The Mutual Influence of Thermal-hydraulics and Materials on Design of SCWR Review of Results of the Project HPLWR Phase 2

Transcription

1 Institute of Nuclear Technology and Energy Systems The Mutual Influence of Thermal-hydraulics and Materials on Design of SCWR Review of Results of the Project HPLWR Phase 2 J. Starflinger, T. Schulenberg, KIT

2 HPLWR High Performance Light Water Reactor 5th Framework Programme of the EU Design Target Data: Operational pressure: Core mass flow: Power output: 25 MPa 1160 kg/s 1000 MWe Constraints: Average core exit temp.: 500 C Max. cladding surface temp.: 625 C Max. linear heat rate: 39 kw/m AREVA NP, 2005 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 2

3 Hot Channel Form Factor Analysis of the Core Definition F h h max av h h max av Maximum enthalpy rise in the Hot Channel Average enthalpy rise in the core Hot Channel by definition is the channel, in which all uncertainties, nonhomogeneities and allowances sum up, leading to the highest enthalpy rise of the entire core under normal operation conditions! Very conservative, provides a very high safety margin IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 3

4 Hot Channel Form Factor vs. Statistical Approach 95/95 Some thoughts F h max h av Maximum enthalpy rise in the Hot Channel There is at least a 95% probability at a 95% confidence level that [NUREG1475] Statistical approaches need a broad validated database (in-pile exp.) Statistical approaches are used to reduce the over-conservatism while keeping the safety margins. Do we really have enough statistical information to perform such an approach? IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 4

5 Design Targets of Hot Channel Factors Hot Channel Factor axial radial Key Parameters Form factors for power profiles Fuel enrichment and distribution, water density distribution, reflector design and properties, fuel and control rod pattern, burn-up, burnable poisons, Radial peaking factor 1.25 Local peaking factor inside FA 1.15 Axial power factor 1.6 Uncertainties 1.2 Material properties of coolant and claddings, physical modelling, hydraulic modelling, heat transfer coefficient, geometry tolerances Allowances 1.15 Power control, flow control, pressure control, inlet temperature control Total Schulenberg, KIT, 2010 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 5

6 Hot Channel Form Factor Analysis of the Core One-Pass Core Designed for 500 C core outlet temperature Coolant average conditions Average Heinecke, AREVA, 2010 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 6

7 Hot Channel Form Factor Analysis of the Core One-Pass Core Hot fuel assembly ( 1.25) + Assembly Power Average Heinecke, AREVA, 2010 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 7

8 Hot Channel Form Factor Analysis of the Core One-Pass Core Hot rod ( = 1.44 ) + Rod Power + Assembly Power Average Heinecke, AREVA, 2010 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 8

9 Hot Channel Form Factor Analysis of the Core One-Pass Core + Assembly Power + Uncertainty + Rod Power Hot rod + uncertainty ( = 1.73 ) Average IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//2016 9

10 Hot Channel Form Factor Analysis of the Core One-Pass Core + Operation + Uncertainty + Rod Power + Assembly Power Average Hot rod + uncertainty + operation ( = 1.98 ) Coolant temperature 1200 C Heinecke, AREVA, 2010 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

11 Hot Channel Form Factor Analysis of the Core Consequences Simple Hot-Channel analysis revealed the unfeasibility of single-pass core design. Idea from T. Schulenberg, KIT: Propose a Three-pass core with intermediate mixing in special mixing chambers. One key-issue of a feasible core design is mixing! not to overheat the core avoid hot streaks from one assembly to another and hot-spots on the cladding surface IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

12 Enthalpy [kj/kg] Three Pass Core Design Proposal for a HPLWR Strategy to overcome hotchannel issue: Power ratio of the core zones 4 : 2 : 1 Heat-up in steps with Intermediate mixing of the coolant Mixing 2000 Mixing 1500 hot channel average Schulenberg, Evaporator Superheater 1 Superheater 2 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

13 Temperatures [ C] Three Pass Core Design Proposal for a HPLWR cladding hot channel average Evaporator Superheater 1 Superheater 2 Schulenberg, 2006 A 3-Pass coolant flow in the core allows 500 C average core exit temperature with 625 C cladding temperature IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

14 Core Arrangement Superheater 1: 52 Clusters Downward Flow Evaporator: 52 Clusters Upward Flow Superheater 2: 52 Clusters, Upward Flow Köhly, 2010 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

15 Details of the Assembly Design Concept Cluster of 3x3 assemblies in square arrangement 40 fuel pins with 8mm diameter p/d = 1.18 wire wraps as grid spacers assembly box with 3 mm thickness incl. thermal insulation moderator box with 2 mm thickness incl. thermal insulation Moderator box Assembly box Wire wrap spacers Himmel, Köhly 2008 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

16 Head and Foot Piece Design of an Assembly Cluster Control rods running inside moderator channels New: Rising moderator water in gaps between assemblies Inlet orifices for moderator water Outlets of moderator water Hofmeister, modified later IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

17 HPLWR Flow Path Upper dome Moderator flow (50%) Inlet flow: 280 C 25 MPa 1179 kg/s Downcomer flow (50%) Downcomer Area Core flow (100%) IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR Köhly, /11/

18 Tasks for the HPLWR Partners Design Support Analyze the core, whether the power peaking factors will be met Neutronics: Simulate neutronics (BOC, EOC) for core and assembly-wise power distribution (input from materials and TH needed) Thermal-hydraulics: Suitable heat transfer correlation with an uncertainty of less than 25%, especially for fuel rod bundles with wire wraps as spacers. Materials & Water Chemistry Identify suitable materials for thick wall and thin wall components, but especially for cladding. IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

19 Overview CFD validation Geometry Medium Source/Institute HPLWR partner Tube SCW Yamagata NRG, USTUTT Tube SCW Herkenrath NRG Tube SC CO2 KAERI NRG SCW Shitsman KTH/USTUTT Tube Tube SCW Ornatskii KTH, USTUTT Annulus SCW Glushchenko USTUTT Annulus SC CO2 KAERI NRG/USTUTT Square annulus SCW Wisconsin univ. USTUTT Square annulus SCW XTJU USTUTT IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

20 Validation of Tube and Annulus Yamagata tube test, D h = 3.75 mm q/g = 0.18 q/g = 0.37 Laurien 2009 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

21 Validation of Tube and Annulus Ornatskii tube test, D h = 3 mm, Shitsman tube test, D h = 8 mm q/g = 1.21 q/g = 0.74 Laurien Anglart 2009 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

22 Results of the Heat Transfer investigation Normal and enhanced heat transfer can be predicted within the 25% uncertainty as requested. Onset of Heat Transfer Deterioration can possibly be predicted, but maximum temperature is uncertain. For use in sub-channel codes, correction factors of a heat transfer correlation shall be derived. HTC av = F geo x F wire x HTC base Conclusion from CFD calculations: Geometry factor F geo = 0.6 Wire factor F wire = 1.1 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

23 HTC Base correlation Example comparison of selected correlations with data HTC, W/m q = 1200 kw/m 2 G = 3500 kg/m 2.s p = 24 MPa d = 10 mm Bishop Dittus-Boelter Jackson Herkenrath Bulk enthalpy, kj/kg Anglart 2009 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

24 Bishop (1965) correlation vs. experimental data Experiment % Sig.=0.16; bias= MPa<=p<27.6MPa N. pts. = Bishop correlation +10% Experimental data in the range of parameters applicable to HPLWR upflow and in range of applicability of the correlation. 236 measurement points Bias is defined as: mean(htc Bishop /HTC Exp ) 1 = 0.44 Anglart 2009 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

25 Jackson, Hall (1979) correlation vs. experimental data upflow 90 Experiment Sig.=0.14; bias= MPa<=p<27.6MPa N. pts. = Jackson correlation -10% +10% Experimental data in the range of parameters applicable to HPLWR upflow and in range of applicability of the correlation. 236 Measurement Points Bias is defined as: mean(htc Jackson /HTC Exp ) 1 = 0.03 Anglart 2009 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

26 Jackson, Hall (1979) vs. experimental data downflow Experiment Sig.=0.11; bias= MPa<=p<27.6MPa N. pts. = Jackson correlation -10% +10% Experimental data in the range of parameters applicable to HPLWR downflow and in range of applicability of the correlation. 87 Measurement Points Bias is defined as: mean(htc Jackson /HTC Exp ) 1 = 0.05 Anglart 2009 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

27 Heat Transfer Correlation HPLWR approach Base correlation HTC base : Look-up tables (e.g. Löwenberg, Groeneveld) will offer best accuracy and should be considered as first choice (not shown here) Jackson correlation is proposed as the second choice, since it offers best agreement with measured data Note: Disadvantage of correlations is that they are not accurate and nonconservative, especially near the supercritical point. Strong interaction between heat transfer and core design Validation experiment needed incl. bundle effects and influence wire wrap spacers on the flow (fuelled loop project). IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

28 Materials Test of 16 materials in autoclaves at different temperatures Investigation of general corrosion, stress-corrosion cracking and creep Main findings: Thick walled components operating at max. 500 C No major structural problems with respect to corrosion (fossil plant technology) Thin walled components at above 600 C: High corrosion rate with licensed low Ni alloys (especially fuel cladding) High impact on core design! Redesign necessary if no suitable materials will be found. IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

29 Oxide Thickness (mm) Materials Influence of high Cr content on oxidation 1000 after 600h at 650 C P91 P ODS (FZK) ODS (EU) 10 PM NG BGA4 800H IN 625 0, Cr(%) Data from VTT, JRC, UJV Rez, IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

30 Assessment Radial Power Profile at BOC, Maraczy et al Radial power profile Power peaking factors per heat up step Local lower peaking factor strongly scattering in one assembly IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

31 Enthalpy Peaking Factors of Assembly 20% 18% 16% 14% 12% 10% 8% 6% 4% 2% 0% Control Rods Gd Burn Out Power Gradients Design Target EVA SH1 SH2 Note: The design target for local coolant enthalpy peaking factors inside fuel assemblies has been met. Factors are not simply additive. Control rod effects rather at BOC. Gd burn out rather at EOC. IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

32 Peak Enthalpy [kj/kg] Assessment Core Zone Enthalpy Peaking Factors Averaged power peaking factors are exceeding the design targets. Maximum 14% at BOC in SH Design Target BOC EOC EVA SH1 SH2 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

33 Peak Coolant Temp. [ C] Assessment Peak Coolant Temperatures in Core Zones EVA peak coolant temperature higher than design target Design Target BOC EOC SH1 peak coolant temperature exceeds design target SH2 peak coolant temperatures close to design target Reason: Clustering of the fuel assemblies. 0 EVA SH1 SH2 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

34 Summary of Uncertainties Peak coolant enthalpy Assembly bending 2% Sub-Channel codes 7% Neutron physical modeling 5% Local flow blockage 3% Total sum of variances 9% Other uncertainties Heat transfer predictions > 20% Material properties (corrosion) unknown! IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

35 Allowances Simulation from Schlagenhaufer, 2010 Temperature control: 10 C = 2% of total coolant enthalpy rise Pressure control: 50 kpa Design Target: 15% There is enough margin for measurement errors. IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

36 Design Targets of Hot Channel Factors Hot Channel Factor axial radial Key Parameters Form factors for power profiles Radial peaking factor Local peaking factor inside FA Axial power factor Fuel enrichment and distribution, water density distribution, reflector design and properties, fuel and control rod pattern, burn-up, burnable poisons, EVA SH1 SH2 Comment Design value exceeded Close to design value Uncertainties Allowances Material 1.09 properties 1.09 of coolant 1.09 and claddings, Heat transfer physical modelling, hydraulic modelling, and materials heat transfer coefficient, geometry tolerances not considered Power 1.02 control, 1.02 flow control, 1.02 pressure Simulation control, inlet temperature control Total IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

37 Assessment Did we meet the design targets? Enthalpy form factor of the HPLWR zones are met, because of very low uncertainty and allowances. Radial peeking factor is too high. The design target of 500 C core outlet temperature at 630 C maximum cladding surface temperature can be met. The 3x3 assembly cluster is too large for the 3 pass core concept, better individual smaller assemblies (better shuffling -> redesign) Core is complicated to analyze and optimize. Single pass core (EVA), only? Uncertainties of heat transfer and material properties still too large. Materials and heat transfer are to be further investigated! IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

38 Advice from A. Schwarzenegger Mix it, baby! IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//

39 Institute of Nuclear Technology and Energy Systems Thank you! Prof. Dr.-Ing. Jörg Starflinger phone +49 (0) fax +49 (0) Universität Stuttgart Institute of Nuclear Technology and Energy Systems Pfaffenwaldring Stuttgart Germany

40 IAEA - Technical Meeting on Heat transfer, Thermal-hydraulics, System Design for SCWR 22/8//