1. IMPACT CAPE-B: Critical Power Analysis Code for BWR Fuel Bundle - Evaluation Method - Analytical Step Calculation Method 4. Detection of Dryout 2. Spacer Effect 1. Fuel Bundle 3. Each Subchannel 3-D Subchannel Analysis with Drift-flux Model 3-D Liquid Droplet Transport Analysis In Turbulent Steam Flow Liquid Film Flow Rate = 0 Liquid Film Flow Analysis

2. (a) Comparison of mass flux  Pressure : 6.9 Mpa  Number of axial subchannel division : 50 Un-heated test (4 test runs) Average mass flux : 651-2671 kg/m 2 s Inlet subcooling : 1174 kJ/kg Heated test (13 test runs) Average mass flux : 719-1464 kg/m 2 s Inlet subcooling : 68-603 kJ/kg Heated length : 1.83 m Power distribution : Uniform Heat flux : 710-2130 W/m 2 IMPACT CAPE-B: Verification of Subchannel Analysis Model (1. Analysis of the test conducted by Lahey, et al.) 0 1000 2000 3000 4000 1000 2000 3000 Measured mass flux (kg/m 2 s) Calculated mass flux (kg/m 2 s) 4000   (Standard deviation)  =7% :Inner :Side :Corner (b) Comparison of steam quality 0.1 0.2 0.3 0.4 0.5 0.10.20.30.40.5 Measured quality Calculated quality +e -e (Measurement error) e=0.024 :Inner :Side :Corner 0

3. PERI IN-3IN-1 IN-2 : 1.30 : 1.15 : 0.90 : 0.45 Radial power distribution 0.6 0.2 0.4 PERIIN-1 IN-2IN-3 Region in bundle Regional average void fraction 0.8 Pressure : 7.2 Mpa Mass flow rate : 1562 kg/m 2 s Inlet subcooling : 50.2 kJ/kg Axial power distribution : Uniform Number of axial subchannel division : 48 IMPACT CAPE-B: Verification of Subchannel Analysis Model (2. Analysis of NUPEC full scale bundle test) : Present calculation : COBRA-BWR Test data

4. IMPACT CAPE-B: Concept of Liquid Film Flow Analysis dG f dz ( G f +dz ) = dG f dz (D - E - B) p e A Fuel rod Dryout Heat transfer to liquid film Entrainment rate: E Evaporation rate: B Deposition rate: D Liquid droplet Inflow to the mesh: G f Mesh height Outflow from the mesh (=Inflow to the next mesh) Liquid film dz

6. Distance from the edge of the spacer (mm) Increment ratio of turbulent fluctuation u'/u' ∞ 1 2 3 4 0 1020304050 ThicknessExp.Cal. 0.5 mm 1.0 mm IMPACT CAPE-B: Turbulent Enhancewment due to the Spacer (Analysis of the test conducted by Nagayoshi, et al.)

7. IMPACT CAPE-B: Test analysis condition for model validation Bundle Type NUPEC 8  8 EPRI 4  4 Bundle No. C2A Ferrule Spacer, 1 W/R Bundle No. III Grid Spacer, 2 W/Rs Bundle No. 301 Grid Spacer, no W/R Pressure (Mpa) 5.5, 7.2, 8.6 7.2, 8.6 4.1, 6.9, 8.6 Mass flux (kg/m 2 s) 590-1,910 570-1,690 700-1,750 Inlet subcooling (kJ/kg) 20-130 10-125 50-610 Heated length (m) 3.7 3.7 1.8 Power Axial 24-step chopped cosine with p/f of 1.4 Uniform Distribution Radial Local p/f: 1.30 Local p/f: 1.18 Local p/f: 1.02 Number of data points 70 72 38 Subchannel Axial 72 72 72 Division Radial 80 81 25 Spacer effect Coordinates Cylindrical Cartesian Cartesian Analysis Mesh division 20  64  88 40  40  90 40  40  90 W/R: Water Rod, p/f: peaking factor

8. 1/4 Subchannel Fuel rod Ferrule type spacer 1/4 Subchannel Fuel rod Grid type spacer IMPACT CAPE-B: Two Typical Spacer Types

9. (a) Comparison at rated pressure IMPACT CAPE-B: Validation analysis for BWR models (Analyses of the NUPEC 8  8 and EPRI 4  4 tests) Calculated critical power (MW) Measured critical power (MW) 0 2 4 6 8 10 12 24681012 Number of data points : 116 Pressure : 6.9 - 7.2 MPa Average difference : 0.5%   =5.1% (Standard deviation) -- ++

10. (b) Comparison with all data IMPACT CAPE-B: Validation analysis for BWR models (Analyses of the NUPEC 8  8 and EPRI 4  4 tests) Measured critical power (MW) Calculated critical power (MW) 0 2 4 6 8 10 12 24681012 Number of data points : 166 Pressure (MPa) : 8.6 : 6.9 - 7.2 : 5.5 : 4.1 Average difference : - 0.3%   =6.3% (Standard deviation) ++ --

11. WR : Water rod Bundle C2A, C2B Bundle III 1.151.10 1.15 1.10 0.98 1.100.98 1.10 0.98 0.60 0.98 1.181.101.15 1.101.15 0.98 0.600.98 0.600.98 1.10 0.98 0.60 0.98 0.60 1.18 WR 0.98 0.99 0.75 0.99 WR 1.15 0.45 0.89 1.15 0.99 1.15 1.18 1.30 0.99 1.15 0.99 0.89 1.18 1.30 1.18 0.89 0.99 0.89 1.18 1.30 0.99 0.89 0.99 0.89 0.99 1.15 1.18 1.30 0.99 1.15 1.18 1.30 0.99 1.15 0.75 0.45 0.99 0.89 0.75 0.45 0.99 1.15 0.99 1.15 0.99 0.89 0.99 0.89 0.75 0.99 0.89 1.301.15 0.450.89 0.99 IMPACT CAPE-B: Comparison of dryout locations Dryout locations Test Cal. C2A III and C2B Bundle

12. Critical power (MW) Mass flux (kg/m 2 s) 5 6 8 10 0 ~ ~ ~ ~ 50010001500 2000 7 9 IMPACT CAPE-B: Effect of radial power peaking Cal.Exp. C2A C2B Bundle No. Spacer Ferrule type Radial power peaking factor : 1.30 Pressure : 7.2 MPa Inlet subcooling : 50.2 kJ/kg Radial power peaking factor : 1.18

13. IMPACT CAPE-B: Critical power difference by spacer type Critical power (MW) Mass flux (kg/m 2 s) 5 6 8 10 500100015002000 7 9 ~ ~ ~ ~ Cal.Exp. Grid Ferrule SpacerBundle No. C2B III Pressure : 7.2 MPa Inlet subcooling : 50 kJ/kg

14. Axial distance (mm) Droplet transport rate (m/s) 0 0.1 50100150200250 0.2 0.3 IMPACT CAPE-B: Droplet deposition characteristics Ferrule Spacer Grid Spacer Spacer Location : Ferrule : Grid