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physics > Nuclear - 27 > Flashcards

Nuclear - 27 Flashcards

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1
Q

What type of radioactive element is used in nuclear reactors?

A

Uranium 235

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2
Q

What type of uranium is naturally found?

A

Uranium 238

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3
Q

What type of Uranium has a higher percentage of Uranium 235?

A

Enriched Uranium

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4
Q

describe the process of nuclear fission

A

Neutrons fired at uranium nuclei and then they split performing fission

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5
Q

What is used to control nuclear fission in reactors?

A

Control rods, absorbing extra neutrons

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6
Q

What are control rods made from?

A

Boron

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7
Q

What does the moderator do in nuclear reactors?

A

slows neutrons, by removing energy

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8
Q

What is the moderator made from?

A

Deuterium often found in water/ graphite

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9
Q

What is the problem with using water as a moderator?

A

Absorbs neutrons

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10
Q

What is the mass defect?

A

the difference in mass

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11
Q

How do you calculate binding energy in watts?

A

mass defect x c^2

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12
Q

1u is equivalent to how much MEV?

A

931.5 MEV

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13
Q

1 MEV is how many joules

A

1.6x10^-13

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14
Q

What type of radiation is released from the moderator in a nuclear fission reactor?

A

gamma radiation/em radiation

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15
Q

Why is uranium 235 better than 238?

A

238 is hard to fission, so more likely for 235

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16
Q

Why are there multiple fuel rods in a reactor?

A

so that they can be replaced in stages and so the neutrons released can go though a moderator before contacting another fuel rod as unlikely to contact same fuel rod

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17
Q

what does Lambda represent in nuclear physics?

A

decay constant

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18
Q

why do the surroundings of a fission reactor become radioactive?

A

they absorb too many neutrons and so become unstable isotopes

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19
Q

What does N mean in nuclear physics?

A

Number of nuclei/ mass number

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20
Q

Why must the ke of a neutron be reduced in a thermal reactor?

A

to increase its chance of fission, when colliding with another uranium atom.

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21
Q

Why is it better for the moderator to have a higher nucleon number?

A

it will have a higher mass and so will absorb a higher amount of ke

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22
Q

How do you calculate the binding energy in Mev?

A

mass defect (u) x 931.3

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23
Q

What are the benefits of using nuclear power?

A

small amounts of C02, output can easily be changed, doesn’t use fossil fuels.

24
Q

When is the strong nuclear force greatest?

A

small distances

25
Q

What do protons repel each other with?

A

electromagnetic force

26
Q

What happens in beta minus decay?

A

it produces an anti neutrino and an electron 0/-1

27
Q

What is removed in the process of ionisation?

A

one or more electron

28
Q

what measures radiation?

A

Geiger counter

29
Q

what does alpha radiation consist of?

A

two protons and two neutrons 4/2

30
Q

is alpha radiation deflected by magnetic fields?

A

yes - not as much as beta

31
Q

what’s the most ionising radiation?

A

alpha

32
Q

what’s the range of alpha radiation?

A

3-5cm

33
Q

what does beta radiation consist of?

A

fast moving electron 0/-1

34
Q

Is beta radiation deflected by magnetic fields?

A

yes very

35
Q

What’s the range of beta radiation?

A

0.5-3m

36
Q

what is beta stopped by?

A

Aluminum

37
Q

What is gamma radiation?

A

high frequency EM wave - photon

38
Q

How ionising is gamma radiation?

A

low

39
Q

What’s the range of gamma radiation?

A

indefinite in air

40
Q

What is background radiation?

A

radiation that we are always exposed to

41
Q

what are the main contributors to background radiation?

A

Radon and Thornon gas, buildings, cosmic rays

42
Q

How will gamma radiation spread out?

A

Inverse square law

43
Q

What are some hazards of radiation?

A

ionising cells causing cancer

44
Q

How must radioactive substances be stored?

A

in a lead lined box, no direct touching

45
Q

describe the motion of decay

A

randomly and spontaneously

46
Q

What does radioactive material decay into?

A

it will decay into something more stable

47
Q

what is coolant

A

A substance that passes through nuclear reactors and is responsible for removing heat from the core. This heat is then used to generate energy.

48
Q

what is critical mass

A

The smallest mass of fissile material required in a fission reactor for a chain reaction to be sustained.

49
Q

what is electron capture

A

A process that occurs in proton-heavy nuclei, in which an electron is drawn into the nucleus, causing a proton to transition into a neutron. An electron neutrino is also produced.

50
Q

what is fusion

A

The joining of two smaller nuclei to form a larger nucleus and to release energy.

51
Q

what is fission

A

The splitting a nucleus, to form two smaller daughter nuclei, neutrons and energy

52
Q

what is half life

A

The average time it takes for the number of radioactive nuclei in a sample to halve.

53
Q

what is the inverse square law

A

​A law that governs the intensity of gamma radiation. It means that the intensity of radiation at any point is inversely proportional to the square of the distance from its source.

54
Q

what is the mass defect

A

The difference in mass between a nucleus and the sum of the masses of its constituent nucleons.

55
Q

what is the closest approach

A

​A method of estimating a nuclear radius by firing a alpha particle at it. It involves calculating the distance at which all the alpha particle’s kinetic energy is converted to electric potential energy

56
Q

why might there be more radioactivity than the sources itself?

A

the products may also decay and be radioactive.

57
Q

what is meant by decays spontaneously?

A

decays without the need for a stimulus

physics (12 decks)

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