Inspired by The Stick and his plans to write a reactor-calc-app, I've even started to code an app (because his program is not yet published, afaik)
Here is what it looks like at the moment:
Currently it's in a very early alpha-state (started coding yesterday [09/10/2011] based on the tutorial in this forum) so expect bugs or incorrect behavior.
Feel free to submit bugs or feature-requests
Requirements : .NET Framework 4 Client Profile
v0902 - initial release
v0903 - fixed some issues (plating not distributing correctly), added experimental heat-flow-feature
v0904 - fixed a cooling issue, tweaked heat-distribution, tweaked heat-flow-feature
v0905 - minor changes (component-name), added reactor-cooling-value
v0906 - added more statistics (internal cooling, heat excess), added controllable simulation-speed, melted items disappear
v0906.1 - installation routine fixed
v0990 - reworked data-model, implemented save/load, addressed some issues, still some bugs with heat-derivators in combination with platings, simulation-speed applies for next tick too
- breeder simulation (isotope cells)
Select whatever components you want and click them onto the work-space.
Right-click removes components from slots.
I think its pretty self-explanatory but if you have any questions just ask in this thread.