[en] New features have been added to TITAN, which is an advanced 3-D thermohydraulic and neutronic coupled code. The new features include a high order feedback model, a xenon model and a capability to handle nonreactangular (zig-zag) geometry. A central rod ejection accident of a typical 3-loop PWR within 0.1 seconds, was simulated with a quarter-core model, comprising 47 assemblies. The results seem reasonable, although different from MEKIN-B results, reported by BNL. The steady state solutions with and without cross-flow were found to have no significant differences. The calculational speed on the Honeywell Multics machine was roughly .4 cpu seconds (about 1500 cpu seconds on IBM 370/160) for convergence. The transient results show power peaking after 0.12 seconds at about 1.50 the initial power, as opposed to the results predicted by MEKIN-B of a factor of 2.0 rise in power. A user's guide is given as an Appendix to the report