A Novel Method for the measurement of 90Sr Using Thermal Ionization Mass Spectrometer

90Sr (t1/2 = 28.8 y) is one of the most common and hazardous fission products released by a nuclear reactor accident. Due to its chemical similarity to calcium, accumulates in bones and irradiates bone marrow, causing high radio-toxicity. Therefore, to assess 90Sr is important in case of a nuclear disaster. Measurement of 90Sr using radiometric methods is a time consuming process since it involves a complex sample preparation and analytical separation required to produce reliable dataThermal ionization mass spectrometry (TIMS) is the technique of choice because of its inherent high precision and accurate measurement of isotopic ratio. Typical abundance sensitivity for strontium isotope ratio measurement with conventional TIMS is about 10-7. By the use of a special lense like the WARP filter for TIMS, an upper limit of 1.0 x 10-10 was achieved. A new 90Sr analysis method was developed using the Isotopx Ltd., Phoenix X62 TIMS. The abundance sensitivity for the 90Sr/88Sr ratio was 2.1×10 10 and this could ensure detection limit of 100 Bq·kg 1 (19 fg·g 1) 90Sr in Fukushima soil samples. The method has been validated using two certified reference materials e.g. wild berry (IRMM-426) and freshwater lake sediment (NIST-4354). This mass spectrometry method is faster than conventional radiometric techniques.第17回同位体科学研究