Published: Jan 1990
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In addition to the data base used to assess normal operating renditions, licensing authorities need postirradiation mechanical properties to evaluate the effects of hypothetical core disruptive accidents in liquid metal fast breeders such as the SNR-300. In particular, the synergistic effects of creep and neutron radiation damage on tensile properties constitute a major concern. The structural steel DIN 1.4948, similar to Type 304, is used for the permanent primary structures such as reactor vessel and core shield of the SNR-300.
Tensile/creep specimens have been irradiated in the HFR, Petten, at 823 K to a total neutron fluence of
We observed that radiation reduces the elongation and subsequently ultimate tensile strength for strain rates below 10−4 s−1. The creep damage reduces the ductility and strength by a smaller, but fairly constant amount, which has a relatively large effect at low strain rates. At a tensile rate of 10−6 s−1, the postirradiation ductility is reduced from 10 to 3% by the creep damage effect. The helium transmutation product from the interaction of thermal neutrons with the 10B (boron) isotope promotes the initiation and propagation of intergranular cracks under creep loads and low-rate tensile testing. The ability of the steel to absorb energy by plastic deformation is strongly reduced by the combined effect of creep and radiation damage.
neutron irradiation, AISI Type 304 stainless steel, creep, tension test, strain rate, ductility
Schaaf, Bob van der
Head, mechanical testing and microscopy laboratory, Netherlands Energy Research Foundation, ECN, LE Petten,