QUENCH-12 VERSUS QUENCH-06 COMPARATIVE CALCULATION ANALYSIS USING SOCRAT 1.1 CODE

Transcription

1 QUENCH- VERSUS QUENCH-6 COMPARATIVE CALCULATION ANALYSIS USING SOCRAT. CODE A.Vasiliev Nuclear Safety Institute of Russian Academy of Sciences (IBRAE) B.Tulskaya, 9 Moscow, Russia

2 Content. Introduction. QUENCH-6 and QUENCH- features. SOCRAT system of numerical codes. SOCRAT calculations of Q-6 and Q-. Possible reasons for differences in Q-6 and Q- hydrogen release behavior 6. Conclusions

3 QUENCH- through QUENCH- Test Results FZK, Karlsruhe, Germany Test Type of Cooldown ZrO layer Thickness, μm Maxim. Temp., K Melt Formation H Total before/during quench Q- Water 8 No 9(6/) Q- Water Q- Water Compl.Oxid. Yes 9(/7) Compl.Oxid. Yes (8/) Q- Steam 7 No (/) Q- Steam 7 No 7(/) Q-6 Water Q-7 Steam Q-8 Steam Q-9 Steam Q- Water Q- Water Q- Water 66 No 6(/) Compl.Oxid. Yes 98(6/6) Compl.Oxid. Local 8(6/8) Compl.Oxid. Yes 68(6/8) Compl.Oxid. 8 Yes (8/) Compl.Oxid. Yes (9/) 6 Local 8(/) Q-?????

4 QUENCH-6 & QUENCH- QUENCH-6 Conducted in December, PWR geometry and materials Square grid grid spacers (Inconel, Zircaloy- ) Zircaloy- cladding Shroud Preoxidation Total H 6g, g before reflood, g during reflood QUENCH- Conducted in September 7, 6 VVER geometry and materials Hexagonal grid 7 Grid spacers (E-) Zr%Nb cladding (E-) Shroud (Zr.%Nb) (E-) Preoxidation Total H 8g, g before reflood g during reflood

5 QUENCH-6 & QUENCH- Test Bundles Shroud isolation Cooling jacket Shroud isolation Cooling jacket QUENCH-6 QUENCH-

6 QUENCH-6 versus QUENCH-: Main Differences QUENCH-6 rods + corner rods Mass.8+.9 kg ( QUENCH ( QUENCH- mesh) square grid pitch. mm rod diameter. mm coolant flow area.99 - m / g/s Ar & steam Tungsten diameter 6 mm Cladding material: Zircaloy Oxidation surface. - m QUENCH- rods + 6 corner rods Mass.9+.7 kg ( QUENCH ( QUENCH- mesh) hexagonal grid pitch.7 mm rod diameter 9. mm coolant flow area. - m./. g/s Ar & steam Tungsten diameter mm Cladding material: Zr%Nb Oxidation surface.7 - m

7 QUENCH-6 versus QUENCH-: Surface Area and Mass QUENCH-6 = heated + unheated rods (diameter.7/9. mm) corner rods (diameter 6mm) S= M= QUENCH- =8 heated + unheated rods (diameter 9./7.7 mm) 6 corner rods (diameter 6mm) S=.7 M=.9

8 QUENCH-6 versus QUENCH-: Thermal Hydraulics in Square and Hexagonal Grid QUENCH-6 QUENCH- R rod radius s = d d R pitch relative pitch s =. s =.9 Nu = (.s.) Re Pr.8 /

9 QUENCH-6 & QUENCH-: Radiative Thermal Conductivity in Square and Hexagonal Grid in Radial Direction QUENCH-6 QUENCH- κ rad = σbε π d T R κ rad = σbε π d T R σ B d R ε Stefan-Boltzmann constant pitch rod radius emissivity κ, = κrad, VVER. rad PWR

10 SOCRAT : Best Estimate System of Codes for Modeling Phenomena Arising during Severe Accident at NPP with VVER SOCRAT (previous name RATEG/SVECHA) system of codes for modeling thermal hydraulics, degradation phenomena, fission products behavior etc., in the case of accident at NPP with VVER SOCRAT. version Modeling of hydrogen source term SOCRAT. version - Modeling of measures for accident control at NPP with VVER

11 Unheat Rod group Heated Rod group Heated Rod group Heated Rod group Heated Rod 8 group Corner Rod group 6 Hydro channel ZrO Isolation group 7,8 outlet Bypass & jacket group 9 Ar inlet Q-6 CORE water inlet F steam inlet F Ar inlet FM steam inlet F 6

12 Unheat Rod group Heated Rod 6 group Unheat Rod 6 group Unheat Rod 6 group Heated Rod group Corner Rod 6 group 6 Hydro channel ZrO Isolation group 7,8 outlet Bypass & jacket group 9 Ar inlet Q- CORE water inlet F steam inlet F Ar inlet FM steam inlet F 6

13 QUENCH-6 & QUENCH-: Total Electric Power 6 Total electric power, W 8 QUENCH-6 QUENCH- 6 8

14 QUENCH-6 & QUENCH-: Electric Power in Different Parts QUENCH-6 QUENCH- 6 6 Electric power, W 8 Electric power, W total electric power electric power except R ext electric power in core

15 QUENCH-6 & QUENCH-: Integral Heat Balance QUENCH-6 QUENCH- Power, W Power, W total electric power heat transferred by gas heat to shroud chemical power

16 QUENCH-6 & QUENCH-: Radiative Heat Fluxes Q-6 radiative heat to shroud Q- radiative heat to shroud Radiative power, W Q-6 radiation absorption in gas Q- radiation absorption in gas 6 8

17 Radiation Absorption in QUENCH-6 and QUENCH- W ε g ε(-ε)σ B (T -T g)s power absorbed in the bundle S ε g = exp( al g m) emissivity of gas surface of heat elements Optical thickness is about. at K and. at K W W during the test 7

18 QUENCH-6 & QUENCH-: Steam Starvation. reflood steam starvation Oxygen part consumed.8. Q-6 Q

19 QUENCH-6: Cladding Temperature at Different Elevations --- SOCRAT experiment Temperature, K 9mm 7mm mm mm 6 8

20 QUENCH-6: Cladding Temperature at Reflood --- SOCRAT experiment

21 QUENCH-6: Hydrogen Generation.6 reflood - SOCRAT - experiment Hydrogen generation, kg.. 6 8

22 QUENCH-6: SOCRAT Zirconium Dioxide Layer Thickness 8 6 ZrO layer thickness, μm 8 6 Axial level, mm

23 QUENCH-: Cladding Temperature at Different Elevations --- SOCRAT experiment Temperature, K 6 8 9mm 7mm mm mm 6 8

24 QUENCH-: Cladding Temperature at Reflood 6 9mm 7mm --- SOCRAT experiment Temperature, K mm mm

25 QUENCH-: Hydrogen Generation.8.6 reflood - SOCRAT - experiment Hydrogen production, kg.. 6 8

26 QUENCH-: SOCRAT Zirconium Dioxide Layer Thickness 6 ZrO layer thickness, μm 8 6 Axial level, mm

27 QUENCH-6 & QUENCH-: Experimental Cladding Temperature and Hydrogen Generation.8 QUENCH- TFSU / QUENCH-6 TFS / QUENCH-6 TFS /.6 reflood Temperature, K Hydrogen production, kg.. QUENCH-6 QUENCH

28 QUENCH-6 & QUENCH-: Experimental Hydrogen Generation at Reflood.8 reflood Hydrogen production, kg.6. reflood QUENCH- QUENCH

29 What is the main reason for larger H production in QUENCH- in comparison to QUENCH-6? Enhanced oxidation surface in Q-? Zr%Nb breakaway oxidation? Or just longer excursion time in Q- and possible melt oxidation?

30 Breakaway Oxidation in VVER E- Cladding At 9 C<T< C the breakaway effect in oxidation kinetics Multiple bends and twists at parabolic curve of oxidation at long exposition time, spallation after achievement of oxide film thickness µm Solyany V.I., Bibilashvili Yu.K., Dranenko V.V. et al. Investigation of corrosion behavior of cladding made of Zr%Nb alloy in a steam at high temperatures VANT: Atomnoe materialovedeniye, 988, (7)

31 QUENCH-: SOCRAT H Release from One Rod for Different Elevations. Hydrogen release from one rod, kg... mm mm 6mm 7mm 8mm 9mm mm mm mm 6 8

32 Oxidation Surface in Q- is larger than in Q-6 by Factor.7.8 Hydrogen production, kg.6.. QUENCH-6 QUENCH- reflood The basic difference in H production is at reflood phase. The melt oxidation in QUENCH- might be considerable. 6 8

33 Conclusions SOCRAT. was used for calculation analysis of QUENCH-6 and QUENCH- experiments Both tests revealed very similar behaviour which is supported also by SOCRAT. calculations Longer excursion time and melt oxidation seem to be the basic reasons for enhanced H generation in QUENCH- in comparison to QUENCH-6