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AbstractAbstract
[en] A radiochemical investigation is performed to measure the cumulative fission product yields of several lantanides and yttrium nuclides in the 238U by fission neutron spectra. Natural and depleted uranium are irradiated under the same experimental conditions in order to find a way to subtract the contribution of the 235U fission. 235U percentage in the natural uranium was 3.5 times higher than in the depleted uranium. Uranium oxides samples are irradiated inside the core of the Argonaut Reactor, at the Instituto de Engenharia Nuclear, and the lantanides and yttrium are chemically separated. The fission products gamma activities were detected, counted and analysed in a system constituted by a high resolution Ge(Li) detector, 4096 multichannel analyser and a PDP-11 computer. Cumulative yields for fission products with half-lives between 1 to 33 hours are measured: 93Y, 141La, 142La, 143Ce and 149Nd. The chain total yields are calculated. The cumulative fission yields measured for 93Y, 141La, 142La, 143Ce and 149Nd are 4,49%, 4,54%, 4,95%, 4,16% and 1,37% respectively and they are in good agreement with the values found in the literature. (Author)
[pt]
Realiza-se uma investigacao radioquimica para medir rendimentos de fissao cumulativos de nuclideos de lantanideos e itrio, na fissao do 238U com neutrons do espectro de fissao. Para subtrair a contribuicao da fissao do 235U, irradiam-se, nas mesmas condicoes experimentais, amostras de uranio natural e de uranio emmpobrecido. A percentagem de 235U no uranio natural e 3,5 vezes maior do que no uranio empobrecido. Amostras de oxido de uranio sao irradiadas no nucleo do Reator Argonauta do Instituto de Engenharia Nuclear, e os lantanideos e itrio foram quimicamente separados. As atividades gama dos produtos de fissao sao detectadas, contadas e analisadas em um sistema constituido por um detector Ge(Li) de alta resolucao, um analisador de 4096 canais e um computador PDP-11. Medem-se os rendimentos cumulativos dos produtos de fissao de meias vidas entre 1 e 33 horas: 93Y, 141La, 142La, 143Ce e 149Nd. Calculam-se os rendimentos totais de cadeia. Os rendimentos cumulativos de fissao obtidos para 93Y, 141La, 142La, 143Ce e 149Nd sao 4,49%, 4,54%, 4,95%, 4,16% e 1,37% respectivamente e eles sao concordantes com os valores da literatura. (Autor)Original Title
Determinacao de rendimentos dos produtos de fissao, lantanideos e itrio, na fissao do 238U com neutrons do espectro de fissao
Source
Jun 1981; 84 p; Tese (M.Sc.).
Record Type
Miscellaneous
Literature Type
Thesis/Dissertation
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ACTINIDE NUCLEI, ALPHA DECAY RADIOISOTOPES, BARYONS, BETA DECAY RADIOISOTOPES, BETA-MINUS DECAY RADIOISOTOPES, CERIUM ISOTOPES, DAYS LIVING RADIOISOTOPES, ELEMENTARY PARTICLES, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, FERMIONS, HADRONS, HEAVY NUCLEI, HOURS LIVING RADIOISOTOPES, INTERMEDIATE MASS NUCLEI, LANTHANUM ISOTOPES, MATERIALS, NEODYMIUM ISOTOPES, NEUTRONS, NUCLEAR REACTION YIELD, NUCLEI, NUCLEONS, ODD-EVEN NUCLEI, ODD-ODD NUCLEI, RADIOACTIVE MATERIALS, RADIOISOTOPES, RARE EARTH NUCLEI, URANIUM ISOTOPES, YEARS LIVING RADIOISOTOPES, YTTRIUM ISOTOPES
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