  Ray effects are the inherent problem of discrete ordinates method. RAY3D, a
functional module of ARES which is a discrete ordinates code system, employs a
semi-analytic first collision source method to mitigate ray effects. This
method decomposes the flux into uncollided and collided components, and then
calculates them with analytical method and discrete ordinates method
respectively. In this article, RAY3D is validated by the Kobayashi benchmarks
and applied to the neutron beamline shielding problem of China Spallation
Neutron Source (CSNS) target station. Numerical results of the Kobayashi
benchmarks indicate that DONTRAN3D with RAY3D solutions agree well with the
Monte Carlo solutions. The dose rate at the end of the neutron beamline is less
than 10.83 {\mu}Sv/h in CSNS target station neutron beamline shutter model.
RAY3D can effectively mitigate ray effects and obtain relatively reasonable
results.
