236U identification in the new AMS beamline at the TANDAR accelerator

Abstract

236U (T1/2 = 23 My) is an excellent monitor for nuclear contamination in the environment. Indeed, spent nuclear fuels present isotopic ratios 236U/238U several orders of magnitude higher than natural samples. 236U also provides a useful fingerprint to identify and trace nuclear material for safeguards purposes. Here we describe a new beamline for the discrimination of 236U using the accelerator mass spectrometry (AMS) technique. This system comprises a Wien velocity filter and a 6.7 m long time-of-flight (ToF) path with a focusing quadrupole. The ToF is determined by a time zero detector and a surface barrier detector, which also provides an energy measurement. The capability of the system to discriminate 236U from the much more abundant isotopes 235U and 238U is shown. While sensitivity values of 236U/238U∼ 10−8 were achieved, ongoing works aim to improve this performance.