topic test - nuclear physics

Question 1

nuclide

Answer 1

atom with a particular number of protons and a particular number of neutrons

Question 2

nuclear stability

Answer 2

the result of SNF overcoming the electrostatic repulsion between protons in the nucleus, thus “holding” the atom together

Question 3

characteristic feature of all unstable nuclei that commence decaying?

Answer 3

radioactive nuclei that undergo spontaneous decay have an imbalance between strong nuclear force and electrostatic force, due to either excess or lack of neutrons, resulting in instability

Question 4

radiation

Answer 4

energy released as electromagnetic radiation and/or high-speed particles from the nucleus of an unstable isotope in an attempt to attain more stability

Question 5

radioactive decay

(spontaneous transmutation)

Answer 5

emission of radiation energy and/or particles from nucleus to achieve a more stable state (giving up energy for stability)

Question 6

radiopharmaceuticals

Answer 6

compound formed by chemically attaching a radioisotope to it

Question 7

binding energy

Answer 7

energy required to hold the constituent parts together as a nucleus

Question 8

absorbed dose

Answer 8

physical dose quantity absorbed by a target material when irradiated with some form of nuclear radiation, measured in Grays (Gy)

Question 9

dose equivalent

Answer 9

equivalent dose that accounts for type of radiation using a weighted factor to quantify biological effects, measured in Seiverts (Sv)

Question 10

nuclear fusion

Answer 10

reaction in which two or more lighter nuclei combine to form a heavier, more stable nuclide, with the release of energy

Question 11

applications of nuclear fusion

Answer 11

• potential alternative, cleaner source of energy:
  
  • no high-level radioactive waste
  • does not require mining and refining processes
  • reduced likelihood of catastrophic accidents
  • releases significantly large amounts of energy per reactants
• development of thermonuclear fusion weapons (hydrogen bombs)

Question 12

nuclear fission

Answer 12

splitting of heavy nucleus into lighter, more stable nuclei (roughly equal)

Question 13

fissile materials

Answer 13

composed of atoms that can be split by neutrons in a self-sustaining chain reaction (i.e. net release of neutrons) to release enormous amounts of energy

Question 14

fission chain reaction

Answer 14

self-sustaining process where fast-moving neutrons ejected from one fission reaction result in neutron captures that trigger more reactiosn

Question 15

controlled nuclear fission

Answer 15

production of thermal energy

Question 16

uncontrolled accelerating chain reaction

Answer 16

can release energy explosively

Question 17

critical mass

Answer 17

minimum amount of given fissionable material necessary to achieve a self-sustaining nuclear chain reaction under special conditions

dependant on: kind of fissionable materials, concentration/purity, geometry of surrounding reaction system (surface area, space, shape e.g. pellets)

Question 18

conditions for a self-sustaining chain reaction

Answer 18

1. must be fissile material e.g. uranium-235
2. must be at, or greater than, critical mass level (material, purity, geometry)

Question 19

ways to protect from radiation

Answer 19

1. limit TIME of exposure
   (reduces total absorbed dose)
2. maximise DISTANCE from radiation sources
   (reduces concentration of radiation by the inverse square law)
3. wear protective clothing and use protective SHIELDING devices
   (blocks radiation from penetrating to living tissue)

Question 20

harms of radon gas when ingested

Answer 20

inhaled as a gas => easily taken into lungs
(internal dose more dangerous, as it doesn’t need to penetrate)

decays to solid, radioactive polonium which remains in lungs

alpha emitter, which is ionising to body cells (cell death, preventing reproduction, permanent mutations etc)

Question 21

advantages and disadvantages of nuclear fission power

Answer 21

✅ no CO2 or air pollution
✅ produces more energy/kg than coal
❌ radioactive waste needs to be stored
❌ harmful radiation if reactor meltdown (escapes)
❌ expensive (time, money)
❌ need to mine uranium

Question 22

advantages and disadvantages of fusion as power source

Answer 22

✅ produces more energy than fission with no waste
❌ requires very high temperatures

currently not a feasible alternative but scientists are still working on it

Question 23

symptoms of radiation sickness begin to appear in people who receive doses greater than ________________ over a short time period

Answer 23

~ 0.5 Sv

(usually single exposure)