Authors & Affiliations
Orlova E.A.1, Orlov A.V.1, Solomatin A.E.2, Zasorin I.I.2
1 National Research Nuclear University of MEPhI, Obninsk, Russia 2 A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
Orlova E.A. – Leading Researcher, Cand. Sci. (Techn.), Associate Professor, National Research Nuclear University of MEPhI.
Orlov A.V. – Leading Specialist, Cand. Sci. (Phis.-Maht.), Associate Professor, National Research Nuclear University of MEPhI.
Zasorin I.I. – Leading Enginear, A.I. Leypunsky Institute for Physics and Power Engineering.
And widely used on the nuclear power plants (NPP) sodium is the most studied. The vital issue limiting its application is powerful exothermic interaction with water. Temperature of a torch of burning of sodium at contact with water vapor reaches 1600 K. The problem of protection of steel tubes against destruction at emission of water vapor in sodium is solved by timely detection of a small leak today.
Generally in contact with sodium threefold oxides are stable. Penetration of sodium into steel leads to damage of structural material in the presence of chemical reaction with formation of ferro-chromates of sodium and is defined by oxygen level in sodium of existence of these compounds. Formation of compounds of sodium with iron and chrome in steel at its contact with sodium hydroxide submits to dependence on time in degree 0.5 that testifies to the diffusive mechanism of interaction. Penetration of sodium into steel 10X18H9, 10X18H10T with formation of the Na (FexCr1-x)O2 compound on a surface there were also zones with the volume structure aligned (α) in deeper layers as a result of contact with NaOH during 6 h at 1000 K made about 250 microns.
At the same time, NaCrO2 on the surface of chrome for lack of iron does not exceed 30 microns and has anticorrosive properties and also high electrical resistance (about 1 megohm).
It is shown that the distilled sodium gets in steel 10X2M and 10X18H10T at 923 and 1023 K to for 500 h on depth less than 2 microns, i.e. it is occluded in blankets and has no significant effect on properties of steel.
sodium, steel, water, permeability, oxygen, compounds, nuclear power plants
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