PAULO ERNESTO DE OLIVEIRA LAINETTI
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Artigo IPEN-doc 23519 Thorium and its future importance for nuclear energy generation2016 - LAINETTI, PAULO E.O.Thorium was discovered in 1828 by the Swedish chemist Jons J. Berzelius. Despite some advantages over uranium for use in nuclear reactors, its main use, in the almost two centuries since its discovery, thorium was restricted to use for gas mantles, especially in the early 20th century. In the beginning of the nuclear era, many countries had interested on thorium, particularly during the 1950-1970 period. There are about 435 nuclear reactors in the world nowadays. They need more than 65,000 tons of uranium yearly. The future world energy needs will increase and, even if we assumed a conservative contribution of nuclear generation, there will be a significant increasing in the uranium prices occur, taking into account that uranium, as used in the present thermal reactors, is a finite resource. Thorium is nearly three times more abundant than uranium in the Earth’s crust. Despite thorium is not a fissile material, 232Th can be converted to 233U (fissile) more efficiently than 238U to 239Pu. Besides this, since it is possible to convert thorium waste into non-radioactive elements, thorium is an environment-friendly alternative energy source. Thorium fuel cycle is also inherently resistant to proliferation. Some papers evaluate the thorium resources in Brazil over 1,200,000 metric t. Then, the thorium alternative must be seriously considered in Brazil for strategic reasons. In this paper a brief history of thorium is presented, besides a review of the world thorium utilization and a discussion about advantages and restrictions of thorium use.Artigo IPEN-doc 23511 Use of dopants for thoria sintering temperature reduction-characterization of THO22016 - TAKIISHI, HIDETOSHI; GENOVA, LUIS A.; CAVALHEIRA, ELTON D.; COTRIM, MARYCEL B.; SANTOS, WILSON; LAINETTI, PAULO E.O.Thorium is nearly three times more abundant than uranium in the Earth’s crust. Some papers evaluate the thorium resources in Brazil over 1,200,000 metric t. These figures mean that the country is probably the biggest thorium resource in the world, with only part of the territory prospected. Nevertheless, Brazil has not a research program for use of thorium in nuclear reactors, even having dedicated special attention to the subject in the beginning of its nuclear activities, in the fifties and sixties. From 1985 until 2003 IPEN operated a pilot plant for thorium nitrate production and purification, used by Brazilian industry for production of gas mantles. This facility produced over 170 metric t of thorium nitrate. Despite the non-nuclear application, the pilot plant was unique in the southern hemisphere. On the other hand, Brazil has the biggest world niobium resources. The Brazilian thorium and niobium resources added to the predictable future importance of alternative fissile materials have motivated this research, since uranium is a finite resource if used in the present thermal nuclear reactors. Besides this, thorium oxide is an important nuclear reactor material. It is a refractory oxide and its ceramic fabrication process involves a very high temperature sintering treatment considering that thoria melting point is very high (3,650 K). Cations of elements of the group VB (V, Nb and Ta) have a known effect in the reduction of thoria sintering temperature. IPEN has initiated an investigation about the use of niobium as a dopant for thoria sintering temperature reduction. The thoria used in the research was produced in the IPEN’s pilot plant and different amounts of niobium oxide (Nb2O5) will be added to thoria by different routes. The powders will be compressed and the compacted pellets will be sintered at different temperatures. The influence of the different parameters in the density of sintered pellets is being investigated. This paper presents the chemical and physical characterization for the thoria used in the investigation.Artigo IPEN-doc 20546 Review of brazilian activities related to the thorium fuel cycle and production of thorium compounds at IPEN-CNEN/SP2014 - LAINETTI, PAULO E. de O.; FREITAS, ANTONIO A. de; MINDRISZ, ANA C.