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 restrict...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.展开更多
The Brazilian＇s interest in the nuclear utilization of thorium has started in the 1950s as a consequence of the abundant occurrence ofmonazite sands. Since the 1960s, IPEN-CNEN/SP （lnstituto de Pesquisas Energ6ticas...The Brazilian＇s interest in the nuclear utilization of thorium has started in the 1950s as a consequence of the abundant occurrence ofmonazite sands. Since the 1960s, IPEN-CNEN/SP （lnstituto de Pesquisas Energ6ticas e Nucleares） has performed some developments related to the thorium fuel cycle. The production and purification of thorium compounds was carried out at IPEN for about 18 years and the main product was the thorium nitrate with high purity, having been produced over 170 metric tons of this material in the period, obtained through solvent extraction. The thorium nitrate was supplied to the domestic industry and used for gas portable lamps （Welsbach mantle）. Although the thorium compounds produced have not been employed in the nuclear area, several studies were conducted. Therefore, those activities and the accumulated experience are of strategic importance, on one hand, due to huge Brazilian thorium reserves, on the other hand, by the resurgence of the interest of thorium for the Generation IV advanced reactors. This paper presents a review of the Brazilian research and development activities related to thorium technology.展开更多
文摘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.
文摘The Brazilian＇s interest in the nuclear utilization of thorium has started in the 1950s as a consequence of the abundant occurrence ofmonazite sands. Since the 1960s, IPEN-CNEN/SP （lnstituto de Pesquisas Energ6ticas e Nucleares） has performed some developments related to the thorium fuel cycle. The production and purification of thorium compounds was carried out at IPEN for about 18 years and the main product was the thorium nitrate with high purity, having been produced over 170 metric tons of this material in the period, obtained through solvent extraction. The thorium nitrate was supplied to the domestic industry and used for gas portable lamps （Welsbach mantle）. Although the thorium compounds produced have not been employed in the nuclear area, several studies were conducted. Therefore, those activities and the accumulated experience are of strategic importance, on one hand, due to huge Brazilian thorium reserves, on the other hand, by the resurgence of the interest of thorium for the Generation IV advanced reactors. This paper presents a review of the Brazilian research and development activities related to thorium technology.
