1. L.SABOTINOV, R.FREITAS, P.DUFEIL, F.DUBOIS IRSN/PSN-RES/SEMIA
CATHARE USERS’ CLUB Use of CATHARE at IRSN with focus on VVER reactors
L.SABOTINOV, R.FREITAS, P.DUFEIL, F.DUBOIS
IRSN/PSN-RES/SEMIA
Grenoble – France October 9 – 11, 2013

2. Contents Use of CATHARE code at IRSN Safety assessment Studies R&D
Examples of applications
Focus on CATHARE use for VVERs
General overview
CATHARE validation based on VVER experimental facilities
CATHARE validation against NPP test data, VVER (V320)
CATHARE application to VVER accident analysis
Conclusions
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3. Use of CATHARE code at IRSN
JHR LOCA transient
Transients with the SOFIA simulator, to reproduce some operational incidents
LB LOCA – IB LOCA
SGTR, FWTR, SLB
Safety assessment
Between one week and one year
Studies
More than one or two years
R&D
Between five and ten years
LOCA analyses for French PWR
PKL-ROCOM-PMK (OECD Projects)
PSB Projects
OECD Benchmarks (BFBT, PSBT, PREMIUM)
VVER projects
SFR studies
Hot Rod Methodology for LOCA analyses
SOFIA simulator, collaboration with AREVA : CATHARE integrated in the 900, 1300 and 1450 MWe configurations, and in the EPR one in 2012
In collaboration with AREVA : Development of the DIAGRAM module in GUITHARE for the I&C
Coupled codes:
HEMERA, DRACCAR/CATHARE3, ICARE/CATHARE2
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4. Engineering simulator at IRSN
SOFIA simulator
SOFIA = Simulator for Observation of Functioning during Incident and Accident
Engineering simulator at IRSN
Nuclear Power Plant of PWR type
Developed and managed in collaboration with AREVA and L-3 COMMUNICATIONS MAPPS since 2005
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5. SOFIA simulator Scope of simulation An efficient tool for:
CATHARE 2 v2.5_1 for primary + secondary and RHR Systems
4 configurations representative for the different types of French reactors (900 – 1300 – 1450 MWe + EPR)
Simulation from FPSS to Cold shutdown states for maintenance just before reactor vessel opening
Transients performed up to cladding temperature ~ 2200°F (~ 1200°C)
An efficient tool for:
Training (over 1000 trainees since 2000, from IRSN, ASN, CEA…)
Emergency response exercises, to prepare the scenario and data used during the exercises
Studies in support of safety evaluation
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6. Focus on CATHARE use for VVERs 1- General overview
Beginning of the IRSN activity, related to CATHARE safety analyses of VVER
mid. 1991
Development of input data decks for VVER modeling
CATHARE Team assistance
IRSN Thermal-hydraulic Working Group on VVER calculations
- WG creation : 1992
- WG objectives:
to assess and adapt CATHARE to VVER analysis
to allow IRSN to propose VVER safety assessment and studies.
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7. "Methodology" : 2 actions in parallel
assessment on the basis of VVER test facilities: PACTEL, PMK, ISB, PSB, REWET, KIT etc.,
reactor calculations and comparison with other codes (ATHLET, APROS, RELAP, DINAMIKA, TECH) for existing calculations and plant measurements
Participation in TACIS, PHARE, EC projects, bilateral activity
More then 15 projects, Examples:
 RUSSIA ( )
TACIS RF/TS/13 « EU TSO Support to Independent Safety Related Analysis of Russian NPPs by Application of Western Codes »
IRSN, GRS, SEC-NRS-Russia
 UKRAINE (1998)
TACIS UK/TS/04 «Support to the Transfer of Accident Analysis Codes to the Ukrainian Safety Authority and its Technical Safety Organizations and Application of these Codes»,
IRSN, GRS, SEC-NRS-Ukraine
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8.  IMPAM-VVER project (EC FIS5-2001-00117, 2001-2004)
 BULGARIA ( )
Projects BNRA-RA-07-01, BNRA-RA-07-02, Review and assessment of the ISAR of BELENE NPP
Task 2: Performance of additional research oriented activities and generic oriented in-depth studies: LARGE BREAK LOSS OF COOLANT ACCIDENT ANALYSIS OF BELENE NUCLEAR POWER PLANT
IRSN, GRS, BNRA
 IMPAM-VVER project (EC FIS , )
(Improved Accident Management of VVER)
IRSN, VTT Energy, LUT, Fortum, KFKI, Paks, FZR
+ NRI Rez, VUJE, IVS, INRNE
Objectives:
- Effective means and criteria for primary depressurization in SB LOCA
- Evaluation of system code capabilities to predict phenomena
Work plan:
WP1: Experimental investigation: PACTEL and PMK-2
WP2: Computer analyses of the experiments + NPP
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9. 2- CATHARE validation, based on VVER experimental facilities
PACTEL : International Standard Problem ISP-33, OECD/NEA, natural circulation (1/305 by volume, 3 loops, 1:1 elevation scaling factor)
PACTEL : EC IMPAM-VVER (7.4% break, F&B)
PMK : Standard Problem Exercises SPE1,2,4, IAEA
ISB (EREC-Russia)
PSB (EREC-Russia), OECD, Czech republic (11% break, PRISE) (1/300 VVER-1000 model)
REWET (Reflooding)
IVO CCFL (Counter-currant flow limitation)
KIT (subcooled boiling)
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10. CATHARE PSB-VVER analysis
11% UP Break
Good prediction of the basic physical phenomena and parameters such as:
primary and secondary pressures, temperatures, void fractions, levels, flow rates etc.
Faster ACCU discharge at the beginning, which leads to higher condensation rate and slight pressure underprediction
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11. Tmax (CATHARE) Tmax measurement
The experimental and calculation results are very sensitive regarding the fuel cladding temperatures, which have periodical nature with strong correlation with the ACCU discharge
The core heat up has been reasonably predicted; this can provide bounding values regarding the safety analysis criteria with appropriate methodology, including uncertainty analysis.
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12. CATHARE PSB-VVER analysis
Large Primary to Secondary Leakage (PRISE), De=100mm
UP pressure
SG-4 pressure
Due to the leak, the primary pressure is decreasing, which leads to the actuation of the scram signal at 21.8 s (UP pressure < 13.7 MPa).
At 25.3 s, the pressure in the broken steam generator (SG #4) reaches 7.16 MPa, then opening and seizure of BRU-A in open position occurs.
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13. primary and secondary pressures, temperatures, flows etc.
Use of CATHARE at IRSN with focus on VVER reactors - CATHARE USERS’ CLUB 2013
Good prediction of the basic physical phenomena and parameters such as:
primary and secondary pressures, temperatures, flows etc.
The final core heatup is in good agreement with the experiment.
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14. CATHARE Assessment of PACTEL LOCA
Experiments with Accident Management (EC IMPAM-VVER)
Test T2.1 Cathare vs. experiment
PACTEL facility
The basic thermal-hydraulic parameters are correctly predicted by Cathare. Timing and amplitude of the key parameter Tclad are also in good agreement with the experiment. Delayed ACCU injection (reduced pressure set-point) has favorable effect on core cooling .
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15. 3- CATHARE modeling and validation against NPP test data, VVER-1000 (V320)
Modeling of primary circuit and steam generator
Information (specification of the VVER-1000 reference plant, more than 50 NPP drawings)
Primary circuit (axial elements, volumes, T-elements)
4 loops modeled separately
(or single loop with PRZ + triple loop)
reactor vessel (downcomer, core,bypass, upper plenum)
hot and cold legs, pumps etc.
Steam generator modeling
point SG
once-through SG
recirculation SG model
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16. ► Modeling (Primary circuit)
Nodalization scheme of VVER-1000 reactor pressure vessel in CATHARE (for LB LOCA )
Core: 163 hexagonal fuel assemblies, 312 fuel rods in each fuel assembly arranged in a triangular lattice. Fuel pellets have central co-axial hole.
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17. ► Secondary circuit and SG
SG secondary side is represented with a recirculation model with a volume element GVVOL1 and an axial element GVDOWN1 with a downcomer and riser parts of the recirculation circuit.
The thermal connection with the primary circuit is modeled in the riser part with three heat exchanging tube bundles.
The steam lines to the turbine are modeled with axial elements and volumes for connection of the steam dump device BRU-A, safety valves and BRU-K.
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18. Validation against NPP test data
Pressure losses in the primary circuit
Nominal steady state
Natural circulation tests
(3.3%, 7.9%,10.9% and 12.5% NP)
Coastdown of the MCP (20% NP)
Turbine load reduction
OECD/V1000-CT Benchmark (Kozloduy-6 pump start-up experiment and vessel mixing experiments)
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19. Example : Coastdown of the RCP (20% NP)
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20. 4. Reactor applications to VVER-1000
Performed calculations
CL LOCA (70 mm, 109 mm, 180 mm, Sensitivity study on MCP trip delay after SI signal, on break modeling etc.)
SGTR (Improvements to the break modeling of horizontal tube bundles (VVER), Sensitivity studies)
SGCB (De=100 mm, Approach to the break modeling of VVER)
AB sequence (HA line break D=279 mm, no active ECCS)
Total Loss of SG Feed Water (TLFW)
Without operator intervention
Operator action : Gas Blow-off System (after 30 min)
Operator action : Opening of PRZ safety valve (after 30 min)
Primary LOCA by pressurizer PORV failure
Large Break LOCA (DBA, BDBA) (Guillotine break 2A, D=850 mm)
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21. Illustration of BDBA LB LOCA ANALYSIS WITH FAILURE OF ACTIVE ECCS
VVER-1000 Belene NPP (V466B)
Guillotine 2A LB LOCA (D=850 mm)
Specific features of BNPP of increased passive systems are taken into account and modelled.
- Hydroaccumulators second stage (HA-2), (8x120 m3)
- Secondary Passive Heat Removal System PHRS (SPOT)
Two scenarios with realistic and atmospheric (0.1MPa) containment counter pressure were calculated.
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22. Maximal fuel cladding temperatures
(realistic containment counter pressure)
The cool-down of the reactor core is achieved and maximal fuel cladding temperature for the time span of 24 hours remains below the limiting temperature of 1200°C, applying realistic boundary conditions regarding the containment counter pressure.
 Confirmation of TECH-M results
fuel cladding temperatures
(Zoom)
fuel cladding temperatures
Hot core
Average core
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23. Counter pressure realist Counter pressure 0.1MPa
More conservative containment conditions (0.1MPa counter pressure) lead to core heat up after 13 hours and fuel melting after 16 hours..
Void fractions (t=16 h)
Counter pressure realist
Counter pressure 0.1MPa
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24. Conclusions :
Important IRSN contribution : ~20 IRSN engineers use CATHARE code:
To performed studies in the frame of expertise
To develop engineering simulators
To develop IRSN methodology and specific tools for safety assessment
To identify the lacks of knowledge and the need of research
Conclusion on VVER applications:
☺► The CATHARE code is able to predict correctly the thermal-hydraulic phenomena in VVER reactors and can be applied for safety studies
☺► Important validation work on CATHARE has been carried out on Separate Effect Tests Facilities and Integral Test Facilities regarding VVERs
Collaboration with different organisms on CATHARE code: INR(Czech Republic), INRNE(Bulgaria), KI(Russia), BARC(India), Bel- V(Belgium), JNRC(Jordan), VARANS(Vietnam) etc.
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25. Continuation of currents applications and developments
Numerous journal publications and presentations at international conferences
Perspectives:
Continuation of currents applications and developments
New applications/developments for new type of reactors
Experimental reactors like the JHR
Gas cooled reactor
Sodium cooled fast reactor
Advanced reactors (EPR, VVER …)
Important involvement on NEPTUNE project, in particular CATHARE3 evaluation
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