03:55:39 Engineered Safeguards actuated on low RCS pressure. Setpoint is (0756:16) 1640 psig. 03:55:39 The Reactor Building high pressure isolation signal actuated (0756:16) and isolated the Reactor Building. The Reactor Building isolation set point is 4 psig. 03:56:04 Reactor Coolant Makeup Pump C (MU-P-1C) was started. (0756:41) 03:59:23 Reactor Building Emergency Cooler B was shutdown. (0800:00) 03:59:53 Reactor Building Emergency Cooler B was started. (0800:30) 04:06:00 Electromatic Relief Block Valve (RC-V2) was shut. (0806:37) 04:08:39 Reactor Coolant Pump 1A (RC-1A) was started. (0809:14) 04:09:14 Reactor Coolant Pump 1A (RC-P-lA) was stopped. (0809:51) 04:l7:17 Reactor Coolant Makeup Pump A (MU-P-1A) was stopped. (0817:54) 04:17:22 Reactor Coolant Makeup Pump C (MU-P-1C) was stopped. No makeup (0817:59) pumps operating. 04:18:17 Operator attempted to start Reactor Coolant Makeup Pump A (MU-P-1A). (0818:54) The pump would not start. 04:18:30 Electromatic Relief Block Valve (RC-V2) was opened. (0819:07) Approximate- 10 -