Bohunice V2 NPP containment model MELCOR to APROS

6th Meeting of the
“European MELCOR User Group”
Bohunice V2 NPP
containment model
MELCOR to APROS
comparison
Peter Juriš, Ján Kubačka
Bratislava, Slovakia
April 15-16, 2014
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Bohunice V2 NPP containment model
MELCOR to APROS comparison
Overview
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Containment of NPP VVER 440/V213
MELCOR containment model
APROS containment model
MELCOR to APROS comparison
Future plans
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VVER 440/V213 Containment
17,0
1,5
PODLAŽIE + 10,5 m
(EGP 013-1-039007)
3,0 1,0
1,0
18
+9,3
+10,5
2,65
0,8
19,9
3,2
1,97
0,8
0,8
A302
6,0
0,8
φ 6,5
0,7
1,8
2,9
4,0
0,6
+6,5
1,0
+10,31
+7,87
3,0
1,752
0,4
+7,3
4,8
14
0,6
4,4
+10,0
1
8,7
0,7
3,0
A306
19,7
2
3
1,5
0,6
A305
0,2
19,3
12,0
39,0
V
3,8
+6,78
+10,5
1,0
10,65
x
1,5
+10,5
4,0
0,8
1,0
24,0
A201
+6,35
10
3,05
0,6
A304
+10,5
1,0
1,8
1,0 3,76
0,5
1
0,25
4,8
1,5
5,75
A137
5,75
1,0
12,3
1,8
A301
0,8
24,0
8,05
0,7
0,8
PRIEČNA ETAŽÉRKA (1.blok)
G
2,0
24,0
D
E
MELCOR Containment Model
MELCOR Containment Model Features
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MELCOR 1.8.5
separated analysis of VVER 440/V213 containment phenomena without
MCCI, applied for Safety analyses
model contains:
64 control volumes
139 flow paths
211 heat structures
verification – code to code comparison with CONTAIN and ASTEC
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MELCOR Containment Model
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APROS containment model
APROS containment model developing project
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intention of SE (Slovenské elektrárne) to use APROS computer code for
analysis and simulation of processes in Bohunice V2 NPP
plant model – primary and secondary circuit
2013 – Containment project
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contracting party: SE, Fortum and VUJE
to develop containment of NPP Bohunice V2 and integrate it into existing
plant model
verification of the model – code to code comparison
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APROS containment model
Extent of APROS containment model
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main containment compartments (with flow paths and heat structures)
containment active spray system TQ20, TQ40, TQ60
pressure suppression system XL
pressure suppression function
passive spraying of bubble tower
possibility of manual draining of coolant from suppression trays
vacuum breaker system
model of the most important ventilation systems
inlet system TL41
outlet system TL71
circulation systems TL10 and TL11
temperature and pressure measurements in containment (input for RTS and
ESFAS)
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Containment compartments
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APROS containment model
13,2
0,8
3,0 1,0
A211
3,0
1,5
1,5
1,5
7,0
A205
24,0
0,7
A203
FLOOR + 6,0 m
(EGP 013-1-039006)
6,0
0,8
19,9
3,2
A210
18
A207
1,97
0,8
A256
4,1
0,6
1,0
1,8
3,3
2,11
A262
0,8
A137
4,76
2,75
A209
5,75
0,6
4,4
1,0
5,35
5,75
1,8
1
A206
A261
+7,11
φ
3,31
0,6
0,7
+6,5
0,8
6,0
0,4
A208
+7,82
4,8
14
A264
7,82
5,2
4,9
0,8
0,8
A253
x
A252
A254
1,5
19,7
19,3
0,2
12,0
39,0
2
10
1,5
3,0
A204
A202
A263
10,0
0,7
10,65
24,0
A201
10,25
1,5
+6,78
0,5
1
0,25
4,8
+6,2
V
8
G
2,0
24,0
D
E
MELCOR to APROS Comparison
Verification of APROS model
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code-to-code comparison with MELCOR code
3 transients with stand alone containment model
LOCA 2x500 mm
LOCA 107 mm
Steam-line break
1 transient with integrated model (unit model)
LOCA 2x500 mm
verification was based on qualitative assessment and engineering
judgments according IAEA SRS No. 23
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MELCOR to APROS Comparison
LOCA 2x500 mm (stand alone model)
Chronological sequence of important events
Time from initiating event [s] / Relevant value
Event
Initiating event (break of main pipeline)
Signal ESFAS U01 „Confinement overpressure >
10 kPa“, signal for confinement spray start
Maximum SG boxes pressure
APROS
MELCOR
0
0
0.5 s
0.5 s
11 s
9s
234.2
kPaabs
203.8 kPaabs
11 s
29 s
126.5 °C
147.0 °C
126.5 °C
137.1 °C
31 s
45 s
195.6 kPaabs
178.1 kPaabs
737 s*
1166 s*
Minimum pressure in SG boxes
94.3 kPaabs
91.4 kPaabs
Interval of the spray system operation
45 s - end
41 s - end
Start passive spraying
46 s
45 s
End of passive spraying
225 s
170 s
1.27E+06/4.23E+05 kg
1.12E+06/1.12E+05 kg
Recirculation regime initiation
1093 s
1093 s
End of calculation
3600 s
3600 s
Maximum SG boxes temperature
Maximum SG boxes temperature at pressure
peak
Maximum pressure inside air traps
Sub-pressure operation of the confinement
Initial and final mass of water in the trays
*) sub-pressure operation of the containment is not preserved till the end of the calculation
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MELCOR to APROS Comparison
LOCA 2x500 mm (stand alone model)
Pressure in the right side of Steam Generator Box
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MELCOR to APROS Comparison
LOCA 2x500 mm (stand alone model)
Temperature in the right side of Steam Generator Box
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MELCOR to APROS Comparison
LOCA 2x500 mm (stand alone model)
Pressure in bubble tower 1st floor
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MELCOR to APROS Comparison
LOCA 2x500 mm (stand alone model)
Volumetric flow through active spray
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MELCOR to APROS Comparison
LOCA 2x500 mm (stand alone model)
Active spray water temperature
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MELCOR to APROS Comparison
LOCA 2x500 mm (stand alone model)
Flow through passive spray 1st – 3rd floor
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MELCOR to APROS Comparison
LOCA 107 mm (stand alone model)
Chronological sequence of important events
Time from initiating event [s] / Relevant value
Event
Initiating event (break of main pipeline)
Signal ESFAS U01 „Confinement overpressure >
10 kPa“, signal for confinement spray start
Maximum SG boxes pressure
Maximum SG boxes temperature
Maximum SG boxes temperature at pressure
peak
Maximum pressure inside air traps
Sub-pressure operation of the confinement
Minimum pressure in SG boxes
Interval of the spray system operation
APROS
MELCOR
0
0
4.4 s
4.2 s
259 s
546 s
159.5 kPaabs
168.6 kPaabs
591 s
590 s
176.7 °C
148.5 °C
113.2 °C
145.9 °C
258 s
570 s
153.7
kPaabs
163.4 kPaabs
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-
130.9 kPaabs
122.0 kPaabs
47 s - 1100 s;
1950s - end
45 s - end
Start passive spraying
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End of passive spraying
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Recirculation regime initiation
1104 s
1104 s
End of calculation
3600 s
3600 s
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MELCOR to APROS Comparison
LOCA 107 mm (stand alone model)
Pressure in the right side of Steam Generator Box
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MELCOR to APROS Comparison
LOCA 107 mm (stand alone model)
Temperature in the right side of Steam Generator Box
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MELCOR to APROS Comparison
LOCA 107 mm (stand alone model)
Pressure in bubble tower 1st floor
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MELCOR to APROS Comparison
LOCA 107 mm (stand alone model)
Flow through passive spray 1st – 3rd floor
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MELCOR to APROS Comparison
Conclusion
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In spite of flashing phenomenon results show good agreement of compared
analysed scenarios.
APROS containment model is fully capable to analyze containment
response to a wide range of postulated initiating events.
Comparison of the APROS containment model using detail nodalization of
room A201 of VVER 440/V213 containment with the MELCOR 1.8.5
containment model showed applicability of the proposed detailed
nodalization. Similar nodalization is being prepared for new containment
model for MELCOR 2.1.
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Future plans
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Containment model for MELCOR 2.1 (May 2014)
Complex model for MELCOR 2.1 (September 2014)
Verification and validation of models for MELCOR 2.1
To use new MELCOR models for present projects related to containment
phenomena
Upcoming project – Developing DBA a SA model for APROS
verification of developed models will be done by code to code
comparison with models for RELAP5, MELCOR 1.8.5 and 2.1
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Thank you for attention
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