An in-core fuel management code package HEX-ICFM is developed for Xi'an Pulsed Reactor.The orthogonal design model and the loading pattern optimization program HEX-ORTH are studied.The cell calculation is performed using WIMS-D/4.A two dimensional hexagonal geometry multigroup nodal theory code SIXTUS-2 is used for core diffusion calculation.The core physical parameters are calculated using HEX-ICFM for the first cycle of Xi'an Pulsed Reactor.With the fuel of end of cycle 3 and 30 fresh fuel rods the optimum loading patterns are calculated for the objective function max(K^BOC_eff)using HEX-ORTH.

The sampling method by coupling criticality source direction biasing and the exponential transform is established for duct shielding calculation.In sample problem studying,the optimal source direction biasing parameter p₁、exponential transform parameter p₂ are supposed and the variance of duct calculating results by using this method is shown to reduce efficiently.Correction calculation for the duct of Nuclear Power Institute of China (NPIC) pulsed reactor shows the results are more close to the measured ones.