JPS6195290A - Method of reducing dosage of nuclear power plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to reduce the radiation wQ of the primary system piping through which the primary cooling water of a water-cooled nuclear reactor flows. A method for reducing the radiation weight of an atomic power plant with a reduced rate is summarized.

[Technical background of the invention] Generally, the primary cooling water system of a pressurized water nuclear power plant (PWR plant). It consists of the main equipment that can be accepted by 3rd U4. In other words, reference numeral 1 denotes a pressurized water reactor (hereinafter referred to as PWR), and this PWRl includes a path 2 that connects cooling water heated in the reactor to a steam generator 5 and a line that supplies primary cooling water into the reactor. 3 is connected.

In the above configuration, the cooling water heated by the PWRl is pressurized by the pressurizer 4 and sent to the steam generator 5, where the PWR
Transfers the thermal energy generated in Rl to the secondary system. The cooling water that has transferred thermal energy to the secondary system by the steam generator 5 is supplied to the PWRl through the yarn path 3 by the primary cooling water pump 6, but some of the cold 11N water is purified by the purifier 7. Thereafter, it is fed to PWR 1 through yarn path 3.

[Problems with Background Art] By the way, radionuclides such as cobalt-58 (CO > .) cobalt-60 ("Co") are dissolved in the form of ions in the primary coolant of such a pressurized water nuclear power plant cap. These radionuclides are mainly produced by steam generation9.
．． Corrosion products such as Ni and CO released from the heat exchanger tubes in the vessel 5 flow into the PWR i together with the primary cooling water and are activated by neutron irradiation. However, these radionuclides are incorporated into the Fe2O2 oxide film that is formed on the computer surface of the primary cooling water system and easily absorbs divalent metal ions, and adheres to the inner surface of the piping. If radioactive nuclides adhere to the inner surface of the piping in this way, it will cause the radiation vAI rate of the secondary system piping to rise, and during periodic inspections, etc., workers should not open the hJlrJJ function. I was afraid of getting hit by one dash line.

[Object of the invention] The present invention was made to solve the above problems, and its purpose is to prevent the accumulation of radioactivity in the primary system piping of a water-cooled fJI nuclear power plant [and to reduce the radiation dose rate]. An object of the present invention is to provide a method of reducing radiation dose in a nuclear power plant, which can suppress the radiation field on holidays during periodic inspections to a low level.

[Summary of the Invention] In order to achieve the above object, the present invention is characterized by the following method. In other words, if you trace the primary system piping of a water-cooled nuclear power plant, 'Co2
The radiation dose reduction method involves injecting zinc ions into the secondary system as a method for suppressing the adhesion of copper-prone corrosion products such as CO2. It may be supplied by lead ions or by chemicals containing zinc.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

1 is a schematic system diagram for explaining one embodiment of the present invention, in which the same parts as in FIG. 3 are given the same reference numerals, and the explanation of the overlapping parts is omitted.

In Fig. 1, the symbol @10 is a device for supplying zinc ions.'' In this figure, a device 10 for supplying zinc ions is provided at the outlet of the steam generator 5, but in reality, if it is a -order system piping, In addition, the zinc ions injected into the piping from the zinc ion supply device 10 are supplied by zinc ions generated by electrolysis or chemicals containing zinc.

Next, the operation of this embodiment using the above method will be explained. - When the zinc ion water injected into the next system passes through the piping of the water-cooled n1 water system, the
Fe, r711, which reacts with the oxide film of
This results in the formation of a 0*-shaped oxide film.

Figure 2 shows the zinc content in the oxide film and 15% of the primary system piping.
It shows the relationship with the 1QJ line f6 rate.

As shown in FIG. 2 (1), if zinc is incorporated into the oxide film, the zinc content increases and the group 04 wire Fe4 ratio of the primary system piping decreases.

Therefore, in the secondary system piping] 60 ("CO')
21 Pal 1-58<”Co) Even if the radioactive nuclide of the cap flows in, the inner surface of the pipe will remain ill!
Since ψ(Fc 27n 04 ) is formed, radionuclides are prevented from shielding the inner surface of the pipe.

According to this embodiment, by injecting il+1 lead ion into the primary cooling water system of the nuclear reactor, 1ITi lead is introduced onto the inner surface of the primary system piping, and a thick oxide film is formed inside the piping. Since it is possible to prevent the +Jri f1 nuclide for b'l from entering the surface, the radiation dose rate of the primary system piping can be reduced, and the exposure dose for work 0 can be kept to a low level during periodic inspections, etc. It becomes possible. It goes without saying that the present invention is applicable not only to light water reactor nuclear power plants but also to other light water reactor nuclear power plants. [Effect of the invention 1 As is clear from the above explanation, the present invention is water-cooled] As a method for suppressing the adhesion of radioactive corrosive products and acids to a JL nuclear power plant, zinc ions are injected into the -2 system. This method is characterized in that the zinc ions to be implanted are supplied by electrolytic zinc ions or by a chemical containing zinc.

Therefore, according to the present invention, Z
Since n2+ is taken in, accumulation of radionuclide ions in C01+ and CO juice can be prevented.

Therefore, it is possible to provide a radiation dose reduction method for a nuclear power plant, which can reduce the radiation field rate and suppress the exposure of 6C/l workers to a low level during periodic inspections and the like.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams for explaining one embodiment of the present invention. Figure 1 is a system diagram schematically showing the sub-cooling water system of a pressurized water nuclear power generation plant, and Figure 2 is a system diagram schematically showing a sub-cooling water system in a pressurized water nuclear power plant. Figure 3 is a diagram schematically showing the relationship between the zinc content and the radiation of the primary system piping. 1・・・・・・・・・PWR 4・・・・・・・・・Pressurizer 5・・・・・・・・・Steam generator 6・・・・・・・・・−Water cooling water Bomb 7...
...Purification device 10...Lead ion supply device Patent attorney Noriyuki Noriyuki (and one other person) Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A method for reducing radiation dose in a nuclear power plant, which comprises injecting zinc ions into the primary piping of a water-cooled nuclear power plant. (2) The method for reducing radiation dose in a nuclear power plant according to claim 1, wherein the zinc ions are produced by electrolytic zinc ions or zinc-containing chemicals.