TEMAS RELACIONADOS COM O ACIDENTE NUCLEAR DO JAPÃO

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1 TEMAS RELACIONADOS COM O ACIDENTE NUCLEAR DO JAPÃO Funcionamento de uma usina nuclear Aspectos de segurança Prof. Nemitala Added junho 2011

2 Geração de energia elétrica Movimentação de turbina Variação de fluxo magnético em espiras Térmoelétrica Hidroelétrica Gasto de elemento combustível Nuclear

3 Combustível Fissão induzida por neutron Urânio (235/238) ou Plutônio (239) Partículas pesadas + neutrons (>1) (reação em cadeia) Controle Limitar número fissões Absorção de neutros (barras de Cd) Fissão induzida por neutron Moderador Melhorar eficiência Ajustar energia neutrons Urânio (235) neutrons térmicos Água ou grafite (baixar energia)

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6 Nuclear power plants in commercial operation Reactor type Pressurised Water Reactor (PWR) Main Countries Num GWe Fuel Coolant Moderator US, France, Japan, Russia, China enriched UO 2 water water Boiling Water Reactor (BWR) US, Japan, Sweden enriched UO 2 water water Pressurised Heavy Water Reactor 'CANDU' (PHWR) Canada natural UO 2 heavy water Gas-cooled Reactor (AGR & Magnox) UK heavy water natural U (metal), CO 2 graphite enriched UO 2 Light Water Graphite Reactor (RBMK) Russia enriched UO 2 water graphite Fast Neutron Reactor (FBR) Japan, Russia PuO 2 and UO 2 liquid sodium Other Russia enriched UO 2 water graphite TOTAL none

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10 Usinas no Brasil Name Type Capacity (MW e ), net/gross Status Angra-1 PWR 626MWe Net CNAA-Central Commercial Operation Angra-2 PWR 1275MWe Net CNAA-Central Commercial Operation Research Reactors São Paulo IEA-R1 Pool-type reactor, 5MW IPEN-Instituto de Pesquisas Energéticas e Nucleares, São Paulo, SP (criticality ) Belo Horizonte IPR-R1 TRIGA Mark I, 250 kw - CDTN-Centro de Desenvolvimento de Tecnologia Nuclear, Belo Horizonte, MG (criticality ) Rio de Janeiro ARGONAUTA Argonaut class reactor, 100 kw IEN-Instituto de Engenharia Nuclear,Rio de Janeiro, RJ (criticality ) São Paulo IPEN/MB-01 Critical assembly, 0.1 kw IPEN-Instituto de Pesquisas Energéticas e Nucleares,São Paulo, SP (criticality )] wikipedia

11 Aspectos de segurança Usinas nucleares usam uma proporção de 3-4% de U-235 e 96-97% de U-238. Reatores nucleares para pesquisa, como os do Instituto de Pesquisas Energéticas e Nucleares (Ipen), usam cerca de 20% de U Já as bombas atômicas usam 90% de U-235. O urânio natural possui somente 0,7% de U-235. When a meltdown occurs in a reactor, the reactor "melts". That is, the temperature rises in the core so much that the fuel rods actually turn to liquid, like ice turns into water when heated. If the core continued to heat, the reactor would get so hot that the steel walls of the core would also melt. In a complete reactor meltdown, the extremely hot (about 2700 Celsius) molten uranium fuel rods would melt through the bottom of the reactor and actually sink about 50 feet into the earth beneath the power plant. The molten uranium would react with groundwater, producing large explosions of radioactive steam and debris that would affect nearby towns and population centers. Comciencia.com +?

12 Combustível acondicionado em discos cerâmicos dentro de tubos de Zircônio (1400 C para danificar) Fusão do elemento cerâmico + urânio (2800 C)

13 International Nuclear and Radiological Event Scale (INES) was introduced in 1990 by the International Atomic Energy Agency (IAEA) in order to enable prompt communication of safety significance information in case of nuclear accidents. logarithmic INES level of an incident is assigned well after the incident occurs Acidentes em usinas nucleares

14 Radiation accidents Serious radiation accidents include: 1959, 1964, Santa Susana Field Laboratory, Los Angeles, California. Partial meltdowns. September 1957 Mayak nuclear waste storage tank explosion at Chelyabinsk. Two hundred plus fatalities, believed to be a conservative estimate; 270,000 people were exposed to dangerous radiation levels. Over thirty small communities had been removed from Soviet maps between 1958 and (INES level 6). July 1961 Soviet submarine K-19 accident. Eight fatalities and more than 30 people were overexposed to radiation Radiation accident in Mexico City, four fatalities. January 1969 Lucens reactor in Switzerland undergoes partial core meltdown leading to massive radioactive contamination of a cavern Church Rock uranium mill spill in New Mexico, USA. March 1984 Radiation accident in Morocco, eight fatalities. August 1985 Soviet submarine K-431 accident. Ten fatalities and 49 other people suffered radiation injuries. September 1987 Goiania accident. Four fatalities and 249 other people received serious radiation contamination. December 1990 Radiotherapy accident in Zaragoza. Eleven fatalities and 27 other patients were injured. April accident at the Tomsk-7 Reprocessing Complex, when a tank exploded while being cleaned with nitric acid. The explosion released a cloud of radioactive gas. (INES level 4) Radiotherapy accident in Costa Rica. Thirteen fatalities and 114 other patients received an overdose of radiation. February Three deaths and ten injuries resulted in Samut Prakarn when a radiation-therapy unit was dismantled. April Mayapuri radiological accident, India, one fatality. March Fukushima I nuclear accidents, Japan (current event).

15 Dose Absorvida (D) Dose Energia Massa depositada = Gy =J/kg Dose Equivalente (H eq ) = D x Qualidade (Sv) (Gy) Tipo de radiação Fator de Qualidade Raios X, gama e elétrons 1 Neutrons térmicos 2,3 Neutrons e prótons de energia desconhecida Partículas com carga unitária e massa > 1 e energia desconhecida Partículas alfa e partículas com carga múltiplas Fragmentos de fissão

16 Dose Efetiva (H ef ) = H eq x W i Fatores Peso (W) 0,20 gonadas 0,12 médula óssea, pulmão,cólon, estomago 0,05 bexiga, mama, fígado, esôfago, tireóide 0,01 pele, superfícies ósseas 0,05 - outros Dose Equivalente Limites Trabalhadores População Dose Efetiva (Corpo int) 20 msv/ano [1] 1 msv/ano [2] Cristalino 150 msv/ano 15 msv/ano Pele 500 msv/ano 150 msv/ano Extremidades 500 msv/ano 50 msv/ano [1] média em 5 anos com máximo de 50 m Sv em um ano [2] média em cinco anos [3] - restrição suplementar para gestantes:não podem receber mais de 2 msv de dose equivalente na superfície do abdômen durante o período da gravidez

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18 1 Sv de uma vez - doença Significativamente > 1 Sv morte Dose em tempo curto x tempo longo (cumulativo) mais danos x riscos câncer 0,05 µsv 20 µsv 10 msv 1 Sv

19 Dormir próximo a alguém morar a 80 km de usina nuclear comer 1 banana 0,05 µsv 0,09 µsv 0,10 µsv RX dentário 5 µsv Vôo de NY a LA 40 µsv

20 RX tórax 20 µsv tudo do esquema azul 60 µsv dose max ext 3 Mile Island 1 msv mamografia 3 msv dose durante 1 h Tchernobyl msv dose max anual trabalhador 50 msv

21 1 Sv 10 min núcleo Tchernobyl após explosão tudo do esquema verde: 75 msv Pode ser fatal Sintomas 400 msv 2000 msv Fatal: 8000 msv = 8 Sv 50 Sv

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