Decay heat

[wgurecky]

Description

Add decay heat source term when ractor is shutdown. This does not have to be a physically based model: just 'fake it' is good enough since this isnt a real reactor sim. Currently the simulator does not include a heat source due to radioactive decay of FP after shutdown.

The model does currently produce a tiny amount of power after shutdown due to left over delayed neutron precursors.

Tasks

• On shutdown, add an artificial source into the energy balance that deacys with time.