The Cranach Nuclear Watch

The Cranach Nuclear Watch March 16, 2011

As Japan and the rest of the world worry over what will happen to the earthquake and tsunami damaged nuclear power plants, you should know that here at the Cranach blog we are getting some expert commentary.  MarkB used to work with nuclear power plants, and Carl Vehse–whom you might know merely on this blog as a conservative flamethrower–is by vocation a nuclear chemist.

I appreciate their ongoing explanations of the information that is coming out.

See what they say here and here.

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  • Dan Kempin

    I second the vote of thanks and appreciate the knowledge.

  • Dan Kempin

    I second the vote of thanks and appreciate the knowledge.

  • Louis

    I was a radiation protection officer, because I used to handle radioactive materials in a geochronology lab. I find the media useless in this crisis, as the level of hysteria and general wipping up of emotions makes it difficult to follow what is going on.

    We should continue the attempt at sanity here….

  • Louis

    I was a radiation protection officer, because I used to handle radioactive materials in a geochronology lab. I find the media useless in this crisis, as the level of hysteria and general wipping up of emotions makes it difficult to follow what is going on.

    We should continue the attempt at sanity here….

  • Porcell

    MarkB and Carl, as I understand it, these Fukushima reactors are about 40 years old and are known as generation two reactors that require electrical energy driven water coolant.

    The generation three reactors are said to have better containment and a water coolant system that doesn’t require electrical energy. Could you gentlemen elaborate on this and comment on the relative safety of the generation two reactors?

    BTW, I have found the World Nuclear News Website
    website to be an excellent source of information on the Japanese nuclear situation.

  • Porcell

    MarkB and Carl, as I understand it, these Fukushima reactors are about 40 years old and are known as generation two reactors that require electrical energy driven water coolant.

    The generation three reactors are said to have better containment and a water coolant system that doesn’t require electrical energy. Could you gentlemen elaborate on this and comment on the relative safety of the generation two reactors?

    BTW, I have found the World Nuclear News Website
    website to be an excellent source of information on the Japanese nuclear situation.

  • Porcell

    NRO has a Developing site with up to date info.

  • Porcell

    NRO has a Developing site with up to date info.

  • MarkB

    I believe that Fukushima 1, 2 and 3 are Mark 1 Boiling Water Reactors (BWR). The following link gives you drawings and text about the various differences between Mark 1 through 3 GE BWR systems.

    http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

    I think in the short term the Mark III reactors might have held up better, but a extended period of time without electricity to run pumps will trap the water in the reactor vessel no matter what generation of GE boiling water reactor it is. Since the water is trapped it cannot be cooled and that is why it is generating steam. To release the energy you need to vent the steam which will carry away the energy in it through the laten heat of vaporization. There is a problem with this in that it tends to leave the core or at least part of the core exposed to steam. That with the high temperatures causes the steam to react with the zirconium cladding on the fuel rods. This reaction generates hydrogen and makes the zirconium porous and mechanically weak. The hydrogen is what is causing the explosions that blow off the top of the buildings. The weakened zirconium allows the fuel pellets to fall out of the rods and pile together, which can cause more heating problems.

  • MarkB

    I believe that Fukushima 1, 2 and 3 are Mark 1 Boiling Water Reactors (BWR). The following link gives you drawings and text about the various differences between Mark 1 through 3 GE BWR systems.

    http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

    I think in the short term the Mark III reactors might have held up better, but a extended period of time without electricity to run pumps will trap the water in the reactor vessel no matter what generation of GE boiling water reactor it is. Since the water is trapped it cannot be cooled and that is why it is generating steam. To release the energy you need to vent the steam which will carry away the energy in it through the laten heat of vaporization. There is a problem with this in that it tends to leave the core or at least part of the core exposed to steam. That with the high temperatures causes the steam to react with the zirconium cladding on the fuel rods. This reaction generates hydrogen and makes the zirconium porous and mechanically weak. The hydrogen is what is causing the explosions that blow off the top of the buildings. The weakened zirconium allows the fuel pellets to fall out of the rods and pile together, which can cause more heating problems.

  • MarkB

    One of the reactors I worked on in the US Navy was a design called S5-G. It was used as a prototype reactor in Idaho at the Nuclear Testing Facility west of Idaho Falls, Idaho. Its sister was on the Narwhal submarine. It could operate at up to 50% power level without cooling pumps on a natural convection cycle. This was done to minimize noise.

    I don’t know if civilian nuclear plants could be designed to use natural convection or not, but it would be needed on both the primary (the water in direct contact with the reactor core) and the secondary (the water used to cool the condensate and steam and in the case of emergency cooling to cool the primary). If this could be done and made to be resistant to earthquakes then this type of problem could be avoided. However, this is all in hind sight for the problems at Fukushima. In the future we might want to think about this though.

    Even on the other subs with different reactor systems, the emergency cooling was designed to take advantage of natural convection so nothing had to be up and running to emergency cool the reactor. This was a lot easier to design in on the subs since the ssubs were immersed in water at all times.

  • MarkB

    One of the reactors I worked on in the US Navy was a design called S5-G. It was used as a prototype reactor in Idaho at the Nuclear Testing Facility west of Idaho Falls, Idaho. Its sister was on the Narwhal submarine. It could operate at up to 50% power level without cooling pumps on a natural convection cycle. This was done to minimize noise.

    I don’t know if civilian nuclear plants could be designed to use natural convection or not, but it would be needed on both the primary (the water in direct contact with the reactor core) and the secondary (the water used to cool the condensate and steam and in the case of emergency cooling to cool the primary). If this could be done and made to be resistant to earthquakes then this type of problem could be avoided. However, this is all in hind sight for the problems at Fukushima. In the future we might want to think about this though.

    Even on the other subs with different reactor systems, the emergency cooling was designed to take advantage of natural convection so nothing had to be up and running to emergency cool the reactor. This was a lot easier to design in on the subs since the ssubs were immersed in water at all times.

  • How does this compare with, say, Chernobyl if everything goes wrong? Or Thresher or Scorpion?

  • How does this compare with, say, Chernobyl if everything goes wrong? Or Thresher or Scorpion?

  • Carl Vehse

    The anti-nuclear advocacy group, NIRS, has a “Fact Sheet” indicating that five of the six Fukushima reactors are a GE Mark I design (although build by different companies) and the sixth is a Mark II design.

  • Carl Vehse

    The anti-nuclear advocacy group, NIRS, has a “Fact Sheet” indicating that five of the six Fukushima reactors are a GE Mark I design (although build by different companies) and the sixth is a Mark II design.

  • Seems as appropriate a time as any for this Simpsons quote (for those not familiar with the show, Kent Brockman is the local news anchor in the Simpsons’ town of Springfield):

    Kent Brockman: When cat burglaries start, can mass murders be far behind? This reporter isn’t saying that the burglar is an inhuman monster like the Wolfman, but he very well could be. So, professor: would you say it’s time for everyone to panic?

    Professor: Yes I would, Kent.

    And then, later on in the same episode:

    Kent Brockman: Hordes of panicky people seem to be evacuating the town for some unknown reason. Professor, without knowing precisely what the danger is, would you say it’s time for our viewers to crack each other’s heads open and feast on the goo inside?

    Professor: Mmm, yes I would, Kent.

  • Seems as appropriate a time as any for this Simpsons quote (for those not familiar with the show, Kent Brockman is the local news anchor in the Simpsons’ town of Springfield):

    Kent Brockman: When cat burglaries start, can mass murders be far behind? This reporter isn’t saying that the burglar is an inhuman monster like the Wolfman, but he very well could be. So, professor: would you say it’s time for everyone to panic?

    Professor: Yes I would, Kent.

    And then, later on in the same episode:

    Kent Brockman: Hordes of panicky people seem to be evacuating the town for some unknown reason. Professor, without knowing precisely what the danger is, would you say it’s time for our viewers to crack each other’s heads open and feast on the goo inside?

    Professor: Mmm, yes I would, Kent.

  • I will also offer, without comment, a blog post by a(n American) friend of mine who is living in Tokyo right now on the subject of foreign media coverage.

  • I will also offer, without comment, a blog post by a(n American) friend of mine who is living in Tokyo right now on the subject of foreign media coverage.

  • MarkB

    Bike Bubba:

    Chernobyl was a very different beast. That design used graphite to moderate the reactor and therefore was susceptible to having the reactor core burn. Along with that the main containment building was built similar to a modern steel building design. While the Mark I GE reactors do not have a pressure tight containment building it does have a containment that has not been breach, yet. At Chernobyl the burning of the graphite caused a lot of the high level radioactive contaminates to go up into the atmosphere with the smoke. My understanding is that at Fukushima they are venting steam from the reactor containment that contains some of what I would call medium level radioactive contamination. As the fuel is compromised by the zirc hydrating and possible meltdown there can be more higher level contamination going up with the steam. So far it is not a Japan wide problem nor a world wide problem. Can it become as bad as Chernobyl, maybe if they cannot keep sufficient amounts of water on the core to cool it and they lose the containment itself. They are not at that point right now.

    The problem now is that the levels of radiation are high enough now to put people in jeopardy if they are close to the plants. That means that the time is limited to do things. There are limits on how much radiation each of the workers can get by law and by how much time and radiation they can absorb without doing damage to themselves. They may need to take the Fukushima 50 out of the work cycle and swap them out with other workers to keep their level of radiation absorbtion down. I just saw a report on Foxnews where Japan has raised the acceptable level of exposure by a factor of 3x to accomodate what is happening here and to keep trained, skilled and knowledgeable workers on the job.

    The Thresher and the Scorpion went down in the 60’s due to other than reactor problems. The reactors used in nuclear subs can use emergency cooling that is natural convection designed to eliminate the heat of decay. All done without input from the operators in the worst case. So there should be no contamination from a meltdown of these reactors. One might be concerned about the reactor vessels corroding over time, especially since the primary system is designed out of stainless steel that is susceptible to chloride stress corrosion. This could add contamination to the oceans. It is my understanding that we know where they are and have visited them an are continuing to monitor them for radiation leaks.

  • MarkB

    Bike Bubba:

    Chernobyl was a very different beast. That design used graphite to moderate the reactor and therefore was susceptible to having the reactor core burn. Along with that the main containment building was built similar to a modern steel building design. While the Mark I GE reactors do not have a pressure tight containment building it does have a containment that has not been breach, yet. At Chernobyl the burning of the graphite caused a lot of the high level radioactive contaminates to go up into the atmosphere with the smoke. My understanding is that at Fukushima they are venting steam from the reactor containment that contains some of what I would call medium level radioactive contamination. As the fuel is compromised by the zirc hydrating and possible meltdown there can be more higher level contamination going up with the steam. So far it is not a Japan wide problem nor a world wide problem. Can it become as bad as Chernobyl, maybe if they cannot keep sufficient amounts of water on the core to cool it and they lose the containment itself. They are not at that point right now.

    The problem now is that the levels of radiation are high enough now to put people in jeopardy if they are close to the plants. That means that the time is limited to do things. There are limits on how much radiation each of the workers can get by law and by how much time and radiation they can absorb without doing damage to themselves. They may need to take the Fukushima 50 out of the work cycle and swap them out with other workers to keep their level of radiation absorbtion down. I just saw a report on Foxnews where Japan has raised the acceptable level of exposure by a factor of 3x to accomodate what is happening here and to keep trained, skilled and knowledgeable workers on the job.

    The Thresher and the Scorpion went down in the 60’s due to other than reactor problems. The reactors used in nuclear subs can use emergency cooling that is natural convection designed to eliminate the heat of decay. All done without input from the operators in the worst case. So there should be no contamination from a meltdown of these reactors. One might be concerned about the reactor vessels corroding over time, especially since the primary system is designed out of stainless steel that is susceptible to chloride stress corrosion. This could add contamination to the oceans. It is my understanding that we know where they are and have visited them an are continuing to monitor them for radiation leaks.

  • DonS

    I appreciate this informed, reasoned commentary very much. Thanks to both MarkB and Carl. The problems in Japan are obviously serious, and there will be valuable lessons learned for improving nuclear power safety in future years, as it is most certainly going to need to be a primary source of electrical power if we are going to wean ourselves from fossil fuels.

  • DonS

    I appreciate this informed, reasoned commentary very much. Thanks to both MarkB and Carl. The problems in Japan are obviously serious, and there will be valuable lessons learned for improving nuclear power safety in future years, as it is most certainly going to need to be a primary source of electrical power if we are going to wean ourselves from fossil fuels.

  • DonS

    tODD @ 10: Thanks for the link — great perspective on this whole tragedy.

  • DonS

    tODD @ 10: Thanks for the link — great perspective on this whole tragedy.

  • tODD; that’s great advice. Plus, you can make it into sandwiches!

    Oh, wait, you were….oh boy am I in trouble! :^)

    Mark; thanks. Will keep praying that people will be able to help these things die as gracefully as possible…..

  • tODD; that’s great advice. Plus, you can make it into sandwiches!

    Oh, wait, you were….oh boy am I in trouble! :^)

    Mark; thanks. Will keep praying that people will be able to help these things die as gracefully as possible…..

  • MarkB

    Foxnews just reported that the workers at Fukushima cannot put water into the spent fuel pond at Fukushima #4. The report did not say why. According to the online site Nuclear News the fuel rods from Fukushima #4 were removed over 100 days ago for maintenance. These rods should be mostly cooled down from the decay heat produced from normal operation although they still will be generating heat for years due to radioactive decay of fission byproducts. I don’t know if this is going to be a major problem or not.

  • MarkB

    Foxnews just reported that the workers at Fukushima cannot put water into the spent fuel pond at Fukushima #4. The report did not say why. According to the online site Nuclear News the fuel rods from Fukushima #4 were removed over 100 days ago for maintenance. These rods should be mostly cooled down from the decay heat produced from normal operation although they still will be generating heat for years due to radioactive decay of fission byproducts. I don’t know if this is going to be a major problem or not.

  • MarkB

    Here is a link to a website from MIT about the Nuclear Plant Problems. It has a lot of useful information and seems to be keeping up with events as they go along.

    http://mitnse.com/

    And now the US Nuclear Regulatory Agency has confirmed that the spent fuel storage area at Fukushima #4 is dry. If you want an idea of what that presents a problem go to the above listed link.

  • MarkB

    Here is a link to a website from MIT about the Nuclear Plant Problems. It has a lot of useful information and seems to be keeping up with events as they go along.

    http://mitnse.com/

    And now the US Nuclear Regulatory Agency has confirmed that the spent fuel storage area at Fukushima #4 is dry. If you want an idea of what that presents a problem go to the above listed link.

  • DonS

    http://www.mg.co.za/article/2011-03-22-why-fukushima-made-me-stop-worrying-and-love-nuclear-power

    One liberal’s take on the outcome of the Fukushima nuclear incident.

    A crappy old plant with inadequate safety features was hit by a monster earthquake and a vast tsunami. The electricity supply failed, knocking out the cooling system. The reactors began to explode and melt down. The disaster exposed a familiar legacy of poor design and corner-cutting. Yet, as far as we know, no one has yet received a lethal dose of radiation.

    He’s got a good point. He now says he is a nuke supporter.

  • DonS

    http://www.mg.co.za/article/2011-03-22-why-fukushima-made-me-stop-worrying-and-love-nuclear-power

    One liberal’s take on the outcome of the Fukushima nuclear incident.

    A crappy old plant with inadequate safety features was hit by a monster earthquake and a vast tsunami. The electricity supply failed, knocking out the cooling system. The reactors began to explode and melt down. The disaster exposed a familiar legacy of poor design and corner-cutting. Yet, as far as we know, no one has yet received a lethal dose of radiation.

    He’s got a good point. He now says he is a nuke supporter.