Gabrielli, F.

Sanchez-Espinoza, V. H.

English

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KIT – The Research University in the Helmholtz Association www.kit.eduInstitute for Neutron Physics and Reactor Technology Preliminary Analysis of the QUENCH-19 Test by means of the ASTEC CodeF. Gabrielli, V.H. Sanchez-EspinozaF. Gabrielli2Motivation 27th Int. QUENCH Workshop, 27-29 September 2022 KIT strategy for severe accident (SA) analyses → continuous improvement of thecodes to evaluate the radiological consequences of SAs in current and innovativeNPPs. ATFs have the potential for improving the safety performance of large and integralLWRs during normal/transient operations and SA scenarios. Efforts going on at KIT/INR to extend the ATF-related modelling capabilities(cladding) of the ASTEC code to enable the safety assessment of the innovativereactor concepts employing such materials. Activities triggered by the KIT participation to the OECD/NEA QUENCH-ATF projectand the IAEA CRP ATF-TS. Focus on the implementation of the Steam/FeCrAl oxidation laws in ASTECand analysis of the QUENCH-19 test.F. Gabrielli3Modeling New Materials in the ASTEC Code 27th Int. QUENCH Workshop, 27-29 September 2022 User usually employs the data stored in the available material database, i.e. forZry/ZrO2 Thermo-physical properties. Oxidation models, i.e. Cathcart, Prater-Courtright, Urbanic, Best-fit,.. ASTEC is flexible enough to introduce new materials either by adjusting theproperties of a default material or to fully define behavior and properties by scratch. Approach: Implementation of the Steam/FeCrAl oxidation laws provided by the Quenchexperimental team in the ASTEC database (v2.2_b employed) Same approach for KANTHAL APMF. Gabrielli4ASTEC: FeCrAl Oxidation Model27th Int. QUENCH Workshop, 27-29 September 2022C. KIM, C. TANG, M. GROSSE, M. STEINBRUECK, C. JANG, Y. MAENG, „OXIDATION KINETICS OF NUCLEAR GRADE FeCrAl ALLOYS IN STEAM IN THE TEMPERATURE RANGE 600-1500°C”, TopFuel 2021. Fitting functions for weight gain providedby J. Stuckert (IAEA CRP ATF-TS)𝐾 =     9.62 × 10−12 [g2/cm4s],   𝑇 ≤ 1473 K𝐴𝐵 exp −𝐸𝐵𝑅𝑇 ,   1473 < 𝑇 < 1648 K𝐴𝐹𝑒 exp −𝐸𝐹𝑒𝑅𝑇 ,   𝑇 ≥ 1648 K (𝑚𝑒𝑙𝑡𝑖𝑛𝑔 𝑝𝑜𝑖𝑛𝑡 𝑜𝑓 𝐹𝑒𝑂) AB=3·109 g2/cm4 s EB=594354 J/molAFe=2.4·106 g2/cm4 s EFe=352513 J/molF. Gabrielli5ASTEC: FeCrAl Oxidation Model27th Int. QUENCH Workshop, 27-29 September 2022 Modifying the laws for oxygen mass gain in the database. Assumptions: No information on the oxide thickness growth (similar law as mass gain used) Δh of Zr employed….. STRUCTURE MODEL NAME 'BEST-FIT' LAW 'COEFF' VARIABLE 'T' VUNIT 'K' RUNLOW 0. RUNUPP 5000.SRG VALUE AGAIN 9.62D-10 BGAIN 0.0 ATHIC 2.252D-13 BTHIC 0.0 MODEL 0.5 TERMX  1473.KSRG VALUE AGAIN 3.0D+11 BGAIN 5.94354D5 ATHIC 3.371D3 BTHIC 5.94354D5 MODEL 0.5 TERMX  1648.KSRG VALUE AGAIN 2.4D+08 BGAIN 3.52513D5 ATHIC 0.008682D0 BTHIC 3.52513D5 MODEL 0.5 TERMENDF. Gabrielli6QUENCH-19 Test Conduct27th Int. QUENCH Workshop, 27-29 September 2022Phase 1: heating up to ~600 °C (4 kW).Phase 2: power increase up to 11.5 kW (pre-oxidation).Phase 3: power increased up to 18.12 kW (5 W/s) (Tpct~1500 °C).Phase 4: power reduced to 4.1 kW. Atmosphere of Ar (3.45 g/s) and superheated steam (3.6 g/s).Reflooding at ~9100 sFast initial injection of 4 kg of waterSlow injection 48 ~ g/s of waterF. Gabrielli7ASTEC Model of the QUENCH-19 Test27th Int. QUENCH Workshop, 27-29 September 2022Ch. 3, 8 rods, rext= 41.5 cmCh. 2, 12 rods, rext= 28.4 cmCh. 1, 4 rods, rext=14.2 cmAccidental presence of 4 l water the gapbetween the shroud and the cooling jacketmodelled (J. Stuckert).F. Gabrielli8Results: Clad and Shroud Temp. @850 mm Height27th Int. QUENCH Workshop, 27-29 September 2022 Clad• Results exceed the exp. of about 100 degree in the pre-oxidation phase in Ring 1.• Better agreement in Ring 2 and 3.• Max. temperatures reasonably well reproduced in Ring 1 and 2 (deviation of ~ 100 degree in Ring 3). Shroud• Experimental results reasonably well reproduced.F. Gabrielli9Results: Clad and Shroud Temp. @950 mm Height27th Int. QUENCH Workshop, 27-29 September 2022 Clad• Results exceed the exp. of about 100 degree in the pre-oxidation phase in Ring 1 and 2.• Better agreement in Ring 3.• Max. temperature reasonably well reproduced in Ring 1 and 3 (deviation of ~ 100 degree in Ring 2). Shroud• Results exceed the exp. of about 100 degree in the pre-oxidation phase.• Max. temperature reasonably well reproduced.F. Gabrielli10Results: Cooling Jacket Temperature27th Int. QUENCH Workshop, 27-29 September 2022 Experimental results reasonably well reproduced.@850 mm Height@950 mm HeightF. Gabrielli11Results: Hydrogen Production27th Int. QUENCH Workshop, 27-29 September 2022 The final amount of H2 is reasonably well reproduced. ASTEC results show a good agreement with exp. up about 8000 s. Escalation is anticipated in time with about 50% of the mass rate compared withthe exp. Transition to the escalation is not well reproduced.F. Gabrielli12Results: Hydrogen Production27th Int. QUENCH Workshop, 27-29 September 2022 ‘Smooth’ kinetics behavior is notreproduced. Updating of the model related tothe oxide thickness gain mayimprove the ASTEC vs. exp.agreement.F. Gabrielli13Conclusion27th Int. QUENCH Workshop, 27-29 September 2022 Efforts are going on to extend the capabilities of the ASTEC to model the ATFs. The Steam/FeCrAl oxidation laws implemented in the material database of the code (v2.2_b). The QUENCH-19 test has been analyzed Overestimation of the clad temperatures (~100 degree) and acceptable agreement onthe radial profile Acceptable ASTEC/Exp. agreement concerning the shroud temperatures H2 generation – ASTEC vs. Exp. Total amount reasonable well reproduced The kinetics of the escalation is not well predicted Outlook Refinement of the oxide thickness law necessary. Participation to the OECD/NEA benchmark (blind phase) on ATF-1 experiment.

Preliminary Analysis of the QUENCH 19 Test by means of the ASTEC Code

https://publikationen.bibliothek.kit.edu/1000158073/150612978

Preliminary Analysis of the QUENCH 19 Test by means of the ASTEC Code

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