Fission and Fusion - Atomic Structure Physics

Question 1

What is nuclear fission?

Answer 1

Type of nuclear reactions that used to release energy from large and unstable atoms by splitting them into smaller atoms

Question 2

What is spontaneous fission

Answer 2

Rarely happens, nucleas has to absorb a neutron before it will split

Question 3

What happens during nuclear fission?

Answer 3

1. Nucleus absorbs neutron - triggers fission
2. Forms 2 smaller nuclei, rougly equal in size (daughter nuclei)
3. They emit 2/3 neutrons and gamma radiation
4. These neutrons are absorbed by more unstable atoms and trigger fission again

CHAIN REACTION

Question 4

What happens to the energy not transferred to the kinetic energy stores of the products?

Answer 4

Carried away by gamma rays

Question 5

What can the energy carried away by gamma rays and in the kinetic energy stores od the remaining free neutrons and the other decay products be used to do?

Answer 5

Energy can be used to heat water, making steam to turn turbines and generators

Question 6

What controls the amount of energy produced by fission in a nuclear reactor?

Answer 6

Controlled by changing how quickly the chain reaction can occur - this is done by using control rods

Question 7

What do control rods do?

Answer 7

They are lowered and raised inside a nuclear reactor to absorb neutrons, slow down the chain reaction and control the amount of energy released

Question 8

How do nuclear weapons work?

Answer 8

Uncontrolled chain reactions quickly lead to lots of energy being released as an explosion

Question 9

What is nuclear fusion?

Answer 9

2 light nuclei collide at high speed ans join to create a larger heavier nucleus

Question 10

Which releases more energy?

Answer 10

Fusion

Question 11

What’s the problem with fusion?

Answer 11

The temps and pressures needed are so high that fusion reactors are really hard and expensive to build

Question 12

Why doesn’t the heavier nucleus produced by fusion not have as much mass as the 2 separate , light nuclei did?

Answer 12

Some mass of light nuclei is converted to energy and released

Question 13

Pros of nuclear energy

Answer 13

• Uranium or plutonium fuel is relatively cheap
• Fuel doesnt produce GG gases
• Fuel produces large and steady amount of energy

Question 14

Cons of nuclear energy

Answer 14

• Power plants expensive to build
• Nuclear waste expensive to get rid of
• Risk of major disaster

Question 15

What do all fission products have?

Answer 15

Kinetic energy

Question 16

Why does fusion produce large amounts of energy?

Answer 16

• Some mass of orignal nuclei is being converted to energy rather than being transferred
• So larger nuclei slightly lighter than total 2 light nuclei

Question 17

pros of fusion

Answer 17

• no gg gases produced
• easily make the hydrogen thats needed as fuel

Question 18

Why does fusion only happen at high temp and pressues?

Answer 18

to overcome the repulsion of the positively charged nuclei

Question 19

Which one produces nuclear waste?

Answer 19

Fission