Analysis of instrumented Charpy data in the PR-EDB

A systematic analysis has been performed of the available instrumented Charpy data from surveillance capsule reports which are collected in the Power Reactor Embrittlement Data Base (PR-EDB). Based on ideas by D. Pachur, fractions of the total impact energy that are due to different segments of the load curve are determined and fit separately to Pachur's model. As a first result, a strong linear relation has been found between the upper shelf values, EA, of the energy fractions in segment A and the total upper shelf energy, USE. The relation can be written as: EA = 0.276 USE + 8.64 (joule), and holds for all pressure vessel materials, plates, forgings, and welds, both before and after irradiation in surveillance capsules of commercial power reactors. Based on this relation, a separation into energy fractions can be obtained from the total impact energy alone resulting in an improved fit for Charpy impact data. Conversely, reliable values for the upper shelf energy can be obtained from energy fraction A, if the impact data in the upper shelf region are missing or erratic. The investigation is being extended to data from materials test reactor experiments