中文摘要：

在核反应堆堆芯物理分析中,考虑燃料核素的多普勒效应对反应性的影响是必要的.基于最小二乘拟合法,在自主蒙特卡罗粒子输运程序JMCT中开发了在线多普勒展宽功能.在300—3000 K的温度范围内,利用核数据处理程序（NJOY）制作了系列温度点下的连续能量核数据.在统一的能量网格上,进行最小二乘拟合,得到拟合参数.JMCT利用这些拟合参数,快速计算得到任意温度的核数据,用于输运计算.计算结果表明,拟合得到的核数据与NJOY制作的核数据符合很好,满足精度要求.JMCT临界模型计算结果表明,拟合参数计算有效增殖因数k_（eff）与直接采用NJOY加工得到核数据的计算结果吻合.

英文摘要：

In this paper,we introduce the on-the-fly（OTF） Doppler method which is used to calculate the temperaturedependent cross section.After substituting Adler-Adler multilevel representation into Doppler formulation,the theoretical formulation of temperature dependent cross section is obtained.This theoretical formulation can be approximated by a Taylor series expansion and asymptotic series expansion,which is the base of OTF method.The OTF method can be used to calculate the cross section of any nuclide at any temperature in a range of 300–3000 K based on cross section library of 300 K.For the OTF method,firstly,a series of temperature dependent cross section libraries is produced by NJOY.Secondly,a uniform energy grid is evaluated by the temperature dependent cross section libraries.Thirdly,a polynomial is used to fit the temperature dependent cross section on each energy grid.The coefficient of the polynomial is obtained by single value decomposition algorithm.Finally,the coefficients of the polynomial in all energy grids and the energy grids themselves are written in a text file.To test the cross section polynomial produced by OTF method,we compare the total and absorption cross sections of ~（238）U and ~（235）U calculated by the polynomial with those produced by NJOY.The errors of these cross sections obtained by these two programs are presented in the paper.The text file produced by OTF method can be read by the Monte Carlo code JMCT,which is a coupled neutron/photon transport code developed by IAPCM.After providing the temperature and energy of the particle,the temperature dependent cross sections in two adjacent energy grids are calculated by the polynomial respectively.The cross section of target energy is obtained by linear interpolation.Two benchmarks including a pin-cell model and an assembly model are used to verify the applications of OTF method in JMCT.The results are presented in the paper.