rFeCO3 kfFeCO3*b*max(cFeCO3[M^-1]-KspFeCO3,0) "Reaction rate for FeCO3 precipitation"
rFeOH2 kfFeOH2*b*max(cFe*tcd.cOH^2[M^-3]-KspFeOH2,0) "Reaction rate for FeOH2 precipitation"
theta 1-exp(-tcd.cbtot/ctot_mdis) "Corrosion-product coverage degree"