title: Ultra-trace analysis of plutonium by thermal ionization mass spectrometry with a continuous heating technique without chemical separation.
abstract: Thermal ionization mass spectrometry (TIMS) with a continuous heating technique is known as an effective method for measuring the isotope ratio in trace amounts of uranium. In this study, the analytical performance of thermal ionization mass spectrometry with a continuous heating technique was investigated using a standard plutonium solution (SRM 947). The influence of the heating rate of the evaporation filament on the precision and accuracy of the isotope ratios was examined using a plutonium solution sample at the fg level. Changing the heating rate of the evaporation filament on samples ranging from 0.1fg to 1000fg revealed that the influence of the heating rate on the precision and accuracy of the isotope ratios was slight around the heating rate range of 100-250mA/min. All of the isotope ratios of plutonium (SRM 947), (238)Pu/(239)Pu, (240)Pu/(239)Pu, (241)Pu/(239)Pu and (242)Pu/(239)Pu, were measured down to sample amounts of 70fg. The ratio of (240)Pu/(239)Pu was measured down to a sample amount of 0.1fg, which corresponds to a PuO2 particle with a diameter of 0.2μm. Moreover, the signals of (239)Pu could be detected with a sample amount of 0.03fg, which corresponds to the detection limit of (239)Pu of 0.006fg as estimated by the 3-sigma criterion. (238)Pu and (238)U were clearly distinguished owing to the difference in the evaporation temperature between (238)Pu and (238)U. In addition, (241)Pu and (241)Am formed by the decay of (241)Pu can be discriminated owing to the difference in the evaporation temperature. As a result, the ratios of (238)Pu/(239)Pu and (241)Pu/(239)Pu as well as (240)Pu/(239)Pu and (242)Pu/(239)Pu in plutonium samples could be measured by TIMS with a continuous heating technique and without any chemical separation processes.
authors.affiliation: Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, Republic of Korea. Electronic address: cglee@kaeri.re.kr.
authors.forename: Chi-Gyu
authors.initials: CG
authors.lastname: Lee
authors.affiliation: Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Suzuki
authors.affiliation: Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Japan.
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Esaka
authors.affiliation: Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Magara
authors.affiliation: Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, Republic of Korea.
authors.forename: Kyuseok
authors.initials: K
authors.lastname: Song
keywords: Continuous heating method; Isotope ratios: Ultra-trace amounts of sample; Plutonium; TIMS