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I certainly agree with his main point: the nuclear reactor accidents are a comparatively small part of the earthquake catastrophe. But the rest of the article r

I certainly agree with his main point: the nuclear reactor accidents are a comparatively small part of the earthquake catastrophe. But the rest of the article reads like pure propaganda-- like he started out writing the article with the goal of downplaying rather than assessing the risks involved. I can spot at least one inaccuracy. He claims that TMI showed that there is no risk of nuclear fuel melting through the steel containment structure. But at TMI, the core was actively cooled through the entire incident, and the temperatures were not even high enough to melt the fuel itself. So this does not given any information about what would happen in the absence of cooling.

_delirium 16y ago
I agree his TMI comparison isn't very useful, but about 1/3 of the fuel at TMI did melt, according to http://www.ans.org/pi/resources/sptopics/tmi/whathappened.html http://www.ans.org/pi/resources/sptopics/tmi/whathappened.ht...
webXL 16y ago
I wouldn't call it propaganda if your merely trying to get people to put facts of an entire tragedy into the proper context. Yesterday morning I turned on the ABC and saw this: http://yfrog.com/h7r6rmcj http://yfrog.com/h7r6rmcj CNN has been treating the nuclear accidents with equal importance, just because they know it freaks people out, publishing numerous errors on their website, according to one MIT scientist (Dr Josef Oehmen): https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/ https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-w... Don't get me wrong, there is definitely propaganda on both sides, but the anti-nuclear crowd pouncing on this before we have all the facts, and while there's a race against the clock to find survivors and prevent more loss of life, is counter-productive.
- hcurtiss 16y ago
  Thank you for the Oehmen link. Supremely useful.
  - Lazlo_Nibble 16y ago
    I've seen a lot of people latch on to this writeup as authoritative, and I'm not sure why. Oehmen may indeed be a "research scientist" at MIT but his specialty is supply-chain risk management, not reactor design (http://web.mit.edu/oehmen/www/ http://web.mit.edu/oehmen/www/). Is there any reason to believe that he's anything more than an interested amateur on this topic?
    - knshaum 16y ago
      The post has been moved, and updated by members of MIT's Nuclear Science and Engineering community: http://mitnse.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/ http://mitnse.com/2011/03/13/why-i-am-not-worried-about-japa...
      - Lazlo_Nibble 16y ago
        Possibly relevant: http://geniusnow.com/2011/03/15/the-strange-case-of-josef-oehmen/ http://geniusnow.com/2011/03/15/the-strange-case-of-josef-oe...
mpyne 16y ago
> He claims that TMI showed that there is no risk of nuclear fuel melting through the steel containment structure. But at TMI, the core was actively cooled through the entire incident, and the temperatures were not even high enough to melt the fuel itself. Actually, about 1/3 to 1/2 of the Three Mile Island core melted completely (i.e. far worse than mere zirconium cladding damage). This was because the Three Mile Island core was not continuously cooled. There were a couple of elements to this: 1. In normal operation, the primary system is kept highly pressurized to ensure that the primary coolant does not boil. The way this is done, however, is to use something called a pressurizer, which does have a steam bubble, for much the same reason cars use shock absorbers. When the steam flow was cut off to the turbine generators, that acted as a loss of the heat sink that had been cooling the reactor, which caused pressure to go up. When pressure got too high, a relief valve in the pressurizer automatically lifted to relieve the pressure increase and maintain primary piping integrity. The valve was supposed to automatically shut once the pressure dropped enough, but did not. The indication that the operators had showed that the valve had been commanded to shut, but did not show that the valve had not actually shut. The location of the leak tended to artificially increase water level in the pressurizer by essentially "sucking" it from the reactor vessel (the operators had no indication of reactor vessel water level, since it was normally completely full of liquid). This loss of water from the reactor meant that it uncovered the fuel much quicker than might otherwise be expected. The operators had other ways of telling something was wrong (such as the sharp pressure drop from a stuck open relief valve) but did not put the puzzle together. They even did worse: Automatic safety systems kicked on to force-fill the reactor with cooling water, but the operators were afraid the system would overflow the entire primary (remember, they thought there was still water in the reactor vessel), so they dampened the flow, then shut off the system completely. 2. As steam started forming in the reactor vessel, the coolant loop piping connecting the reactor vessel to the reactor cooling pumps started to fill with steam, which caused the reactor cooling pumps to cavitate (which is certainly not good for the pumps). The operators had indication of this, but assumed the cavitation was due to the pressure drop and, again thinking the core was still covered with water, they shut down the reactor cooling pumps. This represented the loss of the last line of defense against reactor meltdown. It was not until some hours later when a different shift relieved that it was realized that a relief valve was stuck open and that there was no water over the fuel. They started re-established cooling at this point, but the damage was already done.

_delirium 16y ago

I agree his TMI comparison isn't very useful, but about 1/3 of the fuel at TMI did melt, according to http://www.ans.org/pi/resources/sptopics/tmi/whathappened.html http://www.ans.org/pi/resources/sptopics/tmi/whathappened.ht...

webXL 16y ago

I wouldn't call it propaganda if your merely trying to get people to put facts of an entire tragedy into the proper context. Yesterday morning I turned on the ABC and saw this: http://yfrog.com/h7r6rmcj http://yfrog.com/h7r6rmcj CNN has been treating the nuclear accidents with equal importance, just because they know it freaks people out, publishing numerous errors on their website, according to one MIT scientist (Dr Josef Oehmen): https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/ https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-w... Don't get me wrong, there is definitely propaganda on both sides, but the anti-nuclear crowd pouncing on this before we have all the facts, and while there's a race against the clock to find survivors and prevent more loss of life, is counter-productive.

hcurtiss 16y ago
Thank you for the Oehmen link. Supremely useful.
- Lazlo_Nibble 16y ago
  I've seen a lot of people latch on to this writeup as authoritative, and I'm not sure why. Oehmen may indeed be a "research scientist" at MIT but his specialty is supply-chain risk management, not reactor design (http://web.mit.edu/oehmen/www/ http://web.mit.edu/oehmen/www/). Is there any reason to believe that he's anything more than an interested amateur on this topic?
  - knshaum 16y ago
    The post has been moved, and updated by members of MIT's Nuclear Science and Engineering community: http://mitnse.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/ http://mitnse.com/2011/03/13/why-i-am-not-worried-about-japa...
    - Lazlo_Nibble 16y ago
      Possibly relevant: http://geniusnow.com/2011/03/15/the-strange-case-of-josef-oehmen/ http://geniusnow.com/2011/03/15/the-strange-case-of-josef-oe...

mpyne 16y ago

> He claims that TMI showed that there is no risk of nuclear fuel melting through the steel containment structure. But at TMI, the core was actively cooled through the entire incident, and the temperatures were not even high enough to melt the fuel itself. Actually, about 1/3 to 1/2 of the Three Mile Island core melted completely (i.e. far worse than mere zirconium cladding damage). This was because the Three Mile Island core was not continuously cooled. There were a couple of elements to this: 1. In normal operation, the primary system is kept highly pressurized to ensure that the primary coolant does not boil. The way this is done, however, is to use something called a pressurizer, which does have a steam bubble, for much the same reason cars use shock absorbers. When the steam flow was cut off to the turbine generators, that acted as a loss of the heat sink that had been cooling the reactor, which caused pressure to go up. When pressure got too high, a relief valve in the pressurizer automatically lifted to relieve the pressure increase and maintain primary piping integrity. The valve was supposed to automatically shut once the pressure dropped enough, but did not. The indication that the operators had showed that the valve had been commanded to shut, but did not show that the valve had not actually shut. The location of the leak tended to artificially increase water level in the pressurizer by essentially "sucking" it from the reactor vessel (the operators had no indication of reactor vessel water level, since it was normally completely full of liquid). This loss of water from the reactor meant that it uncovered the fuel much quicker than might otherwise be expected. The operators had other ways of telling something was wrong (such as the sharp pressure drop from a stuck open relief valve) but did not put the puzzle together. They even did worse: Automatic safety systems kicked on to force-fill the reactor with cooling water, but the operators were afraid the system would overflow the entire primary (remember, they thought there was still water in the reactor vessel), so they dampened the flow, then shut off the system completely. 2. As steam started forming in the reactor vessel, the coolant loop piping connecting the reactor vessel to the reactor cooling pumps started to fill with steam, which caused the reactor cooling pumps to cavitate (which is certainly not good for the pumps). The operators had indication of this, but assumed the cavitation was due to the pressure drop and, again thinking the core was still covered with water, they shut down the reactor cooling pumps. This represented the loss of the last line of defense against reactor meltdown. It was not until some hours later when a different shift relieved that it was realized that a relief valve was stuck open and that there was no water over the fuel. They started re-established cooling at this point, but the damage was already done.