We are now over 3 months into the Fukushima accident, progress is creeping along at a steady pace. Since our last update there has been lots and lots of new and I won’t try to cover it all. The biggest news I want to share now is that TEPCO has gotten some kind of recirculation cooling working, it was reported today by Will Davis at Atomic Power Review(by far the best blog to keep an eye on for Fukushima news, I highly recommend to read it).
In short water is leaking out of the containment buildings into the turbine buildings, the water is pumped from the turbine buildings into the water treatment facility, then from there its pumped back into the reactor. Its like I described in the last update on may 18th (shown on the picture below) and one of the steps in the plan TEPCO released that month.
If everything goes well now the volumes of contaminated water will start to creep down, a proper toast is in order!
Another fairly recent news is that NRC announced that the spent fuel pools in Fukushima never went dry. That really calls into question Chairman Jaszco’s recommendation for a larger evacuation zone for american citizens in Japan than what the Japanese authorities had decided.
There has also been a lot of bullshit flying around about the situation in Fort Calhoun due to the river flooding around the nuclear power plant. Claims about goverment cover ups, Russian authorities warning about disaster etc. I haven’t bothered to look more in detail into it yet, but so far the reactor has both working diesels and connection to the external grid and quite a bit of margin before the river even comes near to flood over the flood protections. Here is a good post by Neutron Economy about the situation.
This is not so much an April Fools joke as it is a little riddle. It connects to a current event… and to things that happened in the last century. And of course it has something to do with nuclear power.
What are these equations?
This is a comparison between two estimated values… what are they?
Update: we have a winner! Tony scored a perfect bullseye. I’m quoting him here:
‘a’ is the number of iodine atoms that would fill the known universe, if the iodine were at ‘normal’ temperature/pressure.
the second number is the number of radioactive iodine atoms you would have needed, when Chernobyl exploded, in order to have one radioactive iodine atom left today.
An added trivia is that the estimated number of atoms in the known universe is approximately 10^80.
The upshot of all this is this: there is not a single atom of Iodine-131 released by Chernobyl in existence today. The last atom decayed in no more than 4 years after the accident.
Two days ago we first got the report that there is highly radioactive water in the turbine building basement of reactor 1. NISA released this list of isotopes found in the water and its activity per cubic centimeter. I added half lives to the list to make it more understandable.
nuclide
activity(Bq/cm³)
half life
Q value (keV)
Cl-38
1,60E+006
37,24 min
4916,53
As-74
3,90E+002
17,77 days
2151
Y-91
5,20E+004
58,51 days
1544,82
I-131
2,10E+005
8,025 days
970,86
Cs-134
1,60E+005
2,065 days
1233,38
Cs-136
1,70E+004
13,04 days
2548,22
Cs-137
1,80E+006
30,08 years
1175,63
La-140
3,40E+002
1,679 days
3762,22
We see that there is one peculiar things, a high activity of Chloride-38. The only way for Chloride-38 to be created is by Chloride-37 in seawater absorbing a neutron and turning into Cl-38. This would indicate there is still a considerable neutron flux in the core. Forum discussions have been going on about it. The other peculiar thing is the activity levels, the activity per cm³ is just crazily high. I suspect they are really measuring activity per liter and mistakenly report it as cubic centimeter and I will give 2 arguments for that.
1. The activity of the water
They reported that 3 workers had been working in the water for more than an hour, their dosimeters showed a dosage close to 200 mSv and two of the workers didn’t wear rubber boots so they got a large surface dose on their ankles and feet from beta radiation(some reports say up to 6 gray). But this does not match with the activity levels seen in the table I pasted above. If one multiplies the activity in Bq/cm³ with the Q value, i.e the energy released in the decay of one atom, and massage the numbers a bit to get the numbers in joules instead of keV and in cubic meters instead of cubic centimeters. Then one finds that the water is putting out 1.68 Watts per cubic meter of water. Something like 20% of that energy is from gamma rays, the rest is beta rays and recoil energy in the decaying nuclei.
1.68 Watts doesn’t sound like a lot given that a normal water kettle can have a power of 1000 W. But in terms of ionizing radiation 1.68 W is just crazy. Radiation dose is measured in Grays, one Gray is equal to one joule absorbed by one kg of tissue and a Watt is as we know one Joule per second. A one Gray whole body dosage is enough to get radiation sickness, 10 Grays will kill you slowly(over a few days) and 100 Grays kills you instantly.
These workers where working in water that is putting out watts of radiation, that means they should have gotten hundreds of Grays in an hour. It was stated they where knee deep in this water! Now if we instead consider that perhaps they mean activity per liter, misstakenly reported as cubic centimeters, then everything goes down by a factor of 1000(there are one thousand cubic centimeters in a liter). Instead of hundreds of Gray the workers would have gotten hundres of milligray, that is consistent with their dosimeter readings.
2. The neutron flux needed to create Cl-38
The probability that a Cl-37 atom will absorb a neutron and turn into Cl-38 is quite low, 1 barn(this probability is measured in a unit called barns, one barn=10^-24 cm², uranium has as comparison a fission probability of about 600 barns). So one needs a lot of neutrons to create any significant quantity of Cl-38. If one assumes the water concentration of Cl-38 has dropped by a factor 1000 when traveling from the reactor vessel to the water in the turbine hall basement(dilution, decay etc). Then one can make a rough approximation of the neutron flux needed in the core in order to create the Cl-38 concentration seen in the turbine hall(technically solving the Bateman equation for a equilibrium case with one group cross sections).
Neutron flux ends up being around 10¹² neutrons per square centimeter and second. A reactor running at full power produces on the order of 10^14 n/cm²*s. The core would have to be running at about 1% of its full power(10-20 MW thermal) to produce that flux, but I might as well be off by a factor of 10 in my estimate of dilution, which would put the power in the rage from 1-100 MW. We can exclude 100 MW since we have not seen a pressure and temperature spike that high in reactor number 1. We can not exclude 1-10 MW power levels because it is on the same order as the decay energy. But if we also again here assume they mean Bq/liter instead of Bq/cm³ then the needed flux to produce the Cl-38 goes down to something around 1*10^9 neutrons/cm²*s. That kind of neutron flux could plausibly be around from radioactive decay or a very very low power level.
Those 2 factors together makes me believe they are reporting activity levels wrongly. Lets see if I will have to change my opinion when new information arrives.
Notes for the interested.
To convert from the unit eV(electron volt) to joule one multiplies 1 eV with 1.602*10^-19
The Bateman equation describes the time dependent concentration of radionuclides. For the case of a nuclide created by a neutron flux and destroyed by decay one gets this equation
dN/dT= N_37*sigma_37*flux – N_38*lambda_38 Where: N_37=number of Cl37 atoms per cubic centimeter(I assumed saturated salt water at 100 degres, which gives 0.39 grams of salt per cm² which gives 9,74*10^20 Cl37 atoms per cm³) sigma_37=neutron capture cross section, around 1*10^-24 cm² flux=neutron flux in neutrons per cm² and second N_38= Number of Cl-38 atoms per cm³. lambda_38 = decay constant for Cl-38(equals to Ln(2)/half life)
If one assumes equilibrium then dN/dT=0 and one gets that
flux=N_38*lambda_38/(N_37*sigma_37)
One get N_38 from dividing activity with decay constant and then multiplying by a dilution factor.
Here are all the numbers I plugged in in case someone can spot an error.
Reactor 1:
Water level in the core: 1.65 (1.65) meters below the top of fuel assemblies
Flow rate of injected water: 120 liter/minute
Core pressure: 508(517) kPa
Containment pressure: 270(270) kPa
Core temperature(feedwater nozzle): 224.8 Celsius
Core temperature(bottom head): 143.4 Celsius
Dose rate within containment: 34.6 Sv/hour
Reactor 2:
Water level in the core: 1.2 (1.2) meters below the top of fuel assemblies
Flow rate of injected water: 270-280 liter/minute
Core pressure: unknown
Containment pressure: 110 (110) kPa
Core temperature(feedwater nozzle): 123.6 Celsius
Core temperature(bottom head): 111.2 Celsius
Dose rate within containment: 41.6 Sv/hour
Spent fuel pool temperature: 67 Celsius
Reactor 3:
Water level in the core: 2.3 meters below the top of fuel assemblies
Flow rate of injected water: 220 liters/minute
Core pressure: 130 (133) kPa
Containment pressure: 107.3 (107.6) kPa
Core temperature(feedwater nozzle): 13.6 Celsius (obviously error)
Core temperature(bottom head): 121.6 Celsius
Dose rate within containment: 33.7 Sv/hour
No major changes to the status of the reactors. Pressure in all containments seem ok. There is total confusion regarding the measured isotopes in the water in the basements for the turbine halls. It seems impossible to sort it out in any way and we can only wait for TEPCO or NISA to give final word on what they are actually measuring. It is pretty much beyond a doubt that the activities they published yesterday are wrong, it isn’t consistent with the given dose rates.
Update 10:00 (UTC) / 12:00 (CEST) / 19:00 (JST)
No new update from NISA during the night, but a new update from JAIF(link 1, link 2).
Reactor 1:
Water level in the core: 1.65 meters below the top of fuel assemblies
Flow rate of injected water: no new data
Core pressure: 508 kPa
Containment pressure: 270 kPa
Core temperature(feedwater nozzle): no new data
Core temperature(bottom head): no new data
Dose rate within containment: no new data
Reactor 2:
Water level in the core: 1.2 meters below the top of fuel assemblies
Flow rate of injected water: no new data
Core pressure: unknown
Containment pressure: 110 kPa
Core temperature(feedwater nozzle): no new data
Core temperature(bottom head): no new data
Dose rate within containment: no new data
Spent fuel pool temperature: no new data
Reactor 3:
Water level in the core: 2.3 meters below the top of fuel assemblies
Flow rate of injected water: no new data
Core pressure: 130 kPa
Containment pressure: 107.3 kPa
Core temperature(feedwater nozzle): no new data
Core temperature(bottom head): no new data
Dose rate within containment: no new data
Acording to TEPCO the dose rates from the water found in the turbin hall basement:
Reactor 1: 60 mSv/hour
Reactor 2: More than 1000 mSv/hour
Reactor 3. 750 mSv/hour
They have started to drain the water so that work can proceed to restore the pumps.
Anxiety, fear, panic or resignation and passiveness . That’s what many people experience under the current overload of information spread by media and various interest groups. We believe that a sound mind doesn’t need other people to tell it what to think, what to fear or what to trust. It needs clear facts.Here you can find explanations in plain language from nuclear professionals . Ask questions, learn the facts and form your own opinion.
NISA has released their update, link 1, link 2, link 3. I have also reattached the earlier JAIF figures at the bottom of the last update to see if it will fix the bug that gives an error when one clicks on the pictures.
As usual the NISA figures are between (). The NISA data is 3 hours older than the JAIF data.
Reactor 1:
Water level in the core: 1.65(1.65) meters below the top of fuel assemblies
Flow rate of injected water: 7.2 cubic meters per hour
Core pressure: 476 (477) kPa
Containment pressure: 270 (270) kPa *note, in the last update I misstakenly wrote 370 kPa as containment pressure.
Core temperature(feedwater nozzle): 195.3 Celsius
Core temperature(bottom head) 146.3 Celsius
Dose rate within containment: 35.1 Sv/hour
Reactor 2:
Water level in the core: 1.1 (1.1) meters below the top of fuel assemblies
Flow rate of injected water: 18.6 cubic meters per hour
Core pressure: unknown
Containment pressure: 116 (115) kPa
Core temperature(feedwater nozzle): 107 Celcius
Core temperature(bottom head): 100 Celsius
Dose rate within containment: 43.4 Sv/hour
Spent fuel pool temperature: 57 Celsius
Reactor 3:
Water level in the core: 2.3 meters below the top of fuel assemblies
Flow rate of injected water: 14.5 cubic meters per hour
Core pressure: 139 (139) kPa *note, I wrote the wrong pressure in the last update
Containment pressure: 106.6 (106.6) kPa
Core temperature(feedwater nozzle): 37.6 Celsius (sounds like an error on equipment)
Core temperature(bottom head): 106.1 Celsius
Dose rate within containment: 36.1 Sv/hour
Due to my error with containment pressure in the last update I withdraw my speculation that its hard to control the pressure in number 1. Rather it seems like the situation is fairly stable. Otherwise not much new information.
The US Department of Energy has done some arial surveys around Fukushima Daiichi and released the data. I have one pictures from it below(hats of to http://neutroneconomy.blogspot.com/ where I found the pictures). The dose rate unit used on the picture is millirad. 1 millirad=10 microgray =* 10 microsievert *that equality between gray and sievert is only valid for gamma radiation. Gray measures the energy deposited while sievert is weighted in such a way that it expresses a cancer risk. For gamma the weighting factor is 1.
Update 12:00(UTC)/13:00(CET)/21:00(JST)
No NISA updates have been released yet today, JAIF has released their update as usual(one hour old as of writing this).
Reactor 1:
Water level in the core: 1.65 meters below the top of fuel assemblies
Core pressure: 476 kPa
Containment pressure: 370 kPa
Core temperature(feedwater nozzle): no new data
Core temperature(bottom head) no new data
Dose rate within containment: no new data
Reactor 2:
Water level in the core: 1.1 meters below the top of fuel assemblies
Core pressure: unknown
Containment pressure: 116 kPa
Core temperature(feedwater nozzle): no new data
Core temperature(bottom head) no new data
Dose rate within containment: no new data
Reactor 3:
Water level in the core: 2.3 meters below the top of fuel assemblies
Core pressure: 202 kPa
Containment pressure: 106.6 kPa
Core temperature(feedwater nozzle): no new data
Core temperature(bottom head) no new data
Dose rate within containment: no new data
All 3 reactors are now cooled with freshwater instead of sea water. It seems hard for them to get the pressure in the number one reactor under complete control. In JAIF’s written update they say lights are on in all control rooms now. Levels of radioactive materials in the seawater around the plant is climbing. TEPCO is releasing updates on activity in both sea and air, I have attached levels as pictures in the bottom of this update.
The ground deposits of I-131 the prefectures around Fukushima ranges from less than 1 to 16 kBq per square meter. The cesium ground deposits ranges from less than 0.1 to 1.9 kBq per square meter(here are the last 3 MEXT updates on ground deposts link 1, link 2, link 3). The data form the worst effected prefectures are however omitted, we hope MEXT will make those figures available asap! As a comparison the ground deposits of cesium due to Chernobyl ranged from a couple of hundreds to a couple of thousand kBq per square meter.
Not much to add today. The radiation levels in the sea outside Fukushima I are sky-high. The long term effects are hard to predict now since a sea contamination is entirly different from a land contamination, where land is basicly a 2D area, which leads to a thin and high concentration on the surface, and where rains soon concentrate the contamination to “hotspots”. The sea on the other hand is a 3D volume where currents quickly dilute any contaminant by dispersing them over very wide areas.
The JAIF updates from 10:00, 16:00 and 21:00 (JST) for March 26 are pretty much uniform. The big news is that freshwater injection to the cores of 1, 2 and 3 has started as opposed to using salty sea water. Apart from that nothing new. The radiation readings at the main gate (1 km out) has stayed at 170 μSv/h all day. The west gate read 147 μSv/h at 13:30.
There has been no further info yet on the status of the exposed workers or the status of the reactors. Only news about the reactors is that both number 1 and number 3 have now switched to fresh water injection into the core and number 2 was supposed to follow promptly. I end todays updates with a few video clips of the explosion in one of the refineries that was hit worst by the earthquake and tsunami. This disaster has struck so many lifes, so many industries and so many towns that it is hard to fathom.
Uppdate 16:30(UTC) / 17:30(CET) / 00:30(JST)
The 2 workes taken to hospital reportedly got a dose to their feet and lower legs between 2-6 Sieverts from beta radiation. They also got close to 200 mSv from gamma and an unknown internal dose.
They have not shown any signs of acute radiation sickness so far. But the dose to the legs are very worrying and in the worst case might mean amputation.
Update 14:15 (UTC) / 13:15 (CET) / 22:15 (JST)
New updates from JAIF and NISA(link 1, link 2, link3). JAIF status is from 15:00 JST and NISA updates from 10:00 and 12:30 JST. As before the first number is from the JAIF update and the number within () is from the older NISA update.
Reactor 1:
Water level in the core: 1.65 (1.65) meters below the top of fuel assemblies
Core pressure: 450 kPa (450 kPa)
Containment pressure: 295 (295) kPa
Core temperature(feedwater nozzle): 197.8 Celsius
Core temperature(bottom head) 153.6 Celsius
Dose rate within containment: 38.9 Sievert/hour
If one looks at the JAIF status updates one can see a very encouraging piece of information, they have switched from seawater to fresh water injection into the pressure vessel! That is one significant step in the direction of stabilizing the reactor since seawater injection could never be a permanent solution. They are still not using the internal pumps however. The temperature of the core seems to have been brought under control and the high containment pressure is on a slowly declining trend. We can only keep our hopes up that they will be able to avoid venting the containment.
Reactor 2:
Water level in the core: 1.20 (1.2) meters below the top of fuel assemblies
Core pressure: unknown
Containment pressure: 120 (120) kPa
Core temperature(feedwater nozzle): 107 Celsius
Core temperature(bottom head) 105 Celsius
Dose rate within containment: 45.6 Sievert/hour
Reactor 3.
Water level in the core: 2.3 m below the top of fuel assemblies.
Core pressure: 139 (139) kPa
Containment pressure: 107 kPa
Core temperature(feedwater nozzle): 42.8 Celsius (probably junk)
Core temperature(bottom head) 111,6 Celsius
Dose rate within containment: 51 Sievert/hour
Preparations are being made to switch from seawater to fresh water for reactor 2 and 3. If it goes as quickly as for number one it should be done within half a day. Work with electrical equipment on going.
We have earlier warned for the possibility that molten material in the core can be lying on the bottom of the vessel and eating its way through, now that seems unlikely considering how low the bottom head temperatures of the vessel are. All of them are below 200 degrees.
Dose rate at main gate around 200 micro sievert per hour.
Update 12:30 (UTC) / 11:30 (CET) / 20:30 (JST)
TEPCO is preparing to switch from salt water to fresh water for the core cooling. From NHK:
TEPCO says it intends to switch over from pumping sea water to pumping fresh water into the 3 reactors, as salt in the sea water could cause corrosion and buildup, hampering the smooth flow of water inside the structures.
The company has been pumping seawater as an emergency measure.
The power company also says preparations to switch to fresh water were completed at the No.1 reactor on Friday afternoon. Operations to pump fresh water into reactors No.2 and No 3 are expected to start later in the day.
Update 10:00 (UTC) / 11:00 (CET) / 19:00 (JST)
Here are the status tables from the JAIF update described below and summary.
Reactor 1:
Water level in the core: 1.7 meters below the top of fuel assemblies
Core pressure: 465 kPa
Containment pressure: 310 kPa
Core temperature(feedwater nozzle): no new info yet today
Dose rate within containment: no new info yet today
Pressure has decreased by about 60-80 kPa in both vessel and containment since yesterday.
Reactor 2:
Water level in the core: 1.10 meters below the top of fuel assemblies
Core pressure: unknown
Containment pressure: 120 kPa
Core temperature (feedwater nozzle): no new info yet today
Dose rate within containment: no new info yet today
Reactor 3.
Water level in the core: 2.3 m below the top of fuel assemblies.
Core pressure: 139 kPa
Containment pressure: 107 kPa
Core temperature (bottom head): no new info yet today
Dose rate within containment: no new info yet today
Containment damage is again suspected on number 3, otherwise no major changes since yesterday. Let’s hope the containment is not damaged! Luckily the reactors in the possibly damaged containments are behaving more stable than the number one reactor (that has a undamaged containment).
…so far seventeen workers have been exposed to more than 100 mSv of radiation.
100 mSv is the limit where an increase in cancer risk has been proven. At 100 mSv, the lifetime risk of getting cancer increases from about 25-32% to 29-36%.
Keep in mind that this does not say whether or not any of these workers will actually get any cancer, much less die from it. It is safe to assume that just as after Hirosima/Nagasaki, the medical authorities will keep those exposed under very close watch, meaning their chances of getting diagnosed early and thus surviving any cancer will be quite good.
The other change is that the radiation reading at the main gate has gone up again:
The Main Gate: 259.0μSv/h at 11:00, Mar. 25
The pressure in the #1 containment vessel is moving up and down. #2 is stable. The #3 pressure is slowly decreasing. With the worries of a leak from #3, this may have more than one explanation, not all of them good.
Monitoring results of seawater sampled at the coast near the Fukushima Dai-ichi NPS on Mar. 23rd showed that radioactive Iodine, Cesium, Ruthenium, and Tellurium exceeding the regulatory limit were detected. Also, monitoring results of seawater sampled at coasts within about 16km from the Fukushima Dai-ichi NPS in Mar. 23rd showed that radioactive Iodine and Ruthenium exceeding the regulatory limit were detected.
Nuclear Safety Commission of Japan reported the result of preliminary calculation of exposure dose in the surrounding area of Fukushima Dai-ichi NPS.
The dose rate mesaured at the main gate has dropped slightly, from 209.4μSv/h at 12:00, Mar. 24 to 193.8μSv/h at 06:00, Mar. 25.
Water supplies continue to show taints of Iodine-131, but the readings fluctuate and it’s still hard to make out a general trend. Tokyo is no longer under a recommendation not to drink the tap water, but concerned citizens continue to use bottled water to some extent.
Following the latest findings, the Tokyo officials said it will no longer warn against consumption of tap water in the metropolitan area.
”I believe readings will go up and down. But even if levels exceed standards temporarily, it will be no problem as long as they stay (most of the time) within the range throughout the year,” Tokyo Gov. Shintaro Ishihara said at a news conference. ”I hope people in Tokyo would act calmly.”
Still, people in the capital area — located about 220 kilometers from the crippled Fukushima Daiichi nuclear plant — and elsewhere continued to buy up limited supplies of bottled water from shops and vending machines.
The government has asked that people in the 20-30 km zone around the crippled Fukushima plant to evacuate volontarily out of concern for supplies for daily necessities.
The Japanese government has encouraged people living within 20 to 30 kilometers of the troubled nuclear plant in Fukushima Prefecture to leave voluntarily, with concerns over access to daily necessities rather than resident safety prompting the advice, top government spokesman Yukio Edano said Friday.
I end todays updates with some heartbreaking pictures from the tsunami disaster. Its very hard to even just watch these pictures, I hope the resilience of the great japanese people will astonish the world when they rebuild after this disaster.
Some Austrian researchers have analysed data from detectors used to verify the comprehensive test ban treaty and their analysis show that the emissions of iodine and cesium from Fukushima is approaching the same level as from the Chernobyl accident. Fukushima emitted around 1,3*10^17 Bq iodine per day the first days and the total emission from Chernobyl was 1,7*10^18 Bq. By now the iodine emissions must be much lower due to the short half life of iodine and they haven’t reported any containment venting for about a week if my memory serves me right. The core inventory of I-131 is now reduced by more than half due to decay(half life 8.02 days) and the other iodine isotopes have even shorter half life. It will be interesting to see more data on this.
It’s good that the evacuation from the area around the reactor was brisk and that iodine pills have been supplied. So far the ground fallout data from MEXI doesn’t look very bad but it might be due to the direction of the wind as stated in the article.
Update 19:15(UTC)/20:15(CET)/04:15(JST)
It is in the middle of night in Japan right now and the news flow is always a bit slower then for obvious reasons. But NISA has still released a new update (values from 18:05 which makes it older than the JAIF updated I wrote about in the last blog update. They have released a PDF with pictures from the control rooms and plant area, here is a direct link to it. They are ne day old and that is why the control room for reactor 1 is dark(they restored power to it today).
17 workers in total has exceeded a total dose of 100 mSv.
Uppdate 16:00(UTC) / 17:00(CET) / 01:00(JST)
New JAIF and NISA(link 1, link 2, link 3) updates. NISa has added a new file to its update that gives more data, among them the dose rates within the containments. The NISA uppdate is from 11:00 and the JAIF update from 22:00 JST. JAIF numbers first followed by NISA within ().
Reactor 1:
Water level in the core: 1.7 meters(1.7m) below the top of fuel assemblies
Core pressure: 523 kPa (532 kPa)
Containment pressure: 390 kPa (400 kPa)
Core temperature(feedwater nozzle): 175 Celsius
Dose rate within containment: 43.5 Sv/hour
Reactor 2:
Water level in the core: 1.15 meters(1.15m) below the top of fuel assemblies
Core pressure: unknown
Containment pressure: 110 kPa (110 kPa)
Core temperature(feedwater nozzle): 100 Celsius
Dose rate within containment: 48.4 Sv/hour
Reactor 3.
Water level in the core: 2.3 m (2.3 m) below the top of fuel assemblies.
Core pressure: 137 kPa (137 kPa)
Containment pressure: unknown
Core temperature(bottom head): 185.,5 Celsius
Dose rate within containment: 55.9 Sv/hour
The pressure in number 1 went up a bit and then started going down. Temperature has been lowered about 70 degrees Celsius. Dose rate by main gate seems to be on a slow decline. Iodine levels in Tokyo water has gone down below the infant limit of 100 Bq/liter. Testing of pumps are ongoing in reactor number 3. More and more vegetables with levels far exceeding the limits for cesium and iodine is found.
Uppdate 9:00(UTC) / 10:00(CET) / 18:00(JST)
During night(swedish) JAIF(link 1, link 2) and NISA(link 1, link 2) has released new updates. The NISA updates(the schematics of the reactors attached at the end of the post) is by the time of writing 13 hours old and the JAIF update 2 hours old. I will write the JAIF numbers below first and the NISA numbers within parenthesis so one can se the change over the last 11 hours.
Reactor 1.
Water level in the core: 1,7 meters(1,7m) below the top of fuel assemblies
Core pressure: 510 kPa (511 kPa)
Containment pressure: 385 kPa (385 kPa)
Core temperature(feedwater nozzle): 243 Celsius
The situation has been stable for the last 11 hours. Containment pressure and core pressure is up about 20 kPa since yesterdays update. The containment pressure is a bit to high for comfort I would say. All though the highest it has reached during the entire accident was about 800 kPa in one of the reactors so it can plausibly handle even a doubling in an emergency, but if it doesn’t go down soon I am afraid TEPCO are going to have to vent the containment. Venting now could be problematic since the steam will contain quite a lot of activity and it could hamper work for hours due to radiation levels. On a positive note, the lights are now on in the number 1 control room showing that there is some progress in restoring electricity. Lets hope the pace will accelerate soon and that the coolant pumps are functional or at least easy to replace!
Reactor 2.
Water level in the core: 1,2m (1,2m) below the top of the fuel assemblies
Core pressure: Unknown(the readings claim below atmospheric pressure so the gauge is most likely broken)
Containment pressure: 105 kPa (105 kPa)
Core temperature(feedwater nozzle): 102 Celsius
Compared to yesterday pretty much nothing has changed. The core temperature and both core pressure and containment pressure remains low. Nothing new about the radiation levels in the turbine building(reported to be around 500 mSv/hour yesterday) that prevents access for repairing equipment.
Reactor 3.
Water level in the core: 2,3 m (2,3 m) below the top of fuel assemblies.
Core pressure: (142 kPa)
Containment pressure: unknown(JAIF states “downscale”)
Core temperature(feedwater nozzle): 80,7 Celsius
The JAIF update has changed the status of the containment from “might be not damaged” to “not damaged”, that is very good news indeed! It means the only damaged containment is on reactor 2 that appears to be quite stable and cool. Sometime during yesterday they seem to have been able to hook up a pump to one of the pipes leading to the spent fuel pool and they can now provide seawater through the cooling and purification line. Hopefully that means there is no need anymore for blind spraying of the number 3 building. Yesterday they managed to restore lights to the control room, but no news about instrumentation or the filtration system to bring down radiation levels inside the control room.
Reactor 4.
The concreter pump truck continues to deliver water to the spent fuel pool at a rate of 50 000 liters per hour.
General remarks:
We have been hoping for the electricity to be restored to the pumps etc since Saturday now. There is no explanation on what problems they have encountered or the status of the pumps. In the Fukushima Daini plant they had to replace pumps after the quake and tsunami so perhaps pumps needs to be replaced at Daiichi as well. The situation appears stable at the moment, but seawater cooling can not continue forever. At some point the salt depositions in the core will start to cause real problems but I do not know what time span we are talking about. If one estimates the salt deposition from the amount of water that could have been evaporated by the decay heat so far one ends up with several tens of cubic meters of salt. It’s hard to know where all of this salt has been deposited though since we don’t know the flow path of the water. On the bright side it seems like the workers are able to access more of the reactor building now as indicated by the fact that they have switched the path of seawater injection for the number 3 spent fuel pool and the number 1 reactor.
Three workers have been exposed to close to 200 mSv. It’s encouraging that they manage to keep the worker doses below 200 mSv so far. If TEPCO is being honest then its unlikely we will see any acute radiation sickness in workers.
Iodine levels in water and vegetables in prefectures close to Fukushima continues to be high.
We’ll try to keep it in english from now on…
Update 07:30 (UTC) / 16:30 (JST)
JAIF just released their 16:00 update. One bit of happy news there is that they now write that the number 3 containment vessel is “Not damaged”.
Screenshot of the update will follow soon when the guy that has access to saving PDF to JPG gets to his computer. 🙂
Radiation levels in the Tokyo water also seem to be dropping again… but it’s too soon to speak of any general trends. Also no new word on Caesium-137 in farmlands or water.
The work to bring electricity to Fukushima I continues (slowly).
I realised that I forgot to counter the 5th argument by Takahashi. I have now added it.
In the Huffington post Patrick Takahashi flaunts some misconceptions about nuclear and the technological impact the Fukushima accident will have on future new builds. We will take a look at some of the flaws here on his 4 point list.
1. Economics
Patric states that due to increasing regulatory demands on nuclear after this accident the price of nuclear will escalate into the industries oblivion. But that doesn’t necessarily have to be the case and should not be the case of the issue is treated rationally by the regulatory bodies. What Fukushima has shown us is that one can not rely on emergency diesel generators for core cooling and that spent fuel pools are sensitive. Let’s look into those two issues.
A litte riddle… solve it and win pins.
Published by Michael on April 1, 2011This is not so much an April Fools joke as it is a little riddle. It connects to a current event… and to things that happened in the last century. And of course it has something to do with nuclear power.
This is a comparison between two estimated values… what are they?
Update: we have a winner! Tony scored a perfect bullseye. I’m quoting him here:
‘a’ is the number of iodine atoms that would fill the known universe, if the iodine were at ‘normal’ temperature/pressure.
the second number is the number of radioactive iodine atoms you would have needed, when Chernobyl exploded, in order to have one radioactive iodine atom left today.
An added trivia is that the estimated number of atoms in the known universe is approximately 10^80.
The upshot of all this is this: there is not a single atom of Iodine-131 released by Chernobyl in existence today. The last atom decayed in no more than 4 years after the accident.
/Michael
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