"Multi-Dynamic" Isotope Ratio Measurements for Uranium and Plutonium using the "Multiple Ion Counting" Detection System of the TRITON TIMS at IRMM

A "Multiple Ion Counting" (MIC) detection system installed into a thermal ionization mass spectrometer (TIMS) allows the simultaneous detection of up to seven small ion beams with currents of 10-19 - 10-14 Ampere in ion counting mode, corresponding to count rates of 1-60.000 cps (counts per second). In order to circumvent complicated inter-calibration routines for the given set of 7 ion counters the principle of multi-dynamic measurements was implemented in combination with the "Multiple Ion Counting" (MIC) system. The multi-dynamic measurement procedure was applied to diluted samples of isotope reference materials for uranium and plutonium with concentrations at the ppb and the ppt level, respectively. The results for uranium measurements on samples IRMM-186 and NBL-U500 clearly show an improved precision by a factor of ca. 3 for the multi-dynamic measurement procedure compared to measurements carried out using one single ion counter in peak-jumping mode. When using the "Multiple Ion Counting" (MIC) system, the multi-dynamic procedure is also superior compared to the static total evaporation technique, as demonstrated by plutonium measurements on samples of NBL-CRM137. As a conclusion, the multi-dynamic procedures provide improved precision and accuracy compared to previous TIMS measurement techniques. The multi-dynamic measurement technique in combination with the "Multiple Ion Counting" (MIC) system of the TRITON TIMS is suitable for the isotopic analysis on low-level uranium and plutonium samples as well as single uranium or plutonium oxide particles for nuclear safeguards purposes, and will be applied also for the verification analysis of reference particles made of UF6 as produced by IRMM.

RICHTER Stephan;  JAKOPIC Rozle;  BENEDIK Ljudmila;  STOLARZ Anna;  KIPS Ruth;  WELLUM Roger; 

2007-11-08

Office for Official Publications of the European Communities (OPOCE)

JRC41170

https://publications.jrc.ec.europa.eu/repository/handle/JRC41170,