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Science 10: Fission and Fusion 1
Science 10: Radioactivity!
Comparing Fission and Fusion Notes (Ch 11) http://www.atomicarchive.com/Movies/index.shtml Nuclear Reactions: an atom’s nucleus changes by gaining or releasing particles or energy. Protons, neutrons, electrons and/or gamma rays can be lost or gained. There are small changes in mass and really big changes in . How are nuclear reactions different from chemical reactions? Radioactive decay (alpha, beta, gamma) occurs naturally, but scientists can force a nuclear reaction. This is called an nuclear reaction. A nucleus is bombarded with alpha particles, beta particles or gamma rays causing it to become unstable and force it to undergo . Example:
*Important… The sum of the mass numbers on both sides of the equation stays the same. The sum or the charges (atomic numbers) on both sides of the equation stays the same. Questions A:
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Science 10: Fission and Fusion 2
Nuclear FISSION: the of nuclei. One heavy nucleus is split into two or more nuclei, some sub-‐atomic particles and . A heavy nucleus is usually unstable, due to many repelling each other. When fission occurs, is produced and are released.
Equation: þ must equal on both sides of the equation. þ must equal on both sides of the equation. Nuclear fission is used to produce energy in and . Nuclear Power Plant:
Chapter 7 The atomic theory explains radioactivity. • MHR 319
CANDU ReactorsCanada is a leader in the peaceful use of nuclear technology for bothmedical uses and for power generation. Canadian nuclear reactors arecalled CANDU reactors. CANDU stands for “Canadian deuteriumuranium” reactor. Deuterium is an isotope of hydrogen-1 that is twice asheavy as it has both a proton and a neutron in its nucleus.
The design of the CANDU reactor is among the safest in the world,and the reactor can be shut down quickly if a problem arises. Canadaprovides nuclear power technology and expertise to other countries tohelp them establish nuclear power generation stations.
Figure 7.23 shows eight CANDU reactors at the Pickering NuclearGenerating Stations. A diagram of the inside of each reactor is shown inFigure 7.24. The reactor core produces heat as a result of reactions likethe following:
10n ! 235
92U ➔ 9236Kr ! 141
56Ba ! 3 10n ! energy
Nuclear power plants and fossil-fuel burning power plants are similarin that both produce a lot of heat. This heat is used to boil water andgenerate steam, which then drives the turbines that produce electricity. Aturbine is a large rotating device that can be forced to turn when steam isapplied to it. You may recall from earlier science studies that a turbinedrives a generator that produces electricity.
Did You Know?CANDU reactors use heavywater—water in which thehydrogen atoms are deuterium—
as both moderator andcoolant.
Figure 7.23 The Pickering Nuclear Generating Stations inPickering, Ontario, include eight separate reactors. All arevisible in the photo.
reactor building
reactor
steamgenerator
steam
fuel-loadingmachine
turbine building
turbine
circulating water
generator
Figure 7.24 The nuclear fuel produces heat, which isused to make steam. The stream drives turbines that areconnected to electrical generators.
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Questions B:
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Science 10: Fission and Fusion 3
Nuclear Fission: Chain Reactions Chain reaction: one reaction starts the next reaction, which starts the next reaction and so on. This can be used to create nuclear power. This process must be monitored very closely so that it does not get out of control.
Nuclear FUSION: the of nuclei. Two light nuclei are joined into one . In the core of the sun, two hydrogen nuclei join under lots of heat and pressure to form a nucleus. When the helium atom is formed, huge amounts of energy are released.
Equation:
Scientists cannot yet find a safe, manageable method to harness the energy of nuclear fusion. So-‐called “ “ would occur at temperatures and pressures that could be controlled.
Name: ______________________________________ Block: ___________ Date: ______________________________
Science 10: Fission and Fusion 4
Nuclear Equations for Fission and Fusion 1. Categorize the following reactions as fission or fusion by circling the fission reactions.
2. What elements are typically found in fission reactions? 3. What elements are typically found in fusion reactions? 4. a) What is ?
b) What type of reaction is it found in and is it a reactant or product? 5. Summarize the major difference between fission and fusion reactions. 6. For the following reactions identify them as fission or fusion and fill in the missing isotopes.
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Science 10: Fission and Fusion 5
Comparison of Fission and Fusion Reactions
Chapter 7 The atomic theory explains radioactivity. • MHR 321
A large facility is being builtin California to producefusion in a drop of liquidhydrogen. Powerful lasersare to be directed into abubble of hydrogen, causingthe outside of the bubble toexplode and the inside toimplode. The shock of theexplosion should cause heatand pressures similar towhat is found in the centresof stars. This process iscalled inertial confinementfusion. Find out more atwww.bcscience10.ca.
Fusion nuclear equationThe nuclear equation for fusion in the Sun and in fusion reactionexperiments is:
21H ! 3
1H ➔ 42He ! 1
0n ! energy
Researchers have worked for over half a century to find a technologythat will allow us to extract energy from fusion reactions. One of thedifficulties is achieving the high temperatures and pressures needed.Another is simply finding a way to contain a reaction that is so hot thatno vessel can hold it without being destroyed. Fission and fusionreactions are compared in Table 7.11.
Did You Know?
Due to its constant output ofenergy, the Sun loses almost 4 million tonnes of mass each
second as the mass isconverted to energy.
Table 7.11 Comparison of Fission and Fusion Reactions
Fission Reaction Fusion Reaction
Heavy unstable nuclei split apart Two lightweight nuclei join together into two smaller nuclei. to form a heavier nucleus.
Unstable nuclei release a huge Lightweight nuclei release a huge amount of energy when they split. amount of energy when they join.
Heavy nuclei will not release excess Lightweight nuclei will not release energy by splitting if they are as light excess energy if the nucleus generatedas the element iron or lighter. by fusing is heavier than iron.
Fission reactions often produce daughter Fusion reactions often do not produceproducts that are radioactive. This causes products that are radioactive. This a radioactive waste problem for nuclear makes nuclear fusion reactors an energy production. attractive possibility for nuclear
energy production.
Many countries, including Canada, No commercial fusion reactorsgenerate some electrical power are in use or under construction.through fission reactions.
Research continues to try to produce Research continues to try to environmentally friendly nuclear produce a fusion nuclear reactor.power generation.
A fission reaction is used in modern nuclear A fusion reaction is used in modern weapons by itself or to produce an nuclear weapons to generate most of explosion that will generate sufficient heat the energy released in the blast. A and pressure to trigger a fusion reaction. fusion reaction needs the heat and
pressure from a fission nuclear explosion to get it started.
Equation of a typical reaction: Equation of a typical reaction:
10n ! 235
92U ➔ 9236Kr ! 141
56Ba !3 10n ! energy 21H ! 3
1H ➔ 42He ! 1
0n ! energy
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