Dane Sabo
dfca8eab77
M .task/backlog.data M .task/completed.data M .task/pending.data M .task/undo.data A Class_Work/nuce2101/final/latex/SABO_NUCE2101_FINAL.pdf M Class_Work/nuce2101/final/latex/main.aux M Class_Work/nuce2101/final/latex/main.fdb_latexmk M Class_Work/nuce2101/final/latex/main.fls
48 lines
2.3 KiB
TeX
48 lines
2.3 KiB
TeX
\section*{Problem 5}
|
|
\subsection*{Part A}
|
|
|
|
Xenon-135 is primarily produced in a reactor as a fission product or by the
|
|
decay of Iodine-135, which is a direct product of uranium fission. Xenon-135
|
|
decays naturally over time or can absorb neutrons to become other isotopes with
|
|
a much smaller neutron cross section.
|
|
|
|
|
|
|
|
\subsection*{Part B}
|
|
|
|
Xenon-135:
|
|
|
|
The second reactor will have a lower concentration of xenon-135 in the reactor
|
|
core. Xenon-135 will be generated by the decay of iodine-135, but will also
|
|
decay naturally to other elements over time as well as being removed through
|
|
neutron absorption. If the reactors are shut down after a year, the xenon-135 in
|
|
both will spike with the full power reactor having a larger spike, and it will
|
|
take longer for the 100\% power reactor to be able to be restarted until the
|
|
extra xenon-135 has had time to decay away.
|
|
|
|
Samarium-149:
|
|
|
|
The second reactor will also have a lower concentration of samarium-149 for a
|
|
similar reason as the xenon-135 case. There will be less fissile products to
|
|
decay into samarium-149 in the low power reactor. If the reactors are powered
|
|
off, however, both reactors will develop additional samarium-149 concentrations
|
|
that will not decay away naturally as samarium-149 is stable. It will take more reactivity
|
|
to restart the full power reactor from shutdown as the samarium-149
|
|
concentration will be much higher than the low power reactor.
|
|
|
|
\subsection*{Part C}
|
|
|
|
Xenon is the more challenging poison to deal with. First, xenon has a much
|
|
larger cross section and has a more significant effect on reactivity than
|
|
samarium. Second, xenon-135 is not a stable element, and thus has decay effects
|
|
when the reactor is shut down. As such, the amount of time since shutdown is an
|
|
important factor to consider when restarting a reactor with consideration to
|
|
xenon. A miscalculation on xenon concentration can lead to a too-large insertion
|
|
of reactivity on start-up, which doesn't exist in the same way with samarium as
|
|
samarium doesn't decay during shutdown. Finally, xenon is a much faster response
|
|
dynamically compared to samarium. Xenon-135 can quickly change concentrations
|
|
in hours, while samarium-149 concentrations can take weeks to change
|
|
significantly. Human operators are much more likely to be able to cope with the
|
|
longer time constant poison versus misjudging the small time constant effects of
|
|
xenon.
|