Japanese Reactor(s) Update(d) Yet Again

See updates and comments below for a lot of good information, important updates, and discussion. And big thanks to Instapundit for the Installanche! ***** This post is continuing to be updated (and bumped) as needed, and I strongly urge readers to go down into the comments, as there is a lot of very good information there. I can't say thank you enough to Subsunk and and grtflmark for their extensive and authoritative contributions to this thread. Thanks to Old Nuke for also joining in. I hope that they will continue to do so. I am going to add more updates below the fold. Please scroll down, there is a lot there. Also doing some clean-up and organizing to make it easier to read/find info in the post itself. 3 April: Have bumped because of the cracked storage pit and the recovery of two bodies from the plant. See below for details. ***** This is a follow-up to my earthquake/missing person post of this morning, and the updates there. UPDATE: Bumping this up from the comments as it is the best and most intelligent discussion I've seen on the situation, and on nuke plants in general. And it comes from someone who knows their stuff: Subsunk. Good comments LW. Pressurized and Boiling Water Reactors are cooled by pure water. After a Reactor SCRAM (Emergency shutdown, caused by automatic protective action, loss of electrical power, or by operator action once something like an earthquake might happen), the reactor contains fission products that continue to decay away. There are several groups of these fission products all with different half lives (decay away to insignificance) periods. Some have very short half lives and decay away in seconds or minutes. Some in hours, and some in months or years. The heat produced from these decaying fission products has to be carried away by water, or the fuel elements will get too hot and melt and release the really BAD fission products to the atmosphere or the coolant. Usually, assuming the integrity of the reactor vessel containing the water, and the loops of cooling water remains intact, all you should have to do is turn the cooling pumps on and keep the fluid circulating through the core to remove that "decay heat". The problem is that the backup power generator (usually a diesel engine with a DC or AC power generator on it) or the electrical equipment necessary to power these pumps for this Japanese plant appears to have suffered sufficient damage to keep electricity from being generated or the pumps from being turned on. The solution is to truck in emergency generators, or repair systems at all costs to get these pumps running. Once they can be run again, even if they are pumping steam initially, you have to get fluid moving to remove the reactor decay heat. Batteries, or battery banks, no matter how big they are, will never have enough power to keep these huge pumps running for a significant length of time. The backup systems if you can never get these pumps running is to "feed and bleed", or allow the plants natural circulation capabilities to handle the heat rejection. Natural circulation is usually not very effective in huge reactors like commercial reactors because the water has so many twists and turns to make the flow happen. So "feed and bleed is a last resort. You pump fresh water in while you bleed off steam from the reactor pressurizer (a pressure vessel that maintains a high pressure in the reactor vessel so the water doesn't boil and make large volumes of steam inside the core, which is, of course, the hottest part of the system, and therefore prevents flow through the core if you get steam into it) and keep feeding and bleeding to remove this heat. Now this isn't as bad as it might sound because you don't have to bleed a lot of steam off to remove a lot of heat. To make steam from water removes a large heat of vaporization which removes a lot of heat from the water around it. So you only need to bleed off a little steam to remove lots of heat, and add only a little bit of water to make up for that. When you bleed the steam, however, you are bleeding some of the radioactivity (probably not the fission products right away until the core actually starts to melt, but things in water and the corrosion resistant chemicals we use inside these plants which get activated and become radioactive for short periods of time). So the reports of radiation being 1000x the normal level may or may not be serious. The reports of no backup power are very serious though. You have to have power to push the fresh water into the reactor and they may not have it. It depends on where you take the readings, and what the normal radiation levels are to determine how serious this is. For instance, on my ships, the normal background radiation was less than 1 millirem per hour. About the best we could detect with our low range instruments, and anything less is probably not detectable without serious instrumentation and you'll find every rock and fire extinguisher and bunch of bananas is radioactive then. 1000x that background level is 1 Rem per hour. That is a serious dose and will kill you if you stay there in that radiation field for just over 200-300 hours. If the Japs are venting the vessel to remove heat and putting out this level of radiation while they are doing that, it is a serious issue, but we need to remember the wind would carry most of this away, it disperses or decays away relatively rapidly, and it would also decay completely away in a few days or months. Plus that means they are only experiencing those levels while they are venting. Then the level might return to near normal. Until we see whether they get the...

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Posted Apr 02 2011, 09:40 PM by BLACKFIVE