  We describe directed searches for continuous gravitational waves from twelve
well localized non-pulsing candidate neutron stars in young supernova remnants
using data from Advanced LIGO's second observing run. We assumed that each
neutron star is isolated and searched a band of frequencies from 15 to 150\,Hz,
consistent with frequencies expected from known young pulsars. After coherently
integrating spans of data ranging from 12.0 to 55.9 days using the F-statistic
and applying data-based vetoes, we found no evidence of astrophysical signals.
We set upper limits on intrinsic gravitational wave amplitude in some cases
stronger than 10^{-25}, generally about a factor of two better than upper
limits on the same objects from Advanced LIGO's first observing run.
