Physics - Nuclear decay and Nuclear energy Flashcards
What is nuclear fission?
The splitting of a large nucleus to produce two smaller ones.
Fission is another word for splitting.
What is a chain reaction?
A nuclear chain reaction occurs when a neutron splits a nucleus, releasing more neutrons, which in turn go on to split even more nuclei.
What fuel is usually used for nuclear fission?
Uranium or plutonium isotopes are normally used as the fuel in nuclear reactors. Their atoms have relatively large nuclei that are easy to split, especially when hit by neutrons.
What happens when a uranium or plutonium nucleus is hit by a neutron?
-the nucleus splits into two smaller nuclei known as daughter nuclei, which are radioactive
-two or three more neutrons are released
-some energy is released in the form of kinetic energy of the particles produced
What is an example of a moderator? What does it do?
Most nuclear reactors use water as a moderator, it is used to control rate of reaction and can also act as a coolant.
What are absorption rods/control rods?
The control rods are neutron-absorbing rods, which are inserted into the spaces between the fuel rods, and are made from materials such as boron. The control rods can be moved down into the reactor, which slows the reaction down by absorbing more of the neutrons, or moved up so that fewer of the neutrons are absorbed, which means that the reaction remains constant and explosions do not occur.
How are nuclear reactors contained?
The nuclear reactor is housed within a steel pressure container inside another containment building, which is usually made out of concrete. The containment building surrounds the nuclear reactor.
The containment building is designed:
to ensure that radioactive material is confined under all conditions
to ensure that the power plant is protected against all events
to provide radiation shielding under all conditions
What is electrostatic repulsion?
Nuclear fusion involves a deuterium (hydrogen-2) and a tritium (hydrogen-3) nucleus colliding and being forced together. Both nuclei are positively charged and therefore will repel each other. This is known as electrostatic repulsion.
