FRACTURE MECHANICS PROPERTIES OF MATERIALS OF REACTOR PRESSURE VESSEL OF WWER 440

In the paper, evaluation of 9 large scale experiments performed on uncladded cracked beams made of RPV WWER 440 materials (base and weld metal, in initial and aged condition) is described. The experiments were performed with the aim to determine values of fracture mechanics parameters, such as Jc/KJc and Q [1,2], and to compare the obtained Jc/KJc-values with the data obtained from standard (small scale) tests. Using „Master curve “ approach (adjusting data to 1T thickness and using reference temperature To) enabled plotting the data from both large scale and standard tests for all materials into one figure and the effect of crack depth could be examined. The elevated values of J were found for beams containing shallow cracks. For two of specimens containing shallow through cracks, also the Q-stress parameter was calculated. A qualitatively correct relation between elevation of fracture toughness Jc/KJc and loss of constraint expressed by negative values of Q was found for these two specimens. The evaluation of the experiments is not completed to date and creation of the database of Jc/KJc and Q-values will continue in the future