Research On Model Of Activation And Migration Of Corrosion Products In The Primary Loop Of Water-Cooled Reactor

The activated corrosion products(ACPs)are the greatest factor on the radiation protect,the individual and collective dose as well as security analysis,during the operating,maintaining and retiring of nuclear reactor system.In the water-cooled reactor,the corrosion is caused by the contact of water and structure materials,a stable oxide-layer is generated,and the metal ion is released into coolant through the oxidelayer.The oxidation and metal ion in the in-flux region can be activated under neutron flux,and become radioactive item.The radioactive item in the coolant can be carried by coolant to the out-flux region and deposit on the surface of pipe,then the ? radiation field is created,which poses irradiation threaten to the staff.Under normal operation,90% of collective dose is caused by the activated corrosion products deposited on the structure materials contacting with coolant in PWR primary circuit.As for the watercooled fusion reactor,the activated corrosion products become the dominant radioactive source term,because of the absence of fission products.Whether PWR or water-cooled fusion reator,the activated corrosion products have a significant impact on the occupational exposure under normal operation and the potential radioactive release under accident condition,and directly affect the exposure dose level of staff.The research on activated corrosion products is an important technical basis of accident analysis,dose estimation,optimization of radiation protection and management of radioactive waste,in addition,it's also one of the crucial links for nuclear plant to get the license.Most of the activated corrosion products calculation codes are based on the empirical and semi-empirical model home and abroad at present,depending on the operation data of the power plant or experiment,and their application is very limited.The codes only apply to specific reactor and condition,and simulate temperature,pH value and other parameters in limit range.There is great restriction on the variety of radionuclides,only several radionuclides,such as Co-58,Co-60,Fe-59,Cr-51,Mn-54,etc.can be simulated,which can not satisfy the requirement of high-energy neutron activation in fusion reactor.In addition,the pulse operation characteristics of fusion reactor also put forward new claims to the calculation.In this paper,the calculation code of activated corrosion products in the primary circuit of water cooled reactor based on classical empirical model is developed.Then the research on the production and transport mechanism of activated corrosion products is carried out,the mechanism model based on the concentration principle is established,and the calculation code based on the mechanism model is developed,which get rid of dependence on the empirical coefficient of the power plant or experiment,and successfully realise the the automatic matching function of transport direction by the solubility calculation.As a result,the limitation of the previous codes on reactor type and operation condition is broken.With the deposition experiment in the research group,the deposition module is modified successfully by analyzing mechanism calculation and experiment results,which realizes the influence of pH value on deposition behavior.The corrosion experiment of various structural materials under different operating conditions is carried out,which solves the inaccurate problem of corrosion model under fusion reactor condition.The EAF-2007 database is introduced to provide the nuclear date,such as activation date and decay date,which realizes the function of any nuclides.Calculation.The point kernel integration module is introduced to calculate the dose rate and occupational radiation exposure,which realizes the conversion of the corresponding dose rate and radioactivity.Through the above work,it overcomes the limitation of pH value range,breaks the limitation of the previous codes on the material and operation condition,as well as nuclide species,and then makes the results more intuitive by calculating the ?dose field.Based on the above work,the code CATE for the activated corrosion products calculation in PWR and water-cooled fusion reactor is developed.In order to verify the correctness of the model and the applicability of the code,the simulation analysis of MIT-PCCL loop,ITER LIM-OBB loop and Qinshan-II NPP primary loop is carried out,and the calculation results are compared with the published literature results.The calculation results are stayed in the same order of magnitude with the experimental data and code calculation,it is considered to be consistent in the field of source term calculation.And the accuracy of results and reliability of the model are verified from the aspect of experiment verification and code verification.The high temperature,pressure environment and high energy neutron of watercooled fusion reactor have strong corrosion and activation effect on structural materials,and put higher requirements for structural materials.As to the low activation materials produced in China,the influence of domestic low activation materials and traditional austenitic stainless steel on the activated corrosion products in ITER(International Thermonuclear Experimental Reactor)are compared for the first time.At present,CFETR(China Fusion Engineering Test Reactor)is under design stage,the level of activated corrosion product source is the key factor on its license,and may have great influence on the design and operation of fusion reactor.At present,there is no research work on the calculation analysis of the activated corrosion product in CFETR,the activated corrosion product in CFETR blanket loop is calculated and analyzed by the CATE code.