What Happened; Japanese Reactors

WHAT HAPPENED The threatened Japanese nuclear reactors use nuclear fuel to boil water into steam that drives turbines to produce electricity. Here's a schematic showing generally how such a reactor works and what went wrong at one of the Japanese reactors, Fukushima Daiichi 1. 1. The tsunami knocked out power to the nuclear plant. 4. Steam was 5. Vented steam contained hydrogen, which triggered an explosion. vented from the reactor to reduce pressure. 2. Backup generators failed. 5 Secondary containment 3. Pumps failed to Primary containment deliver cool water into the reactor. 4 Steam Power out Core Water Nuclear fuel rods Turbines Control rods Heat exchanger Pumps Power to plant Backup generator 6. Nuclear agency officials say Japan is injecting sea water into the core to avoid a meltdown. SOURCES: US Energy Information Adminstration; Nuclear Energy Institute; AP DAVID BUTLER, PATRICK GARVIN/GLOBE STAFF