FINAL DAY REVISION Flashcards
At what axial location in the core of an idealised cylindrical PWR is film boiling of the coolant most likely to occur if the power were to be increased?
At the core mid-plane
The production of 1 GW (thermal) requires the fissoning of about how much Pu239 per day?
1 fission = 203 MeV = 3.25 E-11 J
1 GW for 24 hours = 8.64 E13 J
# fissions * 239 * 1.66E-27 = 1.05 kg
Which is the order for spent fuel waste safety barriers in a repository, from inner to outer:
bentonite, crystalline rock, fuel cladding, fuel canister
fuel cladding, fuel canister, bentonite, crystalline rock
Which list is in order of increasing maximum fuel cladding temperature?
BWR, PWR, Magnox, Sodium-cooled fast reactor, AGR
What, approximately, are the dimensions of the active core of a PWR?
4m diameter, 4m height
How to calculate the channel temperature rise?
Change in T = 2 * Peak linear rating * L * no. rods / mass flow rate * specific heat capacity * Pi
The expression nvSigma_fv* gives _________
the local fission rate.
Which value of fanning friction factor should be used to calculate the pressure drop?
normal (NOT DARCY WEISBACH)
How to calculate the peak boundary layer temperature difference?
q’’ (peak) = h (T_s - T_infinity)
Consider a typical fuel channel in a gas-cooled reactor (eg. an AGR). If the mass-flow rate of the gas and the reactor power were both decreased by 10%, the effect would be _______
The rate of cladding oxidation would be slightly decreased
Which list is in ascending order of turbine entry temperature?
PWR, AGR, a modern coal fired power station
In descending order, the main forms of energy release from fission of U235 are:
Fission fragment kinetic energy, fission product radiation, prompt
gamma rays, neutron kinetic energy
Neutron current is
neutrons per unit area per unit time in a particular direction.
What is the coolant pressure of a PWR?
150 bar
What is the coolant pressure of an AGR?
40 bar
What is meant by the reflood phase of (some) PWR accidents?
Slow bottom-up re-entry of water to the core
What is the main physical phenomenon that contributes to the pressure drop in the core of an AGR?
Coolant frictional pressure drop
Wigner energy is
neutron induced strain energy in the hexagonal lattice of graphite
A typical PWR generates 1.4GWe. Approximately how many fissions per second does this correspond to:
1 fission = 203 MeV = … J
1.4 GWe / … J * Thermal efficiency
Moderator heating is a mechanism which leads to
a change in reactivity, but there is insufficient information to determine whether it is an increase or decrease
In a large-break loss of coolant accident the ‘bypass’ phase involves
Flow diversion around the baffle due to rapid steam flow from the core immediately following the break
Xe-135 poisoning is thought to play a role in which nuclear accident?
Chernobyl
Which of the following would not be used as a cladding
material in a nuclear reactor?
Gadolinium
Which one of the following is the LEAST important economic
factor in the deployment of nuclear power
Fuel cost
Construction cost
Construction time
Wholesale electricity price
Fuel cost
What might be used as the coolant and the moderator in a
plutonium-breeding reactor?
Sodium, no moderator at all
What is the most important of the following factors that
influences the difference between coolant temperature and
clad temperature in a typical PWR in normal operation?
Coolant density
A prototype fusion reactor is able to maintain an ion density
of 6E+20 ions/m3, at a temperature of 150E+6 K for 0.01
seconds. Which one of the following statements is true?
The reactor would fail to reach ignition
In a supercritical water-cooled reactor, the coolant is
light water at ~230 bar
In a PWR in which a large break loss of coolant accident
occurs
the core depressurizes and the liquid water flashes to steam which exits through the break
