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.
Control Rods. The nuclear chain reaction may be controlled using a device called a control rod. Control rods are made of materials which absorb neutrons. Thus, when a control rod is inserted into a nuclear reactor it reduces the number of free neutrons available to cause the uranium atoms to fission.