Nordheim-Fuchs Model

doublemint

I am looking at the equations for maximum flux/power and energy deposited from the power pulse with reactivity increase >1$ in the Nordheim-Fuchs Model:
P=[itex]\frac{\Lambda \omega^{2}}{2\alpha_{FT}K}[/itex]

E=[itex]\frac{2(\rho-\beta)}{K\alpha_{FT}}[/itex]

With a negative temperature coefficient (\alpha_{FT}), shouldn't the above equations be negative? I've looked at other examples that include reactors with a negative temp coefficient, and they all produce a positive value (they don't show the calculations, just the graphs).

It seems like that just ignore the negative sign, but I want to know why.