Yesterday, Energy Secretary Steven Chu pointed to Unit 2 as the most likely vessel to be breached. I note that the TEPCO spent some time injecting freshwater into Unit 2. which suggests they may be worried about salt accumulation, which we discussed yesterday.
Good times. Full text after the jump.
Update to Information Sheet Regarding the Tohoku Earthquake
The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office
As of 11:00AM (EST), March 25, 2011
• Radiation Levels
o At 7:00PM (JST) on March 25, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 199.5 micro Sv/hour.
o Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on March 25 are shown in the attached PDF file. English version is available at: http://www.mext.go.jp/english/radioactivity_level/detail/1303962.htm
o For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.
• Fukushima Daiichi Unit 1 reactor
o At 11:00AM on March 25, activities for the injection of freshwater in place of seawater into the reactor core started and at 3:37PM, the injection of freshwater into the reactor core started.
o At 2:00PM on March 25, pressure inside the reactor core: 0.342MPa.
o At 2:00PM on March 25, water level inside the reactor core: 1.65 meters below the top of the fuel rods.
o At 2:00PM on March 25, pressure inside the primary containment vessel: 0.280MPaabs.
• Fukushima Daiichi Unit 2 reactor
o At 10:00AM on March 25, the temperature of the spent fuel pool: 82.4 degrees Fahrenheit.
o At 10:30AM on March25, TEPCO began to inject seawater into the spent fuel pool via cooling and purification line, until at 12:19PM (approximately 38 tons in total).
o At 11:00AM on March 25, activities for the injection of freshwater in place of seawater into the reactor core started.
o At 2:00PM on March 25, pressure inside the reactor core: -0.016MPa.
o At 2:00PM on March 25, water level inside the reactor core: 1.4 meters below the top of the fuel rods.
o At 2:00PM on March 25, pressure inside the primary containment vessel: 0.12MPaabs.
o As of 7:00PM on March 25, approximately 96 tons of water in total has been injected into the spent fuel storage pool.
o As of 7:00PM on March 25, external power generation is connected and the functionality of the electric devices is being checked.
o As of 7:30PM on March 25, the injection of seawater into the reactor core continues.
• Fukushima Daiichi Unit 3 reactor
o At 11:00AM on March 25, activities for the injection of freshwater in place of seawater into the reactor core started and at 6:02PM, the injection of freshwater into the reactor core started.
o At 1:28PM on March 25, Kawasaki City Fire Department began to shoot water aimed at the spent fuel pool until 4:00PM (approximately 450 tons in total).
o At 2:00PM on March 25, pressure inside the reactor core: 0.038MPa.
o At 2:00PM on March 25, pressure inside the primary containment vessel: 0.1089MPaabs.
o At 2:10PM on March 25, water level inside the reactor core: 1.9 meters below the top of the fuel rods.
o As of 7:00PM on March 25, approximately 4,497 tons of water in total has been shot to the spent fuel storage pool.
• Fukushima Daiichi Unit 4 reactor
o At 6:05AM on March25, TEPCO began to inject seawater into the spent fuel pool via cooling and purification line, until at 10:20APM.
o At 7:05PM on March 25, TEPCO began to shoot water aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete.
o As of 7:00PM on March 25, approximately 685 tons of water in total has been shot to the spent fuel storage pool.
o As of 7:00PM on March 25, external power generation is connected and the functionality of the electric devices is being checked.
• Fukushima Daiichi Unit 5 reactor
o At 3:00PM on March 25, the temperature of the spent fuel pool: 98.4 degrees Fahrenheit.
o At 3:00PM on March 25, the temperature of the water in the reactor core: 129.0 degrees Fahrenheit.
• Fukushima Daiichi Unit 6 reactor
o At 3:00PM on March 25, the temperature of the spent fuel pool: 69.8 degrees Fahrenheit.
• Fukushima Daiichi Common Spent Fuel Pool
o As of 7:00PM on March 25, approximately 130 tons of water in total has been injected to the spent fuel storage pool.
Our official sources are:
• Office of The Prime Minister of Japan
• Nuclear and Industrial Safety Agency (NISA)
• Tokyo Electric Power Company (TEPCO) Press Releases
• Ministry of Education, Culture, Sports, Science and Technology (MEXT)
bks | March 25, 2011
Did you mean “yesterday” or did you mean last Sunday. If the former can you provide a link? (Not doubting you, just very interested.)
–bks
Jeffrey | March 25, 2011
The word “yesterday” should hyperlink to the 3/24 FEPC statement, as well as my brief mention of Bradshear’s article in the New York Times.
mike | March 25, 2011
why were they still injecting seawater into the fuel pond if the temp was only 86F? that makes no sense given the problems the salt creates – why compound it if there is not currently boil off (or will be soon?) What happens if they over fill the fuel pond(s)? WHere does the runoff go and what radiation levels can be expected? I ask simply because of the lack of precision in delivery methods (ie, fire hose) and the NYT piece that said some of the seawater had gone back into the ocean.
jeannick | March 25, 2011
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if the mains have been reconnected and switched on now , I wonder how they got instrument readings before
jeannick | March 25, 2011
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is there some indication at what stage of refueling was unit 4
were the new rods still in the pond , were the old rods in the pond already
rwendland | March 25, 2011
NISA have an analysis of a sample of “stagnant water on the basement floor of the turbine building of Unit 1″. Note this is another sample, not the the Unit 3 water workers stood in.
What is interesting is that nearly half of the nuclides is Chlorine-38, I guess from using seawater as a coolant. Chlorine-38 has a short half-life of 37.23 mins, producing stable Argon-38, so seems like it would be pretty harmless within hours. Is that right?
http://www.nisa.meti.go.jp/english/files/en20110325-6.pdf
Radioactive_Nuclide Concentration_(Bq/cm3)
Cs-137 1.8×10^6
Cl-38 1.6×10^6
I-131 2.1×10^5
Cs-134 1.6×10^5
Y-91 5.2×10^4
Cs136 1.7×10^4
As-74 3.9×10^2
La-140 3.4×10^
kisch | March 25, 2011
> What is interesting is that nearly half of the nuclides is Chlorine-38,
>I guess from using seawater as a coolant.
> Chlorine-38 has a short half-life of > 37.23 mins,
> producing stable Argon-38,
> so seems like it would be pretty harmless within hours. Is that right?
For me it’s far more worrying where the 38Cl comes from than where it decays to. The only way I know is to produce it by neutron activation from 37Cl (stable, about a quarter of the natural Cl).
Neutron activation needs neutrons. You would get them in abundance from a fission reaction.
So if there’s no other explanation, the 38Cl in the leak water seems to indicate:
- Sea water (source of the 37Cl)
- has recently (less than a few hours, because of the short lifetime of 38Cl)
- been into contact with core material
- with ongoing fission reaction (producing the neutrons)
- and is leaking from there (RPV) straight through all containments.
Meaning a core melt still in progress and leaking.
I hope there’s a better explanation!
Anyone?
Allen Thomson | March 26, 2011
More numbers:
http://www3.nhk.or.jp/daily/english/25_10.html
High radiation detected in water at plant
Friday, March 25, 2011 08:22 +0900 (JST)
Tokyo Electric Power Company says it has detected high levels of radioactive substances in water that 3 workers were exposed to at the troubled Fukushima Daiichi nuclear power plant.
The company says 3.9 million becquerels of radioactive substances per cubic centimeter were detected in the water that the workers were standing in. That is 10,000 times higher than levels of the water inside a nuclear reactor in operation.
The level of radioactive cerium-144 was 2.2 million becquerels. Also, 1.2 million becquerels of iodine-131 was measured. These substances are generated during nuclear fission inside a reactor.
Tokyo Electric says damage to the No.3 reactor and spent nuclear fuel rods in a storage pool may have produced the highly radioactive water.
On Thursday, 2 of the 3 workers were taken to hospital after being exposed to 173 to 180 millisieverts of radiation while standing in 15-centimeters of water in the turbine building adjacent to the reactor. A third worker was also exposed to the higher-level radiation but did not require treatment.
Pieter Kuiper | March 26, 2011
If this info is correct, the interesting question is where this Cl-38 came from. This is not a fission nuclide, but it is produced by neutron capture. If this measurement is reliable, it maens that there still is a neutron chain reaction, making radioactiva isotopes from the seawater.
Thomas | March 26, 2011
Why does it need to be from a chain reaction (I assume you mean some part of the fuel has gone super-critical)? Why can’t the chlorine be picking up neutrons from the sub-critical natural decay of the fuel? The injected water is acting as neutron moderator, after all.
Eve | March 26, 2011
Na-24 values? The half-life is around 15 hrs.
If they have that much Cl-38 then perhaps this also indicates significant leakage from RPV 1?
anonymous | March 26, 2011
The chlorine could be from recriticality inthe spent fuel pond. Who knows how much boron is left and in what configuration after a pool meltdown (or core meltdownfor that matter).
Eve | March 26, 2011
but No. 1 is a spent nuclear fuel pool, unlike No. 4 where there is a mixture of spent and unspent fuel
anonymous | March 26, 2011
The chlorine could just be absorbing neutrons from the non critical bo plutonium decays, acting in effect as a substitute poison for the boron.
rwendland | March 26, 2011
Hopefully.
It must have taken several hours for the water to get from the core or SNF pool to the turbine building floor (note not even within main containment building), then to a test lab. Perhaps about 6+ half-lifes of time – which would indicate original concentration at least two orders of magnitude higher than the 1.6×10^6 Bq/cm3 measurement.
Any idea if plutonium etc decays would give enough neutrons for that?
Eve | March 26, 2011
No. 1 is not MOX (ie. no plutonium)
anonymous | March 26, 2011
Our school (name unmentioned) had a small amount of plutonium in a large drum shaped vat of paraffin (as I recall). We put small amounts of aluminum or copper into the vat near the plutonium and the sample captured neutrons and then decayed which we measured on some type of multichannel spectral analyzer to show the shape of the decay curve/half life/etc… Thus, small amounts of non-critical plutonium can do neutron activation on other materials. I don’t remember if the paraffin acted as a moderator to slow down the neutrons and thus increase the probability of capture. Anyway, something similar could be happening here with the large amounts of plutonium in the mox fuel in #3 reactor or in the spent fuel pool. I don’t know off hand, but I think U-235 gives off similar neutrons and could do the same thing. The neutron densities would be lower if there was not criticality, but there would still be neutron capture and activation of the chlorine. Someone here with more expertise could do the math to see if typical nuclear fuel could activate to create that number of activated chlorine decays. I think what would be more interesting is the fission product ratios as to determining where the waste water came from. Again, beyond my expertise.
Allen Thomson | March 26, 2011
> Our school (name unmentioned) had a small amount of plutonium in a large drum shaped vat of paraffin (as I recall).
A slight quibble, but I suspect your drum contained a plutonium-beryllium “alpha-n” neutron source, where the neutrons were produced when alpha particles from the plutonium struck the beryllium.
Interestingly — I hadn’t known this — the principal plutonium isotope used in such sources appears to be Pu239:
http://www.osti.gov/bridge/servlets/purl/4322217-OU1xwD/+plutonium+beryllium+source+isotope
anonymous | March 26, 2011
Sounds reasonable. It was a long time ago and I probably forgot that detail. Then the neutron production of the raw plutonium is probably not that high. Still doesn’t explain the neutron activated chlorine.