Abstract
Two titanium alloys, Ti 15-3-3-3 and Grade 5 Ti, have been analyzed for their neutronic differences after
being exposed to neutron fluxes from a 5-year operational period in the Second Target Station (STS)
moderators. There are several differences in the original composition of the two alloys where Ti 15-3-3-3
contains Cr and Sn and Grade 5 Ti does not. The differences in original composition propagate through the
analysis to yield discrepancies in decay power density and decay gamma intensity density of more than a
factor of 3.5 at some times during operation. Immediately after the 5-year operational period, Ti 15-3-3-3
has a factor of 3.59 higher intensity of high-energy decay gammas than Grade 5 Ti, and Ti 15-3-3-3 also
has a factor of 3.53 higher decay power than Grade 5 Ti. After 1 year of shutdown, Ti 15-3-3-3 has a 48%
higher intensity of high-energy decay gammas and a 86% greater decay power density when compared
with Grade 5 Ti. The quantities-of-interest in this report are per unit volume and the overall volume of
titanium should be considered when making engineering judgment on final titanium alloy selection.
