JPH01147400A - Shielding structure of steam turbine - Google Patents

Abstract

PURPOSE:To decrease a diffusion radiation does and to avert a large increase in weight by concentrically shielding only the high does part. CONSTITUTION:The steam generated from a nuclear reactor is fed to a high- pressure turbine 1 of a turbine generator and the exhaust steam is fed through a cross around pipe under the surface of an operating floor to the inside of a low-pressure turbine 2 through a CIV 5 and a steam introducing pipe 6. Shielding plates 7, 8 made of steel plates are put over the entire surface of the high-pressure turbine, the CIV 5 and the steam introducing pipe 6. Shielding plates 8, 10 are further mounted on the shielding plate 7 of the high-pressure turbine. A ceiling plate 11 and side plates 12 enclosing a main steam pipe 4 are formed thicker than the other ceiling plate 13 and side plates 14. The main steam pipe 4 which is a high radiation source and the juncture thereof are thereby concentrically covered, by which the diffusion radiation dose is decreased and the weight of the large increase in the weight of the shielding plates is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a steam turbine for a boiling watercolor nuclear power plant, and relates to a double plate structure suitable for preventing radioactivity diffusion.

[Conventional technology]

At the Boiling Watercolor Nuclear Power Plant, Steam Nubin directly uses the steam generated from the nuclear reactor as its driving steam, so barrier walls are required to prevent the spread of radioactivity, including the auxiliary machinery. Auxiliary equipment is placed below the operating floor, and the ceiling, floor, and walls are made of thick concrete to prevent radiation sources and protect the environment around the nuclear power plant.

Additionally, since the height of the building above the operating floor is high, it is difficult to thicken the walls and roof due to the structure of the building, so radiation source countermeasures are generally taken with equipment rather than in the building. It is true.

A steam turbine and a generator are mainly arranged on this operating floor, and some auxiliary equipment such as a reactor feed water pump and its driving turbine are also arranged.

Because these auxiliary equipment are small, they are placed in one room and surrounded by concrete shielding walls to prevent the spread of the virus.

In the case of steam turbines for power generation, they are large and installed on their own mounts, and in consideration of maintainability such as disassembly and inspection during periodic inspections, concrete barriers are not installed, and the turbine itself, especially the radiation dose. The high-pressure turbine, combination intermediate valve, and steam inlet pipe to the low-pressure turbine are covered with removable box-shaped baffles made of thick steel plates to prevent diffusion. However, the permissible amount of radioactivity emitted from a nuclear power plant into the environment is limited regardless of the number of units, so if the plant is to be expanded, the radiation dose may be severely restricted. The thickness of the flexible plate is now required to be even thicker, resulting in a significant increase in weight and problems such as a decrease in ease of maintenance and inspection.

[Means for solving problems]

The above objective is achieved by intensively shielding areas with high radiation doses.

[Problems to be Solved by the Invention] An object of the present invention is to reduce diffused radioactivity and avoid a large increase in weight by optimizing the shape of the flexible plate.

[Effect]

Among steam turbines, the radiation dose is relatively high.

This is the high-pressure turbine section, which is filled with high-temperature, high-pressure steam to do work, and this section is entirely covered with a box-shaped shingle plate that is divided into two parts to improve ease of overhaul. However, within this high-pressure turbine section, the radiation dose is particularly high in the main steam inlet pipe through which the steam generated in the reactor flows, and if this part is targeted, the diffusion dose can be reduced. There is no need to increase the thickness of the high-pressure turbine housing sheet metal body, and on the contrary, the thickness of other parts can be reduced, which prevents deterioration in maintenance and inspection efficiency.

〔Example〕

FIG. 2 shows the planar arrangement of the turbine-generator, and FIG. 3 shows the shield plate structure of a conventional high-pressure turbine.

The turbine-generator is located on the operating floor with a high pressure turbine 1. A low pressure turbine 22 and a generator 3 are arranged on one axis.

A main steam pipe 4 is connected to the high-pressure turbine 1 for introducing steam generated from the nuclear reactor into the high-pressure turbine.
Exhaust steam from the high pressure turbine 1 passes through a cross-around pipe located below the operating floor and passes through the CIV5. The steam flows into the low pressure turbine 2 through the steam introduction pipe 6.

Among these devices, high-pressure turbine 1 with high radioactivity concentration
and CIV5. The steam introduction pipe 6 has a shielding plate 7 made of iron plate,
8 to cover the entire surface to keep out radiation.

The thickness of the shield plate is determined by calculating the effect of radioactivity on the surrounding area of the power plant, but as the number of turbines and generators installed increases, the thickness of the plate becomes considerably thicker in subsequent units, resulting in an increase in weight. This will result in increased costs and decreased ease of maintenance and inspection.

FIG. 1 shows the high-pressure turbine baffle plate structure of the present invention.

The parts with the highest radioactivity concentration among the four steam turbines are the main steam pipe 4 and its connections, into which the steam generated in the nuclear reactor directly flows.

In order to cover the main steam pipe 4 intensively, baffles 9 and 10 are attached to the high-pressure turbine shingle plate 7, and a ceiling plate 11 surrounding the main steam pipe 4 is installed. Connect the side panel 12 to the other ceiling panel 13.
By making it thicker than the side plate 14, the main steam pipe 4 is covered intensively.

By covering the main steam pipe 4 and its connections, which are high radiation sources, in this way, the diffused radioactivity is reduced, and the thickness of the other ceiling panels 13 and side panels 14 can be reduced accordingly. becomes.

In addition, in order to improve the decomposability, the baffle board 9.10 and the ceiling board 11. The side plate 12 can also be installed independently from the other ceiling plate 13° side plate 14.

〔Effect of the invention〕

According to the present invention, by intensively shielding only the high-dose areas, it is possible to reduce the amount of diffused radiation and prevent a large increase in the amount of shield plate nails.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a shield plate according to an embodiment of the present invention, FIG. 2 is a plan view of a turbine-generator, and FIG. 3 is a perspective view of a conventional shield plate. 1... High pressure turbine, 4... Main steam pipe, 7,9.1
0...Shiyahei board, 11...Ceiling board, 12...Side board. Agent Patent attorney Katsuma Ogawa-”’he, no\-4-’

Claims (1)

[Scope of Claims] 1. In a nuclear turbine that directly uses steam generated in a nuclear reactor as its driving steam source, a shield plate is installed around a main steam pipe that introduces the steam from the nuclear reactor into a high-pressure turbine. The structure of the steam turbine is characterized by forming a shelter chamber separate from other high-pressure turbine parts. 2. The steam turbine according to claim 1, wherein the shield plate around the main steam pipe is installed separately from the shield plate of the other high-pressure turbine section. Noshiyahei structure.