How to control a chain reaction
To control the energy released in the reactor moveable control rods are placed between the fuel rods. These control rods are made of boron which absorbs some of the neutrons so fewer neutrons are available to split uranium nuclei. The control rods are raised to increase and lowered to decrease the number of free neutrons.
Materials in nuclear reactors
The chain reaction inside the reactor releases neutrons. If a material is put into the reactor some of these neutrons may be absorbed by the nuclei of its atoms. This will make an atom's nucleus unstable which means it has become radioactive.
How is information from a tracer collected?
By using a detector such as a gamma camera that is conected to a computer.
How are X-rays made?
X-rays are made by firing high-speed electrons at metal targets