FEM-applications in nuclear engineering: Container drop test simulations

Transcription

1 FEM-applications in nuclear engineering: Container drop test simulations Thomas Nierhaus 1, Michael Wohlmuther 2, Thierry Schwoertzig 3, Werner Stratmann Evonik Energy Services GmbH, Essen, Germany 2 Paul-Scherrer-Institut, Villingen, Switzerland 3 Altair Engineering, Antony, France

2 Introduction Container drop test simulations are of frequent interest in safety analyses. - Needed for approval processes - No nuclear contamination in case of container damage Non-linear FEM is a suitable tool for the simulation of container drops. - Altair RADIOSS - Simulation of impact and deformation - Damage analysis Seite 2

3 Background Nuclear waste containers - Highly developped safety technology - Needed for transport and storage of nuclear waste - Requirements: Leakproof, fire-proof, shielding, robust, almost indestructable Certification of the requirements has to be applied - Drop tests - Fire tests - Detonation tests - High pressure underwater tests Seite 3

4 Problem Definition Low/Medium-active nuclear waste will be transported to an interim storage facility - Waste is embedded in a concrete cask packaging - The cask is lowered into a storage pit by a crane - Assumed drop height is 23m - The cask must stand an impact onto an edge - No contamination in case of container damage Seite 4

5 Nuclear waste in primary casks - Four casks modeled by 200k shell elements (Material: Stainless steel, 10mm) - Shielding modeled by solid elements (Material: Lead) - Casks are empty during the crash simulation, damage is analyzed Seite 5

6 Reinforced concrete cask Concrete cask k volume elements - Concrete strength f c =37MPa Reinforcement - 60k beam elements - Steel S500 6mm 8mm 10mm 16mm Seite 6

7 Filler mortar Mortar Type 3 (f c =86MPa) Mortar Type 2 (f c =48MPa) Mortar Type 1 (f c =48MPa) Mortar Type 2 (f c =48MPa) Seite 7

8 Material laws Concrete & Mortar: Elastic-plastic brittle (LAW 24) Failure domain Steel parts: Johnson-Cook (LAW 2) Seite 8

9 Energy balance - Major part (94%) of kinetic energy is absorbed in 10ms. - Hourglass energy only 15% of internal energy (acceptable value). Seite 9

10 Damage to the concrete cask Seite 10

11 Damage to the concrete cask t = 0.5ms t = 1.0ms t = 1.5ms t = 2.5ms t = 6.0ms t = 10.0ms Seite 11

12 Damage to the filler mortar t = 10.0ms Seite 12

13 Damage to the primary casks - Plastic strain rate below 0.4% - Maximum strain at 6.5ms - No damage expected t = 10.0ms Seite 13

14 Conclusions - Container drop test from 23m height has been simulated. - Primary storage casks embedded in reinforced concrete cask with mortar. - Material models LAW 2 (Steel parts) and LAW 24 (Concrete). - 94% of kinetic energy absorbed in 10ms. - Storage casks show plastic strains below 0.4%. - Failure of primary cask material is unlikely. Seite 14

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