C3 - Nuclear Fusion and Fission

0.0(0)
studied byStudied by 3 people
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
Card Sorting

1/52

encourage image

There's no tags or description

Looks like no tags are added yet.

Study Analytics
Name
Mastery
Learn
Test
Matching
Spaced

No study sessions yet.

53 Terms

1
New cards

what happens in chemical reactions

only valence electrons involved, atoms do not change their identity

2
New cards

atoms with different numbers of neutrons

isotopes

3
New cards

what do neutrons do to a nucleus

provides a strong nuclear force which binds the nucleus together despite the repulsion between protons

4
New cards

what happens in light nuclei

strong nuclear force counteracts the electric force (neutrons and protons are equal)

5
New cards

what happens in heavy nuclei

need more neutrons than protons to combat the repulsion between protons

6
New cards

what determines the stability of a nucleus

balance between strong nuclear force from neutrons and electrical force between protons

7
New cards

alpha particles

2 protons and 2 neutrons

blocked by paper

8
New cards

beta particles

electrons

blocked by aluminum

9
New cards

gamma rays

electromagnetic radiation given out due to nucleons reorganizing themselves

blocked by lead

10
New cards

what is nuclear binding energy

the energy required to break the nucleus into its constituent nucleons

11
New cards

what measures the stability of the nucleus

average binding energy per nucleon

12
New cards

relationship between binding energy per nucleon and stability of nucleus

greater, more stable

13
New cards

most stable

iron and nickel

14
New cards

what do fission and fusion do to binding energy per nucleon

increases

15
New cards

two deuterium nuclei

form an He nucleus and a neutron

forms tritium and hydrogen

16
New cards

what does the sun emit

a continuous spectrum in the visible region with some frequencies missing and analyzed with a spectroscope

17
New cards

what does the atmosphere of the sun do

lower temperature than the sun itself

gases can absorb some wavelengths of the sun’s radiation, producing dark absorption lines

18
New cards

what can dark bands do

identify elements present in gases around the sun

19
New cards

absorption lines vs emission lines

dark lines in an absorption spectrum have the same position as the lines in an emission spectrum of the same atom

20
New cards

how do lines in the visible spectrum form

caused from electrons moving from higher to lower energy levels

21
New cards

how do lines in the absorption spectrum form

electrons go from a lower to a higher energy level

22
New cards

how do lines in the emission spectrum form

electrons move from a higher to a lower energy level

23
New cards

why are the atomic energy levels of helium less clear than those of hydrogen

two electrons instead of 1, forming multiple energy states

24
New cards

energy levels of he vs h

helium have a more negative value due to increased nuclear charge pulling electrons closer to the nucleus

25
New cards

benefits of fusion

no massive transport or waste storage

no greenhouse gases are produced

26
New cards

why is a large amount of energy formed from the fission of 235u

mass of products is slightly less than mass of reactants

mass difference converts to energy

27
New cards

how are nuclear reactors designed

only one neutron from each reaction initiates a further reaction to prevent the chain reaction from running out of control

28
New cards

what does the chance that a neutron goes on to cause fission depend on

the number of potential nuclei in the neutron’s path

speed of the neutrons

29
New cards

what do moderators do

slow down neutrons produce by fission that are too quick to produce more reactions

30
New cards

what do control rods to

absorb neutrons to control the chain reaction

made of ca or cd

31
New cards

what is required for a fissile material to sustain a chain reaction

enough fissionable material for the neutron in one fission process to find another fissile nuclei

32
New cards

what is critical mass

the minimum mass of a fissionable material needed to sustain a chain reaction

33
New cards

what does the critical mass depend on

the exact nature of the fuel being used and the shape of the assembly

34
New cards

what is used to sustain the fission of uranium

enriched uranium fuel

35
New cards

what is enrichment

the process by which the percentage composition of uranium-235 is increased to make nuclear fission more likely

36
New cards

what was developed to increase the supply of fissionable 235u

breeder reactors

37
New cards

what do breeder reactors do

convert 238u to plutonium-239

38
New cards

how does 238u convert into 239pu

238u captures a neutron to form 239u

239u decays to 239np with the emission of a beta particle

239np decays into 239pu with the emission of another beta particle

39
New cards

why aren’t moderators needed in a plutonium reactor

plutonium requires faster neutrons than 235u

40
New cards

concerns for breeder reactors

plutonium is toxic and can be made into weapons

breeder reactors are less efficient and require liquid metal coolants

susceptible to accidents

radioactive by-products

41
New cards

what is half life

the time it takes for half of the atoms to decay

concentration of an aqueous isotope to fall to half its initial value

number of atoms of the isotope to fall to half their original value

activity of an isotope to fall to half its initial value

42
New cards

order of radioactive decay

first

43
New cards

rate of decay

rate=decay constant*[A]

44
New cards

does temperature affect the decay constant

no

45
New cards

what is the decay constant dependent on

starting concentrations

46
New cards

how is radioactive waste produced

nuclear power stations

research labs

military establishments

hospitals

47
New cards

problems with energy from nuclear fission

health issues

nuclear meltdown

nuclear weapons

48
New cards

two types of radioactive waste

high and low level

49
New cards

what is low level waste

low levels of activity and shorter half lives

fuel containers, hospital waste

50
New cards

what is high level waste

high levels of activity and longer half lives

spent fuel rods

military

51
New cards

low level waste water storage

stored in cooling ponds of water until the activity has fallen to safe levels

it is then passed through an ion exchange where isotopes are removes

water is diluted and released back into the sea

52
New cards

low level waste concrete storage

stored in steel containers inside concrete lined vaults

53
New cards

high level waste storage

problematic, may undergo further reactions

fuel rods are encased in glass or ceramic before being buried deep in the earth