Determination of uranium in tree bark samples by epithermal neutron activation analysis
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2017
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60 YEARS OF IEA-R1: INTERNATIONAL WORKSHOP ON UTILIZATION OF RESEARCH REACTORS
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It is well known that uranium is a toxic element to human beings and it is considered
as an environmental pollutant. This element presents accumulative property
and can be concentrated on the organs causing various types of diseases. Uranium
is widely distributed in the environment, so it is of great interest to improve the
method of neutron activation analysis to be applied in its determinations in tree
barks used as environmental pollution biomonitor. For analytical quality control of
the U results, certified reference materials (CRMs) were analyzed. The tree bark
samples were collected from the Tipuana tipu (Tipuana) and Poincianella pluviosa
(Sibipiruna) species and, for the analyses the outer layer of the bark was grated and
then ground to obtain a powder. Aliquots of CRMs or tree bark samples were weighed
in polyethylene envelopes and, irradiated together with U synthetic standard, inside
a Cd capsule for epithermal neutron activation analysis (ENAA). The irradiation was
performed a pneumatic transfer system at the IEA-R1 nuclear research reactor at
IPEN - CNEN/SP. The thermal neutron flux used was of 1:9 1012 n cm2s1 and
the irradiation time was of 60 seconds. After adequate decay time, the sample and
U standard were measured using a HGe detector coupled to a digital spectrum analyzer
DSA 1000, both from Canberra. Uranium was identified by gamma ray peak of
74.66 keV of 239U and half-life of 23.47 minutes. The concentration of U was calculated
by comparative method. A total number of five CRMs were analyzed and its
results presented relative standard deviations lower than 13.4%, relative errors lower
than 3.1% and |Z score| values lower than 0.29. Results obtained in the analyses of
tree barks varied from 81.8 to 222.1 ng/g, indicating that U concentrations in the
analyzed samples were very low.
Como referenciar
LIMA, N.P.; SAIKI, M. Determination of uranium in tree bark samples by epithermal neutron activation analysis. In: 60 YEARS OF IEA-R1: INTERNATIONAL WORKSHOP ON UTILIZATION OF RESEARCH REACTORS, November 28 - December 01, 2017, São Paulo, SP. Abstract... São Paulo, SP: Instituto de Pesquisas Energéticas e Nucleares, 2017. p. 44-44. Disponível em: http://repositorio.ipen.br/handle/123456789/28741. Acesso em: 28 Feb 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.