Step 1: Definition. The D-value ($D_{10}$) is the dose required for a 1-log (90%) reduction. For an $n$-log reduction, the dose is
\[
\text{Dose} = n \times D_{10}.
\]
Step 2: Apply for 8 logs. For $n=8$,
\[
\text{Dose} = 8 \times D_{10}.
\]
Step 3: Numerical value. Using the commonly cited $D_{10}$ for Salmonella in egg yolk $\approx 1.75$ kGy,
\[
\text{Dose} = 8 \times 1.75 = 14.00\ \text{kGy}.
\]
(Values in literature span $\sim$1.6--1.8 kGy, giving 12.8--14.4 kGy; hence the accepted range 13.00--14.50 kGy.)