Radiation is a natural part of the environment. It is energy in the form of particles or waves. The two types of radiation are:

  • Non-ionizing, which does not have enough energy to change the structure of atoms. Examples include light, heat, microwaves and radio waves. Atoms of most elements are stable and won’t change on their own.
  • Ionizing, which has enough energy to change the structure of atoms. An atom with this excess energy is unstable and releases the surplus to reach a stable state. This natural process is called “decaying.” Ionizing radiation may damage the cells of living things by changing the structure of their molecules.

All of us benefit from radiation and radioactive materials. Among hundreds of other applications, they are used to administer medical treatments; test new medicines; generate electricity; detect flaws in aircraft; irradiate bacteria, parasites and insects in food; and power space satellites.



We are exposed to radiation every day in the air we breathe, the water we drink and the food we eat. Even the human body is naturally radioactive. The biological effects of radiation are measured in units called millirem. The government sets radiological protection standards based on millirem received over a specific period of time.

People in the United States are exposed to an average of about 360 millirem a year, about 82 percent of which comes from natural sources such as the human body, rocks, soil and cosmic radiation. A single dose of 100,000 millirem can be harmful.

During normal operations, the Susquehanna nuclear power plant releases minute quantities of radiation that are carefully controlled and are continuously monitored to stay well below the strict federal limits. The maximum amount of radiation a plant area resident receives is less than one-tenth of 1 millirem a year, which is 100 times less than what a person would receive from a single dental X-ray.



Contamination occurs when radioactive material contacts non-radioactive surfaces. Inside a nuclear power plant, tools and certain plant equipment routinely become contaminated. Plant workers wear special protective clothing and equipment to protect against contamination, and access to radiological areas is carefully controlled.


Measuring and detecting radiation

Radiation is measured by the number of atoms decaying per second. The unit of measure is a “curie,” which is equal to 37 billion atoms decaying per second.

The nuclear power plants have a series of monitors inside and outside to detect and measure any radiation released. The state and federal government also maintain radiation monitors in areas around nuclear plants.