A statistical analysis of fracture toughness of irradiated low-alloy steel plate and welds

Studies of the effects of neutron irradiation on fracture toughness properties of steels have generally included a minimum number of tests for each material condition. The present study attempts to apply statistical analyses with multiple testing at selected temperatures to assess the accuracy and reliability of the results. Fracture toughness test specimens were irradiated in the Bulk Shielding Reactor at Oak Ridge National Laboratory at 2880C to target neutron fluences of 2 x 10/sup 23/ n/m/sup 2/ (>1 MeV). The materials were ASTM A533 Grade B Class 1 plate (HSST Plate 02) and four submerged-arc welds representing current nuclear pressure vessel fabrication practice. Both unirradiated and irradiated specimens were tested by two separate laboratories, and multiple tests were conducted at selected temperatures. Statistical analyses permitted determination of material and test variability and an interlaboratory comparison. Behavior in both the transition and upper-shelf regions was studied