Urban75 Home About Offline BrixtonBuzz Contact

Fukushima Daiichi nuclear disaster

People have wondered what was happening at reactor 3 from March 19th->March 25th, during which time there were some leaps in certain readings, and several occasions where grey or black smoke was seen coming from the building. Some weeks back someone published a study which claimed this stuff was down to the core melting a 2nd time. Well now TEPCO have done their own analysis which looks like it is trying to refute this theory.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110909_04-e.pdf
 
The changes to water injection at reactor 3 has had mixed results in my opinion. Temperature came down a bit when when put water through the new system, but started to creep back up when they reduced water from the older injection method. So now it looks like they are going to massively increase the injection rate through the new system, to see what happens to temperatures (they are trying to balance the desire not to use to much water, with the desire to see measured temps go below 100C). I think their original hope was that they would be able to switch from a high flow rate via the old method to a much lower flow rate using the new injection point, but temps didn't fall enough to make that possible. They started with reactor 3 because the temps & water injection rate were higher for this reactor than the others, but it was always a tad hopeful that a simple switch of injection point would overcome whatever factors cause reactor 3 to need more water for cooling.

They have now just started a similar process at reactor 2. They have started injecting water through a different system, will gradually increase the rate of this in the coming days, and if all is well they will then reduce water injected via the old method. Some of the measured temperatures at reactor 2 have been slowly creeping back up in recent weeks, not by very significant amounts but still trending in the wrong direction for things like suppression chamber temp.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110914_01-e.pdf

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110916_02-e.pdf

They have been trying to learn more about the state of the reactor vessel for reactor 1, I don't really understand it fully yet but here is a pdf that shows what they found, I get the impression that many uncertainties remain, but will go looking for other interpretations later:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110916_01-e.pdf
 
Uuhhhh. I think I heard something about this before, but really.

http://www3.nhk.or.jp/daily/english/19_03.html

Japan to offer products from disaster areas as ODA
Japan's Foreign Ministry hopes to use products from the country's northeast that was hit by the March 11th quake and tsunami to aid developing countries.

The Foreign Ministry filed a budget request worth more than 220 million dollars with the government, which is working on a third supplementary budget bill for fiscal 2011.

The Ministry says it wants to use part of the requested budget, worth about 65-million dollars, to buy industrial products, including wheelchairs, and marine food products made in Iwate, Miyagi and Fukushima Prefectures, to provide them free of charge to developing countries.

The Ministry says it hopes the program will also help stop radioactive-related rumors from affecting shipments and sales of those products overseas.

Sales of products made in the country's northeast have been hurt by such rumors since the nuclear crisis began at the Fukushima Daiichi power plant in the same region.
 
Catching up with some news I missed in the past, a worker pointed at the site webcam in a dramatic way. He did it for a long time from further away too but that video has lots of dead time before he appears, so here is an abbreviated version that only shows him when he gets close-up.



A website by someone claiming to be the pointer says that this ws done to draw attention to working conditions and related issues.

http://pointatfuku1cam.nobody.jp/e.html
 
The typhoon appears not to have caused any significant problems. Some water has entered various basements, and some cameras including the public webcam stopped working for a number of hours after the worst of the typhoon hit the area.

The IAEA have been meeting this week and ratifying their plan to improve nuclear safety, which is largely centred on the IAEA inspecting plants around the world. Its as much about restoring confidence than nothing else really.

The new PM has been repeating the stuff about bringing forwards 'cold shutdown' to the end of the year rather than next January, this is also more about perception than reality.

Having survived a summer with much less available electricity due to the number of shutdown nuclear plants, fears now turn to winter energy requirements. Business orgs are starting to make noises about the damage that energy shortages are having on business, and are urging swift restart of reactors. In the current climate, which included tens of thousands of Japanese rallying against nuclear at a recent event, they have to be sure to say that of course the reactor safety stress testing must be done first, but the devils in the detail on that one and pressure to restart reactors is only going to increase.
 
Amazingly, despite Japans problems they have a fairly stable economy. Because it's stable it's being bought into and making the £1 look unbearably shit against the yen. It's almost at a £1 for 100 yen or will be soon. When I first visited Japan I think I was enjoying about 240 yen to the pound. A beer was a couple of quid, now it's going to be between £5 and £7 quid.

Actually though, in general things are pretty cheap in Japan so guess it's not going to kill me day to day living wise.
 
Videos showing inside of upper levels of reactors 2 & 3:





The reactor 2 video is shot from a bad angle, but we get some glimpse of what appears to be steam coming from the region where the floor of that level covers the top of the reactor well.

For reactor 3 we can see certain parts of the crane that has fallen down onto the floor above the reactor. We can see the edge of one of the circular sections which are removable and cover the top of the reactor well. Just next to this we can see the removable wall that separates the reactor well from the dryer separator storage pit. We can see that along one thin edge of this wall, there is a gap and steam is coming out. This was previous visible months ago in a lower quality video shot from a helicopter, but its good to see it more clearly and also to know that steam is still coming from this area.

With the current high water injection rate for reactor 3, temperatures are now well down at that reactor, well below 100C by most measurements. At reactor 2 which also has water injected via 2 different systems at the moment, albeit with the total rate not as high as reactor 3, temperatures have fallen but one or two of the reactor pressure vessel temperatures are presently not showing signs of dropping below 100C.

There has been an update to the estimated release rate of radiation in September. I've not got the details in front of me although its still rather high by normal standards, but low compared to the release rate at the height of the crisis on March 15th.

Even with the recent typhoon it sounds like they have more wiggle room when it comes to water storage issues now, in part because the newer SARRY part of the water reprocessing system works better than the previous system, and they are going to ditch the old one completely at some point soon. One thing that has rather offset their progress with these water issues is that it seems pretty large quantities of groundwater and/or rainwater have been entering the basements, so the total volume of water has not gone down by anything like the amount initial calculations suggest it should have.
 
A document discussing workers exposure to radiation:

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110812e14.pdf

About half way through it starts looking in detail at workers who received high radiation doses during the initial phase of the crisis. I've only had a chance to skim the document so far as it is rather long, but it sounds like one of the reasons for the high dose is that they were resting, eating & drinking in the control rooms :(
 
I really don't have time to do this subject justice these days, but in brief:

They managed to get reactor 2 measured RPV temperature below 100C by increasing the water injection rate further. As soon as they managed this, the government removed restrictions in the evacuation preparedness zone (this was an area 20-30km from the plant where residents were still told to prepare to stay indoors or evacuate if there was further trouble).

There was an incident where a pipe they were going to cut at reactor 1, to use for some other purpose, turned out to have high concentrations of hydrogen inside it. They nearly didn't test for this before cutting the pipe, but luckily they decided to.

The government is starting to get its teeth into issues such as 'restructuring' TEPCO, future safety standards, etc. I think they have setup a committee of experts to report to the Diet, investigating the nuclear woe.

An internal TEPCO investigation is suggesting that there was no hydrogen explosion at reactor 2. Seismic monitoring suggests there was only one explosion on March 15th, and they think that was the reactor 4 one. The suppression chamber of reactor 2 is still thought to have failed on March 15th, but not due to a hydrogen explosion. I haven't seen a good article about this in English yet.

As the following video from a couple of days ago shows, they are now pretty close to finishing the covering of reactor 1 building:

 
hayakawamap-route.JPG
 

The fact that UK has different types of reactors to the Fukushima ones, along with our lack of tsunami threat, means that it was always going to be reasonably easy for government, regulators & industry here to dodge the worst implications of Fukushima. Throw in a lack of highly visible, motivated and large anti-nuclear protest movement in the uk (compared to say, Germany), our requirements to have nuclear as part of the future energy mix in order to get the numbers to add up, and a lack of really blatant regulator conflicts of interest (compared to Japan), and the impact is further reduced.

There are still lots of recommendations in the report, so we can expect some good to come of it. Much of this involves 'thinking the unthinkable', e.g. planning for really bad accidents that you think are very unlikely to happen, but are not completely impossible to imagine, especially in the shadow of Fukushima. So for example the standard safety systems will carry on much as before, with an expectation that not all levels of containment will be breached. But some planning will also be done for eventualities where containment fails in some way, and large releases effect a large area. Fuel pool safety will receive more attention, as will issues involving loss of power.

Despite learning shitloads of detail as a result of Fukushima, my overall impression hasn't changed all that much. Chances of severe nuclear accent occurring are pretty low (or we would have had more already), but if the unlikely events come to pass, the stakes become very high indeed. Consensus on health implications is nigh on impossible to achieve, but even if we buy into the version of reality where very low numbers of deaths occur, the impact of contamination and forced evacuation is clearly massive.

At this point there is little sign that Fukushima will derail the UK nuclear agenda, and this report is the icing on that cake. This situation would change if there was another major nuclear accident, if a notable health impact is detected in Japan over time and widely reported and reacted to by the public, or if the wider nuclear industry comes unstuck as a result of Fukushima.
 
I've just read a quick (hour) read of the report. I'm not a nuclear expert - so my comments mean nothing really.

a)The reassurance that tidal waves are not likely in the Uk seems un-reassuring to me. We've only being collecting data for what - 200/300 years at max. Supposing some 'freak storm' came.

b)While we don't have that many active nuclear plants - we've a lot of messy old plants. These seem more scary - seems like some of these places are really 'no-go' areas even on a good day, let alone in on a bad day. How much truth is in this article - I don't know?
http://www.guardian.co.uk/environment/2009/apr/19/sellafield-nuclear-plant-cumbria-hazards

c)Imperial have/had their own nuclear plant (for research). At only 100KW, it's quite small. Still, that's quite cool, I never knew a British uni had anything like this. Some Googling says it's being shut down - old and not paying for it's self as people don't want to do research in the UK

d)We only have one BWR plant in the UK - all ours are gas cooled. I believe this is safer? I've been on night shifts all week so my brain's dead and I didn't really understand it all, but the gas-cooled plants use carbon dioxide. On a day-to-day basis this is safer ( think) but in an unknown problem situation - do they have to find carbon dioxide? That seems more complex than pumping water in. I'm sure this technology is on a basic building block level simple to understand and I could find out on Google, but I'm very tired.....

e)Some mention of the how the situation in Japan was initially dealt with by in many part thanks to the improvisation of the workers - full credit to them - as there was no power to operate valves and automation they were lugging about car batteries or trying to use what sound like road drill pneumatic compressors to operate air controlled valves. Now I've never been inside a nuclear power plant - but I do work as a technical role (electronics not mechanical) in a large building - I work in broadcast - much more cosy than nuclear -but I can't imagine that lugging car batteries around in the dark in a damaged/flooded etc plant while in gas masks etc can be any fun at all.

f)A comment on how that the UK's emergency plans rely on people being there and staying around, putting their work ahead of themselves and family in an emergency -and that culturally the Japanese were very good at this. It says that this is not always the case.... In the Indian Bhopal disaster, all the operating/control staff ran away! I can't help feeling that if something very bad was to happen in the UK....people would do the same!

g) Towards the end there are a lot of statistics on death and nuclear radiation levels. As an example - chance of mother death in childbirth is about 1 in 8000 - seems quite high to me. Radiation wise - people in Cornwall receive quite a lot of radiation as it is. The allowed level for workers in Japan is 250msv i think? Is the scale linear or logarithmic?? Here's the table. Anyways my take on it is that - while any sort of large scale nuclear disaster would be bad here in the UK, and very bad in somewhere less organized - China, Pakistan, Russa etc on the whole - assuming nothing too bad goes wrong - you'll be ok. 'Assuming'. That's a very arrogant word really. The report is all based on the assumption that the UK stays in the relatively cosy condition that it has been for the last 100 years or so. No civil war, no floods, no freak storms, no chemical gas leaks/outbursts, no alien invasion etc. Even non-operational and long term decommissioned plants seem to need long term day to day love and care to keep things under control in the way coal/gas don't. I find that less reassuring.



UK annual average radon dose

1mSv​


CT scan of the head

1.4mSv​


UK average annual radiation dose

2.7mSv​


USA average annual radiation dose

6.2mSv​


CT scan of the chest

6.6mSv​


Average annual radon dose to people in Cornwall

7.8mSv​


Whole body CT scan

10mSv​


Annual exposure limit for nuclear industry employees

20mSv​


Level at which changes in blood cells can be readily observed

100mSv​


Acute radiation effects including nausea and a reduction in white blood cell count

1000mSv​


Dose of radiation which would kill about half of those receiving it in a month

5000mSv​
 
Im tired too, so I will only respond to point b tonight.

Nuclear waste is a huge issue that I haven't discussed too much on this thread because it's an issue which hasn't changed all that much as a result of Fukushima. The issue of how long recently used fuel has to be kept cool was highlighted vividly by Fukushima, along with a slightly less vivid demonstration that failure to address spent fuel issues when it comes to long-term storage has likely contributed to bottlenecks earlier on in the spent fuel management approach. In this case, some of the spent fuel pools located right next to the reactors at Fukushima were rather full. But these issues are somewhat relegated to the sidelines in my mind, compared with the overall long-term cleanup and fuel disposal issues.

There is nothing wrong with the article about Sellafield, just so long as we consider that this is one of the worst examples. Even at the best of times the process of decommissioning our other nuclear plants is tedious and extremely costly, but not as horrific as the Sellafield mess. Still a massive issue though, and although the UK has demonstrated plenty of success with various stages of decommissioning at quite a number of plants, the trickiest problems still tend to be left for some future generation to solve, via the assumption that they will have better tech to deal with things one day.
 
The Tokyo hotspot is being said to stem from old radium bottles at a nearby house, wrather than the Fukushima accident:

http://www.telegraph.co.uk/news/wor...adium-bottles-blamed-for-Tokyo-radiation.html

Other news in brief:

They finished putting the roof on the new structure around unit 1. They sent a robot to look at a part of reactor 1 where steam had been seen coming out of the floor in June. Steam was not visible this time, and radiation levers were lower in that spot, though still very high.

They managed to cut the pipe at reactor 1 which had been found to contain high levels of hydrogen. They found a pipe at reactor 2 that had some hydrogen in it, albeit at lower levels than at reactor 1.

They conducted a drill to see how long it would take crews to restore water injection to the Fukushima reactors if there were to be another huge earthquake, loss of power etc. Unsurprisingly they were able to respond a hell of a lot better than when the disaster originally occurred, getting water injection going again in about an hour and a half if memory serves me correctly.

Also the next update to the roadmap is due out on Monday, and apparently they will also be giving a new estimate for radiation released by the accident.

Sites such as ex-skf continue to bring to attention stories which show the evacuation problems, some dodgy political attitudes, and all manner of food safety issues being handled rather poorly. I have to be a bit careful as the site seems to have an agenda and is full of hyperbole, but even so it seems likely that, at the very least, we are going to find out in the decades ahead whether lots of people eating radioactive caesium is going to have much in the way of health implications :(.
 
Some news from the last week in brief:

Because the temperature of reactor 2 is now measured at well below boiling point, they have tried to repair the equipment which tells them how far above the fuel the water level is in the reactor. I haven't read the results in detail myself yet, but I heard that the level is still many meters below the 'top of fuel' point. I don't really think this is surprising considering that the reactor is likely quite damaged, probably got holes in the bottom and its not known how much of the core actually remains inside the reactor vessel. Here is a document describing the repair mission. http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111021_01-e.pdf

They made another attempt to learn something about the state of reactor 2 & 3 cores using existing sensors that are normally routinely used when the reactor is working properly. This time they tried to use neutron sensors, but rather predictably all they learnt is that all connections to the sensors were either shorted or cut.
http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111019_01-e.pdf

They sent a robot into reactor 2 building to survey all the floors, taking radiation readings to compare to ones from months ago, and also some photos. Unfortunately they lost communication with the robot after several hours of the mission, they may send humans in to retrieve it.
This is a video of the robot on this mission : Inside of Reactor Building of Unit 2, Fukushima Daiichi Nuclaer Power Station (112MB)

They have installed some kind of gas treatment system for reactor 2.
http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111021_04-e.pdf

They have a video from a camera being lowered and raised through the equipment hatch of reactor 3. This is an open shaft that connects multiple floors together and in normal times is used to lower or raise certain equipment between floors. Status of equipment hatch in the reactor building at Unit 3, Fukushima Daiichi Nuclear Power Station (25.6MB)

The October roadmap had an estimate of the continued radioactive releases which was approximately half that of the figure in the previous months report. I can imagine it dropping somewhat due to getting the temperature down well below 100C at reactor 2, but this 'halving' is also down to some rather iffy rounding down of the final estimate.

They have been spraying some water that had low-ish levels of contamination (compared to the highly contaminated water) onto wood they have stored on site which was created when they cut down a lot of trees to create storage space on site. They are killing two birds with one stone, freeing up water storage space and reducing fire risk.

They still have problems with the water decontamination system from time to time, but the newer systems certainly seem to perform better than the original one they got in after the disaster.
 
This video, showing humans surveying certain equipment inside reactor 1 building earlier this month, is a good deal more dramatic than the videos TEPCO usually release. I think its the audio that does it.

 
Thanks for those vids elbows, I don't fancy being the human operative who has to go in and get the failed robot. What's with the bell thing and the wailing (or what sounds like wailing/chanting) in the second vid I wonder? Aliens doesn't even come into it.
 
Well the sounds I think I hear seem to be the sounds of the workers treading on debris, an alarm occasionally going off, and something like the sound of a gas escaping at pressure.

Recent news:

They have started increasing the amount of water being pumped into reactor 1. It sounds like since they put the cover over reactor 1 building there is more condensation than they had hoped, so they are trying to reduce this by bringing temps down even more.

The gas treatment thing for reactor 2 is up and running. After getting it running they have seen an increase in hydrogen levels and so have increased nitrogen injection to keep the hydrogen concentration % below dangerous levels.

2 workers were injured during the operation to dismantle the huge crane that was used to put the covers round reactor 1.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111029_02-e.pdf

French nuclear monitor the IRSN has been studying sea contamination from Fukushima.

http://www.google.com/hostednews/af...ocId=CNG.c9421f165a8f91a7f6c119543aafc7e1.901

PARIS — France's nuclear monitor said on Thursday that the amount of caesium 137 that leaked into the Pacific from the Fukushima disaster was the greatest single nuclear contamination of the sea ever seen.
But, confirming previous assessments, it said caesium levels had been hugely diluted by ocean currents and, except for near-shore species, posed no discernible threat.
From March 21 to mid-July, 27.1 peta becquerels of caesium 137 entered the sea, the Institute for Radiological Protection and Nuclear Safety (IRSN) said.
One peta becquerel is a million billion bequerels, or 10 to the power of 15.
Of the total, 82 percent entered the sea before April 8, through water that was pumped into the Fukushima's damaged reactor units in a bid to cool them down, it said.
"This is the biggest single outflow of man-made radionuclides to the marine environment ever observed," the agency said in a press release.
Caesium is a slow-decaying element, taking 30 years to lose half of its radioactivity.
 
When you say it all, do you mean the entire nuclear disaster, or something specific such as the french report about the sea contamination?

The reactors shutdown when the earthquake happened, but nuclear fuel gives off a lot of heat for a long time, so requires cooling even after the nuclear reaction is stopped. Electricity is required to operate many of the cooling systems and equipment that monitors the reactors etc. Earthquake knocked out electric supply to the site, tsunami knocked out backup generators. Certain cooling systems kept going for a while, but they couldn't restore electricity in time and so eventually the reactors got too hot and pressure inside reactors got too much. They vented the reactors to lower the pressure, but this meant some radioactive substances were released into the air. The nuclear fuel rods started to melt, and this generated hydrogen which leaked into the reactor buildings. At 2 of the reactors this hydrogen exploded, causing the dramatic videos we saw and damage to the buildings. Another reactor building also exploded, but that reactor was out of service for a long time before the earthquake so they aren't sure where the hydrogen came from. It may have come from another reactor via some pipes, or it may have come from a pool where spent nuclear fuel lives, as this fuel also needs to be kept cool for ages but the pool cooling had failed.

One of the reactors, number 2, did not suffer from its building exploding, quite possibly because a wall panel had fallen out earlier, leaving a big hole where hydrogen could escape rather than build up to explosive levels. But at this reactor some bad sounds were heard near a part of the reactor called the suppression chamber. And then radiation levels started to rise at the site, and many of the the estimates for total radiation released seem to think that this reactor may be to blame for the bulk of the radioactive substances that got out into the environment. (although an unknown amount could be from the spent fuel pool of reactor 4 since building 4 exploded around the same time that reactor 2 had its suppression chamber problem). So anyway the large explosions we saw are not a proper guide as to which reactors caused the most radioactive contamination.

The exact state of the cores of the damaged reactors is not known, may be many years before it is. It is assumed that fuel melted at 3 reactors, but they aren't sure exactly where it has ended up. But its pretty clear that containment which is supposed to stop radioactive materials from getting outside has failed in various ways. So when they managed to pump water into the reactors to start cooling them again, this water leaked out of the bottom and started to collect in basements, trenches etc. This water was highly radioactive because it had been in contact with the damaged nuclear fuel, and some of it leaked into the sea.

Radioactive substances that got into the air, either during venting, explosions, fires or leaks from reactor containment vessels, went all over the place. Lots of it went out over the ocean, a relatively small amount went all over the world, but lots went to various locations in Japan as well, falling on the ground and posing problems for decades to come. As far as we know nobody died from radiation from this disaster yet, the human implications have mostly been the evacuations and the economic and psychological effect so far. Any health problems are likely to be more of a medium-long term problem, and there are lots of different opinions about how dangerous this stuff will actually be for people. There are issues with food being contaminated, and as usual we see government balancing the health risk against the economic implications (which can be just as devastating to people). So not surprising to find that this balancing act being done in a manner which doesn't appear to minimise the health risks as much as it should.

Even though a very large and horrible amount of radioactive substances got out, there is still a lot left inside the reactors. So they will have to spend years keeping the situation under control (the reactors still need cooling) and eventually trying to deal with the mess thats left inside the reactors. Some radioactive substances continue to come out of the reactors now, but the rate at which they are escaping is very small compared to the amounts released during the height of the crisis. They are doing various things to gradually reduce these emissions, and they also have a system which is filtering most of the radioactive stuff out of the water they are using to cool the reactors, so they can reuse the same water. But this a does mean that an ever-increasing amount of radioactive waste is being created, e.g. the filters of the water treatment system, which need to be changed every so often.

In some ways this nuclear accident is worse than Chernobyl, in others it isn't, but its still in the same league. Its worse because it can't be blamed on a completely rubbish Soviet design that had no containment, and because 3 reactors were affected (and 4 reactor buildings), and its the worst contamination of the sea/ocean we have seen. Its not as bad as Chernobyl in the sense that loads of workers did not have to sacrifice their lives in the first days to bring the situation under control. Some Fukushima workers could die longer term, but there were not the awful relatively quick deaths that we saw with Chernobyl. In terms of international contamination it doesn't seem anywhere near as bad as Chernobyl. Japan itself is not so lucky, there will most likely be certain no-go areas for decades to come, and areas where people will still live that have levels of contamination that are worrying, and problems with food contamination. The full human cost is quite likely to remain disputed in the same way that the full health consequences of Chernobyl are to this day.
 
And I should point out that there have been some worker deaths, but not attributed to radiation. A few were killed by the tsunami itself, think a crane operator died in the earthquake. There were a number of injuries caused by the explosions at the site, especially reactor 3 explosion. And a couple of workers have died from heart-attacks when working at the site in subsequent months but this has been attributed to existing health problems, the physical strains of the work, heat etc, rather than radiation. Many other workers have received total doses of radiation that are far beyond what people should ideally be exposed to. And some have had internal exposure to radioactive substances which could have health implications in future.
 
Back
Top Bottom