Research On Calculation Methods Of Key Parameters In The Corrosion Products Transport Model For Water-cooled Reactors

Activated corrosion products are an important part of the radioactive source of the water-cooled reactors.They have significant impact on the safety of nuclear facilities.The transport of the corrosion products in the primary cooling circuit is a complex process.Accurate evaluation of their spatial distribution and variation with time is of great theoretical and practical significance.A mathematical model and a code called CATE have been developed by Institute of Reactor Physics and Shielding in North China Electric Power University to simulate the transport of corrosion products in the primary cooling circuit of water-cooled reactors after in-depth study.The flow mass transfer,deposition,precipitation,dissolution,crystallization,erosion,purification,activation,decay and isotope exchange are comprehensively taken into account in the model.However,values of some key parameters,such as solubilities,diffusion coefficients and hydrothermal properties(density,dynamic viscosity,thermal conductivity and dielectric constant),still need to be input by the users in the original version,which greatly limits the capabilities and applications of the code.It's necessary to find methods for the code to estimate those parameters by itself.The solubilities of the corrosion products are calculated based on the principle of Gibbs free energy minimization by using the equilibrium constant method.The mass transfer coefficient in the primary cooling circuit is calculated using corresponding experimental correlations.The diffusion coefficients of dissolved and particulate corrosion products in the coolant are calculated using the Nernst-Einstein equation and the Stocks-Einstein equation,respectively.The hydrothermal properties,namely density,viscosity,thermal conductivity and dielectric constant,which are used in the estimations of the preceding parameters,are calculated using the IAPWS-IF97.Furthermore,some accumulated data and existing rules are summarized for corrosion rate,dissolution coefficient,crystallization coefficient and erosion coefficient so as to provide reference for estimation and follow-up study of those parameters,which haven't yet been able to be accurately estimated by calculation.The above parameter estimation modules are incorporated into CATE code.The simulation results of Fe,58 Co and 60 Co in each zone of MIT PCCL by CATE are in good agreement with those by its foreign counterpart code CRUDTRAN.The calculated shares of Fe,Ni and Cr in the corrosion products in the core and the steam generator are also close to the measured values.Moreover,more element and nuclide species endow CATE with more comprehensive simulation capabilities.