Insights on Accident Information and System Operations during Fukushima Events

<table class="table-group" id="tab3"><tr><td><table class="table"><tr><td class="thead-hr" colspan="3"><hr/></td></tr><tr class="thead"><td align="left">Date</td><td align="center">Time</td><td align="left">Event</td></tr><tr><td class="thead-hr" colspan="3"><hr/></td></tr><tr><td align="left">March 11</td><td align="center">4:04 pm</td><td align="left">RCIC manual start (operator confirmed low reactor water level)</td></tr><tr><td align="center" colspan="3"><hr/></td></tr><tr><td align="left" rowspan="3">March 12</td><td align="center">11:36 am</td><td align="left">RCIC trip. Unable to restart</td></tr><tr><td align="center">12:35 pm</td><td align="left">HPCI autostart<br/>Operators pay attention to reactor level, HPCI flow</td></tr><tr><td align="center">8:36 pm</td><td align="left">Depletion of battery. Loss of reactor level indicator</td></tr><tr><td align="center" colspan="3"><hr/></td></tr><tr><td align="left" rowspan="5">March 13</td><td align="center">2:42 am</td><td align="left">HPCI outlet pressure close to reactor pressure (0.8-0.9 MPa)<br/>Plan to depressurize reactor using SRV (to 0.61 MPa)<br/><b>HPCI manual trip</b></td></tr><tr><td align="center">2:45 am</td><td align="left">Failure in SRV remote open (possibility that battery power low)</td></tr><tr><td align="center">5:00 am</td><td align="left">Reactor pressure = 7.38 MPa</td></tr><tr><td align="center">7:00 am</td><td align="left">Car batteries connected to SRV</td></tr><tr><td align="center">8:41 am</td><td align="left">Venting line-up (except rupture disk) complete</td></tr><tr class="table-tr"><td colspan="3"><hr class="tbody-hr"/></td></tr></table></td></tr></table>

Records related to manual trip of HPCI in Unit 3.

Science and Technology of Nuclear Installations

tab3

Table 3

Table 3: Insights on Accident Information and System Operations during Fukushima Events 