{"id":18115,"date":"2020-06-27T00:23:48","date_gmt":"2020-06-27T00:23:48","guid":{"rendered":"https:\/\/www.radiation-dosimetry.org\/o-que-e-fissao-espontanea-definicao\/"},"modified":"2020-07-24T06:27:47","modified_gmt":"2020-07-24T06:27:47","slug":"o-que-e-fissao-espontanea-definicao","status":"publish","type":"post","link":"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-fissao-espontanea-definicao\/","title":{"rendered":"O que \u00e9 fiss\u00e3o espont\u00e2nea &#8211; defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-u-clearfix su-u-trim\">A fiss\u00e3o espont\u00e2nea \u00e9 um processo de decaimento, no qual um n\u00facleo inst\u00e1vel se divide espontaneamente e aleatoriamente em partes menores (n\u00facleos mais leves).\u00a0As fiss\u00f5es espont\u00e2neas liberam n\u00eautrons como todas as fiss\u00f5es.\u00a0Dosimetria de Radia\u00e7\u00e3o<\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<p><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Nuclear-Fission-min.png\"><img loading=\"lazy\" class=\"alignright size-full wp-image-18640 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Nuclear-Fission-min.png\" alt=\"\" width=\"300\" height=\"200\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Nuclear-Fission-min.png\" \/><\/a>Em geral,\u00a0<strong>a fiss\u00e3o nuclear<\/strong>\u00a0\u00e9 uma\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/nuclear-engineering-fundamentals\/neutron-nuclear-reactions\/\">rea\u00e7\u00e3o nuclear<\/a>\u00a0na qual o n\u00facleo de um \u00e1tomo se\u00a0<strong>divide<\/strong>\u00a0em partes menores (n\u00facleos mais leves).\u00a0O processo de fiss\u00e3o geralmente produz\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/free-neutron\/\">n\u00eautrons<\/a>\u00a0e\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/\">f\u00f3tons\u00a0<\/a><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/free-neutron\/\">livres<\/a>\u00a0(na forma de\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">raios gama<\/a>\u00a0) e libera uma\u00a0<strong>grande quantidade de energia<\/strong>\u00a0.\u00a0Na f\u00edsica nuclear, a fiss\u00e3o nuclear \u00e9\u00a0<strong>uma rea\u00e7\u00e3o nuclear\u00a0<\/strong><strong>ou um processo de decaimento radioativo<\/strong>\u00a0.\u00a0O caso do processo de decaimento \u00e9 chamado de\u00a0<strong>fiss\u00e3o espont\u00e2nea<\/strong>\u00a0\u00a0e \u00e9 um processo muito raro.<\/p>\n<p><strong>A fiss\u00e3o espont\u00e2nea<\/strong>\u00a0tamb\u00e9m \u00e9 poss\u00edvel se estudarmos a\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/binding-energy\/nuclear-binding-curve\/\">curva de liga\u00e7\u00e3o nuclear<\/a>\u00a0.\u00a0Esse tipo de decaimento \u00e9 energeticamente poss\u00edvel para um n\u00facleo com A&gt; 100. Embora se espere que a fiss\u00e3o espont\u00e2nea se torne mais prov\u00e1vel \u00e0 medida que o n\u00famero de massa aumenta, ainda \u00e9 um processo muito raro, mesmo em ur\u00e2nio.<\/p>\n<p><strong>A fiss\u00e3o espont\u00e2nea<\/strong>\u00a0\u00e9 vi\u00e1vel durante os tempos de observa\u00e7\u00e3o pr\u00e1ticos apenas para n\u00fameros de massa superiores a 232. Por exemplo,\u00a0<sup>232<\/sup>\u00a0Th,\u00a0<sup>235<\/sup>\u00a0U e\u00a0<sup>238<\/sup>\u00a0U s\u00e3o\u00a0<a href=\"https:\/\/www.nuclear-power.com\/glossary\/primordial-matter\/\">nucl\u00eddeos primordiais<\/a>\u00a0e deixaram evid\u00eancias de sofrer fiss\u00e3o espont\u00e2nea em seus minerais.<\/p>\n<p>Para elementos transur\u00e2nicos pesados, a taxa de transi\u00e7\u00e3o de fiss\u00e3o espont\u00e2nea aumenta com o n\u00famero de massa e pode se tornar o modo de decaimento dominante em n\u00fameros de massa maiores que cerca de 260.<\/p>\n<p>Da mesma forma que no\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radioactive-decay\/alpha-decay-alpha-radioactivity\/\">decaimento alfa<\/a>\u00a0, tamb\u00e9m ocorre a fiss\u00e3o espont\u00e2nea devido ao\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radioactive-decay\/alpha-decay-alpha-radioactivity\/theory-of-alpha-decay-quantum-tunneling\/\">tunelamento qu\u00e2ntico<\/a>\u00a0.\u00a0As fiss\u00f5es espont\u00e2neas liberam n\u00eautrons como todas as fiss\u00f5es, por isso contribui para o fluxo de n\u00eautrons em um\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/reactor-dynamics\/subcritical-multiplication\/\">reator subcr\u00edtico<\/a>\u00a0.\u00a0Radiois\u00f3topos para os quais a fiss\u00e3o espont\u00e2nea n\u00e3o \u00e9 desprez\u00edvel podem ser usados \u200b\u200bcomo fontes de n\u00eautrons.\u00a0Por exemplo, californio-252 (meia-vida de 2.645 anos, raz\u00e3o de ramifica\u00e7\u00e3o de SF de cerca de 3,1 por cento) pode ser usado para esse fim.<\/p>\n<p>A\u00a0<strong>fiss\u00e3o espont\u00e2nea<\/strong>\u00a0de is\u00f3topos naturais de ur\u00e2nio (ur\u00e2nio 238 e ur\u00e2nio 235) deixa rastros de danos na estrutura cristalina de minerais que cont\u00eam ur\u00e2nio quando os fragmentos de fiss\u00e3o se retraem atrav\u00e9s deles.\u00a0Uma t\u00e9cnica de data\u00e7\u00e3o radiom\u00e9trica baseada na an\u00e1lise dessas trilhas ou rastros de danos deixados por fragmentos de fiss\u00e3o em certos minerais e vidros contendo ur\u00e2nio \u00e9 conhecida como\u00a0<strong>data\u00e7\u00e3o por trilha de fiss\u00e3o<\/strong>\u00a0.<\/p>\n<h2>Fiss\u00e3o espont\u00e2nea de determinados n\u00facleos<\/h2>\n<p>Os principais is\u00f3topos, que devem ser considerados no ciclo de combust\u00edvel de todos os reatores comerciais de \u00e1gua leve, s\u00e3o:<\/p>\n<p><strong>Is\u00f3topos de ur\u00e2nio<\/strong><\/p>\n<ul>\n<li><a title=\"Ur\u00e2nio 238\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/uranium-238\/\"><strong><sup>238<\/sup>\u00a0U<\/strong><\/a>\u00a0.\u00a0<sup>238<\/sup>U pertence ao grupo de<a title=\"Material f\u00e9rtil\" href=\"https:\/\/www.nuclear-power.com\/glossary\/fertile-material\/\">is\u00f3topos f\u00e9rteis<\/a>.\u00a0<sup>238<\/sup>U decai atrav\u00e9s de<a title=\"Alpha Particle\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\">decaimento alfa<\/a>para<sup>234<\/sup>Th com meia-vida de ~ 4,5 \u00d7 10<sup>9<\/sup>anos.\u00a0<sup>238<\/sup>U decai ocasionalmente por fiss\u00e3o espont\u00e2nea com probabilidade de 0,000055%.\u00a0Sua atividade espec\u00edfica \u00e9 muito baixa ~ 3,4 \u00d7 10<sup>-7<\/sup>\u00a0Ci \/ g.<\/li>\n<li><a title=\"Ur\u00e2nio 235\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/uranium-235\/\"><strong><sup>235<\/sup>\u00a0L<\/strong><\/a>\u00a0.\u00a0<sup>235<\/sup>U pertence ao grupo de<a title=\"Material f\u00edssil\" href=\"https:\/\/www.nuclear-power.com\/glossary\/fissile-material\/\">is\u00f3topos f\u00edsseis<\/a>.\u00a0De fato,<sup>235<\/sup>U \u00e9 o \u00fanico n\u00facleo f\u00edssil existente a partir de is\u00f3topos que ocorrem naturalmente e, portanto, \u00e9 um material altamente estrat\u00e9gico.\u00a0<sup>O<\/sup>decaimento de<sup>235<\/sup>U por decaimento alfa (via t\u00f3rio-231) em<sup>231<\/sup>Pa com meia-vida de ~ 7 \u00d7 10<sup>8<\/sup>anos.\u00a0<sup>235<\/sup>U ocasionalmente decai por fiss\u00e3o espont\u00e2nea com probabilidade muito baixa de 0,0000000072%.\u00a0Sua atividade espec\u00edfica \u00e9 muito baixa ~ 2,2 \u00d7 10-6 Ci \/ g.<\/li>\n<li><a title=\"Ur\u00e2nio 234\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/uranium-234\/\"><strong><sup>234<\/sup>\u00a0L<\/strong><\/a>\u00a0.\u00a0<sup>234<\/sup>U pertence ao grupo de<a title=\"Material f\u00e9rtil\" href=\"https:\/\/www.nuclear-power.com\/glossary\/fertile-material\/\">is\u00f3topos f\u00e9rteis<\/a>.\u00a0Decad\u00eancias de<sup>234<\/sup>U por decaimento alfa para<sup>230<\/sup>Th com meia-vida de 246 000 anos.\u00a0<sup>234<\/sup>U ocasionalmente decai por fiss\u00e3o espont\u00e2nea com probabilidade muito baixa de 0,0000000017%.\u00a0Sua atividade espec\u00edfica \u00e9 muito maior ~ 0,0063 Ci \/ g.<\/li>\n<\/ul>\n<p><strong><span>Is\u00f3topos de plut\u00f4nio<\/span><\/strong><\/p>\n<ul>\n<li><strong><sup><span>238<\/span><\/sup><span>\u00a0Pu<\/span><\/strong><span>\u00a0.\u00a0<\/span><sup><span>238<\/span><\/sup><span>\u00a0Pu pertence ao grupo de is\u00f3topos f\u00e9rteis.\u00a0<\/span><sup><span>238<\/span><\/sup><span>\u00a0decaimentos de Pu por decaimento alfa para<\/span><a title=\"Ur\u00e2nio 234\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/uranium-234\/\"><sup><span>\u00a0234<\/span><\/sup><span>\u00a0U<\/span><\/a><span>\u00a0\u00a0com meia-vida de 87,7 anos.\u00a0<\/span><sup><span>238<\/span><\/sup><span>\u00a0Pu gera calor de decomposi\u00e7\u00e3o muito alto e possui uma taxa muito alta de fiss\u00e3o espont\u00e2nea.<\/span><\/li>\n<li><a title=\"Plut\u00f4nio 239\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/plutonium\/plutonium-239\/\"><strong><sup><span>239<\/span><\/sup><span>\u00a0Pu<\/span><\/strong><\/a><span>\u00a0.\u00a0<\/span><sup><span>239<\/span><\/sup><span>Pu pertence ao grupo de is\u00f3topos f\u00edsseis.\u00a0<\/span><sup><span>239<\/span><\/sup><span>decaimentos de Pu por decaimento alfa para<\/span><a title=\"Ur\u00e2nio 235\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/uranium-235\/\"><sup><span>\u00a0235<\/span><\/sup><span>\u00a0U<\/span><\/a><span>\u00a0com meia-vida de 24100 anos.\u00a0Este is\u00f3topo \u00e9 o principal is\u00f3topo f\u00edssil em uso.<\/span><\/li>\n<li><a title=\"Plut\u00f4nio 240\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/plutonium\/plutonium-240\/\"><strong><sup><span>240<\/span><\/sup><span>\u00a0Pu<\/span><\/strong><\/a><span>\u00a0.\u00a0<\/span><sup><span>240<\/span><\/sup><span>Pu pertence ao grupo de<\/span><a title=\"Material f\u00e9rtil\" href=\"https:\/\/www.nuclear-power.com\/glossary\/fertile-material\/\"><span>is\u00f3topos f\u00e9rteis<\/span><\/a><span>.\u00a0<\/span><sup><span>240<\/span><\/sup><span>Pu decai por via alfa para<\/span><a title=\"Ur\u00e2nio 236\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/uranium-236\/\"><sup><span>\u00a0236<\/span><\/sup><span>\u00a0U<\/span><\/a><span>\u00a0com meia-vida de 6560 anos.\u00a0<\/span><sup><span>O 240<\/span><\/sup><span>Pu possui uma taxa muito alta de fiss\u00e3o espont\u00e2nea e uma se\u00e7\u00e3o transversal de captura radiativa alta para n\u00eautrons t\u00e9rmicos e tamb\u00e9m para resson\u00e2ncia.<\/span><\/li>\n<li><a title=\"Plut\u00f4nio 241\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/plutonium\/plutonium-241\/\"><strong><sup><span>241<\/span><\/sup><span>\u00a0Pu<\/span><\/strong><\/a><span>\u00a0.\u00a0<\/span><sup><span>241<\/span><\/sup><span>Pu pertence ao grupo de is\u00f3topos f\u00edsseis.\u00a0<\/span><sup><span>241<\/span><\/sup><span>Pu decai por via beta negativa para<\/span><sup><span>241<\/span><\/sup><span>AM com meia-vida de 14,3 anos.\u00a0Este is\u00f3topo f\u00edssil decai para is\u00f3topo n\u00e3o f\u00edssil com alta se\u00e7\u00e3o de captura radiativa para n\u00eautrons t\u00e9rmicos.\u00a0Um impacto na reatividade do combust\u00edvel nuclear \u00e9 \u00f3bvio.<\/span><\/li>\n<\/ul>\n<p><strong><span>Outros is\u00f3topos<\/span><\/strong><\/p>\n<ul>\n<li><sup><span>242<\/span><\/sup><span>\u00a0Cm.\u00a0Decaimentos de\u00a0<\/span><sup><span>242<\/span><\/sup><span>\u00a0Cm via decaimento alfa com meia-vida de 162 dias.\u00a0<\/span><sup><span>242<\/span><\/sup><span>\u00a0Cm ocasionalmente decai por fiss\u00e3o espont\u00e2nea com probabilidade de 0,0000061%.<\/span><\/li>\n<li><sup><span>252<\/span><\/sup><span>\u00a0Cf.\u00a0<\/span><sup><span>252<\/span><\/sup><span>\u00a0Cf (meia-vida 2.645 anos, raz\u00e3o de desvio SF de cerca de 3,1%) pode ser usado na fonte prim\u00e1ria de n\u00eautrons para melhor monitoramento das opera\u00e7\u00f5es de inicializa\u00e7\u00e3o e desligamento do reator quando o reator \u00e9 subcr\u00edtico.<\/span><\/li>\n<\/ul>\n<figure id=\"attachment_25153\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-25153\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/JANIS-Half-Life-Spontaneous-Fission.png\"><img loading=\"lazy\" class=\"size-large wp-image-25153 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/JANIS-Half-Life-Spontaneous-Fission-1024x513.png\" alt=\"JANIS - Meia-vida - Fiss\u00e3o espont\u00e2nea\" width=\"1024\" height=\"513\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/JANIS-Half-Life-Spontaneous-Fission-1024x513.png\" \/><\/a><figcaption id=\"caption-attachment-25153\" class=\"wp-caption-text\"><span>Fonte dos dados: JANIS (Software de Informa\u00e7\u00e3o de Dados Nucleares baseado em Java);\u00a0Biblioteca de Dados Nucleares JEFF-3.1.1<\/span><\/figcaption><\/figure>\n<h2><span>Fiss\u00e3o espont\u00e2nea e n\u00eautrons de origem<\/span><\/h2>\n<p><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Plutonium-breeding.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-12356 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Plutonium-breeding-300x225.png\" alt=\"cria\u00e7\u00e3o de plut\u00f4nio\" width=\"300\" height=\"225\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Plutonium-breeding-300x225.png\" \/><\/a><span>O termo\u00a0<\/span><strong><span>&#8221;\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/reactor-dynamics\/subcritical-multiplication\/source-neutrons-and-external-source-of-neutrons\/\"><span>n\u00eautrons de origem<\/span><\/a><span>\u00a0&#8220;<\/span><\/strong><span>\u00a0refere-se a n\u00eautrons que n\u00e3o sejam\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/fission\/prompt-neutrons\/prompt-neutrons-and-delayed-neutrons\/\"><span>n\u00eautrons de fiss\u00e3o r\u00e1pida ou retardada<\/span><\/a><span>\u00a0.\u00a0Em geral, eles v\u00eam de outras fontes que n\u00e3o a fiss\u00e3o induzida por n\u00eautrons.\u00a0Esses n\u00eautrons s\u00e3o muito importantes durante as opera\u00e7\u00f5es de inicializa\u00e7\u00e3o e desligamento do reator quando o reator \u00e9 subcr\u00edtico, porque permitem monitorar a subcriticalidade de um reator geralmente atrav\u00e9s de detectores de n\u00eautrons excore na faixa da fonte.<\/span><\/p>\n<p><span>Nos reatores nucleares, tamb\u00e9m a fiss\u00e3o espont\u00e2nea \u00e9 muito importante deste ponto de vista.\u00a0Em um conjunto de combust\u00edvel nuclear irradiado, existem nucl\u00eddeos que passam por um processo de fiss\u00e3o espont\u00e2nea.\u00a0Como foi escrito, a fiss\u00e3o espont\u00e2nea \u00e9, de fato, uma forma de decaimento radioativo que \u00e9 encontrada apenas em elementos qu\u00edmicos muito pesados \u200b\u200b(especialmente elementos transur\u00e2nicos).\u00a0Por exemplo,\u00a0<\/span><sup><span>240<\/span><\/sup><span>\u00a0Pu tem uma taxa muito alta de fiss\u00e3o espont\u00e2nea.\u00a0Para combust\u00edvel de alta combust\u00e3o, os n\u00eautrons fonte s\u00e3o fornecidos predominantemente por fiss\u00e3o espont\u00e2nea dos n\u00facleos de c\u00fario (Cm-242 e Cm-244).<\/span><\/p>\n<h2><span>Fonte prim\u00e1ria de n\u00eautrons<\/span><\/h2>\n<p><span>\u00c0s vezes, os n\u00eautrons de origem devem ser adicionados artificialmente ao sistema.\u00a0A fonte externa de n\u00eautrons cont\u00e9m um material que emite n\u00eautrons e revestimento para fornecer uma barreira entre o refrigerante do reator e o material.\u00a0Fontes externas geralmente s\u00e3o carregadas diretamente no n\u00facleo do reator (por exemplo, nos tubos de dedal guia).\u00a0Fontes de n\u00eautrons, baseadas na\u00a0<\/span><strong><span>fiss\u00e3o espont\u00e2nea,<\/span><\/strong><span>\u00a0s\u00e3o conhecidas como\u00a0<\/span><strong><span>fontes prim\u00e1rias<\/span><\/strong><span>\u00a0.\u00a0A fonte prim\u00e1ria de n\u00eautrons n\u00e3o precisa ser irradiada para produzir n\u00eautrons.\u00a0Essas fontes podem ser usadas especialmente no caso de um primeiro n\u00facleo (ou seja, um n\u00facleo que consiste apenas de combust\u00edvel novo).\u00a0A fonte prim\u00e1ria de n\u00eautrons \u00e9 baseada na rea\u00e7\u00e3o de fiss\u00e3o espont\u00e2nea.\u00a0A fonte de fiss\u00e3o espont\u00e2nea mais comumente usada \u00e9 o is\u00f3topo radioativo\u00a0<\/span><strong><span>californium-252<\/span><\/strong><span>.\u00a0Cf-252 e todas as outras fontes de n\u00eautrons de fiss\u00e3o espont\u00e2nea s\u00e3o produzidas por irradia\u00e7\u00e3o de ur\u00e2nio ou outro elemento transur\u00e2nico em um reator nuclear, onde os n\u00eautrons s\u00e3o absorvidos no material de partida e em seus produtos de rea\u00e7\u00e3o subsequentes, transmutando o material de partida no is\u00f3topo SF.<\/span><\/p>\n<\/div>\n<p>&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.<\/p>\n<p>Este artigo \u00e9 baseado na tradu\u00e7\u00e3o autom\u00e1tica do artigo original em ingl\u00eas. Para mais informa\u00e7\u00f5es, consulte o artigo em ingl\u00eas. Voc\u00ea pode nos ajudar. Se voc\u00ea deseja corrigir a tradu\u00e7\u00e3o, envie-a para: translations@nuclear-power.com ou preencha o formul\u00e1rio de tradu\u00e7\u00e3o on-line. Agradecemos sua ajuda, atualizaremos a tradu\u00e7\u00e3o o mais r\u00e1pido poss\u00edvel. Obrigado.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>A fiss\u00e3o espont\u00e2nea \u00e9 um processo de decaimento, no qual um n\u00facleo inst\u00e1vel se divide espontaneamente e aleatoriamente em partes menores (n\u00facleos mais leves).\u00a0As fiss\u00f5es espont\u00e2neas liberam n\u00eautrons como todas as fiss\u00f5es.\u00a0Dosimetria de Radia\u00e7\u00e3o Em geral,\u00a0a fiss\u00e3o nuclear\u00a0\u00e9 uma\u00a0rea\u00e7\u00e3o nuclear\u00a0na qual o n\u00facleo de um \u00e1tomo se\u00a0divide\u00a0em partes menores (n\u00facleos mais leves).\u00a0O processo de fiss\u00e3o &#8230; <a title=\"O que \u00e9 fiss\u00e3o espont\u00e2nea &#8211; defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-fissao-espontanea-definicao\/\" aria-label=\"More on O que \u00e9 fiss\u00e3o espont\u00e2nea &#8211; defini\u00e7\u00e3o\">Ler mais<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[51],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>O que \u00e9 fiss\u00e3o espont\u00e2nea - defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"A fiss\u00e3o espont\u00e2nea \u00e9 um processo de decaimento, no qual um n\u00facleo inst\u00e1vel se divide espontaneamente e aleatoriamente em partes menores (n\u00facleos mais leves). 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