POSSIBILITIES OF NEUTRON ACTIVATION ANALYSIS FOR STUDYING THE CORROSION BEHAVIOR OF METALLIC MATERIALS IN MOLTEN SALTS

Abstract

For the BREST-OD-300 reactor facility [1, 2], the technology for evaluating mixed nitride uranium-plutonium spent economical fuel is being determined [3–9]. To separate MNUP SNF from fuel claddings made of materials with high radiation resistance – ferritic-martensitic steel EP-823 [10–16], it is planned to use pyrometallurgical grades of “soft chlorination” [17]. When alloying and impurity elements of steel EP-823 are dissolved in molten salts of eutectic composition based on lithium and potassium chlorides, the melt will be contaminated. For the same reason, the formation of volatile compounds will occur, with their further mass transfer from hot to cold sections of process equipment. When studying the corrosion behavior of metals and alloys in liquid media, the problem often arises of determining small amounts of dissolution products in solution. This problem arises, for example, the rate of dissolution of microimpurities. The sensitivity of the usual, traditional methods used in corrosion testing such as mass loss or colorimetric determination of corrosion products in solution is often insufficient to make appropriate measurements. In these cases, the most effective is the use of the radiochemical method of neutron activation analysis based on. qualitative and quantitative determination of chemical elements, based on the measurement of the radiation characteristics of radionuclides formed during the irradiation of materials with neutrons. This paper presents the results of a study of the corrosion behavior and mass transfer of corrosion products of EP-823 steel pre-irradiated in the IVV-2M research nuclear reactor in molten salts 2KCl–3LiCl and 2KCl–3LiCl–PbCl2 at temperatures of 500 and 650°C for 24 h. It is shown that the method of neutron activation analysis can be used to study the corrosion behavior of EP-823 steel in molten salts of various compositions.