Group items tagged

A Wired Magazine article dated December 15, 2009 cites a poster session presentation of the research of the Chernobyl exclusion zone at the American Geophysical Union conference in 2009, and says radioactive cesium may be remaining in the soil far longer than what the half life (30 years) suggests. To note: it was a poster session presentation, and I'm looking to see if it has been formally published in a scientific paper since then.

From Wired Magazine (12/15/2009): SAN FRANCISCO — Chernobyl, the worst nuclear accident in history, created an inadvertent laboratory to study the impacts of radiation — and more than twenty years later, the site still holds surprises.

Reinhabiting the large exclusion zone around the accident site may have to wait longer than expected. Radioactive cesium isn’t disappearing from the environment as quickly as predicted, according to new research presented here Monday at the meeting of the American Geophysical Union. Cesium 137’s half-life — the time it takes for half of a given amount of material to decay — is 30 years. In addition to that, cesium-137’s total ecological half-life — the time for half the cesium to disappear from the local environment through processes such as migration, weathering, and removal by organisms is also typically 30 years or less, but the amount of cesium in soil near Chernobyl isn’t decreasing nearly that fast. And scientists don’t know why.

The information comes from a strange source - the husband and wife comedian couple cum independent journalists attending and reporting on TEPCO and the government press conferences when they are not on stage. In their blogpost on August 11 (in Japanese), they relate their talk with a researcher at the University of Tokyo who has submitted a scientific paper to a foreign academic society. This researcher, whom they say they cannot name because the paper is being reviewed right now, went to Fukushima and collected soil samples, rice hay samples, and water samples. He even went to the front of Fukushima I Nuclear Power Plant and collected samples there.

He also went to Iitate-mura. And he tells the couple that he found neptunium-239 in Iitate-mura, about 38 kilometers from the plant, in approximately the same amount as he found at the front gate of Fukushima I Nuclear Power Plant. That is the topic of his paper. The couple says in the very intelligent post that they cannot provide details because the paper is in review (but they also say the researcher has given them permission to talk about it in general terms), but it was in several thousand becquerels. There is no mention of whether it was per kilogram or per square meter or per something else.

There is no mention of when the researcher went to Iitate-mura. I could be wrong but the indication from the post is that it was after the news that chlorine-38 detection at Fukushima I Nuke Plant was false. TEPCO retracted the earlier announcement of chlorine-38 detection, on April 20. Uranium-239, whose half life is about 24 minutes, decays into neptunium-239 through beta decay. Neptunium-239, gamma emitter whose half life is about 2.4 days, decays into plutonium-239 whose half life is 24,200 years.

About the previous post http://fukushima-diary.com/2011/09/news-japan-after-the-typhoon/ I received a message from a reader of this blog. It was to suggest the yellow powder could be plutonium. Here is the explanation. http://sti.srs.gov/fulltext/ms2002705/ms2002705.html source for text below

Plutonium-239 is one of the two fissile materials used for the production of nuclear weapons and in some nuclear reactors as a source of energy. The other fissile material is uranium-235. Plutonium-239 is virtually nonexistent in nature. It is made by bombarding uranium-238 with neutrons in a nuclear reactor. Uranium-238 is present in quantity in most reactor fuel; hence plutonium-239 is continuously made in these reactors. Since plutonium-239 can itself be split by neutrons to release energy, plutonium-239 provides a portion of the energy generation in a nuclear reactor. The physical properties of plutonium metal are summarized in Table 1.

Only two plutonium isotopes have commercial and military applications. Plutonium-238, which is made in nuclear reactors from neptunium-237, is used to make compact thermoelectric generators; plutonium-239 is used for nuclear weapons and for energy; plutonium-241, although fissile, (see next paragraph) is impractical both as a nuclear fuel and a material for nuclear warheads. Some of the reasons are far higher cost , shorter half-life, and higher radioactivity than plutonium-239. Isotopes of plutonium with mass numbers 240 through 242 are made along with plutonium-239 in nuclear reactors, but they are contaminants with no commercial applications. In this fact sheet we focus on civilian and military plutonium (which are interchangeable in practice–see Table 5), which consist mainly of plutonium-239 mixed with varying amounts of other isotopes, notably plutonium-240, -241, and -242.

[MAXIMUM ALERT] Neptunium 239 Potentially Detected In Saint Louis 9/14/11 Radioactive Rainfall.  Updates and video will follow shortly. The source has a calculated average 2.4 day half life. The half life matches Neptunium 239. Np239 decays into Plutonium 239. The source would probably be Americium 243 created in the MOX fuel reactor at Fukushima Unit 3

Updated to add: IF WE ARE LUCKY, the source will not be Americium 243 but rather Uranium 239 (in Fukushima); given the 2.4 day half life of Np 239, it is possible that source came directly across the jet-stream as Np-239. The result would be higher levels of Np-239 and Plutonium 239 the further west one went from Saint Louis. 

UPDATE 9/17/11: The video below records raw data being taken from the 1.33 mR/hr radioactive rainfall which fell in Saint Louis, Mo on 9/14/11. This data was taken after shorter half life contamination had mostly burned off. The data shown is from one hour total count readings taken of the radioactive source, and local background. The raw data from the later part of the video has yet to be fully analyzed.

Radioactive fallout from the crippled Fukushima No. 1 nuclear plant has caused widespread fear, prompting the government in August to adopt basic targets for decontamination efforts in and around Fukushima Prefecture.

But the government's plan falls short and efforts should focus in particular on residential areas with more aggressive decontamination measures and goals, including reducing current radiation levels by 90 percent, two radiation experts said when interviewed by The Japan Times. "I really doubt their seriousness (about decontamination)," said radiation expert Tomoya Yamauchi, a professor at the Graduate School of Maritime Sciences at Kobe University.

Areas with radiation exposure readings representing more than 20 millisieverts per year have been declared no-go zones, and the government has shifted the focus of its decontamination plan to areas with radiation readings, based on an annual accumulative amount, of between 20 millisieverts and more than 1 millisievert, with the goal of reducing the contamination by 50 to 60 percent over two years. Decontamination efforts by humans, however, are expected to only yield a reduction of 10 to 20 percent. Nature, including the impact of rain, wind and the normal degradation of the radioactivity of cesium-134, whose half-life is roughly two years, is assumed to do the rest, thus reaching the best-case scenario of cutting the contamination by 60 percent.

TEPCO denies new leak at Fukushima plant, Asahi, July 1, 2011:

Radioactive tellurium-129m was detected for the first time in seawater near the water intake of the Fukushima No. 1 nuclear power plant’s No. 1 reactor, Tokyo Electric Power Co., the plant operator, said June 29. Seven hundred and twenty becquerels of the substance was detected per liter of water collected on June 4. [...] Tellurium-129m has a short half-life of about 34 days. Its detection near the intake indicates the possibility of a new leak of radioactive water into the sea. [...]

Japanese Nuclear Emergency Director: You Have No Right To A Radiation-Free Life, Gizmodo by Andrew Tarantola, July 26, 2011:

This footage, from a recent meeting of indignant Japanese citizens and feckless Japanese government types should be a little shocking. Sadly, it’s just more of the same – ineptitude and inaction. By denying the right to avoiding radiation? OK, shocking. [...] One Fukushima resident asks, “As other people do, people in Fukushima have the right to avoid the radiation exposure and live a healthy life, too. Don’t you think so?” A Nuclear Safety Commission Of Japan rep, when pushed to go beyond his canned non-answer, deadpans “I don’t know if they have that right.” The crowd reacts as you would expect when told they nuclear-threatened welfare isn’t a concern. [...]

plus cesium-134 (half-life of about 2 years) and silver-110m (half life about 250 days). Strontium-90's half life is about 30 years.

From Jiji Tsushin (8/24/2011)

China's State Oceanic Administration announced on August 24 that strontium-90 was detected in the firefly squid caught off the coast of Fukushima Prefecture in the amount that was 29 times as high as the marine organisms along the coast of China. Cesium-134, which is normally never detected in the marine organisms along the coast of China, and silver-110m, a gamma-ray emitter, were also detected.

Six months after the nuclear meltdowns in Fukushima Prefecture, the public's awareness of the threat posed by radiation is entering a new phase: the realization that the biggest danger now and in the future is from contaminated soil.

The iodine-131 ejected into the sky by the Fukushima No. 1 power station disaster was quickly detected in vegetables and tap water — even as far away as Tokyo, 220 km south of the plant. But contamination levels are now so low they are virtually undetectable, thanks to the short half-life of iodine-131 — eight days — and stepped up filtering by water companies.

But cesium is proving to be a tougher foe. The element's various isotopes have half-lives ranging from two to 30 years, generating concern about the food chain in Fukushima Prefecture, a predominantly agricultural region, as the elements wash fallout into the ground. The root of the problem is, well — roots. Cesium-134 and cesium-137 are viewed as potential health threats because vegetables can absorb the isotopes from the soil they're planted in.

It's the same researcher who said several thousand becquerels/kg of neptunium-239 was found in the soil in Iitate-mura, about 35 km northwest of Fukushima I Nuclear Power Plant. It seems it's not just Iitate-mura that got doused with neptunium, which decays into plutonium. Date City, about 25 km northwest from Iitate-mura and 60 km from Fukushima I Nuclear Power Plant, also got a large amount of neptunium.To recap, uranium-239, whose half life is about 24 minutes, decays into neptunium-239 with a half life of about 2.5 days, which then decays into plutonium-239 whose half life is 24,200 years.

Again, the reason for withholding the information is explained in the article below as "the research paper being peer-reviewed by a foreign scientific journal" - a make-or-break event, apparently, for a young researcher at a prestigious university in Japan - and as precaution against the possible Japanese government action to squash the information. The article was written by the same husband & wife comedian couple who first wrote about neptunium in Iitate-mura on their blog magazine in early August.I'm sure the nuclear experts who have appeared on TV to soothe the populace ever since the March 11 nuclear accident has the good explanation for neptunium-239 in these locations. They've kept saying "No way plutonium will be found outside the compound, because it is heavy and it doesn't fly". Oh I get it. It's plutonium they were talking about, not neptunium which decays into plutonium. My bad.From Nikkan SPA September 13 issue (part on Date City only):

The email began thus:

No one wants to think about the massive aqueous deposition of radioactive materials into the Pacific Ocean, that much is now clear. By September estimates of released contamination had risen to over  3,500 terabecquerels of cesium-137 released into the sea directly from the plant between March 11 and the end of May. Another 10,000 terabecquerels of cesium fell into the ocean after escaping from the reactors in the form of steam.

Initially reports had quieted concerns by stating that the materials would be diluted so vastly that the radioactivity would not be able to accumulate, and would not affect the environment.  The experts claimed they would track the deposition and floating radioactive debris field making its way on a trans-Pacific trip to the United States. Apparently, the experts in Japan didn't get the message.  The Japanese regularly tested the seawater only for 'popular' Iodine and Cesium isotopes instead of all known fission-produced radioactive materials, for the first 3 months after the disaster.  By March 31st, radioactive contamination concentration was 4,385 times the legal limit, up from 3,355 times on Tuesday, according to Kyodo. In response, the government had pledged to increase radiation monitoring on land and by sea and to consider increasing the evacuation zone — however time has shown little action would follow these vows.

Experts Don't Fear A Radiation Graveyard Water was constantly required for the workers to be able to get any cooling into Reactors 1-4, when water went in, steam came out.  The ocean quickly became the radiation dumping ground, as untold tonnes of contaminated water has been confirmed to have directly flowed into the ocean, and TEPCO continually assured Japanese citizens that the majority of dispersal would occur over the Pacific.

The POTRBLOG team has been able to identify a 19.25 hour half life and a follow on  4.8 day half life component in the radioactive fallout which rained down on Saint Louis, Missouri on Monday 17th of October 2011. The half lives and decay chain indicate the presence of radioactive Iodine 133 and its daughter product Xenon 133. Additional longer half life components are also present. Further updates, and data will follow 1st Update

The Ministry of Education and Science announced on October 31 the "result" of the survey they did in June. Much like announcing the result in July (2PM on July 29, to be exact) of the survey they did in March about radioactive fallout in Tohoku and Kanto, where radioactive iodine, cesium tellurium and silver were found in abundance in Tokyo (see my post on August 1).So, if tellurium and silver fell in Tokyo, it is very small wonder that they were in Fukushima soil within the 100-kilometer radius of Fukushima I Nuclear Power Plant.

Maps from the Ministry's announcement on October 31 are as follows. The amounts of tellurium and silver have been adjusted to the amounts as of June 14. I re-oriented and enlarged the maps for easier viewing but the resolution is not that great.Tellurium-129m, half life about 34 days (the unit is becquerels/square meter):

Silver-110m probably came from melted control rods, and went all the way to Tokyo.The announcement is NOT accompanied by the table that has actual measurements at these locations. But Mainichi Shinbun (10/31/2011) reports that the highest amount of tellurium-129m was found in Okuma-machi at 2.66 million becquerels/square meter.The Ministry's fallback position of course is "they won't affect the health very much because the radiation from these nuclides is "small" compared to those from radioactive cesium.Sure. They are shorter-life nuclides, which means radioactivity is stronger. Even if they simply pass through the body without accumulation, I would think they zap the body with radiation as they pass through. External exposure is another matter. I fearfully recall that many kindergarteners and elementary school pupils all over Tohoku and Kanto were made to plant rice with bare feet and hands back in April and May. (And they are made to dig up the sweet potatoes with bare hands now.)

Japan’s six reactor Fukushima Daichi nuclear complex has inadvertently become the world’s bell-weather poster child for the inherent risks of nuclear power ever since the 11 March Tohoku offshore earthquake, measuring 9.0 on the Richter scale, triggered a devastating tsunami that effectively destroyed the complex. Ever since, specialists have wrangled about how damaging the consequences of the earthquake and subsequent tsunami actually were, not only for the facility but the rest of the world. The Fukushima Daichi complex was one of the 25 largest nuclear power stations in the world and the Fukushima I reactor was the first GE designed nuclear plant to be constructed and run entirely by the Tokyo Electric Power Company, or TEPCO.

in the aftermath of the disaster, both TEPCO and the Japanese government were at pains to minimize the disaster’s consequences, hardly surprising given the country’s densely populated regions. But now, an independent study has effectively demolished TEPCO and the Japanese government’s carefully constructed minimalist scenario. Mainichi news agency reported that France’s l’Institut de Radioprotection et de Surete Nucleaire (Institute for Radiological Protection and Nuclear Safety, or IRSN) has issued a recent report stating that the amount of radioactive cesium-137 that entered the Pacific after 11 March was probably nearly 30 times the amount stated by Tokyo Electric Power Co. in May.

According to IRSN, the amount of the radioactive isotope cesium-137 that flowed into the ocean from the Fukushima Daiichi nuclear plant between March 21 and mid-July reached an estimated 27.1 quadrillion becquerels. Why should this matter? Aren’t the Japanese authorities on top of the issue? Cesium-137 can cause burns, acute radiation sickness and even death at sufficient doses. It can contaminate food and water and, if ingested, gets distributed around the body, where it builds up in soft tissues, such as muscles. Over time, it is expelled from the body in urine. And where might tingested cesium-137 come from?

The impacts on the ocean of releases of radionuclides from the Fukushima Dai-ichi nuclear power plants remain unclear. However, information has been made public regarding the concentrations of radioactive isotopes of iodine and cesium in ocean water near the discharge point. These data allow us to draw some basic conclusions about the relative levels of radionuclides released which can be compared to prior ocean studies and be used to address dose consequences as discussed by Garnier-Laplace et al. in this journal.(1) The data show peak ocean discharges in early April, one month after the earthquake and a factor of 1000 decrease in the month following. Interestingly, the concentrations through the end of July remain higher than expected implying continued releases from the reactors or other contaminated sources, such as groundwater or coastal sediments. By July, levels of 137Cs are still more than 10 000 times higher than levels measured in 2010 in the coastal waters off Japan. Although some radionuclides are significantly elevated, dose calculations suggest minimal impact on marine biota or humans due to direct exposure in surrounding ocean waters, though considerations for biological uptake and consumption of seafood are discussed and further study is warranted.

there was no large explosive release of core reactor material, so most of the isotopes reported to have spread thus far via atmospheric fallout are primarily the radioactive gases plus fission products such as cesium, which are volatilized at the high temperatures in the reactor core, or during explosions and fires. However, some nonvolatile activation products and fuel rod materials may have been released when the corrosive brines and acidic waters used to cool the reactors interacted with the ruptured fuel rods, carrying radioactive materials into the ground and ocean. The full magnitude of the release has not been well documented, nor is there data on many of the possible isotopes released, but we do have significant information on the concentration of several isotopes of Cs and I in the ocean near the release point which have been publically available since shortly after the accident started.

We present a comparison of selected data made publicly available from a Japanese company and agencies and compare these to prior published radionuclide concentrations in the oceans. The primary sources included TEPCO (Tokyo Electric Power Company), which reported data in regular press releases(3) and are compiled here (Supporting Information Table S1). These TEPCO data were obtained by initially sampling 500 mL surface ocean water from shore and direct counting on high-purity germanium gamma detectors for 15 min at laboratories at the Fukushima Dai-ni NPPs. They reported initially results for 131I (t1/2 = 8.02 days), 134Cs (t1/2 = 2.065 years) and 137Cs (t1/2 = 30.07 years). Data from MEXT (Ministry of Education, Culture, Sports, Science and Technology—Japan) were also released on a public Web site(4) and are based on similar direct counting methods. In general MEXT data were obtained by sampling 2000 mL seawater and direct counting on high-purity germanium gamma detectors for 1 h in a 2 L Marinelli beaker at laboratories in the Japan Atomic Energy Agency. The detection limit of 137Cs measurements are about 20 000 Bq m–3 for TEPCO data and 10 000 Bq m–3 for MEXT data, respectively. These measurements were conducted based on a guideline described by MEXT.(5) Both sources are considered reliable given the common activity ratios and prior studies and expertise evident by several Japanese groups involved in making these measurements. The purpose of these early monitoring activities was out of concern for immediate health effects, and thus were often reported relative to statutory limits adopted by Japanese authorities, and thus not in concentration units (reported as scaling factors above “normal”). Here we convert values from both sources to radionuclide activity units common to prior ocean studies of fallout in the ocean (Bq m–3) for ease of comparison to previously published data.