  The efficiency of $^{99}$Mo nuclei trapping by clinoptilolite particles using
Monte Carlo simulation was studied. The simulation showed the carrier particle
traps almost all of the incident $^{99}$Mo nuclei for the photon energies 12-18
MeV. The ratio of the $^{99}$Mo nuclei reaching the carrier to the total number
of $^{99}$Mo nuclei escaping the nanoparticle is below 1.5% in for the photon
energies 12-18 MeV. High specific activity of produced $^{99}$Mo nuclide
requires optimization of the clinoptilolite carrier particles concentration in
the suspension.
