Abstract: A special simulant assembly was designed for measuring the physical featuresof the test fuel assembly of Qinshan Nuclear Power Plant. The power ratio ofthe designed assembly to the HWRR was determined successfully by means ofdirectly measuring the γ--activity of the fuel rods. The assembly reactivity andthe LOCA reactivity were calibrated with the reactivity curve for control rodbank. The neutron flux and the power distribution in fuel rods were obtained byusing the foil--detector activation method. In addition, special measures were takento give the consideration to both Mo--Tc generator production and the require-ments of hydro--thermal condition of the tested fuel assembly during the irradia-tion test period.