There is an awful lot of panic and speculation regarding the situation at the Fukushima #1 (Daiichi) Nuclear Power Plant and in particular its possible effects on the Tokyo Metro area. What is really going on?
Short answer – things seem to be pretty safe for now, but there is still a possibility of danger if things don’t go well.
Since I am continually updating this post (first published on March 15 at 6:40PM) I have reassigned the date to bring it back to the top, but edited the formatting slightly to keep its length from blocking out the other recent posts.
I have also been very active on twitter the last week and will continue to post there more often than here, but probably less often than I have been since I have a lot of other stuff to take care of. You can follow me there @mutantfroginc.
To read from the beginning just click below (if on the main page) or scroll down, and to jump to the latest posts click on the link at the top.
For the initial postdetails, I have copied the text that Matt Alt has already posted on his blog and then adding some minor corrections and additional information.
[Start of information collated by Matt Alt]
The bottom line is, the Tokyo metro area seems to be safe for now and there is no need to panic or evacuate. I base this on the following data points. They are collected from information announced in government press conferences and from other sources cited below.Point 1: A seivert (whether milli- or micro-) is a dose. The units are expressed per hour. The effect is cumulative, not instant. This means that at a 2 millisievert level, you would need to be exposed to the source for 100 hours to be irradiated to the point that is considered clinical radiation poisoning (200 millisieverts, according to this chart translated by @gakurunaman). But the current background radiation in Tokyo is somewhere around 0.3 microsieverts. That’s something like three ten thousandths of a millisievert.
Point 2: As reported by NHK and corroborated by datafeed from the Hino monitoring station, metropolitan Tokyo radiation levels rose from a normal reading of around 20-30 CPM (0.2 – 0.3 microseiverts per hour) up to to 89 CPM (0.89 microseiverts per hour) for an hour, then dropped to close to normal background levels again. They remain normal as of this writing.
Point 3: Tepco released a graph showing a spike of 12,000 microseiverts (12 millisieverts per hour) at front gate of the Fukushima nuclear power plant. It has since dropped to below 2,000 microsieverts (2 millisieverts per hour) This seems to correspond to the fire at reactor #4, which has since been extinguished.
Even still, again note @gakurunaman’s chart showing comparative radiation levels. Even one hour at 12 milliseiverts (the max reading taken at the gate of the plant) is equivalent to less than 2 CT Scans. These readings were taken at the front gate of the nuclear plant in Fukushima. They decline rapidly with distance from the reactors. Again, metro Tokyo readings remain normal.
Point 4: The situation at the #1 and #3 reactors is under control, with seawater being pumped in now to keep the cores cool. There was no core breach. The situation at #2 is that water is being pumped in but the level is not rising. This needs to be watched closely. The fire in Reactor #4 was extinguished earlier today. A measure of radiation and some radioactive isotopes may have been released in this fire, but the release of radiation and material seems to have stopped with the extinguishing of the fire. As stated above, radiation levels are corroborated by the Hino geiger counter datafeed.
Again, PLEASE comment if you have info that contradicts any of the above.
This is a fluid situation, and an environmental disaster around the reactor site, but Tokyo residents and those outside of the evacuation zone do not seem to be in immediate danger as of this writing. The people in the most danger are the workers inside the plant. By exposing themselves to higher than normal radiation levels, they are sacrificing their health to keep the rest of us safe, and are the unsung heroes of this potential crisis.
[Following is my additional explanation]
As I said, the above is basically accurate.
Below is a graph someone made of the radiation level measurements released by Tokyo Power Company earlier today. The information is derived from a chart in a PDF file, which also includes wind direction and other data, until 1:30 pm.
As you can see, the spike occurred at around 9am, but by 1:30pm the radiation levels had dropped precipitously. There was apparently a fire at the #4 reactor at around 9:30am, so they would appear to be related events although I am not sure of the details.
At a press conference starting at 4:25PM, Chief Cabinet Secretary Edano announced that by 3PM the levels had dropped by 50% from what they were at 1:30, the last data released directly to the public by Tokyo Power. (See video of the press conference here.)
Below we have a graph of readings made by a geiger counter somewhere in Hino, which is a city in the western part of Tokyo Prefecture, covering the time period between 1am and 4pm on March 15. The geiger counter’s recent readings are online, but I don’t see a way to scroll back and see past readings. Luckily I saved the earlier readings to upload here.
There are a few important things that we can learn from these graphs.
First, that an elevated radiation level was measured in Hino, but that the levels were still extremely low, and not remotely dangerous.
Second, that the relative radiation measurements in Hino matched the relative levels measured at the Fukushima plant. What I mean is that even though the levels measured in Hino remained extremely low, the similar graph shape shows that they rose in an amount proportional to the rise at Fukushima. This is strong evidence that the Hino geiger counter was in fact measuring radiation from Fukushima.
Third, by looking at the time stamps we can see that it took around 3.5 hours for the radiation to reach Hino from Fukushima. As the Tokyo Power PDF includes wind direction measurements, we can see that during the time period between the initial spike in Fukushima at 9am and the spike in Hino at 1:30pm the wind was mainly headed in a southerly direction, meaning that it was traveling directly from Fukushima towards Tokyo. This suggests strongly that even in a worst-case scenario there would several hours of warning between the time of a radiation release in Fukushima and its arrival in Tokyo, but that since the wind is usually blowing in a different direction, the odds are good that there would in fact be several more hours.
As mentioned above in the entry I copied from Matt Alt, there appear to have been no dangerous levels of radiation except in the immediate vicinity of the power plant, from which all but core staff have been evacuated.
Basically, it appears that the situation is gradually moving towards stability and that residents outside of the evacuation zone should be safe.
I also want to add that there has been a completely fake map showing nuclear fallout from Fukushima arriving in North America. I will not embed it here because just seeing it might cause some people to panic before they read the text.
Finally, in the unlikely event that there is a serious amount of radiation released, here are safety tips I heard on Japanese TV this afternoon:
Remain indoors if at all possible. Keep windows and doors closed, keep any air vents closed, keep air conditioners and other air circulating devices off. Do NOT bring inside anything from the outside, such as laundry being hung to dry, shoes left outside the door, etc. Do NOT eat any food that had been outdoors during radiation.
If you go outside, cover up as completely as possible, including hoods and masks and gloves. When you return inside, strip off any clothing that has been exposed to radioactive air and immediately seal it in a plastic bag.
AGAIN, there is currently no reason to think that such precautions will be necessary, but it is still important to know them just in case.
I will continue to follow current events on my twitter feed, and please let me know if there are any errors in or extra information that should be added to this post.
Tokyo Power has issued an updated measurement chart through 4:30PM verifying the numbers given by Edano at his afternoon press conference. It also shows that radiation measurements at the plant have continued to decline since the 3PM value he cited.
Tokyo Power (TEPCO) just had another big press conference, and their spokesmen were a lot less mumbly and awkward, the press was also a lot less patient and a lot more aggressive in asking questions. As usual, Michael has done a good job live-tweeting it, and then summarizing on his blog, which I will excerpt below.
Latest on reactor 4. Apparently two large 8m holes have been made in the outer wall housing the building of the reactor. An explosion was heard around 6.00 this morning and a fire recorded as having broken out at 9.00. It went out by itself by 11.00. TEPCO now think that the large increase in radiation noted today (400mSv) was from this explosion at reactor 4. Also, there is the possibility that the nuclear fuel rods are exposed to the outside. Unlike reactors 1-3, reactors 4-6 were in a state of rest and the nuclear fuel roads being stored in the spent fuel pool. With the explosion and two large holes now in the building of unit 4, it is possible that radiation is leaking out. TEPCO also gave some figures for the current temperatures in reactors 4-6. Reactors 5 and 6 are around 60 degrees, while reactor 4 is at 84. The usual temperature is 40 degrees. (via TBS, NHK)
[Update March 16, 1:40am]
I don’t have anything to add regarding the unfolding situation at Fukushima Plant #1 (Daiichi) at this time, but a new chart just released by TEPCO of measurements being taken at Plant #2 (Daini) shows EXTREMELY low levels of radiation there – only around 10mSv at 6pm yesterday, when the chart ends. This compares with a level of about
400mSv 400μSvat the same time at Plant #1. This appears to confirm that Plant #2 was successfully deactivated safely and without particular incident, and suggests that it is intact enough to reactivate after an appropriate period of repairs and safety upgrades.
[Update March 16, 3:45am]
Plenty of people have been wondering why helicopters haven’t been used to dump water into the dangerously hot fuel storage pool at reactor 4. Well, NHK just reported why. Basically, the fuel is being kept in a big pool of water to keep the radiation from getting into the air, but the cooling system on reactor 4 is failing and it is hot enough so the water in the pool may be boiling off. (see yesterday’s 9:30pm update above) If that happens, the fuel may be exposed to air, and emit dangerous levels of radiation. The pool is normally covered with a roof which would serve to help trap the radiation inside, but an explosion in the vicinity of unit 4 has knocked two holes in the roof. TEPCO was hoping they would be able to use the water carrying helicopters used for fighting forest fires and such, but in a nasty twist the holes in the roof are large enough to allow radiation leakage, but also too far from the pool, and too small, to make them an efficient means of water delivery. This is exacerbated by the fact that helicopters just carry a not so large load of water at one time, and cannot provide a constant stream. They are now studying whether it might be possible to use land-based fire fighting equipment, presumably by aiming hoses onto the roof and flooding the pool area that way (just my guess as far as that last half-sentence goes).
[Minor update] I missed an important fact from the NHK article in my previous update: the temperature sensor in the pool failed after the 84C reading above, which means they do not have current temperature readings for the pool in Reactor #4.
[Update: March 16, 5am] I need to sleep but wanted to do one more quick update.
TEPCO has released another batch of sensor readings, and they started spiking again heavily at 11pm last night (the 15th). After seeing values of only 400μSv/hour at 6pm, the previous last released measurement. Here are the values from just before the spike began until the end of the chart.
Time (pm) μSv/hour Wind direction
10:00 313.2 SE
10:30 431.8 SE
11:00 4548 W
11:10 6960 N
11:15 2761 S
11:20 3648 E
11:25 4976 NW
11:30 8080 NW
11:35 6308 E
Above is the graph from the Hino Geiger counter as of writing time, 5:50am. As you can see the most recent reading was made at 5:43am, and the measurements are trending upwards again. The key at the bottom of the page tells us that the CPM units reported on this graph are roughly 100CPM =1 microsievert/hr. The highest value being measured so far is therefore still very low, or around 0.5 microsievert/hr. During the previous spike, when the radiation measured at the Fukushima plant was 12,000 microsievert/hr, the radiation measured at the Hino Geiger counter went only about as high as 0.8 or 0.9 microsievert/hr, and even then only for what looks like a few seconds or a couple of minutes at most (i.e. one data point.)
There are also two more updates on NHK. I will give rough translations of both of them below.
- The first, posted at 4:41am, is titled “Is damage to the fuel rods at #1 (Daiichi) plant proceeding?”
Infusion of cooling water is not proceeding, and we have learned damage to two of the three reactors at Fukushima #1 Nuclear Power Plant where fuel rods have been exposed may be proceeding rapidly.
At a conference held by the prefecture’s disaster response office on the 15th, the results of an estimate by TEPCO of on how much of the total fuel rods small holes are opening, and the volume of radioactive material leaking into the cooling water at 2 of the reactors. According to that, in the case of fuel rods that are feared to be damaged, Unit #1 was estimated at 43% at 1pm on the 15th but at 3:25pm had risen to 70%. Unit 2 also jumped rapidly from 14% to 33%. In these two units the water level of cooling water within the reactor had lowered, exposing the fuel rods, and seawater is being pumped inside, but the water level is not recovering properly and the fuel rods are reaching a high temperature and there is a risk that they could melt, it was pointed out. If damage to the fuel rods proceeds, then radioactive material will leak to the outside. In light of the tendency for pressure to drop within both reactors, TEPCO will severely observe movement in this data while proceeding with seawater infusion.
- The second, posted at 5:15am, is titled “Water level within reactor #5 pretty low”
The Nuclear and Industrial Safety Agency (NISA) at a pre-dawn press conference, announced that the water level inside the reactor, which has fuel rods inside, is fairly low, in unit #5 of Fukushima Plant #1. However, NISA said that there is an undamaged electrical generator in the neighboring Unit #6, which has not been damaged by the tsunami, and “it will be possible to adjust the water volume.”
According to NISA, at the time of the earthquake and tsunami on the 11th of this month, the reactor of Unit #5 was stopped safely for period maintenance. However, the fuel was already inside the reactor in preparation for normal operation, and it was necessary to circulate water to keep the fuel cool. But the diesel generator was smashed by the tsunami, it was not possible to circulate sufficient water, and pressure increased within the reactor. When, due to this, they attempted to open a valve to release pressure, steam escaped and at present, 9pm of the 15th [note: yes, it is confusing that they say this at a pre-dawn press conference on the 16th but call 9pm on the 15th “present”] the water level has declined to only 2 meters and 2 centimeters above the fuel. Compared to 5 hours earlier, at 4pm on the 15th, this is a decline of 40cm. However, there is an undamaged generator in the neighboring Unit #6 and that is being used to supply water to reactors in both units #5 and #6, and NISA says that “as there is a healthy generator, we will be able to adjust the water volume.”
[Update: March 16, 6:15am]
Tobias Harris is currently attending an MIT press conference and live-tweeting it, I will relay below, completely unedited.
I’m sitting in the last row of a packed house. Richard Lester, department chair, opens with condolences for Japan.
One of the panelists, Mujid Kazimi, is the “TEPCO Professor of Nuclear Engineering.”
“Taking in lots of information, much of it I’m afraid not very good” – Lester
“Unit 1 at #Fukushima Dai-ichi was scheduled to be shut down on 26 March 2011.” – Kazimi
Ian Hutchinson speaking next, providing timeline of events.
In third explosion, at reactor 2, pressure suppression system was damaged. Hadn’t realized that.
That was what led to the big increase in the escape of radioactive material.
Michael Golay up next.
Golay: Tsunami flooded switch gear system, which made it difficult to recover electric power. Not enough to just bring in generators.
Now Q & A.
Graduate student just asked three rather big questions chosen from a notepad full of them.
Question as to where the salt water is being injected. Answer: in the vessel, as well as in containment, as best we know.Q. Japanese student asks about the worst-case scenarios.A. Fuel alrdy dmgd. If water lost, could lead to melting, molten fuel goes down, steam released up. Chern.-like explo. unlikely.Possibility of releases that are “sizable,” of iodine and cesium.Next question is about health effects, putting it in relative terms.A. Doses about 20x background in Tokyo, fell quickly. 30x-40x elsewhere. Doses have to be experienced a few days to be like chest x-ray.“No evidence of any health impact of those dose rates.”One worker received 10rems, twice annual occupational limit in Japan. Increases chance of cancer for someone like him from 25% to 25.3%.Q: Why were plants build right by the ocean? Why not higher elevation?A. Reasonable question, will be examined. <laughter> Can’t answer why not elevated. Could have elevated backup power. Can’t tell why.Plants did what they had to do — shutdown — but it was the tsunami that complicated matters.The main concern is that spent fuel is not in the containment chambers. If melts, potential for volatiles to escape is much greater.Q. TEPCO and authorities criticized for not providing information. What is your opinion about flow of information?A. Difficult for non-Japanese speakers to assess. Written materials in Eng. prov. by TEPCO are “limited.” Also sporadic.But need certain humility when expecting Japanese company to provide lots of info. in English. BUT even in Jap. info. “parsimonious.”May not just be unwilling: could be people in control rooms having trouble figuring out what’s going wrong; Tok. might not be getting info.Kazimi: compared with earlier incidents TEPCO trying to be upfront with info., updates. Have to wait until end to assess. Tryng not to alrm.Golay: A bit of perspective. Not getting media frenzy as with TMI and Chern. Question of degree. Not as much misinfo.Golay: Parsimony to avoid inciting fears. May ultimately have to evacuate more, but will be easier if people aren’t already panicked.Q. What happens over the longer term managing the spent fuel? What happens going forward? What options?A. Once again compare to TMI. Takes effort not to expose workers, poss. to clean up.Follow-up Q. What about impact of the infrastructure around plant due to quake and tsunami?A. Key thing is getting electric power back. Could get power there from the sea…Shouldn’t take more than a week or two.Q. Advances in decayed heat tech.?A. If you get air circulation to remove heat, that would be a good design goal. Need continuous path for heat to flow.Looks like last Q. Prospects for long-term contamination surrounding plant?A. Very little released and dispersed beyond containment. If larger release, people in area facing perm. or long-term relocation.Or living with high cesium levels, which has long half life. Will depend on Japanese regs. for permitting return.WIll depend on what’s ultimately released. Cesium-137, gets in ground, water table, food — that’s the big problem, for ag., livestock, etc.Almost no data when it comes to what we can live with when it comes to elev. background levels. Data avail is total dose deliv. in < 1 min.Don’t really know how much is too much to live with.
The Nuclear and Industrial Safety Agency has reported that radiation was emitted from what is thought to be unit 2 at Fukushima nuclear plant 1. The Suppression Pool (pressure control room) was damaged in a third explosion recently and it is thought that the increase in radiation was due to that. At 10.40, NISA recorded 10mSv/hour at the entrance of the plant, but 30 minutes later this value had fallen to 2.7mSv/h. The workers on site had retreated at the time of the large radiation release, but went back in after it fell again. It was suggested that the radiation increase was due to the white smoke coming out of unit 3 earlier this morning, but TEPCO said it was likely due to unit 2.
[Update March 22, 3:30am]
Apologies for the lack of updates, but since my last one the situation at Fukushima has became far more stable and most of the earlier urgency has drained away. The quality of news available in English has also improved significantly since the early days, with the government adding English simultaneous translation to press conferences, posting far more, and more timely, information in English, having press conferences aimed at foreign press, and so on, which has significantly reduced the need for persons such as myself to continue this thread.
Furthermore, as I am moving at the end of the month I have to pack my things, clean my house, etc. all of which takes quite a bit of time-time that I had been spending on following the disaster news.
So, in short, I will continue to blog on various aspects of the disaster and recovery efforts, but will be updating this particular post less often unless the situation takes a dramatic turn for the worse.
But first, the important thing is that the situation at all six reactors at Fukushima Daiichi seems to be more or less under control. Radiation levels at the plant have decreased significantly, despite the presence of visible smoke at reactors #2 and #3. External power has been restored to much of the facility, which will allow for reactivation of the cooling system.
The New York Times now has a good page devoted just to tracking the condition of these six reactors, which is the easiest place to get all that information at once in English. It may still be a little bit behind the Japanese news, but is much more current than a few days ago.
Here is a good timeline of the entire reactor crisis so far.
The government is also now releasing FAR more information, including radiation measurements for both drinking water and air for all prefectures – and even in English! As you can see, the levels were undetectable for most prefectures, but were much higher in areas closer to Fukushima. I must admit that I do not really understand these units, but the important thing – as you can see most dramatically on the excellent graphs made by Phillip at fleep.com,
The negative side of the story is the news that some amount of radiation was detected in nearby agricultural products such as spinach and milk, which is of course a concern – especially when you recall that milk was one of the main vectors for transmitting radiation to civilians after the Chernobyl disaster. This is because small amounts of radiation contaminating grass is eaten by grazing cows and concentrated into a much higher dose, similar to how large fish such as tuna contain uncomfortable high levels of mercury collected from the small fish that make up their diet. But precisely because this is such a well known part of the Chernobyl story, the reaction to the news is very careful, and shipment of agricultural products from affected areas has been banned, and Tepco will compensate farmers whose produce must be destroyed.
The World Health Organization has put together a good FAQ on radiation health risks in Japan, and the page on food safety reads in part:
Food contaminated with radioactive material will not appear spoiled, but consuming such food will increase the amount of radioactivity a person is exposed to and could increase the health risks associated with exposure. For example, it could increase prevalence of certain cancers in the future. The exact effects on specific organs will depend on which radionuclides have been ingested and the amount being ingested.
Certain foods in several prefectures have been blocked from the market due to positive radiation tests, but even if you live fairly close to Fukushima, food that makes it to your local store should be safe, and again – don’t foolishly start downing anti-radiation pills or hoarding salt unless medical personnel advice it. People in the 30km radius are being given meds, but I’m pretty sure that if you are reading this then you are a lot further away from the plant than 30km.
- Dangerous amounts of radiation under these regulations are based on dosage over an entire year, so having a little bit of food or water over the line is probably still safe.
- If radiation higher than the legal limit is detected on vegetables than shipment of all vegetables of the same type from the same region is banned.
- If tiny amounts below the limit still bother you than peeling the outer layer and extra rinsing should eliminate it.
- All of the affected veggies so far are leafy vegetables like spinach, kakina (another green leafy veggie), and shungiku (edible chrysanthemum) so radioactive particles can stick to them more easily. It is very unlikely that root vegetables could be contaminated in this situation.
- Milk at 5 towns in Fukushima exceeded the legal limit, and milk all throughout the surrounding area was tested but found safe.
- Even these “unsafe” amounts are still pretty small, and if you have accidentally had just one or two servings of radioactive milk or leaves it shouldn’t be enough to harm you.
- At present, all prefectures in Japan are testing drinking water daily (as I linked to above), but even water unsafe for drinking will likely still be within safe levels for washing clothes or even bathing.
- Note that the safe limit for an infant (or pregnant woman, I assume-but it doesn’t say) is much lower than for adults. Limit for an adult is 300 Becquerels per kilogram of body weight, but for infants under one year is only 100.
- Testing is being carried out daily, and if you live in or near the irradiated zones then be sure to check the latest news every day until the whole crisis seems to be past.
And to finish off for now, see this spectacular radiation dose chart by the creator of the brillian webcomic xkcd, who is a master of visualizing information. Of all the many radiation dose tables I have seen in the past week, this puts things into the best perspective. (Click on it to get a legible size.)