Checking of seismic and tsunami hazard for coastal NPP of Chinese continent after Fukushima nuclear accident

A checking on seismic and tsunami hazard for coastal nuclear power plant (NPP) of Chinese continent has been made after Japanese Fukushima nuclear accident caused by earthquake tsunami. The results of the checking are introduced briefly in this paper,including the evaluations of seismic and tsunami hazard in NPP siting period,checking results on seismic and tsunami hazard. Because Chinese coastal area belongs to the continental shelf and far from the boundary of plate collision,the tsunami hazard is not significant for coastal area of Chinese continent. However,the effect from tsunami still can't be excluded absolutely since calculated result of Manila trench tsunami source although the tsunami wave is lower than water level from storm surge. The research about earthquake tsunami will continue in future. The tsunami warning system and emergency program of NPP will be established based on principle of defense in depth in China.

Impact Analysis of the 2011 Fukushima Nuclear Power Plant Accidents by Running Spectrum Analysis on Newspaper

Huge amount of digital data of the Great East Japan Earthquake is provided by the highly-developed digital data technology. But the method and technique for analysis of these huge digital data are not developed sufficiently. This paper proposes a running spectrum technique for text data and analyzing changes of disaster phase during the disaster management cycle. Impact analysis of the nuclear power plant accidents have been performed by using Fukushima Minpo newspaper for its verification. The result shows the dynamic characteristics of the nuclear power plant accidents. As the time interval B becomes longer, the analysis data is used from wide range period along with the smoothing effect. When observing different time intervals B, fewer keywords have been ranked in the longer time intervals of B. The proposed technique is a powerful tool to effective and efficient disaster response and management. analyze effectively the huge amount of digital data for the

A numerical investigation into the long-term behaviors of Fukushima-derived ^(137)Cs in the ocean

The Fukushima nuclear accident in 2011 released large amounts of radionuclides, including ^（137）Cs, into the Pacific Ocean. A quasi-global ocean radioactive transport model with horizontal grid spacing of 0.5°×0.5° and 21 vertical layers was thereafter established to study the long-term transport of the Fukushima-derived ^（137）Cs in the ocean.The simulation shows that the plume of ^（137）Cs would be rapidly transported eastward alongside the Kuroshio Current and its extensions. Contaminated waters with concentrations lower than 2 Bq/m3 would reach the west coast of North America 4 or 5 years after the accident. The ^（137）Cs tends to be carried, despite its very low concentration, into the Indian and South Pacific Oceans by 2016 via various branches of ocean currents.Meanwhile, the ^（137）Cs concentrations in the western part of the North Pacific Ocean decrease rapidly with time. Up to now the highly contaminated waters have remained in the upper 400 m, showing no evidence of significant penetration to deeper layers.

Monitoring long-term ecological impacts from release of Fukushima radiation water into ocean

After 10 years of the Fukushima Nuclear Accident,Japan decided to release the nuclear wastewater into the Pacific Ocean on 13 April 2021.It is apparent that Japan has chosen the most cost-efficient way to deal with the contaminated water,however,great opposition and concerns have been raised internationally due to the ecotoxicological features of radioactive materials and their harmful impacts on the environment.Here we an-alyze the ecological impacts caused by the nuclear accident and the potential impacts of releasing the nuclear wastewater into the ocean.Science-based solutions are proposed through a third-party evaluation and strict envi-ronmental assessment,multi-stakeholder public participation,integrated monitoring of the neighboring coastal countries,long-term international collaborative research,and setting up international convention for ecological compensation.

Records of Fukushima accident-derived cesium-137 in the Chukchi Sea sediment:Implication for a new time marker?

The Fukushima accident released a large amount of~(137)Cs into the environment.In this study,we used a sediment core collected from the Chukchi Sea during the 2018 Arctic Xuelong Scientific Expedition to investigate the Fukushima accidentderived~(137)Cs.Using~(210)Pb(~(210)Pbex)and~(137)Cs chronology,we find that the~(137)Cs peak at 2 cm corresponds to the year 2011±1.This implies that the Fukushima accident-derived~(137)Cs arrived in the Chukchi Sea much earlier than that by oceanic current transport.Our three calculation results(sediment core deposition flux:(4.0±0.4)×10^(-6)Bq cm^(-2)d^(-1);atmospheric deposition flux:(1.4–2.5)×10^(-5)Bq cm^(-2)d^(-1);biological deposition flux:(4.0±0.9)×10^(-6)Bq cm^(-2)d^(-1))suggest that atmospheric deposition and biological transport could cause such peak records.The results indicate that the 2011 peak of~(137)Cs can serve as a new temporal marker for estimating the sedimentation rate in the region affected by the Fukushima accident.We state that assessing the impact of coastal accidents and subsequent wastewater discharge in marine environments needs more consideration of biological carryover in addition to physical oceanography transport.

Radioactive source terms for the Fukushima nuclear accident

A large amount of radioactivity was released into the environment after the Fukushima nuclear accident （FNA） in Japan in 2011. This radioactivity had a significant impact on the global environment, and there was much public concern about its effects. The subsequent assessment of the FNA and the environmental remediation required are proving to be long and complicated tasks. The assessments are based on the radioactive source terms for the FNA, which determine the level of damage caused by the nuclear accident. We investigated the radioactive source terms from three aspects： the amount and composition of the radionuclides; the activity and atomic ratio of the radionuclides; and comparison with other historical events. The total amount of radioactivity, excluding the radioactive noble gases （85Kr and 133Xe）, released by the FNA was about 10% of that released by the Chernobyl nuclear accident in 1986 and 〈1%o of the global fallout from the atmosphere nuclear explosion. However, the FNA was the most serious nuclear accident in terms of radioactive pollution of the marine environment. The recovery actions carried out after the FNA have been evaluated and the environmental impacts of the FNA are discussed.

The comparison of ensemble or deterministic dispersion modeling on global dispersion during Fukushima Dai-ichi nuclear accident

Ensemble forcasting,originally developed for weather prediction,is lately being extended to atmospheric dispersion applications,which is a new,effective methodology for improving the atmospheric dispersion numerical modeling.In March 2011,due to the massive 9.0 earthquakes and ensuing tsunami that struck off the northern coast of the island of Honshu,the Fukushima Nuclear Plant I had the substantial leak of radioactive materials into surrounding environment and atmosphere.To aim at the global dispersion modeling of atmospheric radionuclides from Fukushima Nuclear Accident,this paper presents two approaches of atmospheric dispersion forecasting:ensemble dispersion modeling(EDM) and deterministic dispersion modeling(DDM),conducts the globally dispersion modeling cases for Fukushima nuclear accident,and analyzes and evaluates the simulation results using observation data.In this paper,EDM includes three different perturbation methods:meteorological perturbation method,turbulence perturbation method,and physical parameterization ensemble forecasting method.The simulation results show that the trajectories from EDM have a better performance,which is in better agreement with the atmospheric circulation and observation data; the spread from DDM is slower and not as far as EDM.Additionally,the results from EDM display a better performance in the modeling of transport from Japan to China East Sea on April 4.The reasons for these results are:the techniques of MET and TUR are performed by adding perturbations on mean wind and turbulent velocity,respectively; the various different flow fields will result in far spreading in horizontal and the simulation results closer to observation; PHY is performed by using different diffusion physical parameterizations and produces the perturbations on vertical wind,which results the spreading in smaller range and discontinuous in horizontal.Finally,the comparative analysis between modeling results and observation data shows that all cases results are in good agreement with trends of observed radionuclides surface concentration; however,the modeling surface concentration is smaller than observation,especially in DDM and PHY.Furthermore,the EDM results show that MET and TUR are of more evolutionary advantage than PHY in modeling of average and maximum concentration.Therefore,this study can serve as a reference to atmospheric dispersion and environmental emergency response(EER).

Study on Sampling Technique of Atmospheric Radionuclide

Atmospheric radionuclide monitoring usually includes two sampling techniques, namely ultra-high volume aerosol samplers to collect at- mospheric particles by using filter media, and radioactive noble gas samplers to collect atmospheric noble gas based on adsorption method. Atmos- pheric sampling techniques have been researched in Northwest Institute of Nuclear Technology since the Comprehensive Nuclear-Test-Ban Treaty （CTBT） was signed in 1996. Several ultra-high volume aerosol samplers and some types of radioactive xenon isotopes samplers had been devel- oped. For the aerosol sampler, the sampling flow is between 450 and 800 m3/h, with the minimum detectable concentration （MDC） of 131I less than 5 pBq/m3. For the xenon sampler, the sampling capacity of xenon is more than 4 ml per day, with MDC of l=Xe less than 0.25 mBq/m3. After the nuclear accident of Fukushima in 2011, monitoring of the atmospheric radionuclide was carried out for 3 months at Xi＇an, and part of radionuclide was detected with concentrations hiaher than their backorounds in the period, includina 131I.134Cs. 137Cs and 133Xe.

Advance on monitoring of radioactivity in food in China and Japan after Fukushima nuclear accident

After the nuclear accident at the Fukushima Daiichi Nuclear Power Plant(Fukushima nuclear accident)in 2011,Japan quickly took emergency measures to reduce radiation hazards posed by the released radioactive materials.As a neighboring country of Japan across the East China Sea,China has also taken some corresponding prevention and control measures.China has continuously strengthened the monitoring of radioactivity in food in recent years.This paper discusses the revision of standards for radioactivity in food,the improvement of methods and equipment,and the updating of monitoring systems performed in China and Japan over the last ten years after the Fukushima Daiichi accident.In addition,this paper outlines the recent problems left over from the nuclear accident,puts forward some views on the progress of important topics,and gives some thoughts and prospects on the further improvement of the monitoring systems of radioactivity in food in China.

Cesium removal from radioactive wastewater by adsorption and membrane technology

Radiocesium is frequently present in radioactive wastewater,while its removal is still a challenge due to its small hydrated radius,high diffusion coefficient,and similar chemical behavior to other alkali metal elements with high background concentrations.This review summarized and analyzed the recent advances in the removal of Cs+from aqueous solutions,with a particular focus on adsorption and membrane separation methods.Various inorganic,organic,and biological adsorbents have undergone assessments to determine their efficacy in the removal of cesium ions.Additionally,membrane-based separation techniques,including reverse osmosis,forward osmosis,and membrane distillation,have also shown promise in effectively separating cesium ions from radioactive wastewater.Additionally,this review summarized the main approaches,including Kurion/SARRY system+desalination system and advanced liquid processing system,implemented after the Fukushima Daiichi nuclear power plant accident in Japan to remove radionuclides from contaminated water.Adsorption technology and membrane separation technology play a vital role in treatment of contaminated water.

Risk communication in the post-Fukushima era

In the long-term phases,clear risk communication in the post-Fukushima era is necessary and significant.It is the most urgent in this post-accident phase is for residents to access to all the information available within the scope of current knowledge in order to support their life decisions.For full recovery,authorities,specialists,international organizations,media,and the public will need to work together.The speed of innovation in risk communication should catch up to the development speed of the internet.Long-term communication will be necessary.Learning about the Fukushima nuclear accident experience is essential for the prevention and risk communication of possible accidents in the future.