The number of fissions per second is given by:
\[
\frac{\text{Power output (W)}}{\text{Energy per fission (J)}}
\]
Given that 1 MeV = \( 1.6 \times 10^{-13} \) J, the energy per fission is:
\[
200 \times 1.6 \times 10^{-13} = 3.2 \times 10^{-11} \text{ J}
\]
Power output is 1000 kW = \( 10^6 \) W. Thus,
\[
\frac{10^6}{3.2 \times 10^{-11}} = 3.125 \times 10^{16} \text{ fissions/s}
\]