  This paper discusses the design and implementation of a Python-based toolset
to aid in assessing the response of the UK's Advanced Gas Reactor nuclear power
stations to earthquakes. The seismic analyses themselves are carried out with a
commercial Finite Element solver, but understanding the raw model output this
produces requires customised post-processing and visualisation tools. Extending
the existing tools had become increasingly difficult and a decision was made to
develop a new, Python-based toolset. This comprises of a post-processing
framework (aftershock) which includes an embedded Python interpreter, and a
plotting package (afterplot) based on numpy and matplotlib. The new toolset had
to be significantly more flexible and easier to maintain than the existing
code-base, while allowing the majority of development to be carried out by
engineers with little training in software development. The resulting
architecture will be described with a focus on exploring how the design drivers
were met and the successes and challenges arising from the choices made.
