Numerous steps have been taken by the Carolina Power & Light Company to assure the safety of its H. B. Robinson Unit 2 reactor vessel in the event that pressurized thermal shock should occur. Included is a phenomenological study of radiation damage underway that combines statistical modeling with atomic arrangements as determined by a field ion microprobe.

The field ion microprobe is being used to determine the atomic arrangement of nickel relative to copper in a high copper, medium nickel weld, irradiated to 4.1 × 10¹⁹ neutrons (n)/cm² > 1 MeV and a medium copper, high nickel weld, irradiated to 2 × 10¹⁹ n/cm².

Statistical modeling has determined that manganese is a significant factor in the increase in yield strength during irradiation. Its distribution in relation to carbon and nitrogen and other atoms is included in the field ion microprobe investigation.

Core redesign for flux reduction and advanced neutron dosimetry methods also are described.