Sometimes other signs and symptoms precede sudden cardiac arrest. These may include fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, weakness, palpitations or vomiting. But sudden cardiac arrest often occurs with no warning.
In the core of nuclear reactors, the fission of uranium atoms releases energy that heats water to about 520 degrees Farenheit. This hot water is then used to spin turbines that are connected to generators, producing electricity.
breeder reactor - a nuclear reactor that produces more fissile material than it burns. control rod - a steel or aluminum rod that can be moved up or down to control the rate of the nuclear reaction. core - the chamber of a nuclear reactor containing the fissile material where the reaction takes place.