ROSA/LSTF Tests and Posttest Analyses by RELAP5 Code for Accident Management Measures during PWR Station Blackout Transient with Loss of Primary Coolant and Gas Inflow

Table 3

Chronology of major events in LSTF tests.

Event	Time (s)
	TR-LF-18	TR-LF-17	TR-LF-16
Break valve open, termination of feedwater in both SGs, and scram signal		0
Start of primary coolant pumps coastdown		19
Start of core power decay		21
Stop of primary coolant pumps		269
Empty PZR	145	370	410
Onset of SG secondary-side depressurization by fully opening relief valves in both SGs	602	1210	8
Onset of AFW injection into secondary-side of both SGs	615	1220	26
Initiation of ACC system in both loops	1200	1870	1470
Termination of ACC system in loop-A	2820	3810	6830
Termination of ACC system in loop-B	3040	4000	7320
Achievement of SG secondary-side liquid level up to 12 m	6000	7200	5600
Onset of primary depressurization by fully opening PZR relief valve	None	9400	12520
Primary pressure decrease to 1 MPa	7000	12900	15300
Start of coolant injection from low-pressure injection system into cold legs in both loops	8700	14400	17220
Break valve closure	9051	15063	18169
Core power off	9067	15090	18129