Fission and Fusion

Question 1

Nuclear fission =

Answer 1

type of nuclear reaction that is used to release energy from large and unstable atoms (eg
uranium or plutonium) by splitting them into 2 smaller atoms and releasing 2 or 3 neutrons

Question 2

why is spontaneous fission rare

Answer 2

needs to absorb a neutronbefore it will split

Question 3

describe the process of nuclear fission

Answer 3

• fire a neutron to a large unstable nuclei –> makes it even more unstable –> splits into 2 smaller daughter nuclei + release 2/3 neutrons + ENERGY (gamma)
• these neutrons repeat process with another nuclei
• CHAIN REACTION

Question 4

how is the amount of energy produced by fission in a nuclear reactor controlled

Answer 4

• by changing how quicky the Chain reaction can occur
• Control rods (boron) - lowered + raised inside nuclear reactor to absorb neutrons, slow down chain reaction and control amount of energy released

Question 5

what happens when nuclear fission becomes uncontrolled

Answer 5

• lots of energy released –> explosion

Question 6

Nuclear Fusion =

Answer 6

the process of forcing 2 atoms nuclei together to form a single larger nucleus

Question 7

describe the process of nuclear fusion

Answer 7

1. 2 light nuclei collide at very high speed and fuse to create a larger, heavier nucleus
2. E.g. hydrogen nuclei can fuse to produce helium nucleus
3. heavier nucleus8 produced does not have as much mass s the 2 sperate, light nuclei did.—> Some of the **mass of the lighter nuclei is converted into energy and released
4. Fusion releases a lot of energy (more than fission)

Question 8

why do we still not mainly use fusion for a source of energy

Answer 8

temperatures and pressures needed for fusion are so high that fusion reactors are really hard + expensive to build