Charpy-V (C V) and dynamic tear (DT) test comparisons are developed for the irradiated condition of two 12 in. thick A533-B steel plates and a submerged arc weld deposit. Materials for the investigation were donated by the U.S. Atomic Energy Commission's Heavy Section Steel Technology (HSST) Program. Individual plates were identified as HSST plates 01 and 02; the weld was identified as weld 50. Low temperature (<300°F, 149°C) and elevated temperature (550°F, 288°C) irradiations were conducted. Fluences for the eight irradiation experiments ranged from 2.5–3.3 × 10 19 n/cm 2 (> 1 MeV). Postirradiation C V and DT mid-energy transition temperature increases were found comparable for both plate and weld deposit (quarter thickness position evaluations). For the case of plate, percentage reductions in C V and DT shelf energy with irradiation also compared well. As a result, preirradiation DT to C V shelf energy ratios appeared to be retained with irradiation. Shelf observations are in agreement with recent findings for A543, A302-B, and other A533 steel plates which illustrate a DT to C V shelf energy ratio of 8.0:1 for pre- and postirradiation conditions. It is concluded that postirradiation DT properties of A533-B plate, including mid-energy transition and shelf level, can be calculated with reasonable accuracy from postirradiation C V results for use in fracture safety analyses. Assessments of shelf level toughness before and after irradiation are developed by ratio analysis diagram (RAD) procedures. Unlike observations for plate, a significant reduction in DT to C V shelf energy ratio by irradiation was found for the weld deposit. Weld metal fracture appearances suggest preferred paths for fracture within the duplex (layered) microstructure. Radiation embrittlement sensitivity at 550°F (288°C) was found to increase with increasing copper content as expected; however, embrittlement sensitivities of all three materials exceeded expectations. An influence of nickel content on radiation embrittlement sensitivity development is proposed.