Nuclear power plant end-of-life reactivity control method

Abstract

The invention belongs to the nuclear power plant reactivity control field and discloses a nuclear power plant end-of-life reactivity control method. The method includes the following steps that: (1) after a set is started, primary loop ammonia addition amount is controlled; (2) when the set operates normally, ammonia is added continuously; (3) the position of a tenth group of adjustment rods is adjusted at end of life; (4) a primary loop coolant purification system is adjusted, and alkali metal in a coolant is removed; (5) a primary loop boric acid storage and processing system is put into operation, and boron is removed; and (6) the pressure of a secondary loop is decreased. With the nuclear power plant end-of-life reactivity control method of the invention adopted, the reactivity of a reactor of a nuclear power plant can be controlled safely and effectively, and fuel consumption can be increased, and pollution can be reduced.

Description

technical field [0001] The invention belongs to the field of reactivity control of nuclear power plants, in particular to a method for controlling reactivity of nuclear power plants at the end of their service life. Background technique [0002] As the power consumption of the unit increases, the corresponding reactivity needs to be compensated. The first method to compensate the reactivity is to reduce the concentration of boric acid in the primary circuit coolant, and the main way to reduce the concentration of boric acid is to use filters to gradually remove boric acid and boric acid in the primary circuit. Change the water to dilute the operation. At the end of the nuclear power plant's life cycle design, when the concentration of boric acid in the primary circuit coolant is lower than 0.3g / L, the KBB (primary circuit boric acid storage and processing system) filter is put into operation to start the boron removal operation. [0003] Due to the particularity of the desi...

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Problems solved by technology

[0003] Due to the particularity of the design of the primary circuit water chemical conditions of the power station, in order to ensure the reduction rate of the boric acid concentration at the end of the service life, the flow through the filter will gradually increase, resulting in a gradual decrease in the hydrogen concentration in the reactor coolant system. In order to ensure the control of the hydrogen concentration Indicators, the method of adding hydrazine and ammonia water to the primary circuit must be adopted to increase the hydrogen concentration, resulting in an increase in the alkali metal ions in the primary circuit coolant, but the original design KBE (primary circuit coolant purification system) cannot be effectively removed at the end of its life. Alkali metals, prone to water chemistry deviations

[0004] The design of the boron removal process is unreasonable. When it works, it continuously circulates the degasser of the KBA (primary circuit up-filling and down-discharging system) to remove boron, remove the boric acid in the KBA degasser as much as possible, and then use the KBA pump to remove the KBA. The clear water in the aerator is returned to the primary circuit. The whole process is an infinite dilution process, and the definite amount of boron removal cannot be guaranteed. It is difficult to reduce the concentration of boric acid to the lowest value at the end of the service life. Relying on the maximum design flow rate of 40t / h to remove boron cannot maintain the full power operation of the reactor, and the method of removing boron simply by changing water and diluting operation will easily lead to deviations in ammonia potassium concentration and hydrogen concentration, and the amount of wastewater generated by water change exceeds that of the three-waste system processing power

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