Twenty different boron-doped Czochralski silicon materials have been analyzed for light-induced degradation. The carrier lifetime degradation was monitored by an automated quasi-steady-state photoconductance setup with an externally controlled bias lamp for in-situ illumination between measurements. Logarithmic plots of the time-resolved lifetime decays clearly displayed the previously reported rapid and slow decays, but a satisfactory fit to a single exponential function could not be achieved. We found, however, that both decay curves, for all the investigated samples, can be fitted very well to the solution of a simple second-order rate equation. This indicates that the defect generation process can be described by second-order reaction kinetics. The new information is used to discuss the role of holes in the defect reaction and the rate-determining steps of the rapid and slow defect reactions.