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Measurement of Pu and U isotopes on the 1 MV AMS system at the Centro Nacional de Aceleradores

Abstract

In the last decade, compact AMS systems have demonstrated their potential to measure actinides (236U, 239,240,244Pu, 237Np). With an appropriate detection system, kinematic filters with enough mass resolution, and a simple chemical procedure, the determination of plutonium isotopes and 237Np at environmental levels is currently possible with this new generation of facilities with even better performance than with conventional AMS systems. However, the measurement of 236U (T1/2=23.4 My), produced by neutron capture on 235U, is still a challenge, due to the interference caused by 235U and 238U. In this work, we will explore the possibilities that the 1 MV AMS system at the CNA offers for the measurement of uranium isotopes at environmental levels, in terms of detection limit, efficiency, and precision. Considering the very promising 239Pu/238U mass suppression factor achieved with our system, of about 10-9, a limiting 236U/238U atomic ratio of about 10-11 was expected, approaching the levels expected in natural uranium. However, to date, only the 10-9 level has been obtained, possibly due to the lack of an appropriate uranium material. Currently, different natural uranium materials are being studied, in order to elucidate the origin of the interference. On the other hand, we will discuss the status of the plutonium measurements at our facility, based on the experience we have accumulated in recent years from the analysis of different matrixes over a wide range of plutonium concentrations.

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Measurement of Pu and U isotopes on the 1 MV AMS system at the Centro Nacional de Aceleradores

Author: Chamizo, E.; García León, Manuel; García-Tenorio García-Balmaseda, Rafael; Hotchkis, M.
Year: 2011
Source: https://idus.us.es/bitstreams/75c95e31-a2e8-49a6-b5a1-0c590daa5abe/download
AMS-12 Con e ence, 2011
180
FOR#P105 POSTER SESSION 2 Thu sday 24 h Ma ch, 1400 - 1540
Measu emen o Pu and U iso opes on he 1 MV AMS sys em a he Cen o
Nacional de Acele ado es
Chamizo E 1, Ga cía-León M 2, Ga cía-Teno io R 1, Ho chkis M 3
1 Cen o Nacional de Acele ado es (CNA), A da. Thomas Al a Edison 7, Isla de la Ca uja, 41092
Se ille, Spain,
2 Dp o. de Física A ómica Molecula y Nuclea , Uni e sidad de Se illa, P.O. Box 1065, 41080
Se ille, Spain,
3 Aus alian Nuclea Science and Technology O ganisa ion, Locked Bag 2001, Ki awee DC, NSW
2232, Aus alia
In he las decade, compac AMS sys ems ha e demons a ed hei po en ial o measu e ac inides
(236U, 239,240,244Pu, 237Np). Wi h an app op ia e de ec ion sys em, kinema ic il e s wi h enough
mass esolu ion, and a simple chemical p ocedu e, he de e mina ion o plu onium iso opes and
237Np a en i onmen al le els is cu en ly possible wi h his new gene a ion o acili ies wi h e en
be e pe o mance han wi h con en ional AMS sys ems. Howe e , he measu emen o 236U
(T1/2=23.4 My), p oduced by neu on cap u e on 235U, is s ill a challenge, due o he in e e ence
caused by 235U and 238U. In his wo k, we will explo e he possibili ies ha he 1 MV AMS sys em a
he CNA o e s o he measu emen o u anium iso opes a en i onmen al le els, in e ms o
de ec ion limi , e iciency, and p ecision. Conside ing he e y p omising 239Pu/238U mass
supp ession ac o achie ed wi h ou sys em, o abou 10-9, a limi ing 236U/238U a omic a io o
abou 10-11 was expec ed, app oaching he le els expec ed in na u al u anium. Howe e , o da e,
only he 10-9 le el has been ob ained, possibly due o he lack o an app op ia e u anium ma e ial.
Cu en ly, di e en na u al u anium ma e ials a e being s udied, in o de o elucida e he o igin o
he in e e ence. On he o he hand, we will discuss he s a us o he plu onium measu emen s a
ou acili y, based on he expe ience we ha e accumula ed in ecen yea s om he analysis o
di e en ma ixes o e a wide ange o plu onium concen a ions.