TEPCO ponders the source of the Iodine-131 and concludes it is probably from reactor 3. Apropos of our discussions earlier today and yesterday.
Full-text after the jump.
TEPCO Earthquake Information Update on March 25: Fukushima-Daiichi Status
(1) Result of the investigation on exposure to radiation of workers
(2) High radiation water may come from the unit 3 reactor, not spent fuel pool
(3) Status of water injection to the pool.
(1) Result of the investigation on highly radiated workers
Bellow are the investigation results of their working environment. Radiation dose rate of surface of the water is approximately 400mSv/h.
Result of gamma-ray nuclide analyses based on sampling of puddle
We are assessing radiation dose of 2 worker’s leg skin by beta ray. This incident would be caused because the workers regarded radiation dose of working area as low from survey result of radiation dose on March 23, it was about 0.5 mSv/hr at 5:00 and no major water puddle there. Workers continued working without recognizing change of work environment although their APD were alarming during the work
TEPCO has thoroughly instructed its employees and contractor workers to pay attention to the alarm of their APD and evacuate when necessary.
Regarding this event, Fukushima Labor Bureau gave TEPCO verbal instructions. After summerising lessons learned and future measures to this event, TEPCO will report related government ministries and agencies to make sure radiation control thoroughly.
(2)High radiation water may come from the unit 3 reactor, not spent fuel pool
As for the leakage of radioactive materials at Unit 3 turbine building, we assume the water came from the reactor. We collected sample of the contaminated water in the turbine building of Unit 3 and conducted the gamma-emitting nuclide analysis. We confirmed the following nuclides with short half-life.
Nuclides half-life (days) density (bq/cubic centimeter) Iodine 131 08.06 1.2 x 10E6 Cesium 136 13.16 2.3 x 10E4 Balium 140 12.75 5.2 x 10E4
There are 148 fuel rods with less than one year of cooling period in the spent fuel pool at Unit 3. Those fuel rods were transferred to the spent fuel pool between Jun 23 and 28, 2010 having had more than 200 days of cooling period. Nuclides with short half-life had sufficient time for decay in the spent fuel pool, so it seems possible that the contaminated water in the turbine building is from the reactor.
We do not deny possibility that there might be certain damage to the reactor of Unit 3. Even should that be the case, as plant parameters such as the reactor pressure and D/W pressure is stable , we presume that RPV is not seriously damaged.
We are injecting seawater and from the night of March 25, fresh water into the reactor. The water turns into steam and comes out from the reactor vessel through the SRV, then depressurized at the suppression chamber and condensed to water. This flow of water is cooling the reactor. Having experienced fluctuations of temperature and pressure, the containment function might be loosened somewhere. In any event, the above is a possibility, not yet confirmed.
(3) Water injection into the pools and the reactors
Unit 1: Sea water injection into the reactor pressure vessel, from 3:37 pm on March 25th, we have started to inject fresh water into it.
Unit 2: From 10:30 am on March 25th, seawater injection through Fuel Pool Cooling and Filtering System (FPC) was started. This finished at 0:19 pm.
Unit 3 From 5:35 am on March 24th, seawater injection through Fuel Pool Cooling and Filtering System (FPC) was started and finished at 4:05 pm.
Spraying at the spent fuel pool by Kawasaki City Fire Department was carried out from 1:28 pm to 4:00 pm on March 25th.
Unit 4: From 2:35 pm on March 24th, spraying water by the concrete pumping vehicle was conducted and ended at approximately 5:30 pm on the same day.
From 6:05 am on March 25th, seawater injection through Fuel Pool Cooling and Filtering System (FPC) was started and finished at 10:20 am.
Why is Plutonium not listed? That is the real danger here.
With a half life of 30,000 years.
Because they have found any plutonium outside of the reactor vessel. What the radionuclides suggest is recent criticality in the core and a breach.
Same goes for No. 1 as well – criticallity and a breach/leak based on the results, including Cl-38, from yesterday.
They need to report on Na-24 values (a half-life around 15 hrs) plus Cl-38. This can be chased to when they started the saltwater injection and followed up.
Speaking of I-131, check the results of rainwater sampling at U.C. Berkeley, *8,500 km from Fukushima*. They picked up a data point at 20 becquerels/liter which is just one-fifth of the alert level in Japan for drinking water (100):
http://www.nuc.berkeley.edu/RainWaterSampling
While not dangerous, that also not insignificant.
–bks
TEPCO Deadly Embrace in Reactor 2:
To fix the reactor they must fix the leak of 3 billion becquerel/cc seawater.
To fix the leak they must find the leak.
To find the leak they must fix the reactor.
–bks
p.s. No, 3 billion becquerels/cc is not hyperbole. That’s the news from NHK-TV English.
“TOKYO (Reuters) – Plutonium has been found in soil at various points within Japan’s stricken Fukushima Daiichi nuclear complex but does not present a risk to human health, operator Tokyo Electric Power Co (TEPCO) said on Monday.
TEPCO vice-president Sakae Muto told journalists at the company’s latest briefing that test results showing the plutonium came from samples taken a week ago”
http://news.yahoo.com/s/nm/20110328/ts_nm/us_japan_plutonium
–bks
Thank you for the continuous updates. I am currently living in Yokosuka, Japan and trying to wade through the sensationalized media is a daunting task. Though alot of what you discuss is far over my head I can honestly say I am learning from this event. As an aside, which may get reported later, the US Navy just dispatched two fresh water barges from the Naval base with 500,000 gallons of freshwater for the Fukushima plant http://www.navy.mil/search/display.asp?story_id=59318.
When are we going to see some real reports with methods, data and error bars? And time series?
This is not science, this is not engineering, this is public relations.
On NHK-TV (English) on the 11pm 26 March news, it was stated that the highly radioactive seawater in one of the turbine rooms was “like a swimming pool” 1.5 meters deep, and the cause of a 10-fold increase in the measurement of I-131 in the ocean.
Also, this JAIF report is most peculiar:
“Fukushima Daiichi nuclear power station has been in serious condition since some units lost cooling function. TEPCO is trying to recover components for cooling that should be driven by external AC power. However, working condition in high radiation area is so bad and there is no prospect of accomplishing the work for this recovery. (05:15, March 26)”
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1301116660P.pdf
–bks
There have been various theories about how that apparently reactor coolant water (or rather, seawater as temporary emergency coolant) got into the turbine hall. One is that there is a leak in reactor 3 primary containment and some of the injected water has migrated though the lower levels (turbine hall is lower and towards the sea from the reactor building).
Another theory is that the containment is completely intact, but steam and volatile gasses deliberately released from drywell or pressure suppression pool to secondary containment have migrated through ventilation ducts and condensed in the turbine hall.
The third theory is that contaiment is otherwise intact, but two main steam isolation valves are leaking and that there is also a separate leak in the turbine hall steam pipes. Somehow the tech commentator to NHK thought the third explanation with its multiple failures is the most convincing, go figure.
Another theory could be that they are picking up radioactive seawater from outside the plant and dropping it in with helicopters. I don’t think this is the case, because it would be diluted, but it also can not be excluded yet. Nor do I think theory 2 above is likely, because it would have had to have been a tremendous amount of steam coming through to the turbine hall.
As for reports – I don’t know about you, but when I’m writing manuscripts and I’m cold, I sit on my hands to keep them warm. After looking at the pictures of the insides of the cold control and equipment rooms, I don’t think they have the time with putting the error bars in those graphs, let alone get the statistics darn right. It looks like they are cold and under stress. When do they get to pee, eat, drink or catch their breath or monitor themselves before they go craap?
I think I would be working with maximum levels picked off their dosimeters, depending on the available readers or post-encounter readers. Also there are many other hazards – ie. wiring, lose masonry etc… in four reactors!
Eve, they’re not doing isotopic assays inside the reactor buildings. That is done outside. The preparation of the reports is certainly being done at TEPCO HQ where the chairs are comfy and the temperature is controlled. Only the sampling is being done inside.
–bks
For sure you are right, the isotopic analysis would be done outside, but I’m pretty sure the’re pressed when they’re in those buildings.
Daichi Reactor 1,3 isotopes:
http://www.tepco.co.jp/en/press/corp-com/release/11032503-e.html
http://www.nisa.meti.go.jp/english/files/en20110325-6.pdf
http://www.tepco.co.jp/en/press/corp-com/release/11032605-e.html
In addition to the Cl-38, I find it troubling that I-132, I-133, Ru-105, Te-129 are detected. These have very short half lives, and must have been recently created. Daini is seeing I-132 as well.
sidd
I did not see Te-129 being listed as detected, but they did detect Te-132 which has a half-life of 3.2 days
You can’t look half life of just the nuclide itself, you have to also look at the half life of all of its possible precursors. For example, Te-132 with half life 3.2 days decays into I-132. That means that once the initial I-132 has decayed, the amount of it remains constant at level where as much I-132 decay away as is created from Te-132. Thus, the effective half life I-132 is 3.2 days after the initial amount is gone.
I was merely remarking Te-129 was not on any report.
Na-24, Cl-38 and definitely P-32 from S-32 would all serve as markers for neutron capture, particularly if we take that the seawater was pulsed in at a specific time point after the accident. The isotopes could be chased up with time and followed as a marker of core criticallity. Evaluation of neutron dose in the stagnant versus new water pools could tell us a clearer picture of each of reactors leaks as well, not to mention the configurations of the melt with fuel and surrounding materials. One must know how they intend to flush with freshwater and approximate how much seawater passed through.
The Bq/cc listed are equiv to a tenth of a Curie
per liter.
That’s rather serious.
So now NHK have dropped their netcast, where is the best place to keep up with this. I am lost without the broadcast.
We should spare a thought for the two workers who stepped in the Unit 3 puddle on 24 March, previously reported to have received a radiation dose in the range of 170-180 millisieverts.
IAEA report today “the level of local exposure to the workers legs was estimated to be between 2 and 6 sieverts”. (Update 27 March, 03:00 UTC) By the radiation chart posted here a few days ago, that’s between “severe radiation poisoning” and the mid-point of “survival possible with prompt treatment” and “fatal even with treatment”.
Nevertheless the IAEA report “While the patients did not require medical treatment, doctors decided to keep them in hospital and monitor their progress over coming days.”
I hope that is a very good sign for them.
I think they mean that 2-6 Sv is a local dose to the legs, not a whole body dose. Because there are less vital tissues in the legs and feet, a large dose there is not nearly as harmful as a similar dose to the torso, or a whole body dose which obviously covers the torso as well.
There are weighting factors for different human tissue types that are used to assess the equivalent dose depending on how serious radiation damage to that tissue can be. They are mostly used for radiation therapy, where a very narrow and focused radiation beam (or intersecting beams) are used and a relatively high dose is administered to a very small region.
The most critical tissue in the legs is the bone marrow, but even when it’s severely damaged or destroyed, if bone marrow in other parts of the body survives, it will not diminish the immune system that much and the bone marrow in the legs eventually heals completely.
2-6 Sv to the legs might be something on the order of 20-300 Sv of total body dose, depending on the composition of the radiation (beta/gamma energy distribution). However, it’s somewhat confusing that they would state the leg dose in Sv, because Sv should be used for only total body equivalent doses, just to avoid this kind of confusion. Properly reported, they should have stated that the dose is absorbed dose of 2-6 Gy (grays) and then give an estimate for the whole body equivalent dose in Sv.
No way they would release someone with real 2-6 Sv from a hospital after a few days of observation, because their very survival would repend on very high intensity hospital treatment, including extensive measures to ensure high level of protection from pathogens (isolation, extra sterilization measures, UV lamps, air filtration etc.), due to immunosuppression caused by the radiation exposure.
“20-300 Sv” obviously meant 20-300 mSv. The workers were due to be released from the hospital today afternoon JST (so are probably already released), according to NISA’s “Seismic Damage Information (the 57th Release) (As of 15:30 March 27th, 2011)”.
fyi, on the SFP heat loads:
http://allthingsnuclear.org/post/4133270698/where-did-the-water-in-the-spent-fuel-pools-go
NY Timess has a status page:
http://www.nytimes.com/interactive/2011/03/16/world/asia/reactors-status.html
Yesterday they were reporting a vertical crack in the containment vessel for #3, wwhich (I read elsewhere) they were told by an anonymous source. the internal search engine for the NYT does show that statement but it’s been removed from the article in which it occurred, as far as I can tell. They seem to be the source for other reports of this on the internet.
Greg ladin over at scienceblogs has been doing reporting daily and having someone in Japan do updates from summaries of media there, but that is, after all, second-hand reports of possibly garbled media:
http://scienceblogs.com/gregladen/
Neither seems to have updated today.
dang, I’m awaiting moderation, either because of links or because I changed the user name I’m using.
Greg Laden over at scienceblogs dot com has been doing updates, with someone in Japan trying to summarize media reports from there. He’s posted an update since I left my previous comment. If you go to the scienceblogs home page tghere’s a pulldown menu where you can select “Greg Laden’s Blog”.
The NY Times has a status page on all the reactors that they’ve been updating, but they haven’t yet today. It”s reachable from one of the sidebars within the main article on the Japan situation which is reachable from their home page.
They appear to have been the original source of the claim that reactor number 3 has a crack in the containment vessel, but they seem to have edited this out of the article.
New IP address, I believe. We try to limit automatic approval to trusted commenters.
I little background on the war about information flow between the government and TEPCO that may explain why things seem to be kept in the dark.
On March 15/16 the Prime Minister criticized TEPCO for not coming through with information. He set up a common headquarter in the TEPCO building.
TEPCO’s boss was miffed, became “ill” and gave orders from a different office.
It is not known what cured Mr. Shimizu. Maybe he decided to become responsible or maybe the government caved in.
When recently changing reactor refilling from seawater to freshwater TEPCO reported that it added boric acid to the freshwater for unit no 2. Such was not added for unit 1 and 3.
Why is boric acid, fission suppression, needed in no 2?
Could some of the short half life nucleotides come from some reaction in no 2?
There’s lot of speculation on recriticality, but pretty much all of it is based on likely misidentifications by TEPCO analysis. For a starter, I-131 is NOT a sign of recriticality. With half-life of 8 days, it has decayed down to 1/4 of it’s original amount. In other words, there’s still a lot of it around, enough to easily explain the detected amounts, especially if it is combined with increased water (as opposed to steam) leakage as apparently is the case.
The two short-term nuclides TEPCO at some time reported to have detected were Cl-38 and I-134. These share one characteristic: they have on signature gamma energy and that’s around 4.71 MeV. Anyone who has done gamma spectroscopy will immediatly consider identification by single peak in that energy range extremely unreliable. It seems that TEPCO is detecting a high-energy peak that they are at turns attributing to different nuclides without considering the likelyhood that they indeed would be present.
The reason it’s very unlikely that these nuclides were present is that it would require recriticality. And if there were recriticality, there would be a lot of other nuclides that would be much easier to detect and identify correctly. There’s no way a recriticality even would be detected solely by Cl-38/I-134. So, combined with the unreliability of the identification, I would need a lot more evidence before I would consider recriticality a possibility.
No one understands what’s going on in those reactors. There are no models for what happens when you introduce raw seawater. These readings are not from the day of the tsunami, these readings are from the last couple of days. Why not send in a TEPCO executive to take several samples an then have them analyzed by the independent experts?
The very fact that they would make a mistake in analysis should be enough to force them to put that task in other hands.
“High levels of radiation exceeding 1,000 millisieverts per hour have been detected in water in a trench outside the No. 2 reactor’s building at the troubled Fukushima Daiichi nuclear plant, with the contaminated water suspected to have come from the reactor’s core, where fuel rods have partially melted, authorities said Monday.”
http://english.kyodonews.jp/news/2011/03/81572.html
Outside???
–bks
The “trench” as they call it appears to be a collection well system for water leakage from the plant, built between the turbine halls and the sea. Thus far reactor coolant has been detected in the turbine hall, so it’s not at all surprising that it has continued to leak down grade towards the sea.
Those buildings and their underground spaces have been damaged by the quake and tsunami, so leaked water staying inside would probably be less likely than this. They have not beeb able to go “uphill” closer to the source of the leak probably due to high radiation fields.
Here is a picture of (reactor 1) 1st basement level floor plan, which shows how extensive the underground structures are. The most likely leak sources, the pressure suppression pool rooms, are all below ground level.