Fukushima Reactors Research Articles

Opening Fukushima floodgates: Modelling 137Cs impact in marine biota

A numerical model was applied to simulate the transport of 137Cs released with the waters which were used to cool Fukushima reactors. These stored waters will be released to the Pacific Ocean according to Japanese government plans. The radionuclide transport model is Lagrangian and includes radionuclide interactions with sediments and an integrated dynamic foodweb model for biota uptake. Calculations made from a conservative approach indicate that expected concentrations in sediments and marine fish would be orders of magnitude below those detected after Fukushima accident and also lower than those resulting from global fallout background.

Around the World

In science news around the world, international agencies lift a moratorium on research on the eradicated rinderpest virus, the European Union announces new plans for its Joint Technology Initiatives, the chair of Japan's Nuclear Regulatory Authority finds that Fukushima's reactors are polluting ocean waters, and more.

Concentration of Strontium-90 at Selected Hot Spots in Japan

This study is dedicated to the environmental monitoring of radionuclides released in the course of the Fukushima nuclear accident. The activity concentrations of β− -emitting 90Sr and β−/γ-emitting 134Cs and 137Cs from several hot spots in Japan were determined in soil and vegetation samples. The 90Sr contamination levels of the samples were relatively low and did not exceed the Bq⋅g−1 range. They were up four orders of magnitude lower than the respective 137Cs levels. This study, therefore, experimentally confirms previous predictions indicating a low release of 90Sr from the Fukushima reactors, due to its low volatility. The radiocesium contamination could be clearly attributed to the Fukushima nuclear accident via its activity ratio fingerprint (134Cs/137Cs). Although the correlation between 90Sr and 137Cs is relatively weak, the data set suggests an intrinsic coexistence of both radionuclides in the contaminations caused by the Fukushima nuclear accident. This observation is of great importance not only for remediation campaigns but also for the current food monitoring campaigns, which currently rely on the assumption that the activity concentrations of β−-emitting 90Sr (which is relatively laborious to determine) is not higher than 10% of the level of γ-emitting 137Cs (which can be measured quickly). This assumption could be confirmed for the samples investigated herein.

After Fukushima: The precautionary principle revisited

Etienne de Villiers, more than other theologians, elaborates on basic elements of a Christian ethics of responsibility. He distinguishes between retrospective and prospective responsibility. The prospective aspect attracted awareness after the nuclear accident in the Fukushima reactors on 11 March 2011. The question on how to respond in an ethically responsible manner to catastrophic risks was put back on the agenda. The article takes up this question and discusses the answer given in the international debate by the introduction of the �precautionary principle�. The principle is described with its background in the �heuristics of fear�, proposed by the philosopher Hans Jonas. Four criticisms are discussed in detail relating to the problems of scientific uncertainty, the burden of proof, the weight of damages and the perils of precaution. That leads to a reformulation of the precautionary principle as a concrete element within an ethics of responsibility.

Cosmic Ray Radiography of the Damaged Cores of the Fukushima Reactors

The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei. The interaction with the electrons leads to continuous energy loss and stopping of the muons. The interaction with nuclei leads to angle "diffusion." Two muon-imaging methods that use flux attenuation and multiple Coulomb scattering of cosmic-ray muons are being studied as tools for diagnosing the damaged cores of the Fukushima reactors. Here, we compare these two methods. We conclude that the scattering method can provide detailed information about the core. Attenuation has low contrast and little sensitivity to the core.

Monitoring of Aerosol and Fallout Radioactivity in Belgrade After the Fukushima Reactors Accident

After the accident in Fukushima reactors, a daily monitoring programme was initiated in two laboratories in Belgrade, one at the Vincа Institute for Nuclear Sciences and the other at Institute for Occupational Health Karajovic. Samples of aerosol and fallout, as well as the random samples of food and water, were collected and analysed, using gross alpha/beta and gamma spectrometry, in order to establish the presence of traces of isotopes indicating Fukushima fallout. Gamma spectrometry measurement of these samples showed clear evi- dence of fission products 131 I, 134 Cs and 137 Cs wtihin 2 weeks after the accident. The activity dimin- ished with time due to dispersion in air and, in case of 131 I, short half-life.

Interactions between Nuclear Fuel and Water at the Fukushima Daiichi Reactors

Used nuclear fuel is a redox-sensitive semiconductor consisting of uranium dioxide containing a few percent of fission products and up to about one percent transuranium elements, mainly plutonium. The rapid increase in temperature in the cores of the Fukushima reactors was caused by the loss of coolant in the aftermath of the damage from the tsunami. Temperatures probably well above 2000 °C caused melting of not only the UO2 in the fuel but also the zircaloy cladding and steel, forming a quenched melt, termed corium . Substantial amounts of volatile fission products, such as Cs and I, were released during melting, but the less volatile fission products and the actinides (probably >99.9%) were incorporated into the corium as the melt cooled and was quenched. The corium still contains these radionuclides, which leads to a very large long-term radiotoxicity of the molten reactor core. The challenge for environmental scientists is to assess the long-term interactions between water and the mixture of corium and potentially still-existing unmelted fuel, particularly if the molten reactor core is left in place and covered with a sarcophagus for hundreds of years. Part of the answer to this question can be found in the knowledge that has been gained from research into the disposal of spent nuclear fuel in a geologic repository.

The similar effects of low-dose ionizing radiation and non-ionizing radiation from background environmental levels of exposure

The meltdown and release of radioactivity (ionizing radiation) from four damaged nuclear reactors at the Fukushima Nuclear Facility in Japan in March 2011 continues to contaminate air and ocean water even 1 year later. Chronic exposure to low-dose ionizing radiation will occur over large populations well into the future. This has caused grave concern among researchers and the public over the very long period of time expected for decommissioning alone (current estimate from official sources is 30–40 years based on TEPCO in Mid-and long-term roadmap towards the decommissioning of Fukushima Daiichi nuclear power units 1–4, 2011) and the presumed adverse effects of chronic, low-dose ionizing radiation on children, adults and the environment. Ultimately, radioactive materials from Fukushima will circulate for many years, making health impacts a predictable concern for many generations (Yasunari et al. in PNAS 108(49):19530–19534, 2011). There is long-standing scientific evidence to suggest that low-dose ionizing radiation (LD-IR) and low-intensity non-ionizing electromagnetic radiation (LI-NIER) in the form of extremely low-frequency electromagnetic fields and radiofrequency radiation (RFR) share similar biological effects. Public health implications are significant for reconstruction efforts to rebuild in post-Fukushima Japan. It is relevant to identify and reduce exposure pathways for chronic, low-dose ionizing radiation in post-Fukushima Japan given current scientific knowledge. Intentional planning, rather than conventional planning, is needed to reduce concomitant chronic low-intensity exposure to non-ionizing radiation. These are reasonably well-established risks to health in the scientific literature, as evidenced by their classification by World Health Organization International Agency for Research on Cancer as Possible Human Carcinogens. Reducing preventable, adverse health exposures in the newly rebuilt environment to both LD-IR and LI-NIER is an achievable goal for Japan. Recovery and reconstruction efforts in Japan to restore the communications and energy infrastructure, in particular, should pursue strategies for reduction and/or prevention of both kinds of exposures. The design life of buildings replaced today is probably 35–50 years into the future. Cumulative health risks may be somewhat mitigated if the double exposure (to both chronic low-dose IR from the Fukushima reactors and LI-NIER [EMF and RFR] in new buildings and infrastructure) can be dealt with effectively in early planning and design in Japan’s reconstruction.

Extraction of radioactive cesium using innovative functionalized porous materials

A new approach to an efficient and selective extraction of Cs+ ions from water, sea water enriched with Cs+ and a radioactive solution simulating the effluents of the Fukushima reactors (137Cs, 29 kBq L−1) was developed by using porous silica- or glass-based nanocomposites containing Prussian blue type nanoparticles, Co2+/[Fe(CN)6]3−, with sizes below 10 nm. A particular emphasis is given on the kinetics of cesium sorption fitted by using the classical reaction order model as well as a diffusion model in order to better understand the sorption mechanism. Compared to the amount of Co2+/[Fe(CN)6]3− nanoparticles, the sorption capacities of studied nanocomposites are more than three times higher than the ones observed for the respective bulk materials. These nanocomposites present a high selectivity to Cs+ and extract it in trace amounts.

Measurement of airborne 131I, 134Cs and 137Cs due to the Fukushima reactor incident in Milan (Italy)

After the earthquake and the tsunami occurred in Japan on March 2011, four of the Fukushima reactors had released in air a large amount of radioactive isotopes that diffused all over the world. The presence of airborne 131I, 134Cs, and 137Cs in air particulate due to this accident were detected and measured in the Low Radioactivity Laboratory operating in the Department of Environmental Sciences of the University of Milano-Bicocca. The sensitivity of the detecting apparatus is of 0.2 uBq/m3 of air. Concentration and time distribution of these radiocontaminations ranging from a few to 400 uBq/m3 for the 131I and of a few tens of uBq/m3 for the 137Cs and 134Cs.

Observations of Fukushima fallout in Great Britain

Following the Fukushima accident in March 2011, grass samples were collected from 42 sites around Great Britain during April 2011. Iodine-131 was measurable in grass samples across the country with activity concentrations ranging from 10 to 55 Bq kg−1 dry matter. Concentrations were similar to those reported in other European countries. Rainwater and some foodstuffs were also analysed from a limited number of sites. Of these, 131I was only detectable in sheep’s milk (c. 2 Bq kg−1). Caesium-134, which can be attributed to releases from the Fukushima reactors, was detectable in six of the grass samples (4–8 Bq kg−1 dry matter); 137Cs was detected in a larger number of grass samples although previous release sources (atmospheric weapons test and the 1986 Chernobyl and 1957 Windscale accidents) are likely to have contributed to this.

Creation path of 35 S from Fukushima not so obvious

In PNAS, Priyadarshi et al. (1) reported the detection of unusual levels of atmospheric 35S in California related to releases from the Fukushima nuclear plant. The authors stated that the 35S was generated by “leaking neutrons,” activating the chlorine in the seawater that was used to cool the Fukushima reactors via the nuclear reaction 35Cl(n,p)35S. The authors calculated “that 4e11 neutrons per m2 were released,” of which “2e8 neutrons per m2 reacted with 35Cl.”

Deciphering the Measured Ratios of Iodine-131 to Cesium-137 at the Fukushima Reactors

We calculate the relative abundance of the radioactive isotopes Iodine-131 and Cesium-137 produced by nuclear fission in reactors and compare it with data taken at the troubled Fukushima Dai-ichi nuclear power plant. The ratio of radioactivities of these two isotopes can be used to obtain information about when the nuclear reactions terminated.

Shutdown of fukushima reactors is ahead of schedule

This past April, when the Japanese government and Tokyo Electric Power Co. (TEPCO) jointly unveiled their plan to bring the damaged reactors of the Fukushima Dai'ichi nuclear power plant to a cold shutdown and gain control of the release of radioactive materials, they set a tentative completion date for mid-January 2012.

Richard Doll and Alice Stewart: Reputation and the Shaping of Scientific "Truth"

As the world watched the Fukushima reactors release radionuclides into the ocean and atmosphere, the warnings of Dr. Alice Stewart about radiation risk and the reassurances of Sir Richard Doll assumed renewed relevance. Doll and Stewart, pioneer cancer epidemiologists who made major contributions in the 1950s-he by demonstrating the link between lung cancer and smoking, she by discovering that fetal X-rays double the chance of a childhood cancer-were locked into opposition about low-dose radiation risk. When she went public with the discovery that radiation at a fraction of the dose "known" to be dangerous could kill a child, her reputation plummeted, whereas Doll, foremost among her detractors, was knighted and lauded as "the world's most distinguished medical epidemiologist" for his work. Their lives and careers, so closely intertwined, took contrary courses, he becoming "more of the establishment" (as he said), while she became more oppositional. When it was discovered, after his death, that he'd been taking large sums of money from industries whose chemicals he was clearing of cancer risk, his reputation remained unscathed; it is now enshrined in the "Authorized Biography" (2009) commissioned by the Wellcome Institute, along with Doll's denigration of Stewart as an "embittered" woman and biased scientist. Stewart lived long enough to see radiation science move her way, to see international committees affirm, in the 1990s, that there is no threshold beneath which radiation ceases to be dangerous; recent evidence from Chernobyl is bearing out her warnings. But a look at the making and breaking of these reputations reveals the power of status, position, and image to shape scientific "knowledge" and social policy.

Tracking of Airborne Radionuclides from the Damaged Fukushima Dai-Ichi Nuclear Reactors by European Networks

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous (131)I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous (131)I and the large underestimation of the total (131)I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous (131)I fraction to total (131)I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the (134)Cs to (137)Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total (131)I inventory that has passed over Europe during this period was <1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe.

Disaster Preparation: Lessons from Japan

On 11 March 2011, the earthquake and tsunami in Japan claimed thousands of lives, disrupted the lives of hundreds of thousands, and destroyed regional power and transportation infrastructure. Backup systems intended to maintain cooling for three operating nuclear reactors and the spent-fuel pools failed. Experts in various technical fields from Japan, the United States, and around the world worked to understand and mitigate the consequences of unplanned releases of radioactivity. As a team of U.S. health and medical subject matter experts deployed to Japan in the early days after the tsunami, we have identified the elements that remain most challenging in preparing for future disasters. ![Figure][1] Support. The U.S. Navy delivers relief supplies to an evacuation center in northern Japan. CREDIT: MASS COMMUNICATION SPECIALIST 1ST CLASS BEN FARONE, US NAVY/WIKIMEDIA COMMONS Given the reality of the uncertainty in the physical state of the Fukushima reactors, the ability to make accurate predictions based on models was limited. We found that the absence of such information led to suspicion by the public that data were not being reported. Information was being provided by a variety of sources, including international news media. Cultural differences and national sovereignty must be understood and respected when determining how to present, disseminate, and discuss information. Although the public was justifiably concerned about possible radiation health effects, we believe that lack of understanding of radiation and its effects resulted in unnecessary fear. The misunderstanding extended to the purpose of potassium iodide (KI), which should not be distributed indiscriminately, but rather used to protect those with active thyroids, particularly infants, young adults, and teens who are at risk from the exposure resulting from internal contamination. There was also uncertainty about the best KI dosage and administration schedule, partly because Japanese dosage guidance differed from that provided by the United States. Fortunately, in this case KI prescriptions were reduced to very few people, primarily those working close to the reactors. We also observed differences in risk tolerance. Compared with those far from the site, a local population may choose to accept a modestly greater risk from low-level radioactive contamination in order to restore their economy and way of life. Cultural differences also may alter the acceptable level of risk (such as the amount of iodine normally contained in the diet) or how to balance risk and benefit. Less stringent requirements can be acceptable for adults, compared with infants and children, although conflicting protective action guidelines create public confusion. When evacuation is initiated, it is crucial to identify the criteria that must be met before residents are permitted to return. Each decision requires the assessment of competing risks at a time when outcomes are uncertain. For example, initially imposing a travel warning and limiting entry of people and removal of food products from a 50-mile zone around the radiation source were sensible. However, there are risks in mass movements of people, including transportation accidents, trauma from disrupting lives, separating people from their normal support structure (including care for chronic medical conditions), and diverting personnel who might be needed elsewhere. If evacuation is maintained for too long, there can be serious health (including mental health), family, and economic consequences. In rapidly evolving situations, scientists who advise decision-makers must think like clinicians and make decisions based on the best information available at the time. 1. The contents in this manuscript are from the authors and do not represent U.S. government policy or opinion. [1]: pending:yes

Will nuclear energy charge ahead? [The Data

The Japanese earthquake and its devastating consequences for the Fukushima reactors will surely affect how governments and their citizens feel about nuclear power in the coming months. Nonetheless, as of January, 65 new nuclear power plants, capable of producing over 62 gigawatts, were under construction in 16 countries, according to the Nuclear Energy Institute, a trade group in Washington, D.C. In 2009, construction began on 11 plants, the most in one year since 1987.

Current Designs Address Safety Problems in Fukushima Reactors

Nuclear reactor designers say that the reactors being built or planned today are quite different—and they say much safer—than those that are still smoldering in Japan.