Stuckert, J.

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KIT – University of the State of Baden-Württemberg and National Large-scale Research Center of the Helmholtz Association Institute of Apllied Materials www.kit.edu presented by J. Stuckert VVER Materials Meeting  Material behavior during reflood test QUENCH-12 with a VVER bundle. Results of ISTC project # 1648.2 2/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Objectives of the QUENCH-16 test  • investigation of the effects of VVER materials and bundle geometry on core reflood   •   comparison with the PWR bundle on the base of repeat of the test QUENCH-06 (ISP-45) scenario 3/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Cross section of the PWR test column Cross section of the VVER test column (QUENCH-12) 1 unheated rod cladding Zry-4 ø10.75/9.3 mm central thermocouple pellet ZrO2 ø9.15/2.5mm  thermal insulation ZrO2 fibre thickn. 37 mm  2 removable corner rods Zry-4 ø6 mm  2 instrumented tubes Zry-4 ø6/4.2 mm  shroud Zry-4 ø84.76/80mm cooling jacket 20 heated rods cladding Zry-4 ø10.75/9.3 mm W-heater ø6mm pellet ZrO2 ø9.15/6.15mm pitch 14.3 pitch 12.75 3 removable corner rods Zr1%Nb ø6 mm  3 instrumented tubes Zr1%Nb ø6/4.2 mm  18 heated rods cladding Zr1%Nb ø9.15/7.73 mm W-heater ø4mm pellet ZrO2 ø7.54/4.15mm Shroud Zr2.5%Nb ø88/83.5mm 13 unheated rods cladding Zr1%Nb ø9.15/7.73 mm central thermocouple pellet ZrO2 ø7.54/4.15mm  Comparison of PWR and VVER test columns  4/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Time schedule of Project performance July 1999 1st Proposal from RIAR and ELECTROSTAL on a VVER bundle test in the QUENCH facility 2001 ISTC development grant for Project 1648  October 2002  Recommendation of 2nd CEG-CM (Karlsruhe) for 1648.2  with highly priority March 2003 Approval of Project 1648.2 by the ISTC Governing Board June 2004 Start of Project 1648.2 March 2005 Contract between RIAR and KIT on delivery of the VVER bundle components October 2005 Delivery of bundle components to KIT: 1) etched and anodized Zr1%Nb cladding tubes,  2)Zr2.5%Nb shroud tube,  3) Zr2.5%Nb flange tube,  4) Zr1%Nb holder rods, 5)Zr1%Nb corner rods,  6) Zr1%Nb corner tubes,  7) Zr1%Nb spacing grids. 27 September 2006 Conducting of the QUENCH/VVER test (QUENCH-12) by KIT 2006 - 2008 Evaluation of the test data; metallographic examination of bundle by RIAR and KIT December 2007 Report FZKA-7353 on the post-test modelling with the SVECHA code (IBRAE-KIT-ITU) March 2008 Report FZKA-7307on results of the QUENCH-12 test 5/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg bundle bottom bundle top shroud with heat insulation  test containment with instrumented bundle Test bundle preparation 6/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Pre-test modelling support:  1. SCDAP/SIM simulations: Paul Scherer Institute, Switzerland.  2. ICARE/CATHARE simulations: Kurchatov Institute, Moscow, with support from IRSN Cadarache).  7/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 051015200 2000 4000 6000 8000Time, sEl. power, kW30090015002100Temperature, KPower_Q12 T_950mm_Q12    T_950mm_Q6heatup transientpreoxidation quenchingTest performance: el. power profile in accordance to the pre-test calculations provided good reproduction of temperature history in comparison with the reference test QUENCH-06 8/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg temperature distributions for three time points (from bottom to top): 1) 5960 s (end of pre-oxidation), 2) 7150 s (middle of transient), 3) 7265 s (before reflood) 550 mm 950 mm QUENCH-12: inhomogeneous radial temperature distribution 9/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg -250-5015035055075095011501350500 700 900 1100 1300 1500 1700 1900 2100T, KElevation, mmQ6_7170s_trans_end Q12_7265s_trans_endAxial bundle temperature profiles for QUENCH-06 and QUENCH-12 on beginning and end of transient phase beginning of transient end of transient -250-5015035055075095011501350500 700 900 1100 1300 1500 1700 1900 2100T, KElevation, mmQ6_5950s_preox_end Q12_5972s_preox_end10/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 0,00,51,01,52,02,53,07000 7050 7100 7150 7200 7250 7300 7350 7400 7450 7500Time, sRate, mg/s0102030405060Integral, grate_H2_Q12 rate_H2_Q6 intl_H2_Q12 intl_H2_Q6reflood QUENCH-12reflood QUENCH-06Comparison of hydrogen release during QUENCH-12 and QUENCH-06  11/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Q-06: H2 uptake in cladding measured by hot extraction 0510152025303540550 750 950 1150Bundle elevation, mmHydrogen, at%corner rod D (preox)corner rod F (tansient)corner rod B (end of test)Comparison of hydrogen uptake by bundle during QUENCH-06 and QUENCH-12  Q-12: H2 uptake in corner rods measured by neutron radiography 0510152025303540550 750 950 1150Elevation, mmHydrogen, at%Q6_hydrogen absorbed in claddings; at%12/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg QUENCH-12:  axial sections of different ZrO2 spalling intensity on corner rods withdrawn during the test B after test F before reflood D after preoxidation F D F D 13/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 1st rod  700 mm 2nd rod  940 mm 1st rod  940 mm 2nd rod  1120 mm 1st rod  1120 mm 3rd rod  700 mm 2nd rod  700 mm 3rd rod  820 mm  QUENCH-12:  Structure of the residual oxide layer on the surface of three withdrawn corner rods at different bundle elevations Breakaway structure was formed generally during pre-oxidation by temperatures about: 850°C (@700 mm),  1100°C (@940 mm), 900°C (@1120 mm) 14/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 900 mm: circumferential and longitudinal cracks at the cladding; nodular breakaway corrosion at the shroud 650 mm: spalled oxide scales at shroud and cladding 400 mm: circumferential spalling of the oxide layer on the surface of fuel rod simulator cladding -400mm: spalled oxide scales as debris at the bundle bottom QUENCH-12: post-test videoscope observations of breakaway oxidation  at different elevations of the bundle 15/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 01002003004005006007008009001000550 650 750 850 950 1050 1150Bundle elevation, mmZrO2 thickness, µmZrO2 residual ZrO2 (1.56*exhausted metal)Cladding oxidation: measured thickness of residual oxide and oxide thickness calculated on the base of residual metal QUENCH-12: axial distribution of oxide layer 16/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 1920181820212017172016211617192221171717201030507090ZrO2 thickness , µm12345R1R2R3R4R5300500700900110013000 2000 4000 6000 8000Time, sTemperature, KQ12_TFSH_4/2/9_550mm Q06_TFS_2/9_550mm436651275547354362513559624735905131706243165951314331315155591030507090ZrO2 thickness, µm12345671 2 3 4 5 6 7 8 9 10 11Comparison of oxide cladding thicknesses for QUENCH-06 and QUENCH-12 at elevation 550 mm  QUENCH-06: average value and median deviation: 19 ± 2 µm for all rods, 21 ± 1 µm for inner heated rods, 18 ± 1 µm for outer heated rods QUENCH-12: average value and median deviation: 42 ± 12 µm for unheated rods, 52 ± 10 µm for heated rods  17/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg β-Zr α-Zr(O) ZrO2 β-Zr α-Zr(O) ZrO2 Comparison cross-sections of QUENCH-06 and QUENCH-12 at elevation 550 mm  Q12 cladding: spalling of oxide scales due to breakaway effect Q12: rubble on spacer grid consists of spalled cladding scales and fragments of partially oxidized cladding  Q06 oxidized cladding Q06 cross-section 18/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 1291351311331441431241211191461231361111241331391401161101231255060708090100110120130ZrO2 thickness , µm12345R1R2R3R4R55990827082787478865974788266781179874867455909062826282787890665060708090100110120130ZrO2 thickness, µm12345671 2 3 4 5 6 7 8 9 10 11Comparison of oxide cladding thicknesses for QUENCH-06 and QUENCH-12 at elevation 750 mm  QUENCH-06: average value and median deviation: 129 ± 9 µm for all rods, 138 ± 5 µm for inner heated rods, 123 ± 6 µm for outer heated rods QUENCH-12: average value and median deviation: 79 ± 11 µm for unheated rods, 77 ± 8 µm for heated rods  19/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Comparison cross-sections of QUENCH-06 and QUENCH-12 at elevation 750 mm  Q06 cross-section; few bundle deformation Q12 cross-section; moderate bundle deformation β-Zr α-Zr(O) ZrO2 β-Zr α-Zr(O) ZrO2 Q12 cladding: spalling of oxide scales due to breakaway effect Q06 oxidized cladding 20/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 42783648919369315410399904347759180313770401030507090110ZrO2 thickness, µm12345R1R2R3R4R57009001100130015000 2000 4000 6000 8000Time, sTemperature, KQ12_TFSU 9/3/15 Q06_TFS 5/1443628659457660681033759111824360123645394101518010543846862805380661030507090110ZrO2 thickness, µm12345671 2 3 4 5 6 7 8 9 10 11Comparison of oxide cladding thicknesses for QUENCH-06 and QUENCH-12 at elevation 1150 mm  QUENCH-06: average value and median deviation: 64 ± 22 µm for all rods, 86 ± 9 µm for inner heated rods, 46 ± 11 µm for outer heated rods QUENCH-12: average value and median deviation: 69 ± 15 µm for unheated rods, 72 ± 21 µm for heated rods  21/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Comparison cross-sections of QUENCH-06 and QUENCH-12 at elevation 1150 mm  Q06 cross-section Q12 cross-section Q12 cladding: spalling of oxide scales due to breakaway effect Q06 oxidized cladding β-Zr α-Zr(O) ZrO2 β-Zr α-Zr(O) ZrO2 22/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg 02004006008001000120014000 5000 10000 15000 20000 250000 1 2 3 4 5 6 70200400600800100012001400123  4  5  678910Time (h)Time (s)Cladding temperature (oC)Breakaway long-term oxidation  during the Paks cleaning tank incident (destroying of 30 VVER fuel assemblies)  Results of modeling (FRAP-T6 code) breakaway region 23/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Melt formation for QUENCH-06 and QUENCH-12 at elevation 950 mm  Q06: melting of cladding internal metal layer and shroud external metal layer Q12: melting of cladding internal player; oxide layer failure; molten pools formation between rods; shroud external metal layer melting 24/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Melt formation for QUENCH-06 and QUENCH-12 at elevation 950 mm  Q12: molten pool between rods Q06: melting of cladding metal layer  25/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Measured oxide layer thickness profiles of the rod B (withdrawn from the bundle at the end of the test), central rod, averaged for 31 rods, all at final state, compared to the calculated oxide layer thickness profile of the central rod (final state). Q-12 test results Calculated and measured oxide thickness. Final state 0501001502002503003504004505005506006507007508008509009501000400 500 600 700 800 900 1000 1100 1200 1300 1400Elevation, mmOxide thickness, µmExperiment rod BExperiment central rodExperiment aver. 31 rodsCalculated aver. temp.Calculated max. temp.QUENCH-12: results of the SVECHA simulation (IBRAE with support from ITU) Q-12 calculation results Hydrogen production rate 00,050,10,150,20,250,30,350,40,450,50,550,60,650,70,750,87000 7050 7100 7150 7200 7250 7300 7350 7400 7450 7500Time, sHydrogen production rate, g/sExperimentCalculationExperimentally measured and calculated hydrogen production rate.  Quenching phase of the test. Amount of hydrogen released during quenching: 24 g (exp); 9.9 g (calc.)  In the SVECHA/QUENCH code the thermal boundary conditions for the central rod are predetermined by specifying the temperatures of the “effective channel” inner wall on the basis of experimentally measured temperatures. The inner surface of the effective channel represents the surfaces of the heated rods surrounding the central rod.  26/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg SUMMARY   • The QUENCH-12 experiment investigated the effects of VVER materials and bundle geometry on core reflood, in comparison with test QUENCH-06 (ISP-45) with Western PWR geometry.  • The electrical power changing during the test corresponds completely to calculated values up to reflood phase. The temperatures at all bundle elevations during preoxidation are about 30 - 40 K lower than during corresponding phase of QUENCH-06.  • Two corner rods were withdrawn at the end of preoxidation and transient phases correspondingly. The third corner rod was withdrawn after the test. The surface of the rods shows intensive traces of the break-away effect influence. Many oxide scales with thickness about 100 µm were spalled during withdrawn.  • The surfaces of the E-110 rod simulator and E-125 shroud evident also influence of the breakaway oxidation. However the ZrO2 scales spalling is fewer intensive than by corner rods. Possible reasons can be 1) different mechanical properties of tube and massive rod; 2) other surface preparation of cladding and rods. 27/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg  SUMMARY (cont.)    • Following reflood initiation, a moderate temperature excursion of ca. 50 K was observed, over a longer period than in QUENCH-06. The temperatures at elevations between 850 mm and 1050 mm exceeded the melting temperature of β-Zr.  • Post-test bundle examinations performed at RIAR and KIT showed significantly more oxidised cladding surfaces in comparison to QUENCH-06. Also the radial oxidation inhomogeneity is much higher for QUENCH-12 bundle.  • The hydrogen content in the corner rods reached a value more than 30 at% at the bundle elevations of  850 and 1100 mm.   • The total hydrogen production was 58 g (for QUENCH-06: 36 g), during the reflood was released 24 g hydrogen (for QUENCH-06: 4 g). This may be attributed partly to the longer excursion time in QUENCH-12. Other reasons for the increased hydrogen production may be extensive damaging of the cladding surfaces due to the breakaway oxidation and local melt formation with subsequent melt oxidation. 28/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg SUMMARY (modelling)    • The SVECHA/QUENCH code (IBRAE) was applied to the simulation of the QUENCH -12 bundle test. The calculations adequately reproduce temperature evolution of the central rod at different elevations during the whole test duration including quenching phase.  • The calculated oxide thickness at the end of the test was significantly underestimated, especially at 950 mm. This fact may be explained by more intensive oxidation during transient and quenching phases through friable cracked oxide structure formed due to break-away oxidation previously.  • The details of the experimentally measured time dependence of the hydrogen production rate are well reproduced by the calculations at the preoxidation and transient phases. Calculations underestimate hydrogen production rate at the end of transient and quenching phase of the test. 29/29 22.04  - 23.04.2013 J. Stuckert – QUENCH-12 (VVER) VVER materials meeting, St. Petersburg Thank you for your attention    http://www.iam.kit.edu/wpt/english/471.php/  http://quench.forschung.kit.edu/  

Material behavior during reflood test QUENCH-12 with a VVER bundle. Results of ISTC project #1648.2

https://publikationen.bibliothek.kit.edu/230091376/3816283

Material behavior during reflood test QUENCH-12 with a VVER bundle. Results of ISTC project #1648.2

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