Patent Number: 
Section: claims

1. A method for control of oxygen concentration in a coolant of a reactor plant including a reactor, the coolant located in the reactor, a gas system with an outlet to a space near the coolant of the reactor, a mass-exchange apparatus installed in the coolant, which contains solid-phase oxides of coolant and is adapted to flowing of the coolant through it, a disperser installed partially in the coolant and partially in the space near the coolant and adapted to supply gas from the space near the coolant to the coolant, and an oxygen sensor in the coolant, the method comprising:estimating an oxygen concentration in the coolant based on data received from the oxygen sensor in the coolant;comparing the estimated oxygen concentration in the coolant with a predetermined permissible value;estimating a change in oxygen concentration in the coolant;if the estimated change in oxygen concentration in the coolant shows reduction in concentration, then comparing a reduction value and/or a reduction rate of the oxygen concentration with a corresponding predetermined threshold value;if the estimated oxygen concentration in the coolant is below the predetermined permissible value and the reduction value and/or the reduction rate of the oxygen concentration is below the corresponding predetermined threshold value, then activating the mass-exchange apparatus;if the estimated oxygen concentration in the coolant is below the predetermined permissible value and the estimated reduction value and/or the estimated reduction rate of the oxygen concentration is above the corresponding predetermined threshold value, then supplying oxygen-containing gas from the gas system to the space near the coolant and/or activating the disperser; andif after the activating of the mass-exchange apparatus or after the supplying of the oxygen-containing gas and/or the activating of the disperser, the estimated oxygen concentration in the coolant is greater than or equal to the predetermined permissible value, then deactivating the mass-exchange apparatus or the disperser and/or stopping the supplying of the oxygen-containing gas from the gas system to the space near the coolant, wherein oxygen-free gas is supplied from the gas system to the space near the coolant in addition to stopping the supply of oxygen-containing gas from the gas system to the space near the coolant.