JPS60201297A - 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 (Technical Field of the Invention) The present invention relates to a nuclear power plant in which the radiation dose rate of primary system piping is reduced.

[Problems with technical lifting of inventions]

Generally, the primary cold 7Jl water of a boiling water nuclear power plant contains Kobal i 60 (Go) and Kobal 1-58 ("C
Radioactive substances such as o) are dissolved as ions. These radioactive substances are Fe and Ni generated from the piping of the reactor's water supply system and condensate system.

When corrosion products such as GO flow into the reactor together with primary cooling water, they are activated by neutron irradiation. However, when these radioactive substances enter a recirculation system or purification system through which high-temperature, high-pressure primary cooling water flows, they cause oxidation of Fe3O4, which easily incorporates divalent metal ions, on the inner surface of the piping of these secondary cooling water systems. Since a film is formed, the oxides are taken into the oxide film and adhere to the inner surface of the piping. If radioactive substances such as Go adhere to the inner surface of the piping, the radiation dose rate of the sub-system piping will increase, and workers will be exposed to radiation during periodic inspections, etc.
I! There is a risk of increasing i.

(Objective of the Invention) The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the radiation dose rate of the primary system piping, and to reduce the radiation dose rate of workers during periodic inspections. The object of the present invention is to provide a nuclear power generation plan 1- which is excellent in safety and can suppress eleffi 1ffi to a low level.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention forms a primary cooling water system for a nuclear reactor using piping whose inner surface has been previously formed with a spreadable substance adhesion prevention film.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing one embodiment of the present invention, in which numeral 1 indicates a nuclear reactor pressure vessel (hereinafter referred to as RPV).

Connected to this RPVl are a main steam system 2 for extracting steam generated within the furnace, and a water supply system 4 for supplying primary cooling water into the furnace. The main steam system 2 is connected to the -C water supply system 4 via a condensate system 31, and after steam taken out from within the RPVl is condensed in the condensate system 3, it is returned to the RPVl through the water supply system 4. Further, a recirculation system 5 is connected to the RPV 1 to forcibly circulate cooling water to a reactor core (not shown) housed within the RPV 1. A purification system 6 that purifies a portion of the cooling water that has flowed into the recirculation system 5 is connected between the recirculation system 5 and the water supply system 4 . In addition, in this embodiment, the recirculation system 5 and the purification system 6 are
As shown in Figure 2, an oxide film containing zinc on the inner surface of the radioactive film is used as an anti-adhesion film. (Fez ZnO+)
101 is formed using piping 102. Note that this oxide film (Fe2ZnO+) 101 can be formed, for example, by immersing the pipe in a zinc ion solution (for example, Zn5O4iU solution) and keeping it at a humidity of 30 to 300°C. Apply a thin layer of zinc by plating or vapor deposition,
It can also be formed by exposing it to an air atmosphere at a temperature of 50° C. or higher.

Next, the operation of this embodiment with the above configuration will be explained. R.P.
The steam generated in Vl is sent to the high pressure turbine 8 through the main steam pipe 7 of the main steam system 2, and after excess moisture is removed by the moisture separator 9, it is sent to the low pressure turbine 10.

Then, these high-pressure and low-pressure turbines 8.10 are driven to generate 1 m11 of power. On the other hand, the low pressure turbine 10
The steam that drove the flows into the condensing system 3, is condensed in the condenser 12, and is degassed to form a hot well (
(not shown). The condensate accumulated in this hot well is filtered and desalted by a low-pressure condensate pump 13 through a condensate pipe 14, a condensate filter 15 and a condensate demineralizer 16, and then sent to a high-pressure condensate pump 17. The pressure of the water is increased and sent to the low-pressure feedwater heater 18 of the water supply system 4. Then, low pressure feed water heater 1
The water supplied to 8 is sent to the high-pressure feed water heater 20 by the J water supply pump 19, heated by the high-pressure water heater 20, and then supplied into the RPVl through the water supply pipe 21. The cooling water that has flowed into the RPVl in this way flows into the recirculation system 5, and a part of it is diverted to the +'p conversion system 6. The cooling water flowing into the recirculation system 5 is then pumped into the CRP V 1 through the recirculation piping 23 by the recirculation pump 22.
The cooling water is pumped as driving water to a Qffi jet pump (not shown), and also to the purification system 6: After passing through the purification piping 24 and being purified by the purification device 25, it is passed through the water supply system 4. It is again supplied into RPV1. Here, if the cooling water that has flowed into the recirculation system 5, the purification system 6, etc. contains radioactive substances such as "cod' ℃ 0," the recirculation system 5 and the purification system 6 will be operated as described above. An oxide film (Fe2zn) containing zinc in advance on the inner surface.

4) Since the pipe 102 is formed using the pipe 101, it is possible to prevent radioactive substances such as COI CO from being incorporated into the oxide film.

Figure 3 is a diagram showing the amount of radioactive substances accumulated when an oxide film containing zinc is formed on the inner surface of the pipe and when it is not. storage I
The amount of I is shown, and the horizontal axis shows the number of months that have passed. Further, curve A shows the case where an oxide film containing zinc is formed on the inner surface, and curve B shows the case where it is not formed. As shown in the figure, when an oxide film containing zinc is formed on the inner surface, the amount of radioactive substances accumulated in the primary system piping is extremely small, and hardly changes even with the passage of time. On the other hand, when an oxide film containing zinc is not formed on the inner surface, the amount of radioactive substances accumulated increases as the number of months elapses. As is clear from this, an oxide film (Fe2
When the recirculation system 5 and the purification system 6 are formed using the piping 102 in which ZnO+ > 101 is formed, the amount of accumulated radioactive substances can be suppressed, and the radiation m rate of the -order system piping can be reduced. is possible.

As described above, according to this embodiment, the primary cooling water systems such as the recirculation system 5 and the purification system 6 are formed using the piping 102 on which the oxide film 101 containing zinc is previously formed on the inner surface.
The radiation am rate of the secondary system piping can be reduced, and the radiation exposure of workers during periodic inspections can be kept to a low level. In the above embodiment, an oxide film containing zinc was formed on the inner surface of the pipe 102 as a film to prevent the adhesion of all substances.
According to this book, for example, gold (AU),
Platinum (Pt), aluminum (Afi), zirconium (Zr).

A similar effect can be obtained by forming a radioactive substance adhesion prevention film using non-oxidizing metals such as titanium (Ti) and molybdenum (Mo).
I can do that.

(Effects of the Invention) As is clear from the above description, according to the present invention, the primary cooling water system of the nuclear reactor is formed using piping whose inner surface is preliminarily coated with a film to prevent adhesion of radioactive substances. It is possible to provide a nuclear photoelectric blunt with excellent safety, which can reduce the radiation rate of piping and suppress the radiation exposure of workers to a low level during periodic inspections.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams showing an embodiment of the present invention. Figure 1 is a schematic diagram of a boiling water nuclear photoelectric plan 1~, and Figure 2 is an oxide film containing zinc on the inner surface. The cross-sectional view of the formed piping, FIG. 3, is a microcosm showing the amount of radiant 1i substances accumulated when an oxide film containing zinc is formed on the inner surface of the primary system piping and when it is not. 1... RPV, 2... Main steam system, 3... Double water system,
4...Water supply system, 5...Recirculation system, 6...Purification system. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (3)

[Claims] (1) A nuclear power plant characterized in that a primary cooling water system for a nuclear reactor is formed using piping whose inner surface has been previously coated with a film to prevent adhesion of radioactive substances. (2) The nuclear power plant according to claim 1, wherein the radioactive substance adhesion prevention film is an oxide film containing zinc. (3) The nuclear power plant according to claim 1, wherein the radioactive substance adhesion prevention film is formed of a non-oxidizing metal.