As part of a program to obtain realistic, as opposed to excessively conservative, analysis of reactor transients, a multiple-pin treatment for the analysis of intrasubassembly thermal hydraulics has been included in the SASSYS-1 liquid-metal reactor systems analysis code. This new treatment has made possible a whole new level of verification for the code. The code can now predict the steady-state and transient responses of individual thermocouples within instrumented subassemblies in a reactor rather than just predicting average temperatures for a subassembly. Very good agreement has been achieved between code predictions and the experimental measurements of steady-state and transient temperatures and flow rates in the shutdown heat removal tests in the Experimental Breeder Reactor II (EBR-Il). Detailed multiple-pin calculations for blanket subassemblies in the EBR-II demonstrate that the actual steady-state and transient peak temperatures in these subassemblies are significantly lower than those that would be calculated by simpler models.