In recent years we have accumulated a considerable amount of data on irradiation-induced Charpy 41-J shifts and upper shelf energy reductions, some of which were published. Currently, 67 data sets are in the data bank. The steels investigated are ASTM A533-B, and ASTM A508 Class 2 and Class 3 from several experimental heats and corresponding weld deposits. The irradiations were performed in the 15-MW swimming pool type research reactor FRG-2 at 290°C within the fluence range from 0.5 to 10 × 10 19 cm − 2 , E > 1 Me V .

The experimental transition temperature shifts at 41-J are compared with the predictions of US NRC Reg. Guide 1.99 rev. 1 and prop. rev. 2, and with the predictions made by both Guthrie and Odette. Where applicable, the 41-J shifts are also compared with the predictions of the German nuclear safety standard KTA 3203.

The experiment shows that Reg. Guide 1.99 prop. rev. 2 tends to be nonconservative at high fluence levels for these data, whereas KTA 3203, with its restricted validity range with respect to fluence and copper content, always leads to conservative predictions.