A vectorized source algorithm was developed for the Electric Power Research Institute light water reactor core nodal code SIMULA TE-E. The existing line successive displacement scheme was replaced by configuring the source for all nodes in a given plane as a single vector that could be computed simultaneously. Power distributions and eigenvalues for all test problems agreed exactly with the original scalar code. A factor of 2 to 7 reduction in execution time was achieved for typical pressurized water reactor problems on the CYBER 205.