Development And Verification Of Burnup Model Of A PWR Lattice Calculation Code

As one of the basic codes of nuclear power plant core design and calculation softwares,the states of Pressurized Water Reactor(PWR)lattice code is an important evaluation standard for the independence of nuclear power technology in a country.At present,China's nuclear power industry is developing rapidly but lacks of nuclear reactor-releated softwares with fully independent intellectual property rights.Under this background,the Simulation Center of Harbin Engineering University has independently developed a PWR lattice code named ALPHA based on the experience of international mainstream commercial lattice codes.Based on this,the development and verification of the burnup calculation model and related functions models of the ALPHA code are completed.Firstly,this paper introduces the main framework of the ALPHA lattice calculation code,and describes the characteristics of the selected multigroup data library and the physical methods used by the in-house resonance and transport models.Secondly,the burnup calculation model in ALPHA lattice calculation code is developed based on the method of diagonal padéapproximation with variable order and the traditional Predictor-Corrector(PC)method.Based on the traditional Predictor-Corrector burnup method,the Projected Predictor-Corrector(PPC)method,Logarithm Linear Rate(LLR)method and the High order methods for burnup calculation are completed for coupling strategy model of transport and burnup.In order to establish a few-group constant library for core calculation and meet the needs of actual calculation during reactor operation,the branch-off calculation model and decay calculation models are developed.Finally,these function models of ALPHA lattice calculation code are verified by calculating a series of benchmarks and detailed comparing with a number of internationally popular lattice calculation codes.According to the calculation results,the following conclusions can be obtained:(1)The theoretical method of the burnup calculation model of the ALPHA lattice calculation code,the coupling strategy model of transport and burnup,the branch-off calculation model and the decay calculation model are correct and the calculation results are reasonable,which can meet the calculation requirements of the PWR lattice calculation code;(2)When PPC and LLR burnup methods are used to calculate burnable absorbers,the burnup step length is increased by two times and four times respectively with the calculation accuracy is guaranteed.Similarly,the High-order Predictor-Corrector method can also improve the calculation efficiency under the premise of the calculation accuracy,and the LE/LI method has the same calculation accuracy as LLR;(3)The branch-off calculation and decay calculation models developed in the ALPHA lattice calculation code have high accuracy and can basically meet the needs of actual calculation of the reactor.