Validation of Advanced Computer Codes for VVER Technology: LB-LOCA Transient in PSB-VVER Facility
Table 3
Resulting sequence of main events.
Number
Event description
Exp (sec)
EDO-GP pretest KORSAR
EDO-GP posttest KORSAR
EDO-GP pretest TECH-M
EDO-GP posttest TECH-M
NRI posttest ATHLET
UNIPI posttest R5-3D
Note
(1)
DEGB occurrence
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Imposed event
(2)
Reactor SCRAM
0.0
0.2
0.2
0.2
0.2
0.0
0.0
Imposed event
(3)
MCP trip and coastdown
0.0
0.0
0.0
0.4
0.4
0.0
0.0
Imposed event
(4)
Turbine valve closure begins
0.0
0.0
0.0
0.1
0.1
0.0
0.0
Imposed event
(5)
Flashing of coolant at the outlet of core model
0.4
0.4
1.0
1.0
0.2
0.4
0.2
(6)
UP pressure < 10.8 MPa
0.54
0.4
0.8
0.8
0.9
0.35
0.2
(7)
Coolant reaching saturation in CLs SGs outlet
(i) loop no. 1
2.8
—
—
—
—
—
5.0
(ii) loop no. 2
2.3
—
—
—
—
—
4.9
(iii) loop no. 3
0.03
—
—
—
—
—
2.0
(iv) loop no. 4
3.1
—
—
—
—
—
4.7
(8)
Coolant reached saturation at core inlet
1.0
1.0
1.0
1.0
0.6
1.4
1.3
(9)
Primary pres. below secondary pressure
4.0–4.3
7.7
6.5
9.0
6.0
6.5
5.2
(10)
Stop of FW pumps
4.1–8.7
5.2
4.0
0.4.0
0.4
0.0
0.0
(11)
ECC acc injection start
10.2–10.7
9.2
11
10.0
12.0
10.9
11.1
(12)
PRZ emptied (level < 0.1 m)
11
6.3
7.0
9.7.0
12.4
8.6
11.9
(13)
Turbine valve fully closed
15.5
16.0
15.0
—
—
—
15.7
Imposed event
(14)
Pressure in UP < 2.5 MPa
18.6
14.7
19
18.0
19.8
18.0
17.9
(15)
UP and PRZ pressures equalization
31
8
8
28
30
21
36.8
(16)
ECCS connected to an emergence power supply
40
40
40
40
40
40.3
40
Imposed event
(17)
ECCS HPIS injection
40
40
40
40
40
40
40
(18)
ECCS LPIS injection
40
40
40
40
40
40
40
(19)
ECC acc. injection stop
113
104
95
(i) acc no. 1
89
77
93
88
(ii) acc no. 3
107
77
100
91
(iii) acc no. 4
92
77
96
94
(20)
First dry out occurrence
159
94*
150
177
134
43
153
(21)
End of MCP coastdown
231
232
231
217
231
232
232
(22)
Max. PCT in the core
395
109*
339
232
476**
296
385
(23)
Overall quenching
559
117*
462
—
559
487
493
(24)
All ECCS stop
921
862
872
898
884
903
923
(25)
Second dry out occurrence
1187
106
1258
911
904
1148
1072
Top of the core
(26)
End of calc. (max Tcl = 516°C)
1477
1100
1566
1241
1230
1500***
1360
(*) First out of 5 dryout experienced at different axial levels, especially in the lower part of the core. (**) Second out of two dryout. (***) Corresponding to a maximum cladding temperature equal to 500°C.
