
The 'why I am not worried' article, edited by MIT nuclear scientists - RyanMcGreal
http://mitnse.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/?mit
======
kitsune_
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.

~~~
rimantas
> 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).

~~~
brazzy
_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

~~~
moe
_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".

~~~
daniel-cussen
>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...](http://en.wikipedia.org/wiki/Three_Mile_Island_accident#Health_effects_and_epidemiology).

------
Duff
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?

~~~
cperciva
_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_.)

~~~
timr
_"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.

~~~
cperciva
_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.

~~~
timr
_"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.

~~~
yummyfajitas
_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.

~~~
timr
_"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.

~~~
yummyfajitas
_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?

------
NickM
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.

~~~
gregschlom
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>

~~~
brown9-2
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.

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

Very interesting, thanks.

------
wtracy
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

~~~
bdonlan
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.

------
erickhill
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?...](http://www.nytimes.com/2011/03/16/world/asia/16workers.html?_r=1&hp)

~~~
Element_
They have just been pulled out because of increased radiation.

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

~~~
dicemoose
They're still there and working on the plant.
[http://thelede.blogs.nytimes.com/2011/03/15/latest-
updates-o...](http://thelede.blogs.nytimes.com/2011/03/15/latest-updates-on-
japans-nuclear-crisis-and-earthquake-aftermath-2/#core-group-of-workers-
remain-at-plant)

------
bgrainger
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...](http://earthquake.usgs.gov/earthquakes/glossary.php#magnitude)
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...](http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0001xgp.php)),
the amount of energy released was 15.8 times more than an 8.2 earthquake.

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

~~~
wtallis
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.

------
Gamble180
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.

------
retrogradeorbit
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.

~~~
cperciva
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...

------
JonoW
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?

------
gojomo
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".

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

~~~
Estragon
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.

------
adsr
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.

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

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

~~~
13Psibies
There are reports of two missing:

[http://www.hindustantimes.com/Fresh-fire-at-Japan-nuclear-
re...](http://www.hindustantimes.com/Fresh-fire-at-Japan-nuclear-reactor-
radiation-fears-rise/Article1-673974.aspx)

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

------
RandyHelzerman
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.

~~~
icarus_drowning
>This is typical MIT hubris.

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

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

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

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

------
colinprince
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

~~~
brown9-2
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.

~~~
dkersten
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).

