Calculation and Measurement Method of Evaluating the Leakage of Radioactive Nitrogen16N7 in Steam Generators of Nuclear Reactors of KLT-40 Type

Abstract

The paper analyzes the leakage of the¹⁶ N₇ nitrogen radionuclide which occurs in the 1st loop of the KLT-40 reactor which is used at marine transport facilities for various purposes through the steam generator of the nuclear reactor into the second loop into which water is supplied under pressure P_в with a temperature Т_в >> 100 °C. Radioactive nitrogen spreads in the vapor phase and goes through a spiral steam line to the turbine under high pressure P_п, creating unfavorable conditions from the point of view of radiation safety. The content of the specified radionuclide in steam can be detected and evaluated by g--spectrometry and dosimetry methods, by measuring the volumetric g-activity of steam and the dose rate of g--radiation when the steam enters the turbine. The analysis of the observed leakage effect was carried out on the basis of using a simple physical and mathematical model that takes into account the transfer of water, vapor media and the transfer of radioactive nitrogen in the vapor phase, which made it possible to indicate the cause and determine the area of leakage on the spiral steam pipeline, which was determined from the condition of vapor equality and water pressures in steam line. The paper specifies the main areas of the steam generator design allowing measurements of radiation characteristics and the necessary instrumental equipment taking into account the physical characteristics of the environments in which this equipment will operate in its readings.