Risk of Meltdown

Risk of meltdown Normal operation 3 During normal operation, sea water is pumped into a condenser that converts steam into water, which is pumped back to the reactor. At the core, fuel rods of 1 uranium pellets housed in Spent fuel pool Secondary containment building zirconium produce tremendous heat by nuclear reaction called fission. This heat turns the water Containment Generator into steam, which drives turbines to generate electricity. vessel of concrete and steel Steam Fuel rods Turbine Reactor core Water discharge 7. Control rods Water intake 2 The reaction can be controlled or stopped by control rods that can be raised between the fuel rods. Condenser Sea water Suppression Pool Post-shutdown cooling operations Worst-case scenario (Complete meltdown) If emergency teams are unable to cool the core, uranium can melt into radioactive lava that has a At the time of the earthquake, the control rods were inserted to halt fission in a safety response. But the fuel rods stayed at a high temperature. The cooling system failed when the quake knocked out electricity, and then the tsunami swamped backup diesel generators. Emergency teams started flooding sea water into the core and containment vessel, but structural damage and a lack of power prevented a complete cool-down. chance of burning its way out of the containment system. Exposed spent rods in the pool could also lead to fires. Sea water Sea water SOURCE: Scientific American, Nuclear Energy Institute JAVIER ZARRACINA, DAIGO FUJIWARA/GLOBE STAFF Risk of meltdown Normal operation 3 During normal operation, sea water is pumped into a condenser that converts steam into water, which is pumped back to the reactor. At the core, fuel rods of 1 uranium pellets housed in Spent fuel pool Secondary containment building zirconium produce tremendous heat by nuclear reaction called fission. This heat turns the water Containment Generator into steam, which drives turbines to generate electricity. vessel of concrete and steel Steam Fuel rods Turbine Reactor core Water discharge 7. Control rods Water intake 2 The reaction can be controlled or stopped by control rods that can be raised between the fuel rods. Condenser Sea water Suppression Pool Post-shutdown cooling operations Worst-case scenario (Complete meltdown) If emergency teams are unable to cool the core, uranium can melt into radioactive lava that has a At the time of the earthquake, the control rods were inserted to halt fission in a safety response. But the fuel rods stayed at a high temperature. The cooling system failed when the quake knocked out electricity, and then the tsunami swamped backup diesel generators. Emergency teams started flooding sea water into the core and containment vessel, but structural damage and a lack of power prevented a complete cool-down. chance of burning its way out of the containment system. Exposed spent rods in the pool could also lead to fires. Sea water Sea water SOURCE: Scientific American, Nuclear Energy Institute JAVIER ZARRACINA, DAIGO FUJIWARA/GLOBE STAFF Risk of meltdown Normal operation 3 During normal operation, sea water is pumped into a condenser that converts steam into water, which is pumped back to the reactor. At the core, fuel rods of 1 uranium pellets housed in Spent fuel pool Secondary containment building zirconium produce tremendous heat by nuclear reaction called fission. This heat turns the water Containment Generator into steam, which drives turbines to generate electricity. vessel of concrete and steel Steam Fuel rods Turbine Reactor core Water discharge 7. Control rods Water intake 2 The reaction can be controlled or stopped by control rods that can be raised between the fuel rods. Condenser Sea water Suppression Pool Post-shutdown cooling operations Worst-case scenario (Complete meltdown) If emergency teams are unable to cool the core, uranium can melt into radioactive lava that has a At the time of the earthquake, the control rods were inserted to halt fission in a safety response. But the fuel rods stayed at a high temperature. The cooling system failed when the quake knocked out electricity, and then the tsunami swamped backup diesel generators. Emergency teams started flooding sea water into the core and containment vessel, but structural damage and a lack of power prevented a complete cool-down. chance of burning its way out of the containment system. Exposed spent rods in the pool could also lead to fires. Sea water Sea water SOURCE: Scientific American, Nuclear Energy Institute JAVIER ZARRACINA, DAIGO FUJIWARA/GLOBE STAFF Risk of meltdown Normal operation 3 During normal operation, sea water is pumped into a condenser that converts steam into water, which is pumped back to the reactor. At the core, fuel rods of 1 uranium pellets housed in Spent fuel pool Secondary containment building zirconium produce tremendous heat by nuclear reaction called fission. This heat turns the water Containment Generator into steam, which drives turbines to generate electricity. vessel of concrete and steel Steam Fuel rods Turbine Reactor core Water discharge 7. Control rods Water intake 2 The reaction can be controlled or stopped by control rods that can be raised between the fuel rods. Condenser Sea water Suppression Pool Post-shutdown cooling operations Worst-case scenario (Complete meltdown) If emergency teams are unable to cool the core, uranium can melt into radioactive lava that has a At the time of the earthquake, the control rods were inserted to halt fission in a safety response. But the fuel rods stayed at a high temperature. The cooling system failed when the quake knocked out electricity, and then the tsunami swamped backup diesel generators. Emergency teams started flooding sea water into the core and containment vessel, but structural damage and a lack of power prevented a complete cool-down. chance of burning its way out of the containment system. Exposed spent rods in the pool could also lead to fires. Sea water Sea water SOURCE: Scientific American, Nuclear Energy Institute JAVIER ZARRACINA, DAIGO FUJIWARA/GLOBE STAFF Risk of meltdown Normal operation 3 During normal operation, sea water is pumped into a condenser that converts steam into water, which is pumped back to the reactor. At the core, fuel rods of 1 uranium pellets housed in Spent fuel pool Secondary containment building zirconium produce tremendous heat by nuclear reaction called fission. This heat turns the water Containment Generator into steam, which drives turbines to generate electricity. vessel of concrete and steel Steam Fuel rods Turbine Reactor core Water discharge 7. Control rods Water intake 2 The reaction can be controlled or stopped by control rods that can be raised between the fuel rods. Condenser Sea water Suppression Pool Post-shutdown cooling operations Worst-case scenario (Complete meltdown) If emergency teams are unable to cool the core, uranium can melt into radioactive lava that has a At the time of the earthquake, the control rods were inserted to halt fission in a safety response. But the fuel rods stayed at a high temperature. The cooling system failed when the quake knocked out electricity, and then the tsunami swamped backup diesel generators. Emergency teams started flooding sea water into the core and containment vessel, but structural damage and a lack of power prevented a complete cool-down. chance of burning its way out of the containment system. Exposed spent rods in the pool could also lead to fires. Sea water Sea water SOURCE: Scientific American, Nuclear Energy Institute JAVIER ZARRACINA, DAIGO FUJIWARA/GLOBE STAFF Risk of meltdown Normal operation 3 During normal operation, sea water is pumped into a condenser that converts steam into water, which is pumped back to the reactor. At the core, fuel rods of 1 uranium pellets housed in Spent fuel pool Secondary containment building zirconium produce tremendous heat by nuclear reaction called fission. This heat turns the water Containment Generator into steam, which drives turbines to generate electricity. vessel of concrete and steel Steam Fuel rods Turbine Reactor core Water discharge 7. Control rods Water intake 2 The reaction can be controlled or stopped by control rods that can be raised between the fuel rods. Condenser Sea water Suppression Pool Post-shutdown cooling operations Worst-case scenario (Complete meltdown) If emergency teams are unable to cool the core, uranium can melt into radioactive lava that has a At the time of the earthquake, the control rods were inserted to halt fission in a safety response. But the fuel rods stayed at a high temperature. The cooling system failed when the quake knocked out electricity, and then the tsunami swamped backup diesel generators. Emergency teams started flooding sea water into the core and containment vessel, but structural damage and a lack of power prevented a complete cool-down. chance of burning its way out of the containment system. Exposed spent rods in the pool could also lead to fires. Sea water Sea water SOURCE: Scientific American, Nuclear Energy Institute JAVIER ZARRACINA, DAIGO FUJIWARA/GLOBE STAFF