Week 8 Flashcards
Advantages of nuclear reactors
-Produces large amounts of energy from small amounts of fuel
-No pollutants
-Less waste
-Reliable resource
Disadvantages of nuclear reactors
-Radioactive waste-must be disposed carefully
-Lot of money spent on safety-if something goes wrong can cause major disaster
-More expensive than coal/gas-higher maintenance cost
Are nuclear reactors renewable
Uranium-no
Artificial fuels- yes
Amu meaning
Atomics mass unit- 1/12 mass of carbon-12
Isotope definition
Same number of protons different number of neutrons
What is mass defect
Mass of nucleus is less than total mass of individual nucleons. Caused because of binding energy.
What is binding energy?
Amount of energy needed to separate nucleons. Holds nucleus together against repulsion of protons
What is fusion
Small nuclei join to form heavier nucleus
What is fission
Heavy nucleus splits into two smaller nuclei (used in atomic bombs)
What are the conservation laws
All must be conserved:
1) Nucleon number
2)Charge
3) Momentum
4) Mass/energy
What do unstable atoms emit
Alpha, beta or gamma radiation
What is alpha particle
same as helium.
Mass number 4
Proton number 2
Emitted when atom is too big
What is beta particle
Same as electron
-1 charge.
Mass number stays constant- neutron converts into proton and emits an electron
Happens when nucleus has too many neutrons.
What is a breeding reaction
Amount of fuel produced is greater than amount of fuel required for reaction (Can be removed to fuel other processes)
How does pressurised water reactor work
primary and secondary circuits, both use water.
Primary moderates (slows) neutrons and remove heat.
Secondary raises steam
Operating conditions- 320 degrees Celsius and 160 bars
how does boiler water reactor work
primary circuit only. Water used to moderate neutrons to remove heat and raise steam.
Operating conditions- 300 C and 70 bar
how does pressurised heavy water reactor work
primary and secondary circuit and calandria (heavy water)
Calandria used to moderate neutrons.
Primary circuit (heavy or light water) to remove heat
Secondary circuit to raise steam
Operating conditions: 325 C and 120 bar
how does gas cooler reactor work
primary and secondary circuit.
Primary uses graphite to moderate neutrons and CO2 to remove heat.
Secondary circuit uses water to raise steam.
Operating conditions: 380 C and 7-27 bar
how does advanced gas cooler reactor work
primary and secondary circuit.
Primary uses graphite to moderate neutrons and CO2 to remove heat.
Secondary uses water to raise steam.
Operating conditions: 650 C and 40 bar
Advantages of advanced fuel cycles and deadtors
- fuel recycling extends raw material resources
- move to purely fast reactors would extend resources
