PREPARATION AND DISTRIBUTION OF ENVIRONMENTAL STANDARD SAMPLES FOR URANIUM AND PLUTONIUM

为了制备铀和钚的环境标准样品，在日本的几个地点收集了土壤和地衣。为了使样品长期稳定，这些样品被干燥并进行适当的伽马射线照射。采用电感耦合等离子体质谱法（icp-ms）、热电离体质谱法（tims）和α射线谱法测定样品中铀的同位素比值。测量前，采用液液微萃取系统对铀进行浓缩。该设备由三个简单的萃取池组成，用于相混合、相分离和溶剂收集。从溶剂萃取到制备，金属分离只需一分钟即可完成。该方法的提取率与传统方法相当，可实现快速分离。为了检查我们的同位素数据的准确性，一些样品被送到其他研究方，并进行交叉检查。同位素比值与我们的值吻合较好。这些样品可作为日本铀同位素比背景的标准样品。

FOR THE PREPARATION OF ENVIRONMENTAL STANDARD SAMPLES OF URANIUM AND PLUTONIUM, THE SOIL AND THE LICHEN WERE COLLECTED AT THE SEVERAL POINTS IN JAPAN. IN ORDER TO KEEP SAMPLES STABLE FOR LONG TERM, THESE WERE DRIED AND GAMMA-RAY IRRADIATED APPROPRIATELY. THE ISOTOPIC RATIO OF URANIUM IN THE SAMPLE WAS MEASURED BY ICP-MS (INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY), TIMS(THERMAL IONIZATION MASS SPECTROMETRY) AND ALPHA-RAY SPECTROMETRY. BEFORE THE MEASUREMENT, THE URANIUM WAS CONCENTRATED BY LIQUID-LIQUID MICROEXTRACTION SYSTEM. THE EQUIPMENT IS COMPOSED OF THREE SIMPLE EXTRACTION CELLS FOR PHASE MIXING, PHASE SEPARATION, AND COLLECTION OF A SOLVENT. METAL SEPARATION CAN BE COMPLETED IN A SINGLE OPERATION LASTING ONLY A MINUTE, FROM SOLVENT EXTRACTION TO PREPARATION. THE EXTRACTABILITY IN THE LMES WAS COMPARABLE TO THAT OF TRADITIONAL METHODS, AND THE DEVELOPED METHOD WAS FEASIBLE FOR RAPID SEPARATION. IN ORDER TO CHECK THE PRECISION OF OUR ISOTOPIC DATA, SOME SAMPLES WERE SENT TO THE OTHER RESEARCH PARTIES, AND WERE CROSS-CHECKED. THE ISOTOPE RATIOS WERE GOOD AGREEMENT WITH OUR VALUES. THESE SAMPLES CAN BE APPLIED TO THE STANDARD SAMPLES AS THE BACKGROUND OF URANIUM ISOTOPE RATIO IN JAPAN.