Qualification of TRACE V5.0 Code against Fast Cooldown Transient in the PKL-III Integral Test Facility

Table 2

Post test: resulting sequence of main events.

#	Event description	EXP (sec)	GRNSPG UNIPI; TRACE5	Note
1	Start of transient (break opening) in SG number 1 steam line	0	0	Imposed
2	Heaters in SG number 1 switched off	0	0	Imposed
3	Trip of the MCP and coastdown	0	0	Imposed
4	PRZ heaters switched off	0	0	Imposed
5	Butterfly valves closure	210	210	Imposed
6	MCPs completely stopped	210	210	Imposed
7	Affected SG level lower than <8.0 m	6.4	9
8	Affected SG level lower than <5.0 m	32	175
9	Affected SG level lower than <2.5 m	393	422
10	Affected SG level lower than <1.0 m	579	612
11	Affected SG level lower than <0.1 m (emptied)	828	819
12	Affected SG pressure lower than <3.0 MPa	10.4	10
13	Affected SG pressure lower than <2.0 MPa	47	49
14	Affected SG pressure lower than <1.0 MPa	164	177
15	Affected SG pressure lower than <0.5 MPa	435	404
16	Minimum PRZ level	819	806
17	Minimum mass flow rate in loop 2 to 4	1060	NA
18	Minimum coolant temperature in CL number 1 (phase 1)	525–565	608
19	Minimum core inlet temperature (phase 1)	780–840	867
20	HPIS activated in loops number 1 and number 4 (0.2 kg/s)	1030	1030	Imposed
21	Maximum temperature difference across SG number 1 (phase 1)	380–420	369
22	PRZ safety valve 1st opening (steam released)	1420	1378	Steam discharged
23	Water released through the PRZ safety valve	1840	1887
24	End of calculation	4410	4410