同位素稀释-α能谱法测定水中微量铀及~(234)U/~(238)U比值

DETERMINATION OF THE URANIUM CONTENT AND 234U/238U ISOTOPE RATIO IN NATURAL WATER BY ISOTOPE DILUTION ALPHA SPECTROMETRY.

摘要: <正> 测定了铀、钍、镤和铁于不同介质中在CL-5209萃淋树脂上的分配系数,拟定出分离这些元素的方法,建立起同位素稀释-α能谱同时测定水样中微量铀和~(234)U/~(238)U比值的新方法。水样用硝酸酸化至pH～1,加入~(232)U示踪剂后,放置过夜,让铀同位素交换达到平衡。加入三氯化铁溶液,煮沸15分钟。加氨水至pH～8,使铀和氢氧化铁共沉淀。澄清后过滤。

Abstract: Separation of the uranium from Th, Pa, Fe and other elements by extraction chroma-tography is studied. A method is proposed for measuring uranium content and 234U/238U isotope ratio in natural water by Isotope Dilution Alpha Spectrometry (IDAS). Uranium is coprecipitated with Fe(OH)3 by NH4OH. The precipitate is dissolved in 2N HNO3 and the solution is passed through a column packed with CL-5209 Levextrel resin. Rinse the column with 1N HNO3 solution to strip iron, 4N HC1 solution to extract thorium, 4N HC1 +0.06N HF solution to extract protactinium. Uranium is then eluted by 0.3M (NH4)2C2O4 solution. After electroplating on a nickel disc, the uranium is determined by α-spectrometry. The precision of the determinations is≥±5 % for ppb level of U.