Radiation Dose Assessment Methodologies For Non-human Species Studied

This study is aimed to adapt the demands and tendencies of the development of protection of environment in world and protection of the non-human species in nuclear environment in China. Also, it gives a necessary assessment methodology and technique for beginning and developing on the respect scientific research works. The works provide the tools for radiation dose assessment of real cases and the bases to future theoretic research. In this thesis, compared the methods of GRADED with the methods of FASSET for assessment of non-human species radiation dose rats and radiation effect, reviews and researches have been carried out step by step. Based on the results, it is also put forward the works and the difficulties we should be done in China recently. The results are: That we should build our own application methodology at based on such ways as EU's FASSET and DOE's GRADED. We can use the GRADED methods when we aim at the large area environment assessment and protection, that just one thing we need to do is to add the data set of biological concentration guide (BCGs) of China. We can use the methods of FASSET when we aimed at the assessment of the special species or species cluster, only by using completed some relativity data set of China. Considering about the practicability, effectiveness, flexibility and feasibility, the important contents in methodology and approaches in China are: 1) Building some special dose models of special species only in China, put forward the relatively dose models and geometric model of these species based on the reference spices recommended by ICRP and FASSET. 2) Because the nuclear sites in our country have different geographical and meteorological characteristics. The thing we need to do is assemble the data set of composition of nuclides, concentration and the pathways of transformation of the nuclides. 3) Detailed research works must be done about the life condition of species that may be in the risk. We also ought to investigate the information in some nuclear sites, such as nuclides distribution in the site area, the diffusion pathways of nuclides, the characteristics of environment transformation and the biological enrichment. 4)In FASSET models, because the uniform disposition of nuclides in non-human species body is used, the nuclides concentrations in species body is different in different organs in the real case, so that, the DPUC must be different and we must analyze and correct it when we use it to assess the radiation dose of a special species. 5) For some special species, we must take into account the weight factor in radiation effect assessment. Based on the general analysis and description, in the thesis, detailed analysis was made about some key problems must be done in assessing the radiation dose and its effect in each link, according to the different characteristics of different geography case, and the practical condition of our country. Based on the main achievements in non-human radiation protection area made by international agency and organization, the basic problems of China faced in the related works are considered. A basic methodology being built can be used for non-human species radiation dose assessment. The methods can be used to assess the radiation dose rate of species in real nuclear sites; the dose rate can be calculated by nuclides and exposure pathways. Considering the recent achievement and tendency of this area, consulted about the approaches and methods of radiation dose assessment in international. In this thesis works, the lumped parameter (LP) of GRADED and the DPUC of EU's have been used in dose assessment. On the actual cases of our country, we choose the 404 plant 3# evaporation pool as a research object, based on its recent data set, some works of data analysis and data assemble have being done. On those bases, added with some necessary codes, radiation dose rate of some species living in the site was calculated. Two calculated methods are used in species radiation dose assessment of 404 3# evaporation pool, including the GRADED method was developed by the USA (DOE), and the FASSET method was developed by EU. The result by using the GRADED general classic method is: to the land animals and plants, all the nuclides concentrations are below on the limit values. ⁹⁰Sr in water is 22 times over the guide values (BCGs); to the coastal animals, All the data ⁹⁰Sr and ¹³⁷Cs in water and ⁹⁰Sr, ¹³⁷Cs and ²³⁹Pu in sediment are over the guide limits, the case of ⁹⁰Sr and ¹³⁷Cs is higher more, in those data, ²³⁹Pu is near the guide limit. Considering contribution all of the nuclides in the case of this study, the radiation dose of non-human species rank as: coastal animals are affected by aquatic pathways, coastal animals are affected by sediment pathways. By using the second level GRADED assessment, we have the result of three groups of species to all nuclides of their pathways is: 1) ⁹⁰Sr in water to coastal animals; 2) ⁹⁰Sr in sediment to coastal animals; 3) ¹³⁷Cs in water to coastal animals; 4) ¹³⁷Cs in water to aquatic animals; 5)⁹⁰Sr in sediment to aquatic animals, The new released code of GRADED "RESRED-BIOTA1.0" has the ability to calculate the dose rate of special species in confirmed site. In the theme works, we take an aquatic bird Tadorna Ferruginea as an assessment object, calculated its radiation dose rate with GRADED three levels classic method. The result shows that: To all the pathways, the radiation dose rate of Tadorna Ferruginea in the site can be ranked on nuclides as: ⁹⁰Sr, 0.36Gy/d; ¹³⁷Cs, 0.18Gy/d; ²³⁸U, 0.0013Gy/d. The total radiation dose rate of Tadorna Ferruginea of all pathways is 0.54Gy/d. In this theme work, at the same time, the radiation dose of the special species in 404 plant evaporation pool is assessed with the methods of FASSET, the result giving on different species, different pathways and different nuclides. The assessment results are: the nuclides in soil are all not over the guide limits. The nuclides in 404 plant evaporation pool 3# affected the species live in can be ranked as: ⁹⁰Sr, ¹³⁷Cs, ⁶⁰Co, ²³⁸U, ²³⁵U, ¹³⁴Cs, and ²³⁹Pu. Within it, the radiation dose rates of ⁹⁰Sr to grubs of dragonfly, bulrushes and Tadorna Ferruginea are 3-6 times large than the guide limit value. Radiation dose rate of species made by radioactive materials can be ranked in nuclides: ⁹⁰Sr, ²³⁸U, ¹³⁷Cs, ²³⁹Pu, ²³⁵U, and ⁶⁰Co. The values of ⁹⁰Sr in them are 23-24 times large than the guide limits. The radiation affection of non-human species in the site can be ranked by pathways: coastal animals by nuclides in water, coastal animals by sediment and aquatic animals by aquatic. In addition, the concepts total amount of radioactive nuclides controlling is supposed in the thesis, beside the guide limit of every nuclides, it also puts forward to the real approach and method about the reference limit values. A simple anatomic model of bird was built, the result of simulation indicate that the energy absorbed fraction with anatomic model in low energy is high than with whole body model, that means the difference must be considered in the case of relative low Gamma radiation. As an innovation point of this study is: 1) The methodologies of the GRADED and the FASSET were compared. In the FASSET method, the mean of nuclides concentration of whole body is the basis of dose rate calculation, in the real case, the data that we usually obtained is nuclides concentration of organ of biota. This difficult was solved by means of weighted on the weight of organs. 2)As a real case of the study, it aims at the non-human species have been protected, it is the first that try to assessment and analysis the radiation dose for non-human species in terrestrial ecosystems in China. 3) According to the real biological data set, a simple anatomic model of bird was developed. If we supposed the nuclides in the bird body is equilibrium dynamically, to the case that nuclides lumped in liver of the bird uniformly, a Monte-Carlo simulation was used in energy absorbed fraction calculation. The results with whole body model and with anatomic model were compared, then, based on analysis of the key problem and technique in its application, some advisements for solving these problems and the future research works were recommended. DPUC was calculated in this study, then, it was reviewed and analyzed, it also compared with the value that was provided by whole body model.