2.9 - Nuclear decay and nuclear energy

Question 1

What is nuclear fission?

Answer 1

The splitting of large, unstable nuclei to from smaller more stable nuclei

Question 2

What usually needs to happen to induce fission?

Answer 2

The absorption of a slow moving neutron. This makes the nuclei unstable due to the imbalance in number of protons and neutrons.

Question 3

What term is used to describe nuclei in which fission can be induced through the absorption of slow neutrons?

Answer 3

Fissile Nuclei

Question 4

Alongside two smaller nuclei, what else is emitted in a fission reaction?

Answer 4

Two or three neutrons
Gamma rays (daughter nuclei are radioactive)
Energy

Question 5

What form of energy do all fission products have?

Answer 5

Kinetic energy

Question 6

Name a common fissile nuclei.

Answer 6

Uranuim-235

Question 7

What are the three main components of the core of a nuclear reactor?

Answer 7

1. Fuel rods
2. Control rods
3. Moderator

Question 8

What takes place during a chain reaction in a nuclear reaction?

Answer 8

An unstable nucleus absorbs a neutron
The nucleus undergoes fission and releases 2 or 3 further neutrons
These induce more fission, which results in a chain reaction

Question 9

What is the consequence of an uncontrolled chain reaction?

Answer 9

The rate of fission events becomes to high and results in the production of too much energy
This can lead to a nuclear explosion

Question 10

How is the chain reaction in a fission reactor kept under control?

Answer 10

Control rods are positioned in between the fuel rods
The rate of fission is controlled by moving these rods up and down
The lower the rods are inserted, the slower the rate of fission

Question 11

What is the role of the moderator in a nuclear reactor?

Answer 11

To slow down the neutrons so they are traveling which allow them to be absorbed by fissile nuclei and cause fission

Question 12

How is ionising radiation in the reactor prevented from escaping?

Answer 12

By steel and concrete walls. This is important because radiation can cause cancer.

Question 13

In a nuclear power station only one _____ is allowed to collide with other uranium-235 or plutonium-239 nuclei after a collision. The other neutrons that were released by the collision would cause a nuclear explosion if moveable control rods did not absorb them.

Answer 13

neutron

Question 14

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. Nearly all nuclear power plants have a containment building.

Why is the containment building designed?

Answer 14

1) to ensure that radioactive material is confined under all conditions
2) to ensure that the power plant is protected against all events
3) to provide radiation shielding under all conditions

Question 15

What is nuclear fusion?

Answer 15

The joining of two light nuclei to produce a heavier nucleus and release energy

Question 16

Name two isotopes of hydrogen which are commonly used in nuclear fusion

Answer 16

Deuterium and Tritium

Question 17

Which realises more energy, nuclear fission or nuclear fusion?

Answer 17

Nuclear fusion

Question 18

Explain the difficulty of generating energy through nuclear fusion

Answer 18

Fusion requires very high temperatures which in itself requires large quantities of energy and also requires casing which can withstand them

Question 19

Explain why nuclear fusion is currently not a viable way to produce energy on Earth?

Answer 19

With current equipment/techniques, the energy required is greater than the energy produced, resulting in a net energy loss

Question 20

Why are fission products particularly dangerous?

Answer 20

They have very long half-lives meaning they remain radioactive for a very long time.

Question 21

What is the nuclear symbol for a neutron?

Answer 21

1
n
0

{1 and 0 are before the n on top of one another in small font. The n is then to right of the two numbers and the same size as them on top of one anther}

Question 22

What are the advantages of nuclear fission?

Answer 22

Doesn’t produce CO2
Large amount of power produced
Uses a very small amount of fuel

Question 23

What are the disadvantages of nuclear fission?

Answer 23

Produces radioactive waste with a long half-life
Risk of nuclear meltdown
Expensive to decommission and store waste material

Question 24

What are the advantages of nuclear fusion?

Answer 24

Abundant source of deuterium and tritium in sea water
Doesn’t produce CO2
No long lived radioactive waste

Question 25

What are the disadvantages of nuclear fusion

Answer 25

High temp and pressure required
High energy input required
Radiation from neutrons need to be shielded against