Authors & Affiliations
Kozlov F.A.1, Sorokin A.P.1, Trufanov A.A.1, Konovalov M.A.2
1. A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
2. National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow, Russia
Kozlov F.A. – Adviser to the director of the department, Dr. Sci. (Tech.), Professor, A.I. Leypunsky Institute for Physics and Power Engineering.
Sorokin A.P. – Deputy Director of Safety Department, Dr. Sci. (Tech.), A.I. Leypunsky Institute for Physics and Power Engineering.
Trufanov A.A. – Deputy Director of Safety Department, A.I. Leypunsky Institute for Physics and Power Engineering. Contacts: 1, pl. Bondarenko, Obninsk, Kaluga region, Russia, 249033. Tel.: +7(484) 399-83-63; e-mail:
Konovalov M.A. – graduate student, National Research Nuclear University "Moscow Engineering Physics Institute".
Abstract
The research work on a purification system of liquid metal with sodium coolant advanced NPP is aimed on increasing efficiency and capacity purification system, built-in the reactor vessel. Suggestion is usage of hot trap instead of cold trap in a primary circuit for purification coolant at normal operational regimes and in idle regimes from dissolved oxygen, which is pose danger due to high cor-rosion activity. However cold traps are capable to perform purification of sodium from hydrogen and tritium and retain them along with purification sodium from oxygen. The research results, performed earlier, shows that the increased concentration of hydrogen in sodium, up to concentration of 50 ppm, don't influence on nuclear and physical characteristics of the reactor. In the primary circuit of NPP the limitation factor of maintaining concentration hydrogen at the level lower than 50 ppm is crystallization of hydrogen impurity at the lower temperature of the circuit, which is equal 250°C the idle operational regime, as well as formation a caustic phase in the presence an oxygen, which is raising corrosion intensity of constructional materials corrosion in dozens of times. Main danger of tritium is associated with radiational safety of environment (feed water, introduces into the environment and diffusion tritium through pipelines into the environment). We have analyzed behavior of hydrogen and tritium in circuit of advanced NPP of high power in various regimes of operation, considering information mentioned before. It’s been shown, that concentration of hydrogen in sodium doesn't exceed a solubility limit at 250°C and concentration of tritium in the feed water arriving to environment doesn't exceed standards of safety in modes during plant start-up works and after abnormal coolant pollution, using the “fast cleaning mode” even if there is no purification systems in the primary circuit. However during purification in the idle mode it is necessary to use of small-sized cold traps for hydrogen removal or use hydrogen purification system with the pump through special membranes. More acceptable option, according to authors, is the use of purification system with a pump.
Keywords
fast reactor, regimes of operation, sodium coolant, purification, hydrogen, tritium, cold trap, hot trap, oxygen, concentration, temperature, Solubility, crystallization, evacuation, corrosion of structural materials
Article Text (PDF, in Russian)
UDC 621.039.553.34