SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Sustainable energy

30

Tritium concentrations in Japanese precipitation samples collected after the March 2011 accident at the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) were measured. Values exceeding the pre-accident background were detected at three out of seven localities (Tsukuba, Kashiwa and Hongo) southwest of the FNPP1 at distances varying between 170 and 220km from the source. The highest tritium content was found in the first rainfall in Tsukuba after the accident; however concentrations were 500 times less than the regulatory limit for tritium in drinking water. Tritium concentrations decreased steadily and rapidly with time, becoming indistinguishable from the pre-accident values within five weeks. The atmospheric tritium activities in the vicinity of the FNPP1 during the earliest stage of the accident was estimated to be 1.5×10(3)Bq/m(3), which is potentially capable of producing rainwater exceeding the regulatory limit, but only in the immediate vicinity of the source.

Concepts: Water, Precipitation, Nuclear fission, Nuclear power, Desalination, Sustainable energy, Tritium

30

The events of March 2011 at the nuclear power complex in Fukushima, Japan, raised questions about the safe operation of nuclear power plants, with early retirement of existing nuclear power plants being debated in the policy arena and considered by regulators. Also, the future of building new nuclear power plants is highly uncertain. Should nuclear power policies become more restrictive, one potential option for climate change mitigation will be less available. However, a systematic analysis of nuclear power policies, including early retirement, has been missing in the climate change mitigation literature. We apply an energy economy model framework to derive scenarios and analyze the interactions and tradeoffs between these two policy fields. Our results indicate that early retirement of nuclear power plants leads to discounted cumulative global GDP losses of 0.07% by 2020. If, in addition, new nuclear investments are excluded, total losses will double. The effect of climate policies imposed by an intertemporal carbon budget on incremental costs of policies restricting nuclear power use is small. However, climate policies have much larger impacts than policies restricting the use of nuclear power. The carbon budget leads to cumulative discounted near term reductions of global GDP of 0.64% until 2020. Intertemporal flexibility of the carbon budget approach enables higher near-term emissions as a result of increased power generation from natural gas to fill the emerging gap in electricity supply, while still remaining within the overall carbon budget. Demand reductions and efficiency improvements are the second major response strategy.

Concepts: Nuclear physics, Nuclear fission, Coal, Nuclear power, Energy development, Electricity generation, Sustainable energy, World energy resources and consumption

28

Research interest in bimetallic catalysts is mainly due to their tunable chemical/physical properties by a number of parameters like composition and morphostructure. In catalysis, numerous bimetallic catalysts have been shown to exhibit unique properties which are distinct from those of their monometallic counterparts. To meet the growing energy demand while mitigating the environmental concerns, numerous endeavors have been made to seek green and sustainable energy resources, among which hydrogen has been identified as the most promising one with bimetallic catalysts playing important roles. This tutorial review intends to summarize recent progress in bimetallic catalysts for hydrogen production, specifically focusing on that of reforming technologies as well as the relevant processes like water-gas shift (WGS) and CO preferential oxidation (PROX), and emphasizing on the fundamental understanding of the nature of catalytic sites responsible for generating high purity hydrogen and minimizing carbon monoxide formation. Meanwhile, some important synthesis and characterization methods of bimetallic catalysts developed so far are also summarized.

Concepts: Hydrogen, Catalysis, Nitrogen, Haber process, Sustainable energy, Water gas shift reaction, Hydrogen production, Partial oxidation

27

Japan’s 2011 Fukushima Daiichi Nuclear Power Plant incident required the evacuation of over a million people, creating a large displaced population with potentially increased vulnerability in terms of chronic health conditions. We assessed the long-term impact of evacuation on diabetes, hyperlipidaemia and hypertension.

Concepts: Nuclear physics, Nuclear fission, Coal, Nuclear power, Electricity generation, Sustainable energy

12

Recent understanding that specific algae have high hydrocarbon production potential has attracted considerable attention. Botryococcus braunii is a microalga with an extracellular hydrocarbon matrix, which makes it an appropriate green energy source.

Concepts: Water, Sustainable energy, Botryococcus braunii, Green energy

10

After the 2011 Fukushima Daiichi nuclear power plant accident, little information has been available on individual doses from external exposure among residents living in radioactively contaminated areas near the nuclear plant; in the present study we evaluated yearly changes in the doses from external exposure after the accident and the effects of decontamination on external exposure. This study considered all children less than 16 years of age in Soma City, Fukushima who participated in annual voluntary external exposure screening programs during the five years after the accident (n = 5,363). In total, 14,405 screening results were collected. The median participant age was eight years. The geometric mean levels of annual additional doses from external exposure attributable to the Fukushima accident, decreased each year: 0.60 mSv (range: not detectable (ND)-4.29 mSv), 0.37 mSv (range: ND-3.61 mSv), 0.22 mSv (range: ND-1.44 mSv), 0.20 mSv (range: ND-1.87 mSv), and 0.17 mSv (range: ND-0.85 mSv) in 2011, 2012, 2013, 2014, and 2015, respectively. The proportion of residents with annual additional doses from external exposure of more than 1 mSv dropped from 15.6% in 2011 to zero in 2015. Doses from external exposure decreased more rapidly than those estimated from only physical decay, even in areas without decontamination (which were halved in 395 days from November 15, 2011), presumably due to the weathering effects. While the ratios of geometric mean doses immediately after decontamination to before were slightly lower than those during the same time in areas without decontamination, annual additional doses reduced by decontamination were small (0.04-0.24 mSv in the year of immediately after decontamination was completed). The results of this study showed that the levels of external exposure among Soma residents less than 16 years of age decreased during the five years after the Fukushima Daiichi nuclear power plant accident. Decontamination had only limited and temporal effects on reducing individual external doses.

Concepts: Chernobyl disaster, Nuclear fission, Nuclear power, Radioactive contamination, Nuclear safety, Sustainable energy, Three Mile Island accident, Nuclear Regulatory Commission

6

With a projection of nearly doubling up the world population by 2050, we need wide variety of renewable and clean energy sources to meet the increased energy demand. Solar energy is considered as the leading promising alternate energy source with the pertinent challenge of off sunshine period and uneven worldwide distribution of usable sun light. Although thermoelectricity is considered as a reasonable renewable energy from wasted heat, its mass scale usage is yet to be developed. Here we show, large scale integration of nano-manufactured pellets of thermoelectric nano-materials, embedded into window glasses to generate thermoelectricity using the temperature difference between hot outside and cool inside. For the first time, this work offers an opportunity to potentially generate 304 watts of usable power from 9 m(2) window at a 20°C temperature gradient. If a natural temperature gradient exists, this can serve as a sustainable energy source for green building technology.

Concepts: Energy, Light, Sun, Renewable energy, Nuclear power, Alternative energy, Sustainable energy, World energy resources and consumption

5

After the Fukushima Daiichi Nuclear Power Plant accident in 2011, Iitate village was placed under an evacuation order because the level of radioactive materials drifting from the nuclear plant to the village were above a government-set level for allowing residents to live in the area. The evacuation advisory for most of the village was lifted on March 31, 2017. For displaced residents deciding whether or not to return to their homes, it is important to correctly understand and estimate the realistic individual external doses they will receive after returning to the village. In this study, with the support of residents of the village, we used to a personal dosimeter (D-Shuttle) coupled with a global positioning system (GPS) device to measure and thus understand realistic individual external doses while the residents were in Iitate village and to project the individual external doses for different administrative districts as of April 1, 2017. The measured individual external doses measured by D-Shuttle for 38 study participants showed that the doses measured during time spent inside the village were higher and more widely distributed compared to the doses measured during time spent outside the village. Exposure ratio (ER) was defined as the ratio of additional individual external dose measured by D-Shuttle to the additional ambient dose based on an airborne monitoring survey. The medians of the average ERs were 0.13 (min-max: 0.06- 0.27) for time spent at home and 0.18 (min-max: 0.08 - 0.36) for time spent outdoors. Projected additional annual individual external doses as of April 1st 2017 for different administrative districts in Iitate were calculated using ERs obtained in this study. Assuming that individuals spent 8 h per day on outdoor activities and 16 h on indoor activities, additional annual individual external doses were estimated to be below 3 mSv using the mean of the average ERs for most districts in the village, and these values were well below the individual external doses estimated using the approach taken by the central government. The results of this study provide valuable information both for understanding realistic radiological situations in the village, and for those who want to know their future individual external dose in order to make a decision on whether or not to live in the village.

Concepts: Nuclear physics, Uranium, Nuclear fission, Nuclear power, Sustainable energy, Spent fuel pool

4

Following the Fukushima nuclear power plant disaster, assessment of internal radiation exposure was indispensable to predict radiation-related health threats to residents of neighboring areas. Although many evaluations of internal radiation in residents living north and west of the crippled Fukushima nuclear power plant are available, there is little information on residents living in areas south of the plant, which were similarly affected by radio-contamination from the disaster. To assess the internal radio-contamination in residents living in affected areas to the south of the plant or who were evacuated into Iwaki city, a whole body counter (WBC) screening program of internal radio-contamination was performed on visitors to the Jyoban hospital in Iwaki city, which experienced less contamination than southern areas adjacent to the nuclear plant. The study included 9,206 volunteer subjects, of whom 6,446 were schoolchildren aged 4-15 years. Measurements began one year after the incident and were carried out over the course of two years. Early in the screening period only two schoolchildren showed Cs-137 levels that were over the detection limit (250 Bq/body), although their Cs-134 levels were below the detection limit (220 Bq/body). Among the 2,760 adults tested, 35 (1.3%) had detectable internal radio-contamination, but only for Cs-137 (range: 250 Bq/body to 859 Bq/body), and not Cs-134. Of these 35 subjects, nearly all (34/35) showed elevated Cs-137 levels only during the first year of the screening. With the exception of potassium 40, no other radionuclides were detected during the screening period. The maximum annual effective dose calculated from the detected Cs-137 levels was 0.029 and 0.028 mSv/year for the schoolchildren and adults, respectively, which is far below the 1 mSv/year limit set by the government of Japan. Although the data for radiation exposure during the most critical first year after the incident are unavailable due to a lack of systemic measurements, the present results suggest that internal radio-contamination levels more than one year after the incident were minimal for residents living south of the crippled Fukushima nuclear plant, and that the annual additional effective doses derived from internal Cs contamination were negligible. Thus, internal radio-contamination of residents living in southern radio-contaminated areas appears to be generally well controlled.

Concepts: Chernobyl disaster, Nuclear fission, Nuclear power, Nuclear safety, Sustainable energy

4

The great east Japan earthquake and subsequent tsunamis caused Fukushima Dai-ichi Nuclear Power Plant (NPP) accident. National Institute of Radiological Sciences (NIRS) developed the external dose estimation system for Fukushima residents. The system is being used in the Fukushima health management survey. The doses can be obtained by superimposing the behavior data of the residents on the dose rate maps. For grasping the doses, 18 evacuation patterns of the residents were assumed by considering the actual evacuation information before using the survey data. The doses of the residents from the deliberate evacuation area were relatively higher than those from the area within 20 km radius. The estimated doses varied from around 1 to 6 mSv for the residents evacuated from the representative places in the deliberate evacuation area. The maximum dose in 18 evacuation patterns was estimated to be 19 mSv.

Concepts: Mathematics, Nuclear physics, Nuclear fission, Japan, Nuclear power, Lists of nuclear disasters and radioactive incidents, Electricity generation, Sustainable energy