Short Introduction on MELCOR and ASTEC codes

Transcription

1 Short Introduction on MELCOR and ASTEC codes Dott. Ing. G. Mazzini Ph. D. in Nuclear and Industrial Safety Rez, 05/10/2012

2 Outlooks (1/2) Introduction MELCOR Code Analytic and Functional Sketch MELGEN MELCOR Packages CVH Examples Add Ins and Tools 2

3 Outlooks (2/2) ASTEC Code Analytic and Illustrative Sketch Packages Phenomenology Instants JADE Input and Control Volume Examples Add Ins and Tools MARCUS Portal Difference Between ASTEC and MELCOR 3

4 Introduction The objective of this lecture is tht description of ASTEC and MELCOR Codes, developed for the simulation of Nuclear Power Plant under Severe Accident (SA) conditions and the evaluation of the Sorce Term In Particular Predict the severe accident phenomena such asspreading and candling of molten material of the core; Molten pool formation. Analysis of the Steam/Zircaloy interactions, production and release of Hydrogen (H 2 ) Release of Fission Product and Structural Material(as Aerosol, Gasses, ) Transport, Deposition and Re-suspension of Aerosol (in the primary and containment systems) 4

5 MELCOR Code MELCOR code, set-up by US Sandia National Laboratory, was developed in origin for LWR; at present it is used also for other types of NPP. It: is a fully integrated, engineering-level computer code, able to model the progression of SA. uses mass/energy/momentum balance equations is based on several modules, that define the main phenomena related to SA (CVH, FL, COR, DCH, HS,.) evaluates the Source Term for each SA sequence. Versions:

6 MELCOR Analytic Logic Boundary and Initial Conditions MELCOR code starts with the simulation. Thermal-Hydraulic Behaviour Containment System under severe accident conditions Start of Degradation and Aerosol Dynamics Spray, Recombiner, MCCI, DCH,. Prediction of the Source Term due to Aerosols, for People Protection 6

7 Functional Sketch 7

8 MELGEN MELGEN is the diagnostic program, with different checks: Syntactic : Wrong character inserted during the preparation of the input file (typically *.gen or *.GUI), check about repetitions, etc. Matematics and Logic : natural numbers, real, complex, variables writing, etc. Congruence : incorrect elevations, components that should be related to other components, negative pressures, etc. 8

9 the calculation. MELCOR EXEC generate the PTF, extends and manipulates the file RESTART, the OUTPUT file, etc.. Through the card plot, it can also generate appropriate file.dat similar to the "minor edit" or the Strip File of RELAP. May be complemented by appropriate card, to disable / enable models. May contain coefficients of sensitivity to improve computing performance. 9

10 List of the Modules Modules: Execution (EXEC), Combustion (BUR), Reactor Cavity (CAV), Control Function(CF), Condensation PCCS e ICS (CND), Core (COR), Thermo-Hydraulic Control Volume(CVH),Mass Inventory and Power Generation (DCH), External Data Files (EDF), Fan Cooler (FCL), Fuel Dispersion Interaction (FDI), Junction (FL), Heat Structures (HS), Material Property (MP), Noncondensable Gas Property (NCG), Passive Automatic Recombiners (PAR), Radio Nuclides (RN), ContainmentSprays (SPR), Tables (TF), Transfer Process(TP). 10

11 CVH: In particular is the generic control volume for Vessel, Primary or Secondary, Containment, etc. could stay in a stand-alone configuration could be coupled with FL, RN, HS, COR, etc. Allows also the Time Dependent Volume or Mass/Energy Injection 11

12 In particular FL: declares a junction (area, length, etc..) defines pressure drops (concentrated and distributed) describes the junction (interface between the volumes) Valve e Pumps HS: 1D Nodes (in thickness) Boundary condition and geometric dimensions Could simulate heaters (energy or temperature insertions in specifics nodes) 12

13 In particular COR: 2D melting process, power generation, hydrogen production, relocation phenomena in lower head, etc. DCH: Mass inventory and power/decay heat simulation (ANS Curves, ORIGEN or Tabular) RN : Release through the CORSOR models Release and Size Classes (based on the Rasmussen approach) Transport of Gases and Aerosol with MAEROS 13

14 CVH Volume distribution 14

15 CVH Example (v 1.8.5/1.8.6) Name, Models (EQ/Non EQ), Geometry, RN Type of Volume Type of Volume and Initial Condition Initial Volume Distribution 15

16 CVH Example (v 2.1) Name, User ID, RN Type of Volume Initial Volume Distribution Models (EQ/Non EQ, etc.) Initial Condition 16

17 Add Ins and Tools PTFRead: Done with Excel Macros, it permits to plot directly the MELCOR variables APTPlot: Also for RELAP/TRACE, it allows to plot the variable and to extract the data in vectors or matrices SNAP: Visual editor and running platform for RELAP, TRACE, MELCOR,. Excel Input Deck Converter MELCOR Converter

18 Sviluppo di ASTEC 18

19 Sviluppo di ASTEC 19

20 ASTEC V2 Codes 20

21 In particular. ASTEC uses ICARE/CESAR module Thermal Hydraulic Behavior of the Core and Primary Circuit Core Degradation and Chemical Oxidations ASTEC uses ELSA module Release of Structural Material and Fission Product FPs are divided in Volatile, Semi and Low-Volatile ASTEC uses SOPHAEROS/CPA module employs the Stephan s law evaluates the aerosol dynamics with MAEROS A detailed overview of the physical and mechanical depositions is taken into account for SOPHAEROS 21

22 Phenomenology Instants 22

23 JADE Input Editor 23

24 General Structures JADE and Input View (Calculation Options) Activated modules Time step and principal conditions Message activated for the primary Output 24

25 Primary Structure Primary: CESAR e SOPHAEROS Control Volume Description Geometric conditions Initial conditions 25

26 Containment Structure Containment: IODE e CPA Zone = Control Volume General Data Geometric Data SELE = Altitude of the bottom of the zone ELEV = Altitude of the center of the zone Thermodynamic initial conditions 26

27 ASTEC Runs ASTEC: Add Ins and Tools Error Evaluation General Initial View Documents Editor 27 Demo Pre and Post Processing Data Base 2D Visualizations

28 MARCUS Network Portal Symilar to the Forum of MELCOR (SNL site) 28

29 Difference between ASTEC and MELCOR (1/2) Aspects MELCOR ASTEC Experiences of the Code approximately 30 y approximately 10 y Type of Reactors Gen. II + Gen. III/III+ Gen. II + Gen. III/III+ (PWRs and HTRs) limitations for BWR, CANDU and Passive Type of Input Tabular Informatics Type of Components Aerosol and Elements Distributions General for all Calculations Elements and Size Classes Distributions Time/Local Phases Elements Specification + Size Classes 29 Distributions

30 Difference between ASTEC and MELCOR (2/2) Aspects MELCOR ASTEC Tools Flexibility of the Input Yes Redundancy of Information Externals to the code installation Not evidenced Internal to the code installation Not for such package Yes Online Visualizations Yes (SNAP) Yes Developed NRC SNL IRSN/GRS Chemistry of Released Products No Simplified Iodine Chemistry Simplified Yes in the Containment Oxidation Reactions Yes Yes 30

31 Thank you for your Attention! 31

32 Annex: PHEBUS FPT1 Results from the Ph.D. Final Work

33 FPT1 Containment Analyses Two control volumesare considered (CV and sump) Boundary and initial conditions imposed to simulate the evolution of the first part of the test Calculations use the experimental steam, H 2 and aerosols source rates, as measured at the CV inlet A non-equilibrium model is applied for the simulation of the CV thermal-hydraulics 33

34 Thermo-Hydraulics Results (1/2) Temperature (K) Pressure (Pa) ASTEC MELCOR Experimental ASTEC MELCOR Experimental Time (s) Time (s) Containment atmosphere pressure 34 Containment atmosphere temperature

35 Thermo-Hydraulics Results (2/2) Cond. Rate (kg/s) Rel. humidity (%) ASTEC MELCOR Experimental ASTEC MELCOR Experimental Time (s) Time (s) Condensation Containment rate on relative condensers humidity 35

36 Aerosol Transport Results (1/2) MELCOR ASTEC MELCOR Dep. Mass (g) Dep. Mass (g) ASTEC Time (s) Time (s) Mass of aerosols deposited Total aerosols on heat deposited structures mass 36

37 Aerosol Transport Results (2/2) Susp. Mass (g) Susp. Mass (g) MELCOR MELCOR ASTEC Experimental ASTEC Experimental Time (s) Time (s) Uranium Total aerosol suspended aerosols mass mass 37

38 FPT1 Complete Analyses Two Control volumes (1 for MELCOR) are considered for CV and sump The Circuit nodalization is that of ISP Mesh for the Active Length distributed in 2 Thermo-Hydraulic Control Volumes Steam Inlet 38

39 Temperature [K] [K] Bundle Degradation Results (1/2) AIC ASTEC AIC ASTEC Fuel 2 ASTEC Fuel2 ASTEC Fuel 3 ASTEC Fuel3 ASTEC Fuel 4 ASTEC Fuel4 ASTEC COR-TFU.108 COR-TFU.110 COR-TFU.208 COR-TFU.210 Ref. TCW1 fuel 300 mm Ref. Ref. TCW3 TCW6 Clad fuel mm mm time time [sec] [sec] Fuel temperature between m and m of active length 39

40 Bundle Degradation Results (2/2) 2.50E E-04 Flowrate (kg/s) 1.50E E-04 ASTEC H2 Reference H2 MELCOR H2 5.00E E+00 Molten Pool Mass: 2.03 kg ASTEC code: kg 0.00E E E E E E+04 Time (s) Hydrogen production rate G. Mazzini, Ph. D. Final Defense, Pisa (IT), 05/07/

41 Release Fractions Results FP Element References ASTEC V2.0 MELCOR Nb 95 < Zr 95 < *10-04 Ba 140 < I (±4) Te (±1) La 140 < Cs (±0.8) Mo 99 56(±4) FP Release fraction Ru 103 < *10-04 Ag 110m 15(±5) Release (g) References ASTEC V2.0 MELCOR Bundle Test Section and Circuit Containment

42 Containment Behavior Mass Pressure [gm] [Pa] ASTEC Reference MELCOR Reference ASTEC MELCOR time time [sec] Containment Total suspended atmosphere aerosols pressure mass 42