grid.

Doesn't sound like good engineering by any standard to me.

According to the IAEA, Reactors 1-3 have been in cold shutdown since yesterday, which means they finally are where they were supposed to end up, in a stable situation where no water is boiling off anymore, so all the risk is gone.

It seems that the IAEA is not a useful source of up-to-date information here. Apparently they're bound by agreements not to say anything without TEPCO's approval. The little they've said has been hours or days late.

Unit 2 and 3 are believed to have lost containment integrity. Unit 3 is currently billowing smoke/steam.

> It seems that the IAEA is not a useful source of up-to-date information here.

From the agency's statute page (http://www.iaea.org/About/statute_text.html#A1.2):

> The Agency shall seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world.

Now why would an Agency which is interested in "accelerating" the use of atomic energy for "prosperity" around the world say anything too negative about all this mess?

Ai, I read it wrong. That was reactors 1-3 of the Daini station, not the Daiichi station.

CNN seems to have been doing everything in their power to make things more confusing and worse than it actually has been. To make matters worse, right in the middle of them stating that the reactors were experiencing a meltdown (this is over a day ago), they cut back and forth between videos of the explosion and videos of a natural gas refinery on fire. Classy act, that; clearly they're interested in journalistic integrity and accuracy. The expert they had on was attempting to do away with some of the insane sensationalism they were trying to lead him to admit had minor accuracies in them.

It would be nice if they posted a diff between their version and the original, if only for the people who already read the original and just want to see what changes were made.

Here you go:

Original: http://pastebin.com/UnCYDKbu

Modified: http://pastebin.com/1BAV3A4s

Good online tool to compare both: http://text-compare.com/

Sorry, the tool above doesn't offer a direct link to the diff, so you'll have to do the copy/paste by yourself. Or you could use pastebin's own diff, but it's less clear, in my opinion: http://pastebin.com/diff.php?i=1BAV3A4s

Your last link unreadable.

I think one would need a side-by-side comparison.

Try this for a side-by-side diff: http://dl.dropbox.com/u/171026/japan-nuclear-diff.html

I produced this using a feature of WinMerge (graphical diff utility for Windows, not too shabby) which can produce an HTML report of a diff.

The revisions seem pretty significant.

or: how I learned to stop not worrying and love the daiichi.

Very interesting, thanks.

Idle speculation from someone who is not a nuclear or a chemical engineer:

I'm suddenly wondering if the pressure relief valves for the primary coolant system could be designed with ignition circuits. The idea would be to burn off any hydrogen in a controlled fashion as it exits the coolant system, rather than giving it a chance to accumulate and later detonate. It would be similar to the way oil rigs burn off unwanted natural gas.

No doubt there's some very good reason for not doing this that I'm just not aware of. :-P

I believe the hydrogen that accumulates contains some radition (although mostly harmless) itself: http://mitnse.com/2011/03/15/explanation-of-hydrogen-explosi... (sixth paragraph)

Another article mentioned hydrogen wouldn't ignite with steam present.

By the point you're producing hydrogen, you're already well beyond your design limits...

Moreover, they've already lost primary, secondary, and tertiary power, so what exactly is going to run those ignition circuits? A gas flame near the reactor is just trading one source of explosion for another. And if they _did_ have power, they'd be running the primary (or secondary) coolant loops, and wouldn't have any hydrogen gas generation.

Meanwhile, 2 days after this article was published on March 13: "A small crew of technicians, braving radiation and fire, became the only people remaining at the Fukushima Daiichi Nuclear Power Station on Tuesday — and perhaps Japan’s last chance of preventing a broader nuclear catastrophe."

http://www.nytimes.com/2011/03/16/world/asia/16workers.html?...

They have just been pulled out because of increased radiation.

http://news.ycombinator.com/item?id=2330500

They're still there and working on the plant. http://thelede.blogs.nytimes.com/2011/03/15/latest-updates-o...

One small nitpick: if earthquakes were still measured on the Richter scale, the difference between 8.2 and 8.9 would be 5 times (as stated in the corrected article). However, the USGS uses the Moment magnitude scale (M_w, see http://earthquake.usgs.gov/earthquakes/glossary.php#magnitud... and http://en.wikipedia.org/wiki/Moment_magnitude_scale for details), so the difference between an 8.2 and an 8.9 is 11.2 times--more than double the stated increase. And now that the magnitude has been adjusted to 9.0 (see http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us...), the amount of energy released was 15.8 times more than an 8.2 earthquake.

AFAIK, all reports of the magnitude were on the Richter scale.

I'd suspect that at least half of the journalists reporting on this don't even know that there is a replacement for the Richter scale. Particularly with translation involved, it's pretty easy for one publication to drop the reference to the moment scale and the next publication to reattach the Richter name to the number.

Hi, Jack Gamble here, editor and founder of Nuclear Fissionary. Would kitsune_ care to post a link to where my website allegedly published the story by Dr Oehmen?

The reason I asked is, though I agree with the papers content, Nuclear Fissionary never published it. So basically, kitsune, you're a liar.

As for the attack on Jay Morgan, we're getting a kick out of that. Jay likes to describe himself as a Corporate Bean Counter, but he doesn't work in the nuclear industry like I do. I'm a nuclear engineer, not a lobbyist. I suppose you could describe me as an ADVOCATE for nuclear energy, but I'm no lobbyist.

But if you know of someone was willing to pay me a lobbyists salary to do what I do, I'd gladly take it. Until then, I shall bask in the tens of dollars that Google Adsense has paid out to my website in the last 13 months.

Of course, you're all welcome to come by nuclearfissionary.com and ask me technical questions about what's happening in Japan. Just don't expect me to give you the kind of chicken-little song and dance you're hearing in the media. I don't do fear, I'm a science guy.

He doesn't even get the units right, saying "231 micro sieverts" but specifying no time window. Per day? Per hour? Per minute?

A decent physicist would _never_ make that error.

I've seen lots of nuclear physicists say "micro sieverts" when they mean "micro sieverts per hour". Apparently radiation levels are normally cited in hourly dosages, so people get lazy and don't say the "per hour" part...

To any nuclear experts, question I've got: The Fukushima plant is a 1970's design I believe, what would the situation be if the plant was as modern a design as possible, would the situation there be different?

This was quite a 'walk-back' of the original headline.

It started as "Why I am not worried about Japan’s nuclear reactors" on one site. The title is now "Modified version of original post written by Josef Oehmen", with the content modified and moved to another site.

It also now includes a disclaimer "Note that the title of the original blog does not reflect the views of the authors of the site." Perhaps they should just come out and say, "we're experts and we're worried".

Unfortunately, this version is not as entertaining to read. It does seem much more accurate, though.

Yes, I'm really grateful to them for cutting through the crap. It's nice to have a relatively confident sense of what's going on.

Is there anything in the article to actually support the headline "we're worried"?

I would guess they're worried about some unknown or unprecedented contingency caused by the unique circumstances, as any rational person should be. Still, this has not happened and there is no scientifically sound reason that it should happen, based on our experience.

Just remember that the "original" was a blog post quoting an email posted by someone other than the writer---the "original" title was not the author of the email's.

Perhaps they should just come out and say, "we're experts but please, stop mailing us questions".

In my view, the reason why this new version is less enjoyable to read is, that they've just precised the numbers, labels and terms rather than the conclusion.

I still don't understand why this would be better than official sources of what has taken place. Sure for a background on the design of the plant in laymans terms, but. The event described is of what happened at the 12th, since then there has been more incidents, as noted at the very end of the article and a lot of it is unknown still.

CNN and MSNBC are now reporting that all workers have now been evacuated from Fukushima due to rising radiation levels.

So, there's still nobody hurt then? I hope so.

There are reports of two missing:

http://www.hindustantimes.com/Fresh-fire-at-Japan-nuclear-re...

Well, there are thousands missing elsewhere, I just hope that anyone alive gets found.

5 dead, 2 missing, 22 injured (including some severely).

http://www.nytimes.com/2011/03/16/world/asia/16workers.html?...

Or how I learned to stop worrying and love category 6 nuclear disasters. This is typical MIT hubris. Nobody knew om march 12 what was happening, even the operators, and even now nobody knows how bad thing are or how bad things will get.

>This is typical MIT hubris.

I am getting tired of asking this, but which facts are wrong in the revised article?

I don't know what is wrong with the article since I am not an expert in this.

I do know some of the claim have been contradicted by other experts, however.

One that I haven't seen agreement with is the claim that if the fuel achieves a full melt down, the chances of that melted fuel escaping are low. Most reports I've read aren't so optimistic to say the least.

Another point that is not wrong but simply unmentioned is the danger of high-level nuclear material stored around the plant. When spent nuclear fuel loses it's cooling water, it seems capable of going into meltdown also. There currently seems to be considerable worry about this happening.

http://www.world-nuclear-news.org/RS_Possible_damage_at_Fuku... (updated )

"Concern is growing over the status of fuel cooling ponds at units 4, 5 and 6."

One of the primary reasons the spent fuel problem is not mentioned in the article is because it became an issue fairly recently with the fire in the #4 building. Note that the date on the article is 3/12, whereas the fire and concerns in #4 are fairly recent, occurring on 3/15 and 3/16.

++Also, the spent fuel and the reactors themselves are separate problems, so I fail to see why an article about the reactors in under obligation to mention them.++

UPDATE: I concede that the article should be updated to include the #4 fire, as that is very pertinent (see below).

Indeed, I wouldn't expect to know about this wrinkle and I wouldn't expect an average person to know about it.

But I would expect a (supposed) expert in nuclear power who writes an article titled "why I am not worried" to know about this.

And while I am not an expert, I do know enough to know spent fuel has to be considered part of the system of a nuclear power plant and thus keeping it safe is part of keeping the entire plant safe.

If your accusation is that the article should have been updated to include this, I think that's fair. But my original question was about the facts of the article as is.

Well, it is all in the original title. The author's conclusion of "Why I am not worried" was based on the facts listed in his article. However, given the gravity of the current situation at the power plant we can assume that even though the facts listed in the article were all correct the author has misinterpreted them and reached a conclusion that that is wrong.

Edit: Think of it as a physic text homework problem. You have various facts listed throughout the problem, but your job is to use a correct formulas applied in the right sequences in order to derive a correct answer (aka interpret data "facts"). Simply re-stating the facts won't give you credit for the problem - the correct answer will (aka "conclusion").

Again, I'd posit that given the facts available 3/12, it was the right conclusion.

It was never the right conclusion to believe this kind of energy can be indefinitely managed.

Nuclear reactors are not velociraptors.

Well, my conclusion was totally different - right after the first explosion. Edit: I think you should really stop arguing this by now :) Unfortunately, I can not give you a credit for that problem - there is no partial credit, the answer is wrong so it is an "F".

Well the fact that it was necessary to be revised, should give you a hint that some things were wrong with the original one.

From the looks of the diff, it appears as though all they did was add clarity. Not really revise any of the facts.

I notice that they removed the implication that this reactor design incorporated a core catcher.

chuckle I'm getting tired of reiterating this, but NOBODY KNOWS which facts are right and which facts are wrong. They are epistemically bankrupt in the sense that their state of knowledge cannot rationally support the conclusions they are drawing. As I said, typical MIT hubris.

which facts are true? How would you know? What is your source of info? PR by government, or the PR by the plant operator?

I completely support the nuclear energy and i consider Chernobyls is just a cost of doing business. Yet all this hysteria - everything is ok! everything is doomed! Com'n, we lost 30km area in Chernobyl, we'll lose a few kilometers diameter zone in this case - again it is the low price for the progress - we lost much more land for the roads for cars, we've been killing a lot more of animals and people for other reasons. Relax, we're making progress.

Well, Fukushima daiichi unit 3 uses MOX fuel, a mix of uranium and plutonium, which TEPCO has been experimenting with for a few months now. But neither MOX nor plutonium get any mention in this article. This is not a trivial oversight.

http://www.tepco.co.jp/en/challenge/csr/nuclear/cycle-e.html

mitnse.com was registered just two days ago? With no track record what is the credibility of this site?

From whois:

   Registered through: Automattic
   Domain Name: MITNSE.COM
      Created on: 13-Mar-11
      Expires on: 13-Mar-12
      Last Updated on: 13-Mar-11

mitnse.com is linked to from http://web.mit.edu/nse/.

I imagine it would be either hard to fake that or it'd be noticed quickly if a MIT department's website was hacked.

On the about page, they also state that its linked and that they registered a new domain because they wanted to host on wordpress.com instead of dealing with large traffic themselves and apparently wordpress.com won't work on a sub-domain (or something along those lines).

You left out:

  Registrant:
   MIT Department of Nuclear Science and Engineering
   77 Massachusetts Avenue
   Cambridge
   Cambridge, Massachusetts 02139
   United States

and:

   Administrative Contact:
      Subbiah, Ilavenil  subbiah@mit.edu
      MIT Department of Nuclear Science and Engineering
      77 Massachusetts Avenue
      Cambridge
      Cambridge, Massachusetts 02139
      United States
      617-576-0593      Fax --

Edit: fixed formatting

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