Internal radiocesium contamination of adults and children in Fukushima 7 to 20 months after the Fukushima NPP accident as measured by extensive whole-body-counter surveys

The Fukushima Dai-ichi NPP accident contaminated the soil of densely-populated regions in Fukushima Prefecture with radioactive cesium, which poses significant risks of internal and external exposure to the residents. If we apply the knowledge of post-Chernobyl accident studies, internal exposures in excess of a few mSv/y would be expected to be frequent in Fukushima.Extensive whole-body-counter surveys (n = 32,811) carried out at the Hirata Central Hospital between October, 2011 and November, 2012, however show that the internal exposure levels of residents are much lower than estimated. In particular, the first sampling-bias-free assessment of the internal exposure of children in the town of Miharu, Fukushima, shows that the ¹³⁷Cs body burdens of all children (n = 1,383, ages 6–15, covering 95% of children enrolled in town-operated schools) were below the detection limit of 300 Bq/body in the fall of 2012. These results are not conclusive for the prefecture as a whole, but are consistent with results obtained from other municipalities in the prefecture, and with prefectural data.     

Estimation of the total population moving into and out of the 20 km evacuation zone during the Fukushima NPP accident as calculated using “Auto-GPS” mobile phone data

The first objective data showing the geographical locations of people in Fukushima after the Fukushima Dai-ichi nuclear power plant accident, obtained by an analysis of GPS (Global Positioning System)-enabled mobile phone logs, are presented. The method of estimation is explained, and the flow of people into and out of the 20 km evacuation zone during the accident is visualized.     

Discovery of radioactive silver (110mAg) in spiders and other fauna in the terrestrial environment after the meltdown of Fukushima Dai-ichi nuclear power plant

Six months after the explosion of TEPCO’s Fukushima Dai-ichi nuclear power plant, radioactive silver (^110mAg), was detected in concentrations of 3754 Bq/kg in Nephila clavata (the orb-web spider; Joro-gumo in Japanese) collected at Nimaibashi, Iitate village in Fukushima Prefecture, whereas ^110mAg in the soil was 43.1 Bq/kg. A survey of 35 faunal species in the terrestrial environment during the 3.5 years after the accident showed that most of Anthropoda had two orders higher ^110mAg in their tissues than soils, although silver is not an essential element for their life. However, tracing of the activity of ^110mAg detected in spider Atypus karschi collected regularly at a fixed location showed that it declined much faster than the physical half-life. These results suggest that ^110mAg was at once biologically concentrated by faunal species, especially Arthropoda, through food chain. The factors affecting the subsequent rapid decline of ^110mAg concentration in faunal species are discussed.     

Numerical analysis of buoyant flow in a hemispherical enclosure at high Rayleigh numbers

A numerical analysis is presented for buoyancy driven flow of a Newtonian fluid contained in a two dimensional (R, ) hemispherical enclosure for high Rayleigh (Ra) numbers. It is assumed that the flow is driven by the uniformly distributed internal heat sources within the enclosure. All walls of the cavity are maintained at a constant temperature. Finite volume based SIMPLER algorithm has been used for the present analysis. Discretised governing equations, in primitive variables, are solved by a combination of Three Diagonal Matrix Algorithm (TDMA) and Point Successive Overrelaxation (PSOR) method. A benchmark solution prepared for a Ra number range of 10⁷ to 10¹² and Prandtl (Pr) number 7.0, shows an excellent agreement with the experimental results obtained from the open literature.     

Direct alpha spectrometry for characterising hot particle properties

Non-destructive analysis methods, especially direct alpha spectrometry but also gamma ray spectrometry and scanning electron microscopy were applied to a nuclear bomb particle from the Thule accident. The use of high-resolution direct alpha spectrometry with the aid of Monte Carlo simulations was demonstrated here in order to determine the properties of this particle. In general, the information that can be obtained through direct alpha spectrometry depends on the information available a priori. For example, known elemental composition makes the assessment of particle dimensions possible even if scanning electron microscopy images are unavailable. Although direct alpha spectrometry may be applied for particle characterisation, further developments in spectrum analysis tools are necessary.     

从“福岛第一核电站事故”看我国核能利用的核安全

文章简要说明了福岛第一核电站事故的起因、发展和后果,并对核电站全厂断电、反应堆压力容器及安全壳超压、氢爆等导致事故恶化的原因作了分析.文章还就导致福岛核事故的相关因素与我国核电站的安全设计及防范对策进行了分析比较.在吸取福岛核事故的经验教训方面,文章提出了若干值得引发关注的启示,作为我国在建和在役核电站的改进,以及新设计核电站的参考.文章还就我国能源的状况,核能发展的必要性,以及核能发展的方针进行了探讨.     

Fissile radionuclides in thyroid of the inhabitants of the gomel region in belarus and peculiarities of their distribution

Severe radiation damages with the following substitution of connective tissue are the effect of high doses in microvolumes of the thyroid. Calcium, strontium and uranium deposited into these sections was more as compared to a normal tissue of the thyroid. An estimation of the microdistribution of fissile radionuclides was carried out using the method of fragmental radiography. The analysis of tracks done visually using a microscope magnification of 300 revealed the local density of fission fragments up to 10³ mm⁻². The irradiation of the surrounded cells which contain the hidden genetic damages, initiated by radioiodine, does not exclude their possible promoter role in thyroid cancerogenesis.     

次临界能源包层严重事故缓解系统

针对中国工程物理研究院混合堆次临界能源包层,提出了一种新型的严重事故缓解系统——工程通道注水系统,采用通道注水的方法直接导出燃料区衰变热,同时与非能动安全壳冷却系统结合,实现燃料区非能动长期冷却的建立,阻止燃料区熔化进程发展,保证次临界能源包层的完整性。在保守假设条件下,当燃料区温度达到1220℃时,工程通道注水系统投入运行即可完成严重事故缓解功能。     

基于车联网的事故公共紧急救援呼叫现状及关键技术分析

介绍了欧洲、美国、俄罗斯等地区和国家车辆事故公共紧急救援呼叫的现状,对基于车联网的车辆事故公共紧急救援呼叫中牵涉到的技术指标、通信技术及汽车电子技术进行分析,并介绍了下一代车辆事故紧急救援呼叫发展趋势.最后结合国内现状,对未来国内开展车辆事故紧急救援呼叫进行建议.     

Application of SSNTDs to investigations of radiation accident after-effects

Track methods and devices used for studies conducted after radiation accidents are considered. Solid State Nuclear Track Detectors (SSNTDs) are applied for measurements of contamination in soil, water, biological and other objects of alpha-emitting radionuclides, as well as for estimation of neutron doses by means accident dosimeters. Known radiation accidents (Chernobyl a.o.) and potential emergencies (sunken submarine “Komsomolets”, nuclear reactors) are discussed. Some result of SSNTD application at after-accident period are presented.