  The effective size of Broad Line Region (BLR), so-called the BLR radius, in
galaxies with active galactic nuclei (AGN) scales with the source luminosity.
Therefore by determining this location either observationally through
reverberation mapping or theoretically, one can use AGNs as an interesting
laboratory to test cosmological models. In this article we focus on the
theoretical side of BLR based on the Failed Radiatively Accelerated Dusty
Outflow (FRADO) model. By simulating the dynamics of matter in BLR through a
realistic model of radiation of accretion disk (AD) including the shielding
effect, as well as incorporating the proper values of dust opacities, we
investigate how the radial extension and geometrical height of the BLR depends
on the Eddington ratio [and blackhole mass], and modeling of shielding effect.
We show that assuming a range of Eddington ratios and shielding we are able to
explain the measured time-delays in a sample of reverberation-measured AGNs.
