Energy for Sustainable Society

4Nuclear Energy

Aerial view of Three Mile Island nuclear power plant on March 28, 1979, after the accident. (Photo: DOE, Public Domain.)

The Three Mile Island Unit 2 (TMI‐2) reactor, near Middletown, PA, partially melted down on March 28, 1979. This was the most serious accident in US commercial nuclear power plant operating history.

The facility was closed on September 20, 2019. Decommissioning is expected to take about 60 years.

4.1 Introduction

Unlike other forms of energy, nuclear energy is not a consequence of solar radiation reaching the Earth. Uranium and other radioactive elements used in nuclear reactors were created by nuclear reactions when the solar system was formed, not as a consequence of degradation of vegetation and living organisms like fossil fuels.

Nuclear energy was discovered while scientists were trying to understand the power source of the sun. Speculations started around the middle of the nineteenth century by several scientists including Kelvin and Helmholtz. Eddington proposed in 1920 that the fusion of hydrogen atoms could be the source of energy in the sun. Nuclear fusion was, however, not fully understood until quantum theory was developed in the late 1920s. Today, it is known that fusion reactions occur in the core of the sun and other stars where extremely high temperature hydrogen plasma is held by extremely large gravitational forces. Fusion ...