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ThO2 can produce many nuclides after accelerator bombardment, such as Actinium-225, Radium-223, Molybdenum-99, Iodine-131, Strontium-90, etc. There are many methods for measuring heavy elements such as thorium, but most of them are complicated to operate. Spectrophotometry has the advantages of simple sample preparation and low operation difficulty, and can be used as a quantitative analysis method for thorium and other heavy elements. ThO2 was dissolved with nitric acid and hydrogen fluoride, and the concentration of Th(IV) in ThO2 solution was quantitatively analyzed with Arsenazo III as the chromogenic agent. Under the environment of 2 mol/L hydrochloric acid solution and 0.1 g/L Arsenazo III solution, the coordination ratio of Arsenazo III and Th(IV) is 5 : 2 under the experimental conditions. The maximum absorption wavelength before and after color development is 534.0 nm and 663.2 nm, respectively, and the contrast is 129.2 nm. The method in 0.2-5.0 mg/L is in accordance with Lambert-Beer’s law, the standard curve equation y＝0.06641x+0.00176, R2＝0.99981. The molar absorption coefficient of 1.64×104. Method detection limit is 0.31 μg/L, and quantitative limit is 0.97 μg/L. The method is stable within 4 h. The recovery is 97.33%-104.03%, and the largest standard deviation is 0.32%. The method was compared with GB/T 12690.12-2003, the process was simplified and the results were basically consistent.

Lead-bismuth eutectic (LBE) has excellent physical and chemical properties, it is the coolants of the fourth generation of preferred lead-bismuth reactor and accelerator driven sub-critical system (ADS). Under neutron irradiation condition, LBE produces a large amount of 210Po, which is an important radioactive material and has important applications in industry, agriculture, aerospace and other fields. 210Po in LBE can be extracted by high temperature distillation technology, in the process， corrosion behavior of distillation crucible is very important. In this paper, the static corrosion test was carried out on 316L stainless steel, molybdenum, tungsten metal materials, quartz, alumina, zirconia, ceramic oxide materials and graphite material crucibles at 1 000 ℃ and 5 000 Pa, the quality changes of the candidate materials before and after the test were obtained. After the test, the results were got that the impurity content of LBE introduced by candidate crucibles of different materials, the morphology changes of the inner and outer surfaces of the crucibles in addition the surfaces of LBE, the metallographic appearance of the interface between the alumina crucible and LBE. The results show that the graphite crucible is unstable due to the large change of corrosion and carbonization quality. The 316L stainless steel, molybdenum and tungsten crucibles are unstable due to the large changes in corrosion quality. The quality of crucibles made of quartz, alumina, zirconia and molybdenum materials changes little and is stable at high temperature. 316L stainless steel, quartz, ceramic and graphite crucibles introduce 49.74 ppm impurities into LBE due to complex components and corrosion, which is relatively large. The high purity of alumina, zirconia, molybdenum and tungsten crucibles introduced in LBE impurity content is less than 31 ppm, which is small. The inner and outer surfaces of 316L stainless steel, molybdenum and tungsten crucibles are seriously corroded and lose metallic luster. The outer surface of graphite crucible is rough and porous, the inner surface is smooth without change. The crucible made of quartz material is cracked by slightly knocking, the outer surface is attached with gray material that is hard to be erased. The inner surface is smooth and clean without change. Part of the outer surface of the ceramic crucible turns brownish red, and the rest remained is unchanges. After the test, the inner and outer surfaces of alumina and zirconia crucibles are smooth without corrosion. The metallographic interface between alumina crucible and LBE is clean without corrosion. To sum up, the alumina crucible has good corrosion resistance to LBE, low price, it is suitable for use as a 210Po distillation crucible for LBE high-temperature distillation.