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In this work, the antineutrino spectrum as specifically generated by nuclear reactors is studied. The topics covered include corrections and higher-order effects in reactor antineutrino experiments, one of which is covered in Ref. [1] and another contributes to Ref. [2]. In addition, a practical application, antineutrino safeguards for nuclear reactors, as summarized in Ref. [3,4] and Ref. [5], is explored to determine its viability and limits. The work will focus heavily on theory, simulation, and statistical analyses to explain the corrections, their origins, and their sizes, as well as the applications of the antineutrino signal from nuclear reactors. Chapter [1] serves as an introduction to neutrinos. Their origin is briefly covered, along with neutrino properties and some experimental highlights. The next chapter, Chapter [2], will specifically cover antineutrinos as generated in nuclear reactors. In this chapter, the production and detection methods of reactor neutrinos are introduced as well as a discussion of the theories behind determining the antineutrino spectrum. The mathematical formulation of neutrino oscillation will also be introduced and explained. The first half of this work focuses on two corrections to the reactor antineutrino spectrum. These corrections are generated from two specific sources and are thus named the spent nuclear fuel contribution and the non-linear correction for their respective sources. Chapter [3] contains a discussion of the spent fuel contribution. This correction arises from spent nuclear fuel near the reactor site and involves a detailed application of spent fuel to current reactor antineutrino experiments. Chapter [4] will focus on the non-linear correction, which is caused by neutron-captures within the nuclear reactor environment. Its quantification and impact on future antineutrino experiments are discussed. The research projects presented in the second half, Chapter [5], focus on neutrino applications, specifically reactor monitoring. Chapter [5] is a comprehensive examination of the use of antineutrinos as a reactor safeguards mechanism. This chapter will include the theory behind safeguards, the statistical derivation of power and plutonium measurements, the details of reactor simulations, and the future outlook for non-proliferation through antineutrino monitoring. / Ph. D.

O uso das amostragens ambientais para fins de salvaguardas vêm sendo aplicadas pela Agência Internacional de Energia Atômica AIEA desde 1996 e estão sendo rotineiramente utilizadas como uma medida de fortalecimento complementar aos procedimentos tradicionais de salvaguardas de materiais nucleares. O intuito é verificar se os Estados signatários aos acordos de salvaguardas não estão divergindo suas atividades nucleares pacíficas para atividades nucleares não declaradas. O presente trabalho apresenta um novo protocolo de coleta e análise de esfregaços para identificação de assinaturas nucleares que possam relacionar-se com as atividades nucleares desenvolvidas na instalação inspecionada. Neste trabalho foi utilizada como estudo de caso uma planta real de reconversão de urânio do ciclo do combustível nuclear do IPEN. A estratégia analítica proposta utiliza diferentes técnicas, como medidor de radiação alfa, MEVEDS e ICPMS para identificar assinaturas do urânio aderido ao esfregaço. Na análise dos esfregaços, foi possível identificar partículas de UO2F2 e UF4 através da comparação morfológica e análises semi-quantitativas utilizando a técnica de MEVEDS. Nesse trabalho, utilizaram-se métodos que como resultado tem-se a composição isotópica média da amostra, onde o enriquecimento (fração atômica molar) variou de 1,453 ± 0,023% a 18,24 ± 0,15% no isótopo 235U. Através das coletas realizadas externamente, uma forma não intrusiva de amostragem, foi possível à identificação de atividades de manuseio de material enriquecido com medidas de fração atômica molar de 1,453 ± 0,023% a 6,331 ± 0,055% no isótopo 235U, bem como uso de material reprocessado, através da identificação do isótopo 236U. As incertezas obtidas neste trabalho para a razão n(235U)/n(238U) variaram de 0,40% a 1,68%. / The use of environmental samplings for safeguards purposes has been applied by the International Atomic Energy AgencyIAEA since 1996 and they are routinely used as a complementary measure to strengthen the traditional nuclear safeguards procedures. The aim is verify if the signatory states to the safeguards agreements are not diverging their peaceful nuclear activities to undeclared nuclear activities. This work describes a new protocol of collect and analysis of swipe samples in order to achieve identification of nuclear signatures, which may be related to the nuclear activities developed in the inspected facility. In this work, as a case of study, a real uranium reconversion plant of the nuclear fuel cycle of IPEN was used. The strategy proposed uses different analytical techniques, such as alpha radiation meter, SEM-EDX and ICP-QMS to identify signatures of the uranium adhered to the swipe samples. In the swipe samples analysis, it was possible to identify particles of UO2F2 and UF4 through the morphological comparison and semi-quantitative analysis performed by SEM-EDX technique. The methods used in this work bring the average isotopic composition of the sample as a result, in which the enrichment (molar atomic fraction) ranged from 1.453 ± 0.023% to 18.24 ± 0.15% in the 235U isotope. Through of the external collections, a non-intrusive sampling, it was possible to identify handling activities of enriched material with molar atomic fraction of 1.453 ± 0.023% to 6.331 ± 0.055% in the 235U isotope, as well as the use of reprocessed material by means of the 236U isotope identification. The uncertainties obtained in this work to the n(235U)/n(238U) ratio varied from 0.40% to 1.68%.

<p>The fuel assemblies used at the Swedish nuclear power plants contain typically between 100 and 300 fuel rods. An experimental technique has been demanded for determining the relative activities of specific isotopes in individual fuel rods without dismantling the assemblies. The purpose is to validate production codes, which requires an experimental relative accuracy of <2 % (1 σ).</p><p>Therefore, a new, non-destructive tomographic measurement technique for irradiated nuclear fuel assemblies has been developed. The technique includes two main steps: (1) the gamma-ray flux distribution around the assembly is recorded, and (2) the interior gamma-ray source distribution in the assembly is reconstructed. The use of detailed gamma-ray transport calculations in the reconstruction procedure enables accurate determination of the relative rod-by-rod source distribution.</p><p>To investigate the accuracy achievable, laboratory equipment has been constructed, including a fuel model with a well-known distribution of ¹³⁷Cs. Furthermore, an instrument has been constructed and built for in-pool measurements on irradiated fuel assemblies at nuclear power plants.</p><p>Using the laboratory equipment, a relative accuracy of 1.2 % was obtained (1 σ). The measurements on irradiated fuel resulted in a repeatability of 0.8 %, showing the accuracy that can be achieved using this instrument. The agreement between rod-by-rod data obtained in calculations using the POLCA–7 production code and measured data was 3.1 % (1 σ).</p><p>Additionally, there is a safeguards interest in the tomographic technique for verifying that no fissile material has been diverted from fuel assemblies, i.e. that no fuel rods have been removed or replaced. The applicability has been demonstrated in a measurement on a spent fuel assembly. Furthermore, detection of both the removal of a rod as well as the replacement with a non-active rod has been investigated in detail and quantitatively established using the laboratory equipment.</p>

The fuel assemblies used at the Swedish nuclear power plants contain typically between 100 and 300 fuel rods. An experimental technique has been demanded for determining the relative activities of specific isotopes in individual fuel rods without dismantling the assemblies. The purpose is to validate production codes, which requires an experimental relative accuracy of &lt;2 % (1 σ). Therefore, a new, non-destructive tomographic measurement technique for irradiated nuclear fuel assemblies has been developed. The technique includes two main steps: (1) the gamma-ray flux distribution around the assembly is recorded, and (2) the interior gamma-ray source distribution in the assembly is reconstructed. The use of detailed gamma-ray transport calculations in the reconstruction procedure enables accurate determination of the relative rod-by-rod source distribution. To investigate the accuracy achievable, laboratory equipment has been constructed, including a fuel model with a well-known distribution of 137Cs. Furthermore, an instrument has been constructed and built for in-pool measurements on irradiated fuel assemblies at nuclear power plants. Using the laboratory equipment, a relative accuracy of 1.2 % was obtained (1 σ). The measurements on irradiated fuel resulted in a repeatability of 0.8 %, showing the accuracy that can be achieved using this instrument. The agreement between rod-by-rod data obtained in calculations using the POLCA–7 production code and measured data was 3.1 % (1 σ). Additionally, there is a safeguards interest in the tomographic technique for verifying that no fissile material has been diverted from fuel assemblies, i.e. that no fuel rods have been removed or replaced. The applicability has been demonstrated in a measurement on a spent fuel assembly. Furthermore, detection of both the removal of a rod as well as the replacement with a non-active rod has been investigated in detail and quantitatively established using the laboratory equipment.

Conversion, the process by which natural uranium ore (yellowcake) is purified and converted through a series of chemical processes into uranium hexafluoride gas (UF6), has historically been excluded from the nuclear safeguards requirements of the 235U-based nuclear fuel cycle. With each step in the conversion process from yellowcake to feedstock for UF6, intermediary uranium oxide and uranium fluoride compounds become progressively attractive products for diversion toward activities noncompliant with international treaties. The diversion of this product material could potentially provide feedstock for a clandestine or undeclared enrichment for weapons development for state or non-state entities. With the realization of this potential, the International Atomic Energy Agency (IAEA) has only recently reinterpreted its policies to emphasize safeguarding this feedstock in response to such diversion pathways. This project employs a combination of simulation models and experimental measurements to develop and validate concepts of nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP). In particular, uranyl nitrate (UN) solution exiting solvent extraction was identified as a key measurement point (KMP), where gamma-ray spectroscopy was selected as the process-monitoring tool. The Uranyl Nitrate Calibration Loop Equipment (UNCLE) facility at Oak Ridge National Laboratory was employed to simulate the full-scale operating conditions of a purified uranium-bearing aqueous stream exiting the solvent extraction process in an NUCP. This work investigates gamma-ray signatures UN circulating in the UNCLE facility and evaluates various gamma-ray detector (HPGe, LaBr3 and NaI) sensitivities to UN.

<p>Since their creation, the multilateral development banks have accumulated performance records that include both substantial successes and stunning failures. Nowhere have their performance records been more mixed and controversial than with respect to environmental management issues. The multilateral development banks have financed projects that are widely considered to be environmental disasters, but have also financed projects that successfully included best practice environmental mitigation measures. They have wasted hundreds of millions of dollars financing unsuccessful environmental protection programs, while at the same time they have supported programs that contributed to the rapid development of environmental management capacity in less-developed countries. The purpose of this dissertation is to explore when and why monitoring and evaluation can prompt the multilateral development banks to move away from poor performing projects and towards high performing projects.</p><p>This type of performance-based allocation has been repeatedly highlighted as a key element in the successful delivery of development assistance. To test when the multilateral development banks practice performance-based allocation, I assembled a team that coded environmental performance information from 960 project evaluations, 174 program evaluations, and 74 civil society complaints. I use the resulting data to model when four multilateral development banks - the World Bank, Asian Development Bank, Inter-American Development Bank, and African Development Bank - make performance-based allocation decisions about environmentally-risky and environment-improving operations. In addition, I visited the headquarters of each of these organizations and conducted interviews with 54 staff members about the processes that are in place to use monitoring and evaluation information as part of decision-making.</p><p>I find that the establishment of monitoring and evaluation systems at the MDBs has not created incentives for staff to practice performance-based allocation. Instead, performance information influences allocation decisions when it helps MDB staff approve future projects more quickly. It does so by helping staff identify development projects that are likely to face significant delays due to the inability of the borrowing country to manage negative environmental impacts and to identify the borrowing countries that are likely to successfully implement environment-improving operations.</p> / Dissertation

Made available in DSpace on 2014-10-09T12:42:16Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:15Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:42:16Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:15Z (GMT). No. of bitstreams: 0 / A amostragem ambiental por esfregaço ou swipe samples é uma metodologia que vem sendo empregada rotineiramente pela Agência Internacional de Energia Atômica (AIEA) para verificar se os Estados signatários do Acordo de Salvaguardas estão realizando atividades nucleares não declaradas. A análise dessas amostras ambientais é complementar aos procedimentos de salvaguardas convencionais para a verificação das informações cedidas pelos Estados. Neste trabalho, foi descrita uma metodologia que visa a fortalecer os processos de salvaguarda nuclear e da ciência forense nuclear no país. A proposta é estudar e avaliar a técnica de ablação à laser acoplada a um espectrômetro de massa de alta resolução com fonte de plasma indutivamente acoplado (LA-HR-ICP-MS Laser Ablation High Resolution Inductively Coupled Plasma Mass Spectrometry), como técnica alternativa para a análise das amostras de esfregaço. Adicionalmente, foram empregadas outras técnicas complementares (atividade radioativa, microscopia eletrônica de varredura e espectroscopia de energia dispersiva) com o intuito de garantir maior segurança ao processo de inspeção de salvaguardas e investigações forenses nucleares. A precisão, medida através do desvio padrão relativo (DPR),dos resultados obtidos para as razões isotópicas 234U/238U, 235U/238U e 236U/238U do padrão analisado (CRM -125A) para a medida do fator de discriminação de massa foram, respectivamente, 1,3 %, 0,2 % e 7,6 %. Já as incertezas percentuais (u %), que também contemplam o DPR das medições, variaram de 3,5 % a 29,8 % para as medições da razão isotópica 235U/238U e de 16,6 % a 42,9 % para a razão isotópica 234U/238U. Esses valores mostraram-se compatíveis com outros estudos que utilizaram a mesma técnica para análise de amostras reais coletadas em uma instalação nuclear. As amostras coletadas apresentaram nível de enriquecimento que variou de (2,3 ± 0,7) % (amostra 3 corredor de acesso à instalação) a (17,3 ± 2,8) % (amostra 18 bancada de recuperação de UF4). A partir da coleta de amostras nesses diversos pontos, desde a entrada da instalação até a bancada em que se manuseia o urânio enriquecido, foi possível detectar diversos níveis de enriquecimento no isótopo 235U. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Maria Eneide de Souza Araujo (mearaujo@ipen.br) on 2017-03-10T16:58:27Z No. of bitstreams: 0 / Made available in DSpace on 2017-03-10T16:58:27Z (GMT). No. of bitstreams: 0 / O uso e a aplicação cada vez mais constante da tecnologia nuclear consistente em áreas relacionadas à saúde, energia, industrial, bélica, agrícola, entre outras, faz com que haja a necessidade de uma regulamentação de acordo com os padrões de segurança e proteção radiológica internacionais. Dessa forma, utilizando-se de conceitos provenientes do Direito Constitucional, do Direito Ambiental e do Direito do Trabalho, o enfoque da presente pesquisa foi investigar a difícil questão da competência nuclear e a competência ambiental, a impossibilidade de legislar dos Estados, bem como a falta de regulamentação sobre Rejeitos radioativos. Para tanto, foram atualizados e revisados critérios e métodos de interpretação constitucional para solucionar possíveis antinomias jurídicas advindas de múltipla positivação de normas pelos entes federados que dificultam tanto o asseguramento quanto o aprimoramento da Proteção radiológica do trabalhador e do meio ambiente. Finalmente, a hipótese considerada demonstrou que as mudanças na estrutura legislativa nas três esferas de poderes são necessárias, visando à aplicabilidade de responsabilidade legal na esfera nuclear, principalmente no que se refere às entidades administrativas e estatais. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP