核能是我国能源发展的重要组成部分，很多投入运营及在建的核电站都位于沿海区域，一旦发生事故可能导致放射性物质流入海洋，对海洋生物和公众造成放射性影响。目前在核事故下放射性物质海洋扩散的研究中，缺乏对放射源排放、衰变、沉降等多物理过程耦合的放射性物质海洋扩散模型，对环流条件、核素特征等要素对扩散的影响研究不足。海洋中放射性物质对海洋生物及公众的放射性影响的研究也较为缺乏。本文建立了针对放射性物质在海洋中扩散的数值模拟模式，研究了不同模式配置、核素特征、环流条件下对放射性物质在海洋中扩散模拟的影响，建立了海洋中放射性物质对海洋生物、公众的放射性影响分析方法。主要内容如下：（1）建立针对放射性物质海洋扩散的数值模式。本文在环流模式的基础上，开发了放射源排放模块、衰变模块、沉降模块及结果输出模块，建立了放射性物质排放、衰变、沉降等多物理过程耦合的海洋扩散模式，并利用日本福岛核事故案例，对模式进行了验证。（2）放射性物质海洋扩散研究。基于建立的放射性物质海洋扩散模式，研究了不同模式配置、核素特征、环流条件对放射性物质扩散模拟的影响。提出了新定量评价指标比例对数均方根，可以更加合理地定量评价事故状态下模式的模拟结果。（3）核事故下海洋放射性物质的放射性影响研究。建立了海洋生物体内放射性物质浓度的计算方法，结合放射性物质在海水中的浓度研究了其对海洋生物的放射性影响；评估了核事故下海洋放射性物质对公众的内照射影响；建立了放射性物质探测效率的体源-点源转换方法；分析了核事故泄漏到海洋中的放射性物质对人体的放射性影响。（4）我国滨海核电站核事故下放射性物质海洋扩散及放射性影响分析研究。研究了我国附近海域核事故下放射性物质在不同环流条件下的海洋扩散和浓度时空分布，评估了其对海洋生物和公众的放射性影响。本文的研究可为核事故下放射性物质在海洋中扩散的数值模拟研究、放射性影响分析、核事故安全预案制定和应急处置决策提供支持。
Nuclear power will play an important role in the energy structure of China. Lots of Nuclar Power Plants (NPP) of China are or will be located in the coastal area of ocean. If an accident occurs, the radioactive materials discharged from the NPP would have impact on the marine organisms and the public. In order to analyze this influence, it is feasible to numerial simulate the dispersion processes of the radioactive pollutant and acquire the spatial and temporal distribution of its concentration. Most of previous researches did not take the the hybrid processes of radionuclides discharge, decay, scavenging and so forth into consideration. The impacts of circulation condition and radionuclides property on oceanic dispersion are lack of study. In addition, the radioactive impact on the marine organisms or the public is lack of study.In this paper, a numeral simulation model is established to research the dispersion of radioactive materials. The impacts of model configuration, circulation condition and radionuclides property on oceanic dispersion are researched The methods to evaluate the nuclear impact on the marine organisms and the public are established as well. The main research contents are as follows:(1)Establish a model which could simulates the dispersion of radioactive materials in ocean. On the basis of circulation model, develops the source module, decay module, scavenging module and printout module and upgrades the model to be capable of simulating the oceanic dispersion of radioactive materials. The Fukushima accident in Japan is researched. The validation of the model is accomplished.(2)Research the oceanic dispersion of radioactive materials. Analyzes the impacts on dispersion processes of different circumstances including, model configuration, radionuclides property, and circulation condition.Proposes a new criterion, Root Mean Square of Logarithm of Ratio (RMSLR), to quantitatively evaluate the performance of numerical simulation model under accident circumstances. (3) Analyze the radioactive impact on marine organisms and the public. A method to calculate the concentration of radionuclides in marine organisms is established. On the basis of the radionuclides concentration in sea water, the radioactive impact to the marine organisms is studied. The internal exposure impact on the public is assessed.This paper establishes a transformation method to calculate the detection efficiency between spot source and volumn source. The external exposure impact on the public of radioactive material discharged from nuclear accident is researched.(4) On the basis of abovementioned methods, researches a nuclear power plant of China which is located in the coastline of mainland. The oceanic dispersion of radioactive materials under different cicumstances is studied. The radioactive imparts on marine organisms and the public are analyzed.This study could support the researches on the oceanic dispersion of radioactive materials under nuclear accident circumstances; support the formulation of security plan and emergency decision.
