We analyzed numerically the feasibility of nuclide analysis of spent fuels using an ultraintense, ultrashort laser. The (γ,n) reaction yields for each nuclide such as 129I, 90Sr, and 137Cs were calculated using the bremsstrahlung spectrum and the nuclear reaction cross sections. The dependence of the (γ,n) reaction yield on the irradiation time was derived. We also calculated the dependence of the nuclide ratio on the bremsstrahlung photon temperature. In order to investigate the influence of electron temperature and target thickness on the bremsstrahlung photon spectrum, the calculations were performed using the Monte Carlo code GEANT4. When gold was used as bremsstrahlung converter target at a temperature of the incident electrons of 30 MeV, the target thickness providing maximum nuclear reaction yield was found to be 5 mm.