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Nuclear Power Plant. How A Nuclear Reactor Works. Pressurized Water Reactor - Nuclear Power Plant. A. Main Parts of a Nuclear Reactor. Fuel Pellets stacked in long metal tubes (fuel rods). These are arranged in bundles in the reactor with space between them for control rods. Moderator
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Nuclear Power Plant How A Nuclear Reactor Works
A. Main Parts of a Nuclear Reactor • Fuel • Pellets stacked in long metal tubes (fuel rods). These are arranged in bundles in the reactor with space between them for control rods. • Moderator • Slowsdown neutrons so they have a greater probability of colliding with another uraniumatom. Usually wateror graphite.
A. Main Parts of a Nuclear Reactor (continued) 3. Control System • Controlrods are filled with substances that absorbneutrons (boron or cadmium). These help control the rate of the reaction. 4. Heat Removal System • The reactor must be cooled to prevent overheating and melting of the core. Heat is carried away by water and used for steam production. 5. Radiation Shield • Thermal (steel) shield protects the walls of the reactor vessel from radiation damage. A concrete shield protects the workers from radiation.
B. Disposal Of Nuclear Waste When most usable uranium has fissioned, the “spent” fuel assembly is removed from the reactor. Until a long term storage facility is operational (Yucca Mountain, NV?), “spent” fuel is stored in water pools at the reactor site. Water removes leftover heat and serves as a radiation shield. Typical water pools for nuclear waste storage Underground disposal of radioactive waste (in Finland)
C. Nuclear Meltdown Refers to melting fuel in a reactor when there is an inability to remove heat effectively. Causes include a loss of coolant in the system and/or failure of the reactor to shut down when faulty. If a meltdown does occur, a release of radiation occurs only if there is a major failure in the containment structure (pressure, fire, explosion).
C. Nuclear Meltdown (continued) Chernobyl disaster • Ukraine (Soviet Union), 1986 • Worst nuclear power plant accident in history • 31 peopled during the accident itself, but more people suffered long-term effects like cancer and deformities
C. Nuclear Meltdown (continued) • Fukushima • Japan, March 2011 • Occurred after the power plant was hit by a tsunami • Although no fatalities were reported after the incident, over 300,000 people had to evacuate the area