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Nuclear physics CGP > Nuclear Fission And Fusion Page 166-167 > Flashcards

Nuclear Fission And Fusion Page 166-167 Flashcards

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1
Q

Fission means

A

Splitting up into smaller parts

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2
Q

Large nuclei with at least 83 protons e.g. uranium are… and some can randomly split into ..
This is called

A

Unstable

Two smaller nuclei

Nuclear fission

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3
Q

Nuclear fission is called spontaneous if it… Or induced if…

A

Just happens by it self

We encourage it to happen

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4
Q

Fission can be induced by …

Only …. neutrons (called thermal neutrons) can be captured in this way

A

Making a neutron enter a 235U nucleus causing it to become very unstable

Low energy

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5
Q

What is released during nuclear fission and why

A

Energy is released during nuclear fission because the new smaller nuclei have a higher binding energy per nucleon

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6
Q

The larger the nucleus the more … it will be.

So large nuclei are more likely to..
This means that spontaneous fission limits… that a nucleus can contain
I.e. it limits the number of

A

Unstable

Spontaneously fission

The number of nucleons

Possible elements

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7
Q

Controlled nuclear reactors produced

A

Useful power

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8
Q

We can harness the energy released during nuclear fusion reactions in a
But it’s important that these reactions are very carefully…

A

Thermal Nuclear reactor

Controlled

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9
Q

Nuclear reactors use rods of… as ‘fuel’ for fission reactions

(The roads also contain a lot of… But that doesn’t undergo fission)

A

Uranium that are rich in 235U

238U

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10
Q

Rods of you uranium that are rich in 235U are placed into the nuclear reactor… which keeps workers as far away from the radiation as possible

A

Remotely

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11
Q

In a nuclear reactor:
These fission reactions produce more neutrons which then
This is called a

A

Induce Other nuclei to fission

Chain reaction

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12
Q

In a nuclear reactor:
The neutrons will only cause a chain reaction if they are

Which allows them to

The 235U fuel rods need to be placed in a… To further slowdown and/or…

These slowed down neutrons are called

This happens through …(kinetic energy is conserved) with nuclei of the moderator material

Collisions with particles of a similar mass are more…

Water is often used as a moderator because it

A

Slowed down

Be captured by the uranium nuclei

Moderator ( for example water)

Absorb neutrons

Thermal neutrons

Elastic collisions

Efficient at slowing neutrons down

It contains hydrogen which fits this condition

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13
Q

Nuclear reactors:
You want the chain reaction to continue on its own at a… Where one fission follows another

The Amount of ‘fuel’ you need to do this is called the..

A

Steady rate

Critical mass – any less than the critical mass (sub-critical mass) and the reaction will just peter out

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14
Q

Nuclear reactors use a… mass of fuel (where several new fissions normally follow each fission)

A

Supercritical mass

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15
Q

Nuclear reactor is control the rate of fission using

A

Control rods

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16
Q

Nuclear reactor:
Control rods control The chain reaction by

These … neutrons so that the rate of fission is controlled

A

Limiting the number of neutrons in the reactor

Absorb

17
Q

Control rods are made up of a material that… neutrons e.g.…

And they can be inserted by varying amounts to control the reaction rate

A

Absorbs

Boron

18
Q

Nuclear reactor:
In an emergency the nuclear reactor will be Shut down automatically by the… Which will stop the reaction as quickly as possible

A

The release of the control rods into the reactor

19
Q

Coolant is sent around the nuclear reactor to… produced in the fission

Often the coolant is the same water that is being used in the reactor as a…

The heat from the reactor can then be used to make… For…

A

Remove heat

Moderator

Steam for poweringElectricity generating turbines

20
Q

The nuclear reactor is surrounded by a… Which acts as shielding

This prevents… And reaching the people working in the power station

A

Thick concrete case

Radiation escaping

21
Q

Waste products of fission must be

A

Stored carefully

22
Q

Nuclear fission produces lots of… And creates less greenhouse gases then…

But there are still lots of dangerous waste products

A

Energy

Burning fossil fuels

23
Q

The waste products of nuclear fission usually have a…

This makes them

A

Larger proportion of neutrons than nuclei of a similar atomic number

this makes them unstable and radioactive

24
Q

The waste products of nuclear fusion can be used for practical applications such as

However they may be highly radioactive and so the handling and… Needs great care

A

Traces in medical diagnosis

Storage

25
Q

When material is removed from the reactor it is initially …So it is placed in.. until..

This is done… -Just like the handling of fuel -to limit the radiation workers are exposed to
The radioactive waste is then stored in… Until it’s activity has…

Areas for storage or chosen where there will be… On animals and the environment and any people that live nearby or consulted about this decision to store nuclear waste near them

A

Very hot

Cooling ponds
until the temperature falls to a safe level

Remotely

Sealed containers

Activity has fallen sufficiently

Minimal impact

26
Q

Fusion means…

A

Joining nuclei together

27
Q

Two light nuclei can combine to create..

This is called

A

A larger nucleus

Nuclear fusion

28
Q

A lot of energy is released during nuclear fusion because

A

The new heavier nuclei have a much higher binding energy per nucleon

29
Q

Nuclei need lots of energy to…

A

Fuse

30
Q

All nuclei are…Charged

So there will be an electrostatic (or Coulomb) force of… Between them

A

Positively

Repulsion

31
Q

Nuclei can only fuse if they…

A

Overcome the electrostatic force of repulsion between them And get close enough for the attractive force of the strong interaction to hold them both together

32
Q

About… Of Kinetic energy is needed to make nuclei fuse together – that a lot of energy

A

1Mev

33
Q

In the Sun , hydrogen nuclei fuse in a series of reactions to form

A

Helium

34
Q

Fusion:
Low energy nuclei deflected by …

… Nuclei overcome electrostatic repulsion and are attracted by the…

A

Electrostatic repulsing

High energy

Strong interaction

Nuclear physics CGP (2 decks)

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