Nuclear reactors

studied byStudied by 0 people
0.0(0)
learn
LearnA personalized and smart learning plan
exam
Practice TestTake a test on your terms and definitions
spaced repetition
Spaced RepetitionScientifically backed study method
heart puzzle
Matching GameHow quick can you match all your cards?
flashcards
FlashcardsStudy terms and definitions

1 / 22

flashcard set

Earn XP

Description and Tags

Nuclear reactors for A2 AQA Physics. From required knowledge to safety aspects.

23 Terms

1

What does the moderator do? What is it?

  • reduces the speed of neutrons

  • They slow down by colliding with the molecules of the moderator, resulting in a loss of momentum

  • Neutrons slowed down so they are in thermal equilibrium with the moderator

  • Ensures neutrons are more likely to be absorbed by uranium fuel

New cards
2

What do the control rods do?

  • absorbs neutrons

  • depth of control rods in the fuel rods is varied in order to reduce or increase rate of fission.

  • lowering rods decreases fission rate, more neutrons are absorbed

  • Also a safety precaution, rods can be lowered to ensure no reaction can take place.

New cards
3

What does the coolant do in a nuclear reactor?

  • transfers thermal energy between the water systems of a nuclear power plant

New cards
4

How does the coolant work in a nuclear reactor?

  • heat exchanger mediates thermal energy exchanges between different water systems

  • Coolant is pumped into the reactor at a cold temperature to extract the heat released by the fission reactions

  • In the heat exchanger, the coolant transfers the heat to water that is pumped in externally to produce steam

  • This steam then goes on to power electricity-generating turbines

New cards
5

What are the different water systems in a nuclear reactor?

  • Coolant (usually but not always water) used in the reactor vessel

  • Water and steam that drives the turbine

  • Condenser that cools the steam

New cards
6

What is shielding, what does it do?

Prevents ionising radiation from leaking into the immediate surroundings.

New cards
7

What materials are used for the moderator in a nuclear reactor?

materials that are poor at absorbing neutrons;

  • water

  • graphite

New cards
8

What materials are used for the control rods in a nuclear reactor?

  • boron

  • cadmium

New cards
9

What materials are used for the coolant in a nuclear reactor?

  • water

  • helium

  • molten salt

New cards
10

What materials are used for shielding in a nuclear reactor?

  • lead

  • concrete

New cards
11

What kind of waste does a nuclear reactor produce?

low, intermediate and high level waste.

New cards
12

What is the high-level waste produced from nuclear reactors?

  • fission fragments from fission of U-235 or spent fuel rods

  • Most dangerous type of waste as it has the longest half-life (thousands of years)

  • spent fuel rods are extremely hot so require additional care when being handled/stored

New cards
13

How is high-level waste disposed of/stored?

  • The waste is initially placed in cooling ponds of water close to the reactor for a number of years

  • Isotopes of plutonium and uranium are harvested to be used again

  • Waste is mixed with molten glass and made solid (this is known as vitrification)

  • Then it is encased in containers made from steel, lead, or concrete

  • This type of waste must be stored very deep underground

New cards
14

What is the intermediate level waste produced from nuclear reactors? How is it disposed of/stored?

  • Everything between daily used items and the fuel rods themselves

  • Usually, this is the waste produced when a nuclear power station is decommissioned and taken apart

  • This waste will have a longer half-life than the low-level waste, so it must be encased in cement in steel drums and stored securely underground

New cards
15

What is the low level waste produced from nuclear reactors? How is it disposed of/stored?

  • lightly contaminated waste such as clothing, gloves and tools

  • will be radioactive for a few years so may be encased in concrete and stored several metres underground until can be disposed of with regular waste

  • Has a shorter half-life than intermediate and high-level waste.

New cards
16

What is the critical mass?

New cards
17

What is a thermal neutron?

A neutron that is slow moving (has collided with the moderator?)

New cards
18

What is a chain reaction?

New cards
19

Which two factors must be controlled in a nuclear reactor to produce energy at the required rate?

  • the number of free neutrons in the reactor

  • the energy of the free neutrons

New cards
20

benefits /disadgvantages of usinf water as a moderator in nuclear reactors>

New cards
21

Risks of nuclear power

  • The production of radioactive waste is very dangerous and expensive to deal with

  • A nuclear meltdown, such as at Chernobyl, could have catastrophic consequences on the environment and to the people living in the surrounding area

New cards
22

Benefits of nuclear power

  • Nuclear power stations produce no polluting gases

  • They are highly reliable for the production of electricity

  • They require far less fuel as uranium provides far more energy per kg compared to coal and other fossil fuels

New cards
23

Points that affect nuclear energy in society

  • Nuclear power can scare people if they do not understand it

  • It is dangerous if not handled properly, yet it is invisible which can be difficult for some people to comprehend

  • increased education on nuclear energy, society can use this knowledge to inform their own decisions and opinions

New cards
robot