MEASUREMENT OF SI-30 AS A TRACER BY NEUTRON-INDUCED PROMPT GAMMA-RAY ANALYSIS

The application of stable isotope analysis using neutron-induced promp t gamma-ray analysis (PGA) with cold/thermal neutron beams for the tra cer study of geological materials are discussed. Silicon has three nat ural isotopes differing in abundance: Si-28 (92.23%), Si-29 (4.67%) an d Si-30 (3.10%). For the purpose of the assessment of Si migration in engineered barrier material, enriched Si-30 can be used as a tracer du e to if. nuclear and chemical properties. Isotope analysis of Si-30 wa s performed by PGA during the tracer study. Neutron intensity at the s ample position was 1.4.10(8) n.cm(-2).s(-1), 2.4.10(7) n.cm(-2).s(-1) for cold and thermal neutron guided beams of JRR-3M, respectively. Cal ibration curves and analytical sensitivity of Si-30 were determined ba sed on measurement of standard samples. BG and detection limits for Si -30 analysis were also measured in Japanese bentonite (Kunigel V1 and Kunipia F) and their pore water. Fifteen elements were determined simu ltaneously using PGA.