Manganese adsorption on nickel and other structural materials in a sodium flow

Abstract

Operating experience with sodium-cooled fast reactors has shown that very major complications are caused by the deposition of the radionuclide /sup 54/Mn on the surfaces of the piping and equipment of the primary circuit. The experiments were performed on a convection loop with sodium and with a source of radioactive manganese. Flat specimens of austenitic chromium-nickel steels and alloys as well as flat specimens of molybdenum and nickel were studied. The deposition of manganese on the surface of the specimens was measured by the ..gamma..-radiation of /sup 54/Mn, for which we used a ..gamma..-ray spectrometer with a semiconductor detector. The absolute /sup 54/Mn content in the deposits was determined by a comparison of the activity of the specimen with the activity of a reference source of /sup 54/Mn radiation. The measuring error did not exceed +/- 9%. The /sup 54/Mn content in the sodium was estimated from the activity of sodium samples from the loop as well as from the decrease in the activity of segments of the loop piping after the sodium had been drained. The largest deposit was detected on nickel and ferrite steels were in second place. For steels and alloys with an austenitic structure the /supmore » 54/Mn deposition is even smaller and depends on the nicikel content in the steel, growing as that content increases. The smallest deposition of /sup 54/Mn was observed on molybdenum.« less