1. Nuclear Power Plant
How A Nuclear Reactor Works

2. Pressurized Water Reactor - Nuclear Power Plant

3. 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
Slows down neutrons so they have a greater probability of colliding with another uranium atom. Usually water or graphite.

4. A. Main Parts of a Nuclear Reactor (continued)
3. Control System
Control rods are filled with substances that absorb neutrons (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.

5. 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)

6. 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).

7. C. Nuclear Meltdown (continued)
Chernobyl disaster
Ukraine (Soviet Union), 1986
Worst nuclear power plant accident in history
31 people died during the accident itself, but more people suffered long-term effects like cancer and deformities

8. C. Nuclear Meltdown (continued)
Fukushima Daini Nuclear Power Plant
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, and almost 16,000 died due to the earthquake and tsunami