Unit 5: Nuclear energy

Question 1

What is the equation that links energy and mass

Answer 1

E=MC^2

Question 2

Define mass defect

Answer 2

The difference between the mass of a nucleus and its seperated constituent parts

Question 3

Explain why energy is given when nucleons are “fused”

Answer 3

As they join, the total mass decreases. This lost mass is converted into energy hence e=mc^2

Question 4

Define binding energy

Answer 4

They energy required to separate all of the nucleons in a nucleus

Question 5

State the typically unit used to measure binding energy

Answer 5

MeV

Question 6

How does one calculate binding energy

Answer 6

1 - Convert the atomic mass unit into kg

2 - use e=mc^2

Question 7

State the relationship between mass defect and binding energy

Answer 7

They are equivalent

Question 8

What is implied by a high binding energy per nucleon

Answer 8

More energy is required to remove nucleons from the nucleus

Question 9

At which point on the binding energy/mass number graph do the most stable nuclei occur

Answer 9

The maximum - which is Iron (Fe)

Question 10

Why does fusion release so much energy

Answer 10

For a little change in mass number, comes a huge change in the binding energy per nucleon

Question 11

Explain the process by which energy is released in fission

Answer 11

Large nuclei (past Iron) are split into two smaller nuclei which means there is an increase in the binding energy per nucleon

Question 12

Explain the process of “induced” fission and chain reaction

Answer 12

A neutron is fired at a Uranium-235 nucleus making the nucleus very unstable. This uranium nucleus randomly splits into two smaller nuclei and when this happens more neutron are produced which then induce other nuclei to fission

Question 13

Explain why the neutrons need to be Thermal Neutrons for the chain reaction to take place

Answer 13

Thermal neutrons are slowed down and needs to be so, such that the uranium nuclei accept the neutron thus causing the chain reaction

Question 14

Explain the use of having the fuel rods in moderators(water)

Answer 14

To slow/absorb neutrons such that the reactors does not over heat and meltdown

Question 15

What are control rods and how do they work

Answer 15

Rods made of boron, used to control the rate of the reaction by limiting the number of neutrons in the nuclear reactor.
They are all released in the case of an emergency

Question 16

What is “critical mass”

Answer 16

The amount of fuel needed for the reaction to perpetuate

Question 17

How does the reactor actually generate electricity

Answer 17

Heat from the reactor is used to make steam powering turbines

Question 18

What infrastructure is in place to prevent radiation seeping out

Answer 18

The reactor is surrounded by a thick concrete case.

Question 19

What happens to waste produced in reactors

Answer 19

Placed in cooling pond to decrease temperate then stored underground in sealed contrainers