Radiation is the travel of energetic particles through space. It takes different forms and can be divided into ionizing and non-ionizing radiation.
Ionizing radiation is different. It can cause harm, and great care must be taken when working with ionizing radiation. Everything around us is radioactive: the rocks that we walk on, the food that we eat, the air that we breathe, even our own bodies contain radioactive material, and they all emit radiation. There's radiation from the sky, the stars and the sun. Because of the altitude, air stewardesses and pilots receive more of this cosmic radiation on average than people at sea level (and in fact more than workers in nuclear power plants.)
Alpha, beta and gamma ionizing radiation is emitted from various materials used in nuclear power stations. Radiation is emitted as either particles or waves. The nuclear discharges from a nuclear power plant are well within all the limits set by the government and by nuclear industry regulators. These are limits that are set to maximize safety for the workforce, the local community and the region. Discharges into the sea and air are constantly measured to ensure that people and the environment are not harmed. The radiation exposure that people receive is monitored to ensure that it meets all the limits set down by the regulators and by internationally accepted practice.
Radiation is also one of the three primary modes of heat transfer. All matter with a temperature above absolute zero emits thermal radiation.