The annual interest rate is 10%, compounded semi-annually. Consequently, the rate for each half-year is \( R = 5\% \), and there are \( n = 3 \) compounding periods.
Let the initial sum be denoted by \( P \).
Applying the compound interest formula:
\[ P \times \left(1 + \frac{10}{200}\right)^3 = 18522 \]
To find \( P \):
\[ P = 18522 \times \left(\frac{20}{21}\right)^3 \]
\[ P = 18522 \times \frac{8000}{9261} = 16000 \]
\[ \boxed{P = 16000} \]