When Things Go Awry

On Wednesday, March 28, 1979, the residents of Middleton, PA woke up to a very scary situation. A nuclear power plant near the town had experienced a series of malfunctions that led to the release of some radioactive gases into the atmosphere, along with a partial meltdown of the reactor core. Fortunately, follow-up studies have shown that there were no health effects on workers or the general public. A thorough investigation was conducted that led to significant improvements in safety and operations of these power plants. One of the two reactors was shut down completely, but the other one is still in operation and will be permanently deactivated in 2014.

Nuclear Power Generation

The generation of electricity is critical for operation of businesses, health care delivery, schools, homes, and other areas requiring the use of electrical power. According to 2011 statistics, coal is used for 42% of the total power generated, with natural gas being employed for another 25%. Nuclear power plants are employed in about 19% of the cases, with renewable energy sources supplying the last 13%. All of these fuels are used to heat water to generate steam. The steam then turns a turbine to generate electricity.

Figure 1 shows the layout of a typical nuclear power plant. The radioactive rods are in the red container along with water, which is heated to steam. The energy for this heat comes from fission reactions of uranium. The steam passes through the turbine and causes the turbine to spin, generating electricity. As the steam condenses, it is run through a cooling tower to lower its temperature. The water then recirculates through the reactor core to be used again.

Figure 1. Schematic for a nuclear power plant.

Figure 2. Nuclear submarine.

The control rods play an important role in the modulation of the nuclear chain reaction (usually a collision of a neutron with uranium). Each collision produces more neutrons than were present initially. If left unsupervised, the reaction would soon get out of control. Rods are commonly made of boron or a number of metals and metal alloys. The purpose of the control rods is to absorb neutrons to regulate the rate of the chain reaction so that the water does not overheat and destroy the reactor.

Nuclear power is also used to propel ships. The turbine can be connected to a propeller system. The rotating turbine shaft will turn the propeller to move the ship.

Summary

• The importance of nuclear power in generating electricity is described.
• The operation of a nuclear power plant is described.

Practice

Read the material at the link below and answer the following questions:

http://www.epa.gov/radtown/nuclear-plant.html

1. How hazardous is enriched uranium?
2. How is spent nuclear waste stored?
3. Why are people who live near nuclear power plants issued potassium iodide tablets?

Review

1. How much of our nation’s electricity is provided by nuclear power?
2. What heats the water to generate steam in a nuclear power plant?
3. What is the function of the control rods?