Nuclear Fission and fusion

Question 1

What is nuclear fission

Answer 1

Nuclear fission is the splitting of a large and unstable nuclei into smaller nuclei

Question 2

How much energy does fission release

Answer 2

LOTS of energy

Question 3

What are the two ways fission can occur

Answer 3

-Fission either occurs spontaneously (unforced + by itself) this is rare however

-OR by absorbing a neutron making the nucleus even more unstable causing it to split - forced method.

Question 4

Describe the process of Fission

Answer 4

-Start with large unstable nuclei

-That nuclei then absorbs a neutron making it more unstable

-The nuclei then splits into two daughter nuclei, more neutrons are produced and lots of energy is released

-This process then repeats in a chain reaction.

Question 5

What happens when fission is not controlled properly?

Answer 5

If not controlled properly, the reaction can get out of hand and release significantly large amounts of energy e.g. nuclear bomb.

Question 6

How is fission controlled in nuclear reactors?

Answer 6

Rate of fission is controlled by control rods

They are lowered into the reactor to absorb neutrons and slow down the rate of reaction.

Question 7

Pros of fission

Answer 7

Uranium or plutonium fuel is relatively cheap

-Large and steady amounts of energy are produced

-Doesn’t produce greenhouse gases unlike fossil fuels

Question 8

Cons of fission

Answer 8

-Nuclear power plants are expensive
-Waste is also expensive to dispose of as it has to be buried underground in bunkers

-Risk of major disaster, although very unlikely if controlled properly (Chernobyl)
-This makes people suspicious of using nuclear energy

Question 9

Why are nuclear reactors surrounded by thick concrete

Answer 9

To slow down the rate of fission by absorbing neutrons and ionizing radiation

Question 10

What is nuclear fusion?

Answer 10

Fusion is when 2 smaller nuclei fuse together to form a larger nuclei

Question 11

What releases more energy, Fusion or fission

Answer 11

Fusion produces a lot more energy than Fission

Question 12

Where does Fusion occur

Answer 12

Only occurs in stars

Question 13

Equation to calculate energy

Answer 13

E = Mc2

Question 14

Does nuclear fusion produce any radioactive waste?

Answer 14

No

Question 15

What are the conditions needed for fusion

Answer 15

Extremely high temperature (10,000,000C)

and very high pressure.

Question 16

Differences between fusion and fission

Answer 16

Fusion:
-Fusion of lighter nuclei into heavier nuclei
-Releases tons of energy (way more than fission)
-Only happens inside of stars due to the extremely high temperature and pressure required

Fission:
-Large unstable nuclei splitting into 2 smaller nuclei
-Produces lots of energy (not as much as fusion)
-Used on Earth to produce energy

Question 17

What are the charges of Beta and Alpha particles

Answer 17

Beta is negatively charged and Alpha is positively charged

Question 18

Give 2 differences between Alpha radiation and Beta radiation

Answer 18

-Alpha has a higher mass than Beta

-Beta particles are negatively charged whereas Alpha particles are positively charged

Question 19

What are the hazards of being surrounded by Radon gas

Answer 19

-Radon easily enters the body through inhalation as it is a gas, which can cause irradiation in internal organs, it is also alpha which is extremely dangerous when inside the body.

Question 20

Define the term half-life

Answer 20

The amount of time taken for a radioactive atom’s activity to halve.

Question 21

Describe the process of fission in uranium-235

Answer 21

-Uranium absorbs a neutron and becomes uranium-236
-The nuclei then splits producing more neutrons and two daughter nuclei
-Releases lots of energy
-The reaction then repeats

Question 22

Why do coolants in the reactor have a pressure exerted on them?

Answer 22

-The gas particles collide with the tube walls
-Exerting force on the walls
-Pressure is force exerted over an area

Question 23

What is meant by a chain reaction

Answer 23

Fission releases neutrons
-Daughter cells from previous reaction then absorb the neutrons undergoing fission

Question 24

Why do nuclei move apart from each other

Answer 24

As they are both positively charged, they repel from each other

Question 25

Why does fusion only occur at high temperature and high pressure

Answer 25

-The nuclei are similarly charged so they repel
-They move too slowly at low temperature, so they can’t get close enough for fusion to occur

Question 26

Describe the role of shielding around a nuclear reactor

Answer 26

-It prevents radiation escaping the nuclear reactor by absorbing neutrons.

Question 27

Why is a fusion reactor possibly safer than a fission reactor

Answer 27

-The products aren’t radioactive

-So there is no risk of mutation of cells and cancer

-The products don’t need to be stored long-term as they aren’t as much of a health risk.

-The reactants aren’t as hazardous.

Question 28

Name a fuel used in the reactor of a nuclear power station

Answer 28

Uranium or plutonium

Question 29

If i nucleus is in a fusion reactor and experiences a force to the left, how must the nucleus be behaving?

Answer 29

-The nucleus must be moving downwards.

Question 30

What happens to an atoms proton number and number of neutrons when beta decay occurs?

Answer 30

-It gains 1 proton and loses one neutron.