PRELIMINARY SEQUENCE OF EVENTS TMI 2 ACCIDENT OF MARCH 28, 1979 Issued April 16, 1979 -00:05:00 Three Mile Island Unit Two was at 97% power with the Integrated (0355:36) Control System in full Automatic. Rod groups one thru five were fully withdrawn, rod groups six and seven were 95% withdrawn and rod group eight was 27% withdrawn. Reactor Coolant System total flow was approximately 107.5% of design flow and the Reactor Coolant System pressure was 2155 psig. Reactor Coolant Makeup Pump B (MU-P-1B) was in service supplying makeup and Reactor Coolant Pump Seal injection flow. The Reactor Coolant System soluble boron concentration was approximately 1030 parts per million. Pressurizer Spray Valve (RC-V1) and the pressurizer heaters were in manual control while spraying the pressurizer to equalize boron concen- trations between the pressurizer and the remainder of the Reactor Coolant System. Normal Reactor Coolant System letdown flow was established. Steam Generator parameters were as shown in the following table: Steam Generator A Steam Generator B Loop Feedwater 5.7459 MPPH* 5.7003 MPPH* Operating Level 56% 57.4% Startup Level 158.8 inches 163.4 inches Steam Pressure 910 psig 889.6 psig Feedwater Temperature 462.7F 462.7F *MPPH is Million Pounds Per Hour