P2.6.1 Nuclear Fission

P2 Physics

KS4 ADDITIONAL SCIENCEMr D Powell

Mr Powell 2012Index

P2.6.1 Nuclear fission

a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.

b) Nuclear fission is the splitting of an atomic nucleus.

c) c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.

Mr Powell 2012Index

2001-2007 HAAP Media Ltd, Gwyn Ellsworth

2001-2007 HAAP Media Ltd, Tracy Olson

2001-2007 HAAP Media Ltd, Pantelis Kampas

2001-2007 HAAP Media Ltd, Steve Woods

2001-2007 HAAP Media Ltd, Fernando Audibert

2001-2007 HAAP Media Ltd,

How are they related?

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UK Nuclear Power Stations

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Nuclear fission

• Here a nucleus of uranium-235 has absorbed a neutron and has split into two nuclei and three neutrons.

• Nuclear energy is being released – this is a million times more powerful than an ordinary chemical reaction.

Why do you think the process of nuclear fission cannot be filmed?

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Fission (alternative)

Nuclear power reactors use a reaction called nuclear fission. Two isotopes in common use as nuclear fuels are uranium-235 and plutonium-239.

Fission is another word for splitting. The process of splitting a nucleus is called nuclear fission. Uranium or plutonium isotopes are normally used as the fuel in nuclear reactors, because their atoms have relatively large nuclei that are easy to split, especially when hit by neutrons.

When a uranium-235 or plutonium-239 nucleus is hit by a neutron, the following happens:

the nucleus splits into two smaller nuclei, which are radioactive

two or three more neutrons are released some energy is released

The additional neutrons released may also hit other uranium or plutonium nuclei and cause them to split. Even more neutrons are then released, which in turn can split more nuclei. This is called a chain reaction. The chain reaction in nuclear reactors is controlled to stop it going too fast.

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Reactor compartment

Reactor compartment

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Submarine Nuclear Power Plant

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Nuclear Reactors

They provide the source of radioactive atoms which easily split when a neutron hits them

They dip into the core of the reactor and absorb neutrons so prevent them splitting more atoms.

This is like a radiator in a car and loses thermal energy to the surroundings to cool the reactor and heat water to create steam

The steam pressure turns the turbine which is connected to a magnet in a coil of wire which then turns to create AC electricity.

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Summary Questions Fission

This is when an atom splits into two new atoms, energy and 3n; due to an incoming neutron.

The reaction expands as every generation releases 3 neutrons from one incoming neutron.This is an exponential growth... 1,3,9,27 etc.. Until massive amounts of energy are released.

The reaction can be slowed by using “control rods” made of graphite. This material absorbs the energetic neutrons thus stopping the reaction. We dip the rods into the reactor core to control the chain reaction. When they are removed the reaction speeds up again.

Parts of the reactor become highly radioactive so have to be handed in special ways without human contact directly to the materials

P2.6.1 Nuclear Fission (splitting)

a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.

b) Nuclear fission is the splitting of an atomic nucleus.

c) c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.

P2.6.1 Nuclear Fission (splitting)

a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.

b) Nuclear fission is the splitting of an atomic nucleus.

c) c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.

P2.6.1 Nuclear Fission (splitting)

a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.

b) Nuclear fission is the splitting of an atomic nucleus.

c) c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.

P2.6.1 Nuclear Fission (splitting)

a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.

b) Nuclear fission is the splitting of an atomic nucleus.

c) c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.

P2.6.1 Nuclear Fission (splitting)

a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.

b) Nuclear fission is the splitting of an atomic nucleus.

c) c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.

P2.6.1 Nuclear Fission (splitting)

a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.

b) Nuclear fission is the splitting of an atomic nucleus.

c) c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.

Mr Powell 2012Index

Connection

• Connect your learning to the content of the lesson

• Share the process by which the learning will actually take place

• Explore the outcomes of the learning, emphasising why this will be beneficial for the learner

Demonstration

• Use formative feedback – Assessment for Learning

• Vary the groupings within the classroom for the purpose of learning – individual; pair; group/team; friendship; teacher selected; single sex; mixed sex

• Offer different ways for the students to demonstrate their understanding

• Allow the students to “show off” their learning

Activation

• Construct problem-solving challenges for the students

• Use a multi-sensory approach – VAK• Promote a language of learning to

enable the students to talk about their progress or obstacles to it

• Learning as an active process, so the students aren’t passive receptors

Consolidation

• Structure active reflection on the lesson content and the process of learning

• Seek transfer between “subjects”• Review the learning from this lesson and

preview the learning for the next• Promote ways in which the students will

remember• A “news broadcast” approach to learning