Lecture 7 Flashcards
Flux shape for infinite slab
Flux shape in infinite cylinder
Flux shape in finite cylindrical core
Buckling in finite cylinder
Peak to average power
Diffusion lengths
Diffusivity equation
Multiplication factor with two group approximation
Migration length equation
Reflector savings for
a >> M
Reflector savings for
a << M
Buckling in reflected reactor
Adding a reflector _____ the flux distribution, thus ____ the ratio of peak to average flux
flattens, lowers
The worth changes most rapidly when the tip is _______ of the core, where the flux is largest.
near the midplane
Buckling change with reactivity change equation
Rod bank has large enough effects in reactivity and on the flux distribution that the ______ technique is no loger applicable
pertubation
Change in non-leakage probablity w/ different migration length and buckling
Increased fuel temperature results in a ________ in the resonance escape probablity because of doppler effects
decrease
Magnitidue of fuel temp coefficient _____ with increasing fuel temperature
decreases
Becomes more _______ with burnup because of ______
negative, Pu-240
Moderator temperature coefficient
Moderatore coefficient derives primarily from _____ changes with changes in the __________ playing a secondary role
density, thermal spectrum
MTC becomes more ______ with boron concentration because of larger reduction in poision content from reduced density.
positive
MTC becomes more _____ with burnup primarily because of reduction in boron concentration
negative
Large negative value would be limiting for a ________ incidence
cold water injection
MTC becomes more _______ with control rod insertion because of hardened neutron spectrum and increased leakage
negative
For the fuel temperature coefficient for fast reactors, doppler effect is ______ in magnitude
smaller
For the coolent temperature coefficient for fast reactors, decreased density _____ the neutron spectrum and thus increases ____ and ____.
hardens, eta, kinfinite
For the coolent temperature coefficient for fast reactors, decreased density _____ the migration length, and thus ______ leakage, resulting in ______ reactivity.
lengthens, increases, increased.
Isothermal temperature coefficient, αT
αf + αc
Power coefficient αp=
In PWR, power coefficient becomes ______ with burnup
more negative
The temperature defect is
reactivity decrease from cold shutdown state to hot zero power condition
Power defect is
reactivity decrease from hot zero power to hot full power
Excess reactivity is the value that ρ would take if
all moveable control poisions were instantiously removed from the core.
Factors determining excess reactivity
temp defect, power defect, cycle length
Transient heat transfer model,
Very slow transient with small step reactivity insertion, or Quasi-steady state heat transfer equation
With .95$ insertion, _____ before fuel gains enough temp for ______
large power spike, negative feedback
Without temperature feedback, transients would pass through ______ at one second
prompt critical
Reactavity at t with reactivity insertion, ρ(t)=
Short time phenomena:
typical time intervals of milliseconds to seconds, transient analysis
Medium time phenomena:
hours to days, Xe and Sm effects
Long time phenomena:
several months or years, fuel depletion analysis
I-131 reaches it’s saturation value _____, and will be proportional to the _______
quickly, reactor power
Cs-137 increases ______ with time over the few years the fuel is in the reactor and the amount is proportional to ______
linearly, the total energy produced
Equilibrium concentration of Xenon, X(∞) =
Xenon after reactor shutdown, X(t) =
Xenon reactivity effect, ρ(t) =
For a sufficiently large operating flux, the xenon concentration _____ following shutdown.
rises
Peak concentration occurs _____ hours after shutdown
11.3
Samarium concentration, S(∞) =
Equilibrium concentration of Pm and I
Samarium after reactor shutdown, S(t) =
Samarium concentration _____ following shutdown
rises
Uranium concentration, N(t) =
conversion ratio, CR(t) =
Power as function of p’’‘max, peaking factor, and volume
The achievable maximum power density is dependent on _______ properties and that the _______ and _____ that can be tolerated
material, temperatures, pressures
Fq=
FrFxFl
Fq for a uniform cylindrical core =
3.63Fl
p’’‘(r,z) =
volume averaged coolant outlet temp To =
Average fuel temp Tf=
The temperature at the rod’s hottest point, which is along it’s centerline, determines the limitation on the _______
linear heat rate
