[en] This document contains the accident sequence analyses of internally initiated events for the Zion Unit 1 Nuclear Power Plant. This is one of the five plant analyses conducted as part of the NUREG-1150 effort for the Nuclear Regulatory Commission. The work performed and described here is an extensive reanalysis of the work published in October 1986 as NUREG/CR-4550 Volume 7. It addresses comments from numerous reviewers and provides significantly more detailed modeling of most aspects of the Zion plant. The mean core damage frequency at Zion was calculated to be 3.4E-4 per year, with a 95% upper bound of 8.4E-4 per year and a 5% lower bound of 1.1E-4 per year. Note that this range is based only on the statistical treatment of six specific issues. Reactor coolant pump seal loss of coolant accidents (LOCAs) were the largest contributors to the core damage frequency, accounting for approximately 85% of the total. 8 refs., 37 figs., 169 tabs