Published 1980 | Version v1
Journal article Metadata-only

Determination of 235U isotopic fraction in rocks by thermal neutrons activation analysis

Creators

  • 1. Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo (Brazil). Div. de Radioquimica
  • 2. Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo (Brazil). Centro de Fisica Nuclear

Description

The isotopic fraction of 235U in some uranium racks from the northeast of Brazil was determined, using two methods: thermal neutrons activation analysis followed by both retarded fission neutrons counting and high resolution gamma spectroscopy. For the latter, it was found convenient to carry out an uranium separation prior to irradiation so to eliminate interfering elements which, through activation, may give rise to photopeaks with energies very close to those of 239Np and of 235U fission products. Three types of rocks were analysed: one containing 230 ppm of U3O8 and two uraniferous chalcosilicic rocks containing 2.3 and 1.5% U3O8. Other rocks were sampled but not analysed because their uranium concentrations were extremely low (these concentrations were also determined by activation analysis). (C.L.B.)

Abstract (Portuguese)

Determinou-se a fracao isotopica do 235U em algumas rochas contendo uranio oriundas da regiao Nordeste do Brasil, utilizando-se duas tecnicas: analise por ativacao com neutrons termicos e contagem de neutrons retardados de fissao; analise por ativacao com neutrons termicos e espectrometria gama de alta resolucao. Neste ultimo caso, considerou-se mais conveniente realizar uma separacao do uranio pre-irradiacao, para eliminar a presenca de elementos interferentes que, mediante ativacao, podem dar origem a fotopicos de energias do 235U. Foram analisados tres tipos de rochas: do 'Grupo Estancia', localizado em Sergipe, analisou-se uma rocha contendo 230 ppm de U3O8; do 'Grupo de Garanhuns', localizado em Pernambuco, duas rochas calco-silicaticas uraniferas, contendo 2,3 e 1,5% de U3O8. As outras rochas recebidas nao foram analisadas, por apresentarem concentracoes de uranio muito baixas. Essas concentracoes foram tambem determinadas por analise por ativacao. (Autor)

Additional details

Additional titles

Original title (Portuguese)
Determinacao da fracao isotopica do

Publishing Information

Journal Title
An. Assoc. Bras. Quim.
Journal Volume
31
Journal Issue
3/4
Series
An. Assoc. Bras. Quim.
Journal Page Range
263-271
ISSN
0365-0073

INIS

Country of Publication
Brazil
Country of Input or Organization
Brazil
INIS RN
16023531
Subject category
S37: INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY;
Descriptors DEI
GAMMA SPECTROSCOPY; ISOTOPE RATIO; NEUTRON ACTIVATION ANALYSIS; NEUTRON SPECTROSCOPY; ROCKS; SAMPLE PREPARATION; URANIUM 235
Descriptors DEC
ACTINIDE NUCLEI; ACTIVATION ANALYSIS; ALPHA DECAY RADIOISOTOPES; CHEMICAL ANALYSIS; EVEN-ODD NUCLEI; HEAVY NUCLEI; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; MINUTES LIVING RADIOISOTOPES; NUCLEI; RADIOISOTOPES; SPECTROSCOPY; URANIUM ISOTOPES; YEARS LIVING RADIOISOTOPES