JPS62201393A - 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] [Object of the Invention] (Industrial Field of Application) The present invention relates to fast breeder reactors, and in particular to improvements in the cooling system for reactor vessel walls in tank-type fast breeder reactors. 11'ru.

(Prior art) Figure 6 shows a conventionally known general tank-type fast breeder reactor, which consists of a reactor vessel 1, a reactor vessel 1,
A roof slab 2 that is attached to the upper end of the reactor vessel 1 and forms an outer shell together with the reactor vessel 1;
A pump 3 and an intermediate heat exchanger (IHX) 4 are suspended and supported in the reactor vessel 1 from a partition wall 7 that partitions a hot pool 5 and a cold pool 6 in the reactor vessel 1, and discharged from the pump 3. A discharge pipe 10 is provided for guiding coolant to the reactor core 9 via the high-pressure plenum 8.

By the way, in this type of tank type fast breeder reactor, the temperature of the coolant in the bot boule 5 is as high as about 500 to 540°C, and the temperature of the wall of the reactor vessel in contact with the hot pool 5 is also about the same, so material creep occurs. It is necessary to design considering the characteristics.

Therefore, conventionally, as shown in FIG. 7, a method has been adopted in which the reactor vessel wall is cooled to a temperature that allows for a more conservative design without considering the creep characteristics of the material.

In other words, in this cooling method, as shown in FIG. The coolant is introduced into the annulus formed between the reactor vessel wall and overflowed from the weir 14 installed at the top. It falls into the annulus formed by the partition wall 16 between the receiving wall 15 and the inner container 13, descends, returns to the cold pool 6 through the flow hole 17 provided in the partition wall 7, and joins the main stream. The reactor vessel wall is then maintained at a low temperature by the low-temperature coolant.

(Problems to be Solved by the Invention) As described above, in the conventional reactor vessel wall cold N1 method, the low temperature coolant from the lower plenum 12 is transferred to the inner vessel wall.
A method is adopted in which the water overflows from the weir 14 at the upper end of the weir 14 and falls about 1.5 m, but it is not clear from which part of the circumference of the weir 14 the water will overflow, and the overflow is not necessarily constant. There is a problem with not yelling. For this reason, non-uniform flow due to overflow and falling occurs periodically, and reactor internal structures such as the sodium receiving wall 15 become SiF! However, there is a problem that these may break due to fatigue or the like.

The present invention has been made in consideration of these points, and an object of the present invention is to provide a fast breeder reactor that can stabilize the flow of coolant and improve the reliability of reactor vessel wall cooling.

(Structure of the Invention) (Means for Solving the Problems) The present invention does not adopt the conventional method of overflowing the cold UJ material from the lower plenum through the weir, but instead The coolant in the lower plenum is guided to the annulus formed between them via piping, and the coolant in the annulus is guided to the cold pool via a discharge means.

(Function) In the fast breeder reactor according to the present invention, the coolant in the lower plenum is guided to the annulus section via piping, and the coolant in the annulus section is guided to the cold pool via the discharge means. It becomes possible to stabilize the flow of coolant.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In FIGS. 1 and 3, reference numeral 1 denotes a tank-shaped reactor vessel with an open top. A roof slab 2 is attached to the top opening of the reactor vessel 1, and the outer shell is attached to the top opening of the reactor vessel 1. is formed.

As shown in FIG. 3, the roof slab 2 supports a pump 3 and an intermediate heat exchanger (II-(X) 4), which are suspended within the reactor vessel 1.

Furthermore, the hot pool 5 and cold pool 6 inside the reactor vessel 1 are separated by a bulkhead 7, not shown in FIGS.
A high pressure plenum 8 and a lower plenum 12 are arranged at the lower part of the pump 3 , and the high pressure plenum 8 is connected to the discharge side of the pump 3 via a discharge pipe 10 . The low-temperature coolant discharged from the pump 3 is guided into the high-pressure plenum 8 via the discharge pipe 10, and most of it is guided into the reactor core 9, while some of the coolant is introduced into the high-pressure plenum 8. It is led to a lower plenum 12 via a flow hole 11 provided at the lower part.

On the other hand, on the inside of the reactor vessel 1, as shown in FIGS. 1 to 3, an annulus portion 20 is formed between the reactor vessel wall and a barrier between the inner vessel 21 and the bot boule 5.
is installed, and a thermal liner 22 is installed on the inner peripheral surface of this inner container 21. The low-temperature coolant introduced into the lower plenum 12 is then introduced into the annulus section 20 via a communication pipe 23 that connects the lower plenum 12 and the lower end of the annulus section 20, as shown in FIGS. 1 and 3. , flows in the annulus section 20 as an upward flow.

In the annulus portion 20, a return pipe 24 is provided which is connected at its lower end to the cold pool 6 as shown in FIGS. 1 and 3. The upper end opening 24a of the return pipe 24 is located at a height position suitable for relieving the thermal stress due to the axial temperature gradient from the joint with the roof slab 2 of the reactor vessel 1. The cold fj-1 flow that flows upward in the annulus section 20 flows into the return pipe 24 from the upper end opening 24a as shown in FIG. The water flows down through the cold pool 6 and merges with the mainstream inside the cold pool 6. The required number of return pipes 24 and communication pipes 23 are installed at appropriate intervals in the circumferential direction of the annulus portion 20, and constitute a reactor vessel wall cooling fJ1 flow path.

Next, the operation of this embodiment will be explained.

Most of the low-temperature coolant that flows into the high-pressure plenum 8 from the cold pool 6 when the pump 3 is started flows into the reactor core 9.
At the same time, the remaining portion flows into the lower plenum 12 from the flow hole 11 and is further guided to the lower end of the annulus section 20 through the communication pipe 23.

The coolant guided to the lower end of the annulus section 20 exchanges heat with the hot pool 5 via the inner container 21 while flowing upward in the annulus section 20, and the coolant flows through the upper end opening of the return pipe 24. It rises to the level of section 24a. Thereafter, it flows into the return pipe 24, descends to the cold pool 6, and is mixed with the mainstream.

In this way, by appropriately setting the reactor vessel wall cooling flow rate by adjusting the diameter and number of the communication pipe 23 and the return pipe 24, it is necessary to take into account the creep effect in the wall temperature of the reactor vessel 1. It becomes possible to maintain the temperature below. Further, since the liquid level in the annulus portion 20 is regulated at the position of the upper end opening 24a of the return pipe 24, the liquid level can be stabilized without fluctuations in the liquid level as in the conventional case.

4 and 5 show another embodiment, in which a supply pipe 25 and a flow hole 26 are used in place of the communication pipe 23 and return pipe 24 in the previous embodiment, and the flow of coolant in the annulus section 20 is controlled. is a downward flow.

That is, the supply tube 25 has its lower end connected to the lower plenum 12 as shown in FIG. As shown in FIG. 5, it is set at the same height as the upper end opening 24a of the return pipe 24 in J3 in the above embodiment. The coolant in the lower plenum 12 rises through the supply pipe 25, overflows from the upper end opening 25a, descends within the annulus section 20, and flows through the flow hole 26 provided at the lower end of the annulus section 20. It is guided into the cold pool 6 and merges with the mainstream.

The supply pipe 25 and the flow hole 2G are arranged in multiple stages at predetermined intervals in the circumferential direction of the reactor vessel 1.

The rest of the structure is exactly the same as that of the previous embodiment.

Next, the operation of this embodiment will be explained.

Most of the low-temperature coolant that flows into the high-pressure plenum 8 from the cold pool 6 when the pump 3 is started flows into the reactor core 9.
At the same time, the remainder flows into the lower plenum 12 from the flow hole 11, further passes through the supply pipe 25, overflows from the upper end opening 25a, and is led into the annulus section 20. The coolant guided into the annulus section 20 exchanges heat with the hot pool 5 via the inner container 21 while flowing in the annulus section 20 as a downward flow. It flows into the cold pool 6 from the hole 26 and is mixed with the main stream.

Note that the temperature upper limit due to heat input from the downward flow hot pool 5 flowing within the annulus portion 2o and the temperature rise of the coolant in the supply pipe 25 due to heat input from this heated downward flow are problems. However, by appropriately adjusting the diameter and number of supply pipes 25 and appropriately setting the reactor vessel wall cooling flow hl, the reactor vessel wall temperature can be reduced to a temperature below which there is no need to consider the creep effect. It becomes possible to maintain

As described above, in this embodiment, the reactor vessel wall can be maintained at a low temperature as in the previous embodiment, and by appropriately setting the return flow rate and pressure loss of the coolant from the annulus section 20, the inside of the annulus section 20 can be maintained. The liquid level of the cooling H can be stabilized at a position slightly above the upper end opening 25a of the supply pipe 25.

〔Effect of the invention〕

As explained above, the present invention introduces the cold fJl material in the lower plenum to the annulus formed between the reactor vessel wall and the inner vessel via piping, and also discharges the coolant in the annulus. Since the coolant is led to the cold pool via the means, the flow of the coolant can be stabilized and the reliability of cooling the reactor vessel wall can be improved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the main parts of a fast breeder reactor showing an embodiment of the present invention, Fig. 2 is an enlarged view of the part ■ in Fig. 1, Fig. 3 is a cross-sectional view of the overall structure of the fast breeder reactor, and Fig. 4 1 is a view equivalent to FIG. 1 showing another embodiment of the present invention, FIG. 5 is an enlarged view of the V section in FIG. 4, FIG. 6 is a sectional view showing a general fast breeder reactor, and FIG. FIG. 1 is a diagram corresponding to FIG. 1 showing a reactor vessel wall cooling system in a conventional fast breeder reactor. 1... Reactor vessel, 5... Hot pool, 6...
Cold pool, 8... High pressure plenum, 9... Core, 11.26... Flow hole, 12... Lower plenum, 20... Annulus part, 21... Inner container,
23...Communication pipe, 24...Return pipe, 24a, 25
a... Upper end opening, 25... Supply pipe. Applicant's agent Sato - Yu 1st figure 4 Yansuke 7th figure

Claims (1)

[Claims] 1. An inner vessel installed inside the reactor vessel wall and forming an annulus section between the reactor vessel wall and the hot pool, and an inner vessel installed at the lower part of the high pressure plenum. It includes a flow hole that guides the low-temperature coolant in the high-pressure plenum to the lower plenum, a pipe that guides the coolant led to the lower plenum to the annulus, and a discharge means that guides the coolant in the annulus to the cold pool. A fast breeder reactor characterized by: 2. The piping is formed by a communicating pipe that guides the coolant in the lower plenum to the lower end of the annulus, and the discharge means is formed by a return pipe that is installed upright in the annulus and into which the coolant in the annulus flows from the upper end opening. A fast breeder reactor according to claim 1, characterized in that: 3. The piping is formed by a supply pipe whose upper part is raised into the annulus part and causes the coolant to overflow from the upper end opening into the lower plenum, and the discharge means is formed by a flow hole provided at the lower part of the annulus part. A fast breeder reactor according to claim 1, characterized in that: