JPS58223788A - Overflow and pump-up feedwater device of reactor coolant - 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 an improvement in a nuclear reactor coolant overflow and pumping supply system, and in particular to improvements in thermal stress at the joint between a reactor vessel and a coolant pumping supply pipe. This invention relates to a reactor coolant overflow and pumping supply system that alleviates the problem.

[Technical background of the invention]

In a liquid metal cooled nuclear power plant, when the operating state changes due to starting, stopping, or changing the output of the reactor, the temperature inside the reactor changes, and the coolant expands or contracts accordingly.

To accommodate this expansion and contraction of the coolant, liquid metal cooled nuclear reactors are equipped with coolant overflow and pumping systems.

FIG. 1 shows an example of the configuration of a conventional reactor coolant overflow and pumping supply device, in which a coolant overflow port 6 is opened at the liquid level of the coolant 2 in the reactor vessel 1. ing.

An overflow pipe 4 connected at one end to the overflow port 6 passes through the wall surface of the reactor vessel 1 and opens into a storage tank 5 at the other end.

Further, this tank 5 and the reactor vessel 1 are connected by a pumping supply pipe 7 equipped with an electromagnetic pump 6 for pumping up coolant.

Therefore, as the reactor power increases and the coolant expands,
The coolant in the reactor vessel 1 flows from the overflow port 6 through the overflow pipe 4 into the storage tank 5 and is stored therein.

Furthermore, when the liquid level of the coolant 2 in the reactor vessel 1 falls below a predetermined level, the electromagnetic pump 6 starts to pump up the coolant in the storage tank 5, and the pumping supply distribution ♂, 7□, □ 1□
1□1□0,.

In general, liquid metals such as sodium chloride used as coolants have low specific gravity and specific heat, and have low heat capacity.

In addition, the heat transfer performance of the coolant is very high, so when the reactor power changes, the coolant temperature follows and changes in an extremely short period of time, and the wall temperature of the reactor vessel also changes in a short period of time. Changes over time to follow the coolant temperature.

On the other hand, a relatively large amount of liquid metal that overflowed from the reactor vessel 1 is stored inside the storage tank 5 at a temperature after the start of the power change, so that the temperature after the start of the power change continues to overflow. Even if the liquid metal is at the coolant temperature, the temperature of the entire liquid metal inside the storage tank 5 will not follow rapidly.

Therefore, the liquid metal pumped and supplied to the reactor vessel 1 by the electromagnetic pump 6 has a temperature close to the state before the start of the change in the output of the reactor.

[Problems with background technology]

For this reason, large thermal stress may occur at the joint between the pumping supply pipe 7 and the reactor vessel 1 due to the temperature difference between the two, resulting in a disadvantage that the structural soundness deteriorates.

[Purpose of the invention]

The present invention solves the problems as mentioned above in the prior art, avoids the occurrence of temperature difference at the junction between the reactor vessel and the pumping supply piping, and improves the structural integrity of the reactor coolant overflow. The purpose is to provide a flow and pumping supply device.

[Summary of the invention]

The reactor coolant overflow and pumping supply system of the present invention is used in a liquid metal cooled nuclear power plant, in which an overflow pipe and a pumping supply pipe provided between a reactor vessel and a storage tank have a coaxial structure. The main characteristic is that

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to FIG.

An overflow port 16 opens at the upper limit level of the liquid metal coolant 12 contained in the reactor vessel 11 .

The overflow port 16 and the storage tank 14 are connected by an overflow pipe 15.

A pumping supply pipe 17 that supplies the coolant 16 stored in the storage tank 14 into the reactor vessel 11 surrounds the overflow pipe 15 and has a coaxial structure with it, and the vicinity of its upper end is connected to the reactor vessel 11. It passes through the wall of the container 11 and opens into the coolant 12 slightly below the overflow port 16.

Further, the vicinity of the lower end of the pumping supply pipe 17 passes through the center of the upper lid of the storage tank 14 and opens into the cooling shed 16 slightly above the lower end of the overflow pipe 15 .

The middle of the pumping supply pipe 17 is replaced with a large-diameter tubular duct 18, in which an electromagnetic pump 19 for pumping up the coolant is provided.

This electromagnetic pump includes an internal magnetic core 20 disposed between the overflow pipe 15 and the circular tubular duct 18, and an external magnetic core 21 and a coil 22 disposed outside the circular tubular duct 18, and the coil 22 is energized. According to the inner and outer magnetic cores 20.
A rising force is applied to the coolant between 21 and 21 by electromagnetic induction.

In the nuclear reactor coolant overflow translation and pumping supply device of the present invention configured as described above, the coolant 16 stored in the storage tank 14 is pumped up by the electromagnetic pump 19, and the coolant is pumped up through the pumping supply pipe 17 to the nuclear reactor coolant. The coolant 12 in the reactor vessel 11 is supplied into the reactor vessel 11, but the coolant 12 in the reactor vessel 11 overflows from the overflow port 16 into the overflow pipe 15 provided at the center of the pumping supply pipe 17.
flows, heat exchange takes place between the coolant in both chambers.

7. That is, when the temperature of the coolant 12 in the reactor vessel 11 increases due to an increase in the output of the reactor, a portion of the expanded coolant at both temperatures flows into the overflow pipe 15 from the overflow port 16.

On the other hand, when the electromagnetic pump 19 starts, the relatively low temperature coolant 16 in the storage tank 14 is pumped up and the pumped supply pipe 1
The coolant flowing in the supply pipe 17 is heated by heat exchange with the high temperature coolant flowing in the overflow pipe 15. The temperature of reactor vessel 11 also rose.
The temperature difference at the through-junction with is reduced.

Therefore, the thermal stress that occurs at the joint between the reactor vessel and the pumping supply pipe when the output of the reactor changes is alleviated, and the structural safety thereof is increased.

Further, since the overflow pipe and the pumping supply pipe have a coaxial structure, the piping space is reduced compared to the case where both are piped independently, and the margin in terms of layout design is increased.

Further, the required number of nozzles (not shown) provided on the reactor vessel side and the tank side can also be reduced.

In addition, in the above explanation, we have described an example in which the overflow piping and the pumping supply piping are coaxially structured over almost the entire length, but in some cases, independent piping may be used between the electromagnetic pump and the storage tank as in the past. You can also do that.

Furthermore, it goes without saying that the pump for cooling heel is not limited to the illustrated electromagnetic pump.

〔Effect of the invention〕

As described above, according to the present invention, thermal stress at the joint between the reactor vessel and the coolant pumping supply pipe can be alleviated, and the piping space can be reduced, so that the joint between the reactor vessel and the piping can be reduced. It is possible to increase the structural integrity of the section and the degree of leeway in designing the layout of piping.

[Brief explanation of drawings]

¥J1 is a schematic diagram illustrating a conventional reactor coolant overflow and pumping supply device, and FIG. 2 is a schematic diagram illustrating an embodiment of the present invention device. 1.11・・・・・・Reactor vessel 2.12.16
...Coolant 6.16...Overflow port 4115...Overflow pipe 5.14...Storage tank 6t19...・
...... Electromagnetic pump 7.17 ...... Pumping supply piping 18 ......... Pigeon-shaped duct 20 ......・・・・・・・・・・・・
Internal magnetic core 21 ・・・・・・・・・・・・・・・External magnetic core 22 ・・・・・・・・・・・・・・・Coil agent Noriyuki Chika (and 1 other person) Figure 1

Claims (1)

[Claims] 1. A liquid metal cooled nuclear power plant, characterized in that an overflow pipe and a pumping supply pipe provided between a reactor vessel and a storage tank have a coaxial structure. Furnace coolant overflow and pumping system. 2. One end of the pumping supply pipe surrounding the overflow pipe opens slightly below the overflow port in the reactor vessel, and the other end opens slightly above the lower end of the overflow pipe in the storage tank. A nuclear reactor coolant overflow and pumping supply device according to claim 1. 6. A part of the pumping supply piping is replaced by a large-diameter circular tubular tank, and an electromagnetic pump is installed therein to give upward force to the coolant in the pumping supply piping. A reactor coolant overflow and pumping supply device according to scope 1 or 2. 4. Claim 1, characterized in that the overflow pipe and the pumping supply pipe have a coaxial structure between the reactor vessel and the electromagnetic pump, and an independent structure between the electromagnetic pump and the storage tank. The nuclear reactor coolant overflow and pumping supply device according to any one of Items 1 to 3.