Trend curve exposure parameter data development and testing

Progress in testing and development of trend curve exposure parameter data at HEDL is described. These activities form part of the Light Water Reactor Pressure Vessel Surveillance Dosimetry Improvement Program. The exposure parameters of primary interest are those associated with the production of displaced atoms and helium in different PV steels, particularly, A302B, A533B, and A508. In order to determine the effect(s) of helium, the production of helium from boron (n,α), iron (n,α), nickel (n,α) and low concentrations of impurity elements are being investigated. Preliminary results of these HEDL investigations and related studies suggest that both displaced iron atoms and total helium content need to be considered in the future development, testing, and application of revisions of selected ASTM standards and Reg. Guide 1.99 and for the generation of PWR and BWR plant specific trend curves. (Auth.)