Hungarian Academy of Sciences KFKI Atomic Energy Research Institute Behaviour of irradiated RPV cladding F. Gillemot, M. Horváth, G. Úri, H-W. Viehrig, L. Debarberis, T. Fekete, E. Houndeffo 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 2 Why Clad is important?   In European reactors: crack can propagate from clad –mostly no crack arrest curve!   The highest stress peak during PTS: at clad-base material interface   After some mm-es much less stress   Without the knowing of irradiated clad properties, no elastic-plastic analysis!!   The best mitigation is to reduce unnecessary conservatives   Dave-Bessy event. Clad as structural material saved the unit   1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 3 WWER 440 weld with cladding Surface or underclad crack? Weld Base material 140 mm 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 4 Stresses in cladding at a PTS 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 5 Crack tip in cladding 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 6 Difference between elastic and elastic plastic analysis 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 7 What is cladding? Austenitic steel (ductile, corrosion resistant, tough) However it has :  Welded structure  With 3-10% delta ferrit content to avoid hot cracking 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 8 What is cladding? Austenitic steel (ductile, corrosion resistant, tough) However it has :  Welded structure  With 3-10% delta ferrit content to avoid hot cracking 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 9 Template from Greifswald unit 8 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 10 UT test results Size 10 is about 2 mm gas bubble 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 11 The Ni content in clad and base material (sharp transition) 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 12 Big grain sizes, annealing further increases them 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 13 Typical defect in SA strip cladding weld 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 14 Brittle and ductile fracture surface in clad 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 15 FZR Charpy testing 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 16 Charpy results (note the reduction of upper shelf energy) 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 17 Thermal ageing 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 18 FZR J integral measurement 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 19 Toughness of clad Y. Nikolaev (Kurchatov Institute) Toughness of clad Y. Nikolaev (Kurchatov Institute) The highest values are in the PTS relevant temperature range 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 20 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 21 Tensile results 1. Cladding layer 1 as received 2. Irradiated 0.8*10 20 n/cm 2 E>1MeV 3. Irradiated 2*10 20 n/cm 2 E>1MeV 4. Annealed 475°C 100 hours and reirradiated 2*10 20 n/cm 2 E>1MeV 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 22 Future questions The unknown unknown! 1. 1.Methodology for integrity assessment considering cladding? 2. Which properties are necessary for PTS assesment 3. What properties the regulators will accept: trend curve of:   yield stress   fracture toughness   elongation 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc

Hungarian Academy of Sciences KFKI Atomic Energy Research Institute 23 Thank you for your attention! 1 th Hungarian-Ukrain Joint Conference April 2oo6 Miskolc