Dosing system and method for deoxidant hydrazine for secondary loop system of high-temperature gas cooled reactor nuclear power plant

Abstract

The invention discloses a dosing system and method for a deoxidant that is hydrazine for a secondary loop system of a high-temperature gas cooled reactor nuclear power plant. The dosing system comprises a water feeding and hydrazine adding device which is arranged on an outlet pipeline of a high-pressure heater and used for adding the hydrazine, and a sampling monitoring device which is arranged at an inlet pipe of a steam generator and used for monitoring dissolved oxygen and hydrazine contents and controlling the hydrazine adding amount. According to the dosing system and the method, the flow accelerated corrosion rate of the secondary loop water supply system can be reduced to the maximum extent under the condition that a chemical water treatment agent is not changed in the secondary loop of the nuclear power unit and only the hydrazine dosing position is changed. The sampling position of the secondary loop system is changed, so that the sampled sample is more reasonable and representative.

Description

technical field [0001] The invention relates to the technical field of water chemical working conditions of a high-temperature gas-cooled reactor nuclear power plant, in particular to a dosing system and method for an oxygen scavenger hydrazine in a secondary circuit system of a high-temperature gas-cooled reactor nuclear power plant. Background technique [0002] The steam generator material of the high-temperature gas-cooled reactor nuclear power unit contains nickel-based alloys, which are sensitive to oxygen, and the dissolved oxygen content in the main feed water entering the steam generator is required to be less than 3 μg / L. The oxygen removal methods of the secondary loop water supply system of nuclear power plants are thermal deoxygenation by deaerator and chemical deoxygenation by adding hydrazine to ensure that the main feed water entering the steam generator does not contain oxygen. [0003] However, hydrazine is a reducing agent. After hydrazine is added, the ox...

AI Technical Summary

Problems solved by technology

At present, domestic and foreign nuclear power units have not made clear regulations on this

(2) The cyclic chemical treatment method is changed from the ammonia addition + hydrazine treatment method to the ammonia addition + oxygen addition combined treatment. However, since many components (valves, pipes) of nuclear power plants contain nickel-cobalt alloys, they are sensitive to dissolved oxygen. At present, there is no nuclear power unit in the world that adopts the oxygenation treatment method in the cycle chemical treatment method.

(3) Increasing the amount of ammonia added and increasing the pH value of the water vapor system can only reduce the FAC rate of some water supply pipes to a certain extent, but it will cause high ammonia content in the condensed water, making the condensed water polishing system run in H / OH mode The cycle is greatly shortened, the regeneration cost increases, and the discharge of regeneration waste liquid also increases

[0006] According to the above analysis, it can be known that the four methods of suppressing flow-accelerated corrosion are not the best choice for the established high-temperature gas-cooled reactor nuclear power units.

Images