Abstract
Experiments on the plastic deformation of 34-mm (nominal) U-shaped pipes and their rupture have been performed in order to extend experiments on the mechanical response of pipe structures to the internal radiolytic gas detonation loads at BWR relevant conditions. Stoichiometric hydrogen-oxygen mixtures were used as a worst case of radiolytic gas composition. Austenitic stainless steel (Werkstoff Nr. 1.4435) and ferritic carbon steel (STPT 410) were used for tested tubes. The dynamic tube response was investigated under radiolytic gas detonation loads at initial pressures up to 70 bar and at room temperature. A dynamic stress-strain diagram from elastic to plastic deformations at strain rates from 100 to 2000 s^<-1> with subsequent rupture of the tested tubes was experimentally obtained, using direct strain measurements and high speed movies. Breaking elongations of 45 - 54% for austenitic 2-mm wall thickness tube were achieved due to radiolytic gas detonation loads at 50 and 57 bar of initial pressure. Ferritic tubes (4.5 mm nominal wall thickness) survived detonations of radiolytic gas at initial pressures of 40 and 70 bar. The maximum deformation achieved was less than 0.4% with a strain amplification factor of 1.2-2.5. The present experimental data are required to study the tube integrity under radiolytic gas detonation loads and to obtain experimental data on the dynamic strain-stress relations for computer code validation.
