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Please be aware that there is a lot of scare-mongering and "worst-case" scenarios being reported in the press. (Enviros don't want to waste a crisis for their a

by dmfdmf 16y ago

Please be aware that there is a lot of scare-mongering and "worst-case" scenarios being reported in the press. (Enviros don't want to waste a crisis for their anti-science agenda). It would not be unusual for there to be radiation released during an emergency reactor shutdown (scram) with equipment damage due to the earthquake. It does not necessarily imply core damage or melt down. The primary coolant system of a BWR is radioactive due to neutron activation but that type of radioactivity is short lived, emergency release during over pressure may have been necessary to maintain the integrity of the cooling system. If the reactors are shutdown the situation is fairly stable and the operators have numerous options (and time) to deal with the equipment failure and insure the core is adequately cooled of residual heat. I am waiting for more info as not enough details are getting out at this point... N.B. I used to design BWR feedwater control systems. AMA

marshray 16y ago
The operator is saying they've "lost control of the ability to control pressure in some of the reactors". The cooling systems of three reactors at another plant are "malfunctioning". How do we read that?
- epochwolf 16y ago
  I would say it's technically correct. They have lost primary and backup power to the pumps. This means they really don't have the ability to do much about the pressure right now. The reactor is basically running uncontrolled. They've been scrammed but it takes a long time to stop the reaction. They still have emergency options available like venting the primary coolant loop if the pressure gets too close the limits of the reactor. There is still plenty of time before the reactors go critical.
  - dmfdmf 16y ago
    My details may be off (its been over 10 years) but the post scram core needs to be cooled with forced coolant for something like 30-40 hours. After that it can be cooled by boil off (assuming no core damage) but the down side is radiation release mostly due to neutron activated nitrogen dissolved in the coolant water (which dissipates in 36 hours or so).
    - epochwolf 16y ago
      Yeah, I meant the control rods are all in. This is a potentially dangerous suitation but there is time to still get the reators under control. I doubt the worse case would be a meltdown because you could open the primary loop and stick a hose I it. Edit: this is a good explaination http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Systems http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy...
- dmfdmf 16y ago
  Its hard to read at this point... I am assuming the reactor is shutdown (rods all in) and they are dealing with residual heat (still hot enough to melt the core). The cooling systems (primary and backup and emergency core cooling) may be damaged and they are working around these problems... I would be very surprised if the failures were such that it prevented any method to cool the core. They almost certainly were able to establish some kind of core cooling but it may be temporary and require more actions to fully stabilize. Also, don't forget these quotes are translations from Japanese and may be mis-translations or inadvertent exaggerations (very common when I worked with Japanese engineers).
- patio11 16y ago
  I would read that in knowledge that a Japanese company producing cell phone camera gaskets where any two in a batch of 1,000 were defective would report "the manufacturing process is out of control" and the $10 an hour operator would have scrammed production until the engineers investigated and fixed the machinery. If you knew nothing of Japanese engineering culture, would today's unceasing, relentless drumbeat of lack-of-catastrophe worry you?
  - marshray 16y ago
    When a government minister reports that the cooling system is offline and the pressure is 2.1x design norms, I don't think that's a cultural thing comparable to a 2-in-1000 bad gasket production shutdown. But maybe it is. These guys seem pretty matter-of-fact: http://www.tepco.co.jp/en/press/corp-com/release/index-e.html http://www.tepco.co.jp/en/press/corp-com/release/index-e.htm... For example: "Reactor Core Isolation Cooling System was used to inject water into the reactor to cool it. Today at 4:50AM, water injection by Make-up Water Condensate System begun. Subsequently, at 5:32AM, the temperature of the suppression chamber exceeded 100 degrees. As the reactor pressure suppression function was lost, at 5:32AM, it was determined that a specific incident stipulated in article 15, clause 1 has occurred." This sounds like a mechanical regulatory reporting issue. Other text like: "We have decided to implement measures to reduce the pressure of the reactor containment vessel for those units that cannot confirm certain level of water injection by the Reactor Core Isolation Cooling System, in order to fully secure safety." I'm just wondering how to interpret this. For example, when they say "reactor containment vessel" do they mean the "reactor vessel" or the "containment building" in en.wikipedia.org terminology? Why couldn't they "confirm certain level of water injection" in some units? Is it that the plant design didn't include the necessary sensors, or that they were damaged?
mcritz 16y ago
It's a testament to the quality of the reactor's design that it can survive a richter 9 earthquake. In similar circumstances there would be immeasurable environmental damage caused by a burning coal mine or sunken offshore oil platform.
- dmfdmf 16y ago
  When I was in the nuclear business we used to say the best place to be during the proverbial big-one was onsite.
midnightmagic 16y ago
For which reactors? Are they still operational? Is your name available somewhere that we could verify? You're asking us to accept your authoritative statements based on credentials, but you haven't really left open the option of verifying either with research.
- dmfdmf 16y ago
  As a junior engineer I worked on Kashiwazaki-Kariwa Nuclear Power Station: Units 6 and 7 or K6/K7. I assisted in control system designs for the reactor internal pumps (RIPs) including supporting seismic qualification of the RIP motor controllers. Later I was the lead system engineer for the Feedwater Control System for Lungmen Units 1 and 2 going up in Taiwan. No way to prove it so I could just be a dog posting on the internet.
  - midnightmagic 16y ago
    Good enough for me. Now there's a record of it, and I thank you for your honesty.
- mkramlich 16y ago
  > Is your name available somewhere that we could verify? Does it matter? Sheesh, it's a comment on a forum. He's probably legit. If he's not, who cares? Are you a government leader needing to make a decision that will effect millions and it's all hinging on the veracity of some forum comment here on HN?! :-)
jshen 16y ago
"(Enviros don't want to waste a crisis for their anti-science agenda)" Let's reevaluate this in a few days. It's not looking good at this point. My experience is the opposite of yours, and it's to be highly skeptical of official statements right after a disaster.

by dmfdmf 16y ago

marshray 16y ago

The operator is saying they've "lost control of the ability to control pressure in some of the reactors". The cooling systems of three reactors at another plant are "malfunctioning". How do we read that?

epochwolf 16y ago
I would say it's technically correct. They have lost primary and backup power to the pumps. This means they really don't have the ability to do much about the pressure right now. The reactor is basically running uncontrolled. They've been scrammed but it takes a long time to stop the reaction. They still have emergency options available like venting the primary coolant loop if the pressure gets too close the limits of the reactor. There is still plenty of time before the reactors go critical.
- dmfdmf 16y ago
  My details may be off (its been over 10 years) but the post scram core needs to be cooled with forced coolant for something like 30-40 hours. After that it can be cooled by boil off (assuming no core damage) but the down side is radiation release mostly due to neutron activated nitrogen dissolved in the coolant water (which dissipates in 36 hours or so).
  - epochwolf 16y ago
    Yeah, I meant the control rods are all in. This is a potentially dangerous suitation but there is time to still get the reators under control. I doubt the worse case would be a meltdown because you could open the primary loop and stick a hose I it. Edit: this is a good explaination http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Systems http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy...
dmfdmf 16y ago
Its hard to read at this point... I am assuming the reactor is shutdown (rods all in) and they are dealing with residual heat (still hot enough to melt the core). The cooling systems (primary and backup and emergency core cooling) may be damaged and they are working around these problems... I would be very surprised if the failures were such that it prevented any method to cool the core. They almost certainly were able to establish some kind of core cooling but it may be temporary and require more actions to fully stabilize. Also, don't forget these quotes are translations from Japanese and may be mis-translations or inadvertent exaggerations (very common when I worked with Japanese engineers).
patio11 16y ago
I would read that in knowledge that a Japanese company producing cell phone camera gaskets where any two in a batch of 1,000 were defective would report "the manufacturing process is out of control" and the $10 an hour operator would have scrammed production until the engineers investigated and fixed the machinery. If you knew nothing of Japanese engineering culture, would today's unceasing, relentless drumbeat of lack-of-catastrophe worry you?
- marshray 16y ago
  When a government minister reports that the cooling system is offline and the pressure is 2.1x design norms, I don't think that's a cultural thing comparable to a 2-in-1000 bad gasket production shutdown. But maybe it is. These guys seem pretty matter-of-fact: http://www.tepco.co.jp/en/press/corp-com/release/index-e.html http://www.tepco.co.jp/en/press/corp-com/release/index-e.htm... For example: "Reactor Core Isolation Cooling System was used to inject water into the reactor to cool it. Today at 4:50AM, water injection by Make-up Water Condensate System begun. Subsequently, at 5:32AM, the temperature of the suppression chamber exceeded 100 degrees. As the reactor pressure suppression function was lost, at 5:32AM, it was determined that a specific incident stipulated in article 15, clause 1 has occurred." This sounds like a mechanical regulatory reporting issue. Other text like: "We have decided to implement measures to reduce the pressure of the reactor containment vessel for those units that cannot confirm certain level of water injection by the Reactor Core Isolation Cooling System, in order to fully secure safety." I'm just wondering how to interpret this. For example, when they say "reactor containment vessel" do they mean the "reactor vessel" or the "containment building" in en.wikipedia.org terminology? Why couldn't they "confirm certain level of water injection" in some units? Is it that the plant design didn't include the necessary sensors, or that they were damaged?

mcritz 16y ago

It's a testament to the quality of the reactor's design that it can survive a richter 9 earthquake. In similar circumstances there would be immeasurable environmental damage caused by a burning coal mine or sunken offshore oil platform.

dmfdmf 16y ago
When I was in the nuclear business we used to say the best place to be during the proverbial big-one was onsite.

midnightmagic 16y ago

For which reactors? Are they still operational? Is your name available somewhere that we could verify? You're asking us to accept your authoritative statements based on credentials, but you haven't really left open the option of verifying either with research.

dmfdmf 16y ago
As a junior engineer I worked on Kashiwazaki-Kariwa Nuclear Power Station: Units 6 and 7 or K6/K7. I assisted in control system designs for the reactor internal pumps (RIPs) including supporting seismic qualification of the RIP motor controllers. Later I was the lead system engineer for the Feedwater Control System for Lungmen Units 1 and 2 going up in Taiwan. No way to prove it so I could just be a dog posting on the internet.
- midnightmagic 16y ago
  Good enough for me. Now there's a record of it, and I thank you for your honesty.
mkramlich 16y ago
> Is your name available somewhere that we could verify? Does it matter? Sheesh, it's a comment on a forum. He's probably legit. If he's not, who cares? Are you a government leader needing to make a decision that will effect millions and it's all hinging on the veracity of some forum comment here on HN?! :-)

jshen 16y ago

"(Enviros don't want to waste a crisis for their anti-science agenda)" Let's reevaluate this in a few days. It's not looking good at this point. My experience is the opposite of yours, and it's to be highly skeptical of official statements right after a disaster.