| 90Sr, one of isotopes of strontium, which is the fission products of 233U and 239Pu, is the most important long-lived radionuclide with high-energyβ-rays. It has high fission yield and long physical half-life and biological half-life. In the Environment, the sources of 90Sr include fallout of nuclear explosion, the release of nuclear accidents and the discharge in the section of the nuclear fuel cycle facilities. As the chemical characteristics of strontium are very similar with calcium,90Sr deposits mainly in the bones and teeth of animals who consumed contaminated food with strontium indicating bone marrow and hematopoietic tissue are the potential targets of radioactive strontium. In addition, radioactive sources have been applied more widely in industry, agriculture, medical treatment and other areas of the national economy, while the 90Sr/90Y is one of the commonly radioactive sources and is relatively easy to obtain, and therefore the terrorist attacks of nuclear radiation may be caused.Since the high toxicity, high radioactivity of 90Sr, to protect the public health, the environment and to fit the needs of radiation hygiene and nuclear radiation emergency, it is necessary to establish a rapid analysis method for detecting low-level 90Sr in environmental and biological samples.This thesis presents an overview of radiochemical analyses method for assessing low-level 90Sr in environmental and biological samples. The preparation method of crown ether-4',4"(5")-di-tert-butyldicyclo-hexano-18-crown-6(BtBuCH18C6) chromatography powder with good affinity of strontium was investigated. Finally the rapid method for separating 90Sr from different samples by using chromatography crown ether extraction is established.1. Investigating the conditions of crown ether solvent extraction to separate strontium.Three kinds of crown ethers,18C6, DCH18C6, DtBuCH18C6 were used. The effects of appropriates and concentrations of crown ethers, solvents, and the acidity of aqueous phase on the separation of strontium were evaluated. To determine an appropriate stripping agent the impacts of various stripping agents were studied.2.Optimizing to prepare the crown ether chromatography powder and to separate strontium from samples by using crown ether extraction chromatography column.The effects of the support, the stationary phase and the preparation method of crown ether chromatography powder were studied to determine the optimal preparation condition and method for preparing the crown ether chromatography column. The optimal conditions of the crown extraction chromatography column for strontium separation and the decontamination of the interfering elements were investigated.3. Appling the crown ether extraction chromatography method to analyse the 90Sr of the actual samples.A rapid analysis method for detecting 90Sr in the environmental and biological samples by crown ether extraction chromatography was established. The detection limit was 0.01Bq/g. The actual samples were used to evaluate this method. The results indicated this new method is identical with the national standard recommended methods. The new method took much less time than the standard method and the results can be obtained in 12 hours, while the standard method requires at least 3 days.4. Evaluate the uncertainty of the rapid analysis results of the determination of 90Sr by the crown ether extraction chromatography method. |
PDF Full Text Request