UPDATED most recently on October 17th; previously updated on May 30th, May 22nd, June 21st , July 3rd, August 4th, and September 22nd — see notes I’ve addended to end of Wednesday’s post.
Here’s an analogy: you’ve been wounded, are bleeding profusely, and are taken to the emergency room. But, instead of being able to close the wound, all the nurses can do is keep pumping fresh blood into you, letting it leak out onto the floor of the emergency room — after which the cleanup crews remove it. After awhile, the nurses say, look, we can’t do this forever, what we’re going to do instead is flood the emergency room with blood and submerge you up to your shoulders in blood. That way, the bleeding will stop. It’s an extreme plan, but it is all they’ve got. You never thought you’d be in such a situation. The plan commences. But the emergency room leaks, way too much, for the plan to work. The blood rushes out of the emergency room, the level never rising above your ankles. Now what?
That, I believe, is about where TEPCO finds itself with respect to its plans to stabilize the situation at Fukushima Daiichi Unit I. As explained in my last post, TEPCO’s plan to keep water in the reactor vessel was to flood the surrounding containment vessel with water. A sketch of the plan that includes a diagram is here: http://www.neimagazine.com/story.asp?sectioncode=72&storyCode=2059558 But the containment vessel leaked too much for even that extreme plan to work.
The next plan, based on unofficial information, seems to be just to extend the basic scheme out one more level, that is, to the next level of surrounding container: the buildings in which the reactor containment, which contains the reactor vessel, which holds the molten core, is housed. A sketch of that plan is here: http://www.zerohedge.com/article/tepco-provides-complete-fukushima-status-update-and-roadmap-recovery?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+zerohedge%2Ffeed+%28zero+hedge+-+on+a+long+enough+timeline%2C+the+survival+rate+for+everyone+drops+to+zero%2
To put this all into perspective:
In normal plant operation, the recirculation path is: water is injected into the reactor vessel via piping, then out of the reactor vessel as steam via piping, after which that steam is condensed back to water, and pumped back into the reactor vessel. Here is a sketch of a BWR showing normal operation: http://www.nrc.gov/reactors/bwrs.html
What TEPCO has been doing since the accident is just to inject water (at first, seawater, then freshwater) into the reactor vessel (which now contains molten fuel). But the water just keeps leaking out. The level in the reactor vessel doesn’t rise, and it produces a lot of radioactive water that has to be dealt with. It’s been stored wherever room for it can be found (a tank, the interior of a building); as room ran out, a huge barge was brought near the plant to store it. That what is still being done. More and more radioactive effluent is being generated. This can’t go on indefinitely.
The non-normal method described in the NEI magazine article linked to above ( TEPCO begins flooding Unit 1, 6 May 2011 ) http://www.neimagazine.com/story.asp?sectioncode=72&storyCode=2059558 ) tried in early May, after it was known that the reactor vessel was wounded and leaking water, was this: First, inject fresh water into the reactor vessel via piping. That water leaks out of the reactor vessel into the containment vessel, after which it was to be sucked via piping attached to the containment vessel, cooled via a heat exchanger, and reinjected into the vessel via piping attached to the reactor vessel and normally used for water injection. (The other side of the heat exchanger is connected to the plant cooling system that ultimately rejects the heat to the environment via the plant’s cooling tower.) This non-normal plan, begun around May 5/6, relies upon the containment vessel being intact, or at least not leaking too much. But, it turned out, the containment vessel leaked way too much for this to work.
That was the last workable plan. As stated in my last post, Japan’s nuclear safety regulatory agency gave the go-ahead because, it said, there was no other effective option. That option having failed, the only option now is to try desparate things that involve highly radioactive water being pumped into places it was never meant to be. Now, the proposed circulation path includes the building to which the containment vessel is leaking. The idea of what to do next seems to be to try the following path:
– water gets injected into the reactor core , then
– water leaks out of the reactor vessel to the containment vessel, and then
– water leaks out of the containment vessel to the building floor, and then
– the water on the building floor is pumped through equipment to filter/purify/decontaminate/cool it, and then
– the cleaned-up water is reinjected into the reactor core.
My expertise is largely with PWRs (Pressurized Water Reactors), rather than BWRs. (Boiling Water Reactors), Based on what I know about PWRs, though, I suspect that this approach involves continuous risk. I say this because one of the major problems the US NRC has had to deal with recently on US PWRs is how to ensure that when water that has leaked onto the reactor containment building floor (in a hypothetical accident situation) is pumped through filters/screens, that the debris that the water has picked up via flowing through the building doesn’t clog things up and cause damage to important reactor cooling equipment.
The recirculation of leaked water back into the reactor after an accident in which the reactor vessel leaks is part of the planned recovery process for a type of PWR accident considered practially impossible, so pumping water that has leaked onto the floor of a building back into the reactor is not completely unheard of. (TMI was a PWR, but it never got anywhere near having to do this, as its brand-new reactor vessel did not leak.) However, there are lots of concerns about using a recirculation path that involves water that has leaked onto building floors: about the only thing that can be done to protect against debris in the water damaging equipment or otherwise affecting cooling flow to the reactor core is to ensure that excellent cleanliness procedures are used and constantly enforced in the building into which the water would be leaking in such a situation. But of course for TEPCO this could be too late for that to help, if the flooding has already occurred.
It’s hard to see the path ahead to a cold shutdown. About all that is known is that it is going to be difficult. TEPCO’s claims to be sticking to its schedule of a cold shutdown in 6 to 9 months should be seen for what they are: pure bravado. It would be dangerous to rush or cut corners during the process. Let’s hope nobody makes sticking to that schedule for its own sake a goal.
UPDATED on May 22nd: Yesterday I linked to a blog showing how grout would be used to seal the containment. It’s possible that that schematic might only apply to Unit 2, but I am not sure. It’s very difficult to get the latest information, but today’s press release (http://www.tepco.co.jp/en/press/corp-com/release/11052201-e.html) does not indicate any shift in cooling strategy. Here is a link to a chart from TEPCO on the status of the different units, showing schematics of the various plans. This shows that Unit 1 is only small part of what they are dealing with, that there are so many concerns: groundwater contamination, air contamination, where to put radioactive effluent, etc. This link (below) is to an official press release, but it is from May 17th, so might not reflect the very latest. I’m linking to it to show the extent of how many different things they are dealing with, and because of all the sketches and photographs it contains:
Perhaps they are still planning to try the general approach described in the latest plan identified above after all. If so, it will be interesting to see how they will deal with the issue of debris in the recirculated fluid. I have my doubts about how well this will work, but an alternative option is yet to be found.
Nature magazine published a sketch of the site showing the different categories of what needs to be dealt with awhile ago, which may be helpful in comprehending the extent and variety of the challenges to be dealt with. Although it is five weeks old, it is general enough that it is still accurate, I believe: http://www.nature.com/news/2011/110411/full/472146a/box/1.html
I should mention that I regard everything as provisional at this point. The situation is still very serious, and everything is touch and go — at multiple reactors. In the meantime, radioactive effluents are still being continuously generated from injecting fresh water into the reactors, which then leaks out into buildings and/or the ground.
The article in NATURE magazine “Fukushima set for epic clean-up”, said it might even take a century to clean up the site, and explained why: http://www.nature.com/news/2011/110411/full/472146a.html
Sobering. Very, very sobering.
UPDATED MAY 30th: A recent brief report in Marketwatch (http://www.marketwatch.com/story/tepco-cant-stabilize-reactors-by-year-end-report-2011-05-29 ) pretty much confirms the perceptions and predictions in the post above. It reports news from Japanese media that “Tokyo Electric Power Co. (9501.TO) is coming to the view that it will be impossible to stabilize the crisis at the Fukushima Daiichi nuclear power plant by the end of this year.”
It sounds as though sealing the containment is part of the plan for Unit 1, according TEPCO sources: “Given that the contaminated water has leaked from the No. 1 reactor’s containment vessel, a TEPCO official handling the technical aspects of the crisis, said, ‘We must first determine where it is leaking and seal it.’ ”
And it sounds as though the path to cold shutdown is difficult and full of uncertainty. I said in my post that TEPCO’s statements about not wavering from the timeline for cold shutdown was pure bravado. That shield of bravado is now coming down, it seems, for the Marketwatch article above continues: “The official added, ’Unless we understand the extent of the damage, we don’t even know how long that work alone would take.’ “
My posts on this disaster may have seemed bleaker than the official news coming out of Japan, but now you see why. I was just trying to be accurate. If the truth (or, rather, if what I could garner from the incomplete reports available) would have been cheerier rather than bleaker news, I would have been happy to report it.
One piece of good news for the Fukushima Daiichi nuclear plant as of May 30th: some of the latest reports on Typhoon Songda’s path say that it will not hit it.
UPDATED June 21st, 2011. TEPCO’s latest status reports are out; this one has images (schematics and photographs): http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110517e5.pdf
The way this particular report is organized is via a chart by issue/subissue (leftmost column or columns), then unit # (next column), then the countermeasures that have been identified for that issue. However, these are just identified, not implemented, countermeasures. The next column describes the stage of implementation — for some of the countermeasures, it is blank; for others, some indication of the progress being made towards implementing it is given.
Checking up on the Issue of “I. Cooling” and (1) “cooling the reactors” for Unit 1, we see the chart reflects that the countermeasures of sealing the leakage in the PCV (Primary Containment Vessel) and flooding the PCV up to the level of the primary fuel are identified and illustrated with schematics, but that there is just a blank space under “implementation.” There are entries in “implementation” for the countermeasure of “reuse of processed waters, reactor coolant”, though, for which a schematic is also provided. The schematic shows some processing equipment in the loop, so that the water is to be processed (filtered and run through demineralizers ?) before being injected into the reactors again. But that loop isn’t ready yet.
So it looks as though reuse of injected water has not yet begun. That’s becoming a problem, as the mode of cooling is still to inject water into the reactor and right now there is no option other than letting it run out, adding to the huge volumes of radioactive water collecting at the Fukushima Daiichi site. That’s just for Unit 1 — you can refer to the chart for what’s going on there with respect to other issues and other units.
Of special interest in the chart is the issue of ”I. Cooling”; (2) “Spent Fuel Pool” for Unit 4, since there had been conflicting reports about the status of the pool. Water is still being continually injected, via a “Giraffe” (illustrated with a photograph, which seems to be referring to that piece of equipment as “elephant no. 2″ (?)). It also has a photograph of a small portion of the spent fuel pool.
Who thought, three months ago, that we’d still be using this mode of cooling the reactor and the spent fuel pits as we approach July? You have to feel for the workers who have been working for over three months already, face many more months in demanding conditions, and who continue on. Few people I know have ever faced such an occupational task.
Update on July 3rd, 2011: The Wall Street Journal reports that the reuse of injected water to cool the reactors at Fukushima Daiichi has begun, as of last evening. It is unclear to me which specific reactors this is true of. This is a significant step, if it can continue, for the reasons discussed above.
The Wall Street Journal article, ” Tepco Resumes Cooling Plan at Fukushima Plant” is here: http://online.wsj.com/article/SB10001424052702304760604576422971899892878.html
The article reports two others problems that remain, though (i) even though the water is being reused, there is still radioactive sludge produced in the recycling process, and that has to be dealt with in some way, and (ii) since the workers have to work in protective gear, and the weather is extremely hot, heat stroke is a problem.
Praise to the WSJ for reporting this news.
UPDATED on August 5th, 2011: Good News, Bad News. When I first began writing an update to this post about a week ago, it seemed things were looking up a bit. TEPCO had an updated roadmap. (http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110719e3.pdf ) After fits and starts, a circulation loop for cooling and purification of water was running. Though hardly permanent, it was doing the job, and the important step of being able to cool the reactors without producing large quantities of effluent that had nowhere to go had been accomplished. Work on fortifying the spent fuel pools structurally was progressing well. TEPCO’s summary, though still not very specific, focused on the progress that had been made in reducing levels of radiation, and reported the achievement of a target characterized in terms of trends: ”accomplishment of the Step 1 target ‘Radiation dose is in steady decline’ has been confirmed.’ ”
The WNN reported that temperatures of the spent fuel pool in reactor no. 4 were declining very significantly, too — news celebrated and repeated in many other outlets, including Bloomberg and Business Week. Nuclear engineering international (NEI magazine) gave details: from 83 degrees C to 20 degrees C http://www.neimagazine.com/story.asp?storyCode=2060289 The NEI story featured photographs of the structural work on the spent fuel pool at no. 4, and reported other progress, including a cesium removal system and some reassuring analysis results about seismic loads not having been exceeded. The news now seemed to be about _mitigation_ of a disaster, rather than about the enormity and unfolding of an unmitigated one. The NEI article linked to another report showing progress, reactor by reactor, here: http://www.neimagazine.com/journals/Power/NEI/September_2011/attachments/ENGNEWS01_1312258084P.pdf
Before I had finished writing the post, though: some terrible, terrible news arrived to snatch away the afterglow of the hard-earned achievement that TEPCO had just announced: very high — very, very high, superhigh, off-the-scale (literally, pegged to the highest reading on the geiger counter) levels of radiation were reported at some points on the site. Cesium, too, which is not good to hear. The scrolling newstories of the progress preceding it followed by this news are heartbreaking to view: http://www.neimagazine.com/newsMenu.asp?sectionCode=72&st=&nt= The superhigh radiation readings were at the bottom of exhaust stacks and in the turbine building.
It’s too early to say what this portends. When you ‘clean up’ radiation, it is often a matter of consolidation of radioactive materials onto filters or into a tank that can be moved somewhere else, or of dilution to a level considered acceptable for release into the air or the ocean. Bioremediation is sometimes an exception to this grim truth, and there is some reduction due to decay, of course, but the tough reality about contamination cleanup is that it’s mostly about consolidation, relocation, shielding of whatever can’t be diluted and released to the environment. However, this recent superhigh radiation at the Fukushima site is not a case of such planned consolidation.
Fairewinds released a short video with a possible explanation of how such high contamination might have come about, and why it might have escaped detection for awhile, here: http://www.fairewinds.com/content/lethal-levels-radiation-fukushima-what-are-implications
Yet, I suspect that to those who work with nuclear operations and maintenance, this kind of bad news is probably not all that surprising, although these levels are so high as to take one aback. Constant vigilance is required whenever radioactive material has been released. Twenty five years on, Chernobyl’s sarcophagus still requires periodic attention — and periodic replacement. Although enough money was finally collected to begin work on it, money is still being raised to complete the installation of a new replacement sarcophagus around the highly radioactive remains of that reactor: http://www.dw-world.de/dw/article/0,,15229781,00.html Completion is scheduled for 2015. Someday that sarcophagus around Chernobyl, too will need replacing. Even after all the mitigation milestones are completed at Fukushima, decades from now, surveillance will continue. There will always have to be money in somebody’s budget set aside for it — for centuries, at least. It’s a reminder of the kind of deal involved in choosing to use technologies that can have this kind of major environmental impact.
UPDATE on September 22nd: A few days ago, reports Asahi.com:
Goshi Hosono, the state minister overseeing the Fukushima nuclear accident, said at a Sept. 19 meeting in Vienna of the International Atomic Energy Agency that Japan would reach cold shutdown by the end of the year, a few weeks earlier than initially planned.
Now, this news made headlines, as follows: Reuters: “Fukushima Reactor Cold Shutdown this Year” and the WSJ : ”Fukushima ‘Cold Shutdown’ Could Come Early.” The story is in the quotation marks around the term “cold shutdown.” Cold shutdown is normally used for a certain condition being achieved in an intact reactor, i.e., a reactor that is not leaking water and that contains fuel rods, not a melted core. As the Asahi article clarifies, a few paragraphs down into the article:
While the central government has set the minimum conditions for cold shutdown, it has not yet formally set standards in determining if that state has actually been achieved.
The Nuclear and Industrial Safety Agency is expected to compile standards, including measures taken to continue safe cooling of the reactors, . . .
And, it seems, Hosono’s remark did not indicate any particular change in plans, only that they would like to achieve cold shutdown, whatever that is for these damaged, leaking reactors, by the end of the year.
By all accounts, though, dealing with the radioactive water that the process has produced remains a challenge.
Here are some links to news about it:
Asahi.com English version: http://www.asahi.com/english/TKY201109210394.html (“Fukushima road map leaves out Hosono’s goal for cold shutdown”)
Mainichi: http://mdn.mainichi.jp/mdnnews/news/20110921p2a00m0na013000c.html (“TEPCO burdened with task of treating contaiminated water at damaged nuclear plant”)
AND HERE IS THE REVISED ROADMAP As of September 20th http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110920e4.pdf
As always, Fairewinds continues to provide reliable and well- informed updates and analysis of the situation and its import for other reactors around the world. Also, Fairewinds now has a Japanese edition. At: http://www.fairewinds.com/updates
UPDATED October 17th, 2011: Although I expect an update to the Roadmap soon, it’s worth reporting now that last week the first cover over one of the reactor buildings was completed. Here’s a brief article on it, including a photograph of it: http://mdn.mainichi.jp/mdnnews/news/20111015p2a00m0na019000c.html
There is a sense of calm in seeing it, perhaps, and it is significant. Now that the air around the reactor is enclosed, it can be “processed”, i.e., run through air filters to remove the radioactive particulates. That’s a big public health benefit. But, to put this into perspective, it is just a temporary step. This is going to be a decades-long project. This cover alone is only meant to last two years, and they still have to put covers on two of the other reactors whose buildings’ walls were blown out by explosions. And, it’s not meant to serve all phases of the decontamination process, either:
TEPCO is also considering replacing the cover with a stronger one should the firm decide to remove the fuel from the reactor.
I’ve been reading some of the commentary on the accident that emphasizes that there haven’t been immediate deaths due to radiation release from it. I really don’t get that complacent reaction. There have been mass evacuations and relocations, abandoned homes, homesteads, farms, croplands and herds. Some schools in use are dealing with radioactivity in their schoolyards. Even if you think nobody is going to be hurt (which is unrealistic), these plants are now big sores on the landscape that require massive amounts of attention and money.
There are piles of radioactive refuse already, and they will continue to be produced. Here’s an article about the problem of used radioactive gear, showing that because there is nowhere to put it at the moment, it is just being placed into a very large pile:
The out-of-scale pile is an icon to remember. The reactor building pictured may be covered, but there will continue to be a steady stream of used radioactive filters, used radioactive gear, and, perhaps someday, even used radioactive damaged fuel, emerging from it. The cover will have to be replaced, like a bandage on a wound, again and again. I suppose the used and dismantled covers produced as the years go on will themselves constitute radioactive waste, as well. All of this will be passed on for safekeeping. It’s good to cheer this milestone, but it’s also valuable to keep it in perspective.