JPS61202188A - Tank type fast breeder reactor - 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 tank-type fast breeder reactor in which thermal stress in a core suspension mechanism that suspends and supports a reactor core from a roof slab is alleviated.

[Technical background of the invention]

Figure 2 shows a tank-type fast breeder reactor, in which the reactor vessel 1 containing the primary coolant has an upper opening connected to the roof slab 2.
A reactor core 3 is placed inside the reactor vessel 1 . The core 3 is composed of a plurality of fuel assemblies and control rods (none of which are shown), and is supported by a core support structure 4. The core support structure 4 is supported by a cylindrical core suspension mechanism (core suspension shell) 5 attached to the lower surface of the roof slab 2, whereby the core 3 is accommodated in the core suspension mechanism 5. and is suspended and supported from the roof slab 2 via this core suspension mechanism 5. Furthermore, inside the reactor vessel 1, there is a core resting structure 6 that prevents horizontal shaking of the reactor core 3, a coolant circulation pump 7 that forcibly circulates the primary coolant (sodium), and a The intermediate heat exchanger 8, core upper mechanism 9, etc. that perform heat exchange with the coolant are also supported by the roof slab 2,
It is arranged around the reactor core 3. Note that the secondary coolant is circulated through the outside of the reactor vessel 1. The core suspension mechanism 5 has a flow hole for circulating the primary coolant at a position below the liquid level of the primary coolant.
10 are provided. Further, a cover gas is filled in the space between the liquid level of the primary coolant and the roof slab 2.

The inside of the reactor vessel 1 is divided into a cold pool 11 that accommodates low-temperature coolant before passing through the reactor core 3, and a hot pool 12 that accommodates high-temperature coolant heated in the reactor core 3.
A high-pressure plenum 13 is formed below the core 3. The low-temperature coolant in the cold pool 11 is then sucked into the circulation pump 7 and pressurized into the high-pressure plenum 13.
It is heated by nuclear reaction heat as it passes upward through the reactor core 3, and is passed from the inside of the core suspension mechanism 5 to the communication port 9.
It passes through the hole 1 to reach the inside of the pool 12.

Thereafter, it flows into the intermediate heat exchanger 8, where it exchanges heat with the secondary coolant, and is cooled down to the cold pool 1.
It is returned to 1.

[Problems with background technology]

During reactor operation, the humidity of the coolant in the hot pool 12 normally reaches 500 to 550°C.

Therefore, in order to maintain the strength of the roof slab 2 and to maintain the upper surface side of the roof slab 2 at near room temperature,
Means are provided for cooling the roof slab 2.

On the other hand, since the temperature of the portion below the primary coolant liquid level of the core suspension mechanism 5 changes following the primary coolant,
For example, when the temperature of the primary coolant changes rapidly, such as when starting or stopping a nuclear reactor, there is a risk that large thermal stress will occur in the vicinity of the liquid level of the core suspension mechanism 5. Conventionally, as a measure to alleviate such thermal stress, a sodium packet 14 is attached near the liquid surface of the core suspension mechanism 5 to cover its inner and outer surfaces, resulting in a complicated structure. At the same time, a problem occurred in that the weight of the core suspension mechanism 5 increased. Moreover, in order to avoid sudden changes in the temperature of the primary coolant, there were limits to the reduction of reactor startup and shutdown times.

[Purpose of the invention]

The present invention was made to solve such problems, and its purpose is to reduce thermal stress in the vicinity of the primary coolant liquid surface of the core suspension mechanism that supports the reactor core within the reactor vessel with a simple structure. It is an object of the present invention to provide a tank-type fast breeder reactor that can reduce the reactor's operating pressure, shorten reactor startup and shutdown times, and reduce the weight of the core suspension mechanism.

[Summary of the invention]

In order to achieve the above objectives, the tank-type fast breeder reactor of the present invention:
A reactor vessel containing a primary coolant, a roof slab that closes the upper opening of the reactor vessel, and a distribution system that is attached to the lower surface of the roof slab and that distributes the primary coolant below the liquid level of the primary coolant. A cylindrical core suspension mechanism having a mouth and a plurality of longitudinal slits arranged in parallel in the circumferential direction at a portion including the liquid level height position, and a cylindrical core suspension mechanism that is supported by this core suspension mechanism and placed inside the reactor vessel. The reactor core is characterized by having a reactor core arranged therein, and a plurality of intermediate heat exchangers and circulation pumps arranged around the reactor core and supported by a roof slab.

By arranging multiple vertical slits in parallel in the circumferential direction near the liquid surface of the core suspension mechanism, the area near the liquid surface becomes highly flexible, which reduces the temperature change of the primary coolant. It is possible to alleviate the thermal stress that occurs due to

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, and the same parts as in FIG. 2 are designated by the same reference numerals.

That is, the upper opening of the reactor vessel 1 is closed with the roof slab 2, and the reactor core 3 inside the reactor vessel is supported by the support structure 4.

In the figure, the core support structure 4 is a cylindrical core suspension mechanism 15 attached to the lower surface of the roof slab 2.
The core support structure 4 is supported by this core suspension mechanism 15.

Also, inside the reactor vessel 1, as shown in FIG.
A core upper mechanism 9 and the like are supported by the roof slab 2 and arranged around the core 3. Further, a cover gas is filled in the space between the liquid level of the -water coolant and the roof slab 2. Further, the inside of the reactor vessel 1 is divided into a cold pool 11 and a hot pool 12, and a high pressure plenum 13 is formed below the reactor core 3.

The core suspension mechanism 15 includes: - a cylindrical body 16 that is located below the liquid level of the water coolant and accommodates and supports the core 3; and a plurality of rods that suspend and support this cylindrical body 16 from the roof slab 2. 17..., whereby the core 3 is housed in the core suspension mechanism 15, and is suspended and supported from the roof slab 2 via the core suspension mechanism 1115. . In addition, the adjacent bar 17.
The vertically long slits 18 present between the two serve also as a flow port through which the -water coolant flows.

° Therefore, the low-temperature coolant in the cold pool 11 is sucked into the circulation pump 7, pressurized, and guided into the high-pressure plenum 13. As it passes upward through the reactor core 3, it is heated by nuclear reaction heat, and the cylindrical coolant 16 It rises inside and reaches the hot pool 12 from the inside through the vertical slits 18. Thereafter, it flows into the intermediate heat exchanger 8, where it exchanges heat with the secondary coolant, and is cooled down to the cold pool 11.
will be returned to.

In the above configuration, the portion of the core suspension mechanism 15 near the primary coolant liquid level is composed of a plurality of rods 17, and these rods 17 can sufficiently withstand dimensional changes due to rapid changes in humidity. Because it has excellent flexibility to the extent that it can absorb water, even if the coolant temperature in the hot pool 12 suddenly drops when the reactor is shut down, the multiple rods near the primary coolant liquid level will The material 17... absorbs dimensional changes due to changes in humidity due to its flexibility. Therefore, even without providing the sodium packet shown in FIG. 2, the thermal stress generated in the core suspension mechanism 15 when the reactor operation is stopped can be significantly alleviated with a simple configuration.

Furthermore, since it can withstand rapid changes in water coolant temperature, reactor startup and shutdown times can be shortened.

Furthermore, by configuring the core suspension mechanism 15 from the cylindrical body 16 and the plurality of rods 17 in this manner, the weight is reduced, and the burden on the roof slab 2 is reduced.

Furthermore, the circulation of the primary coolant inside and outside the core hanging Ifill 15 is improved, and the heat removal effect in the hot pool 12 is also promoted.

Note that the present invention is not limited to the above embodiments. For example, the core suspension mechanism may include a plurality of vertically long slits arranged in parallel in the circumferential direction in the vicinity of the primary coolant liquid level of the conventional cylindrical core suspension mechanism 5 as shown in FIG. Also in this case, by extending at least a portion of the plurality of vertically long slits to below the primary coolant liquid level, the extended vertically long slits can also serve as communication ports (flow holes).

〔Effect of the invention〕

As described in detail above, according to the present invention, thermal stress in the vicinity of the primary coolant liquid level of the core suspension mechanism that supports the reactor core within the reactor vessel can be alleviated with a simple configuration, and It is possible to provide a tank-type fast breeder reactor that can shorten start-up and shutdown times and also reduce the weight of the core suspension mechanism.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a tank-type fast breeder reactor showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a tank-type fast breeder reactor showing a conventional example. 1... Reactor vessel, 2... Roof slab, 3...
Core, 7... Coolant circulation pump, 8... Intermediate heat exchanger, 15... Core suspension mechanism, 16... Cylindrical body, 1
7...Bar material, 18...Vertical slit (flow port).

Claims (3)

[Claims] (1) A reactor vessel containing a primary coolant, a roof slab that closes the upper opening of the reactor vessel, and a roof slab that is attached to the lower surface of the roof slab and that supplies the primary coolant below the liquid level of the primary coolant. A cylindrical core suspension mechanism that has a flow port and a plurality of longitudinal slits arranged in parallel in the circumferential direction at a portion including the liquid level height position, and a cylindrical core suspension mechanism that is supported by this core suspension mechanism and that is A tank-type fast breeder reactor comprising a reactor core disposed in a vessel, and a plurality of intermediate heat exchangers and circulation pumps disposed around the core and supported by a roof slab. (2) At least a part of the plurality of vertically elongated slits also serves as the flow port.
Tank-type fast breeder reactor as described in section. (3) The core suspension mechanism is composed of a cylindrical body located below the liquid level of the primary coolant to accommodate and support the core, and a plurality of rods that suspend and support this cylindrical body from the roof slab. A tank-type fast breeder reactor according to claim 1 or 2, characterized in that a vertically elongated slit is formed between adjacent rods.