Made available in DSpace on 2014-10-09T12:28:57Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:31Z (GMT). No. of bitstreams: 1 00703.pdf: 11134536 bytes, checksum: d90c9954ba13bad5e3bf731108fc7f92 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:31:15Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:47Z (GMT). No. of bitstreams: 1 01402.pdf: 2037029 bytes, checksum: 0aeb11d232f899f22a9ef9076c165456 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:53:25Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:32Z (GMT). No. of bitstreams: 1 12213.pdf: 5005382 bytes, checksum: c4bde457760b3a6d6f53b64c21e33010 (MD5) / No presente trabalho, foi utilizada a técnica de aquecimento por microondas para estudar a imobilização de rejeitos radioativos de nível de atividade baixo e médio, como resinas de troca iônica exauridas, empregadas na remoção de íons indesejáveis dos circuitos primários de refrigeração de reatores nucleares refrigerados a água, e aquelas usadas em colunas de separação química e radionuclídica no controle de qualidade de radioisótopos. Matrizes betuminosas reforçadas com alguns tipos de borrachas (Neoprene®, Silicone e Etileno Vinil Acetato - EVA), provenientes de material descartado ou sobras de produção, foram utilizadas para incorporação dos rejeitos radioativos. As irradiações das amostras foram feitas em um forno de microondas caseiro, que opera com freqüência de 2.450MHz e possui potência de 1.000W. As amostras foram caracterizadas, empregando-se ensaios de penetração, resistência à lixiviação, pontos de amolecimento, fulgor e combustão, termogravimetria e microscopia óptica. Os resultados obtidos mostraram-se compatíveis com os padrões dos componentes das matrizes, indicando que esta técnica é uma alternativa bastante útil aos métodos de imobilização convencionais e para esses tipos de rejeitos radioativos. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:26:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:21Z (GMT). No. of bitstreams: 1 00653.pdf: 2722544 bytes, checksum: 26bcce3d962be5c281c69fd5f50fca70 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Pressurizer modeling for predicting the dynamic pressure of the PIUS system is presented. The transient behavior of this model for the PIUS system was investigated. The validity of this model for the PIUS system is limited to transients that are neither too large nor too long in duration. For example, the model is not capable of describing events following a complete loss of liquid for the pressurizer. However, the model can be used for qualitative prediction of the PIUS system behavior for a wide variety of severe transients. A review of pressurizer modeling indicates that the neglecting of the change in the internal energy of the subcooled water during transients is an acceptable assumption. The inherently safe feature of the PIUS system was confirmed through the self-shutdown of the reactor or, in some cases, through reactor power reduction as a result of the ingress of the pool boric acid solution into the primary system. This dynamic model was constructed of three major components: (1) The primary loop, (2) The secondary loop, and (3) The natural convection loop through the pool. A lumped parameter model, uniform heat transfer, and point kinetics have been the main approximations in this model. Other approximations are mentioned during the modeling of each component of the model. The dynamic model was simulated using the DARE-P continuous system simulation language which was developed in the Electrical Engineering Department at the University of Arizona.

A large set of experimental data, obtained in Russia, was analyzed and a new heat-transfer correlation for supercritical water was developed. This experimental dataset was obtained within conditions similar to those for proposed SuperCritical Water-cooled nuclear Reactor (SCWR) concepts. Thus, this new correlation, for forced convective heat transfer in the normal heat-transfer regime, can be used for preliminary heat-transfer calculations in SCWR fuel channels. It has demonstrated a good fit for Heat Transfer Coefficient (HTC) values (±25%) and for wall temperature calculations (±15) for the analyzed dataset. This correlation can be used for supercritical water heat exchangers linked to indirectcycle concepts and the co-generation of hydrogen, for future comparisons with other independent datasets, with bundle data, as the reference case, for the verification of computer codes for SCWR core thermalhydraulics and for the verification of scaling parameters between water and modeling fluids. / UOIT

Made available in DSpace on 2014-10-09T12:24:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:21Z (GMT). No. of bitstreams: 1 00511.pdf: 606198 bytes, checksum: fd262e7d323a2dca01ef1d5e7656e443 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Made available in DSpace on 2014-10-09T12:25:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:48Z (GMT). No. of bitstreams: 1 01099.pdf: 10225038 bytes, checksum: 113532b9074d64302ecc9c6015faef45 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:29:02Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:12Z (GMT). No. of bitstreams: 1 00967.pdf: 5059113 bytes, checksum: bc1fb5c365357208caf91f4f11ac81ea (MD5) / Thesis (Doctor) / IEA/T / Massachusetts Institute of Technology - Cambridge, Mass - MIT

Made available in DSpace on 2014-10-09T12:24:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:16Z (GMT). No. of bitstreams: 1 00880.pdf: 2598559 bytes, checksum: 89e13c93bf1cbf3a2e4a292aaa260a5d (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP