Chemical process for passivation of primary loop system during pre-critical test of nuclear power plant

Abstract

The invention relates to a chemical process for passivation of a primary loop system during a pre-critical test of a nuclear power plant. The chemical process comprises the following steps that duringthe pre-critical test performed after initial loading of nuclear fuel in a core of a nuclear reactor, Zn2+ is added to a coolant so that the Zn2+ contacts the metal surface in the primary loop systemduring the pre-critical test to form an initial zinc-containing oxide film. According to the chemical process, the zinc is added to the coolant during the pre-critical test of a new nuclear power unit, so that the zinc contacts with the metal surface in the primary loop system during the pre-critical test, and the initial zinc-containing oxide film is formed on the metal surface; the reliabilityof the passive film is improved through implementation of zinc-injecting passivation of the new nuclear power unit, good protection is provided for a primary loop metal component during the running life time of nuclear power, long-term stable and reliable operation of the nuclear power unit is ensured, the total amount of corrosion products which can deposit on the fuel and become activated duringnormal power operation is also significantly reduced, and accordingly the fuel performance is improved and the plant dose rate is reduced as much as possible.

Description

technical field [0001] The invention relates to the technical field of nuclear power, in particular to a chemical process for the passivation of a primary circuit system during the pre-critical test of a nuclear power plant. Background technique [0002] Nuclear power plants generally have a loop system, which includes reactor vessels, steam generators, reactor coolant pumps, pressurizers and connecting pipes. The reactor coolant loop includes the reactor coolant pump, the steam generator, and the piping that connects these components to the reactor vessel. Nuclear power plants can have two, three or four reactor coolant circuits. Nuclear fuel is contained in the reactor core, which is contained in the reactor vessel. One function of the primary loop system is to transfer heat from the nuclear fuel to the steam generator. [0003] In order for the primary system to perform its function, the coolant is circulated through the primary system. System materials and surfaces t...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a chemical process for the passivation of the primary circuit system during the pre-criticality test of nuclear power plants, which solves the problem that the passivation film formed according to the existing natural passivation method in the prior art is as long as 60 years in nuclear power units. During the service life, there are unfavorable situations where the protection effect is weakened, and there are problems such as potential fuel performance problems caused by zinc injection passivation of mature nuclear power units, which lead to increased risks, etc.