Nuclear Notes Flashcards
(50 cards)
Sources of energy, examples, and differences.
Primary sources of energy (energy found in nature that has not been subjected to change)- coal -oil -gas -nuclear -hydro -renewables (solar, wind, tide)
Secondary sources of energy (man made energy produced using primary sources) – electricity – hydrogen – alcohols – oil and gas
Globally, what percentage of electricity is generated from nuclear. How about in the UK. Use the latest available figures respectively.
France- 76.3% Germany- 14.1% US- 19.5% Russia- 18.6% UK- 18.9% Japan- 0.5% India- 3.5% China- 3.0%
Name the top 5 countries that have relatively high proportion of electricity generated from nuclear in 2015.
France- 76.3% Ukraine- 56.5% Slovakia- 55.9% Hungary- 52.7% Slovenia- 38.0%
Globally how many operable (not necessarily operating) nuclear reactors are there for electricity generation?
447
How many nuclear power reactors in how many plants are currently operating in the UK to produce electricity?
15 (19 2010)
Roughly, 22g enriched uranium can produce 8000 kWh of electricity in a light water reactor. To generate the same amount of electricity, how many tonnes of black coal is required, and how much greenhouse gas is produced?
3 tonnes of black coal are required to produce 8000 kWh of electricity and 300 kg of fly ash is produced and 8 tonnes of other gaseous emissions are produced
Nuclear vs natural gas power plants: which costs more to build, which produces cheaper electricity, which is more sensitive to fuel cost fluctuation?
Natural gas plants are more sensitive to fuel cost flcutuation
Nuclear power plants are less sensitive to fuel cost fluctuation
What are the three main issues of nuclear energy?
Cost
Safety
Waste
What’s the difference between “mass” and “rest mass”? How do you calculate kinetic energy of neutrons or electrons (particles having a rest mass)? What about photons (particles with no rest mass)?
Mass- the amount of material an object possesses
Rest mass- the mass of an object at rest
Kinetic energy of Electrons:
Kinetic energy of Neutrons:
Kinetic energy of particles with no rest mass: (h=Planck’s constant, v=frequency)
What determines chemistry? And what determines radioactivity?
Chemistry of an element is determined by the electrons in the partly filled outermost shell. An unstable atomic nuclei determines radioactivity.
What are alpha, beta and gamma rays? How far can they typically travel in air and in solids?
Alpha- fast moving helium atoms, typical range (in air)- cm, typical range (in solid)- m
Beta- fast moving electrons, typical range (in air)- m, typical range (in solid)- mm
Gamma- high energy photons, typical range (in air)- km, typical range (in solid)- cm
Fission vs fusion vs radioactive decay. What are they, what they have in common and what differences they have?
Nuclear fission- a large nucleus splits into smaller nuclei when impacted by a neutron. Energy and more neutrons are produced
Nuclear fusion- several small nuclei combine together and release energy
Radioactivity- the spontaneous breakdown of an atomic nucleus
What’s “fissile”, “fissionable” and “fertile”?
Fissile- capable of sustaining a chain reaction of nuclear fission, with neutrons of any energy
Fissionable- capable of undergoing fission
Fertile- can be converted to fissile with bombardment of neutrons in a reactor
Which isotope is the only naturally occurring isotope, found in significant quantities in nature, that can undergo thermal fission?
U-235
U-238 is what and what but not what (of the above three)?
U-238 is fissionable but not fissile (only fission with high energy neutrons) and also fertile ( can be converted into Pu-239)
What does “thermal” mean when it’s used to describe nuclear reaction or neutrons.
Slow
]What is the level of U-235 in natural uranium? What do you expect it to be 2bn years ago?
0.71% of U-235 is in natural uranium. 3.66% is the U-235 proportion 2 billion years ago
What’s mass defect? Roughly how much energy is released per fission of U-235, or per fusion of Deuterium and Tritium?
The mass defect of a nucleus represents the mass of the energy binding the nucleus, and is the difference between the mass of a nucleus and the sum of the masses of the nucleons of which it is composed.
169 MeV of kinetic energy is released per fission of U-235
17.6 MeV of kinetic energy is releaser fusion of Deuterium and Tritium
What does 16O(n, p)16N mean?
a(b,c)d (incident, emerging)
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What neutron interaction is expressed by (n, n), (n, n’), (n, α), (n, p), (n, γ), (n, 3n) respectively?
Scattering elastic neutron interaction- (n,n)
Scattering inelastic neutron interaction- (n,n’)
Absorption reactions radiative capture- (n, γ)
Absorption reactions charged- particle reactions- (n, α), (n, p)
Absorption reactions neutron- producing reactions- (n, 2n), (n, 3n)
“Cross sections” are used for what purpose and for (or not for) what nuclear particles?
Cross sections (1barns= 10-24 cm2) are used to quantity the extent to which neutrons interact with nuclei σ: proportionality constant in the collision rate expression σ: number of collisions with one nucleus / time / intensity σ/A: probability that a neutron in the beam will collide with a nucleus.
How many neutrons are usually produced in a fission reaction? What’s the mechanism by which neutrons are “thermalised” in reactors? Where do delayed neutrons come from, what’s their proportion and significance?
An average number of 2 and 3 neutrons are released per fission reaction
Delayed neutrons come after the fission event and their proportion is less than 1%
Give two main reasons why thermal neutrons are preferred for fission reaction.
Thermal neutrons possess more energy than non-thermal neutrons. So therefore when the thermal neutron combines with a larger atom, fission is more likely to occur.
What’s the purpose of coolant? Give 4 examples of materials used as coolant.
Coolants are used to remove from heat from the core of a reactor Light water (deuterium), heavy water and some gases (thermal reactors) and liquid sodium (fast reactor)
