Radioactivity of 51Cr in stainless steel collected from residences in the JCO neighborhood

Stainless-steel (SS) samples activated by fission neutrons from the JCO criticality accident have been measured by low-background germanium spectrometers. The SS-samples, comprising 14 spoons and 4 other items, were collected from residences located at 130–700 m from the JCO site. Five SS-samples from within a ground distance of 400 m from JCO were identified as containing 51Cr activity, which was produced by the 50Cr(n, γ)51Cr reaction. The chromium specific activities of 51Cr/Cr are preliminarily obtained to be 0.45–0.04 Bq/g-Cr for the 5 samples collected at 130–400 m distance.