JPH03216589A - Stand pipe apparatus - Google Patents

Abstract

PURPOSE:To relax the heat shock of a stand pipe when the flow rate of a cooling material is reduced by providing the stand pipe to the lower partition wall forming a low temp. plenum between the bottom surface of a furnace container and the partition wall so that the lower end of the stand pipe is bonded to the partition wall and the upper end thereof is opened to the furnace container. CONSTITUTION:In this stand pipe apparatus, the cooling material of a low temp. plenum 3c enters the space 11 between a stand pipe 9 and a heat shielding cylinder 10 through an opening 12. Since the space 11 is in contact with the cooling material of the low temp. plenum 3c through the heat shielding cylinder 10 and also in contact with the cooling material of a high temp. plenum 3a through the stand pipe 9, the cooling material in the space 11 is held at an intermediate temp. between the temp. of the high temp. plenum 3a and that of the low temp. plenum 3c. Therefore, the cooling material of the low temp. plenum 3c flows in the stand pipe 9 when the flow rate of the cooling material is reduced and the heat shock of the stand pipe is greatly relaxed.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to fast breeder reactors, and in particular to improvements in standpipe devices thereof.

(Prior Art) Figure 2 is a diagram showing the schematic configuration of a conventional tank-type fast breeder reactor. A reactor core 2 and a primary coolant 3 surrounding the reactor core 2 are housed in the reactor vessel 1 , and an upper opening of the reactor vessel 1 is shielded by a roof slab 4 . Further, an upper partition wall 5 and a lower partition wall 6 are provided in the reactor vessel 1, and these partition walls divide the primary coolant 3 into three areas: a high temperature plenum 3a, an intermediate plenum 3b, and a low temperature plenum 3c. Further, the roof slab 4 supports a primary coolant circulation pump 7 and an intermediate heat exchanger 8, respectively. In addition,
The primary coolant circulation pump 7 is surrounded by a stand pipe 9 whose lower end is joined to the lower partition wall 6 and whose upper end is opened above the primary coolant liquid level.

In the tank-type fast breeder reactor with the above configuration, the primary coolant 3
is circulated through the reactor core 2 by the primary coolant circulation pump 7, absorbs heat from the nuclear reaction of the nuclear fuel in the reactor core 2, raises its temperature, and heats the secondary coolant in the intermediate heat exchanger 8. The heated secondary coolant is led to a steam generator (not shown), where superheated steam for driving the turbine is generated. (Problems to be Solved by the Invention) Generally, in a tank type fast breeder reactor, the liquid level in the low temperature plenum 3c is lower than that in the high temperature plenum 3a at rated flow rate. Also, at low flow rates, the low temperature plenum 3
The liquid level at c rises, and the difference in liquid level height between the two plenums becomes small. Furthermore, when the flow rate decreases rapidly, such as during a trip, the liquid level in the low-temperature plenum will rise rapidly.
Thus, the stand pipe 9 has its upper outer surface exposed to the high temperature plenum 3a. The inner surface is in the air when the flow rate is rated, but when the flow rate decreases, it comes into contact with the coolant rising from the low temperature plenum 3c.

For this reason, the inner surface of the standpipe 9 is subject to thermal shock when the flow rate changes, and some kind of countermeasure is required to alleviate this. As one of the above-mentioned measures, the stand pipe 9 is closed during normal operation.
Although it has been considered to provide cooling to the

The present invention has been made based on the above circumstances, and aims to provide a standpipe device for a tank-type fast breeder reactor that can alleviate thermal shock when the coolant flow rate decreases and has a simple structure. ．． [Structure of the Invention] (Means for Solving the Problems) The standpipe device of the present invention has an outer periphery joined to the inner periphery of the reactor vessel that accommodates the primary coolant and the reactor core, and an inner periphery joined to the outer periphery of the core to change the reactor volume. A stand pipe was provided with its lower end joined to the lower partition wall forming a low-temperature plenum with the bottom surface, and its upper end opened into the air inside the reactor vessel, and the lower end was joined to the lower partition wall on the inner periphery of this stand pipe. A heat shielding cylinder is provided, and a space between the inner periphery of the standpipe and the heat shielding cylinder is communicated with the low temperature plenum.

(Function) In the standpipe device of the present invention having the above configuration, the space between the standpipe and the heat shield cylinder communicates with the low-temperature plenum, and the coolant enters therein. In addition, since the space is in contact with the coolant of the low temperature plenum rising into the heat shield cylinder through the heat shield cylinder, and the coolant of the high temperature plenum is in contact with the coolant in the high temperature plenum through the stand pipe, the coolant in the space is is maintained at a temperature intermediate between the temperature of the hot plenum and the temperature of the cold plenum.

(Embodiment) FIG. 1, in which the same parts as in FIG. 2 are denoted by the same reference numerals, is a diagram showing a schematic configuration of an embodiment of the present invention.

In this figure, a heat shielding cylinder 10 is provided on the inner periphery of the standpipe 9 over its entire length.

At the lower end of the heat shielding tube 10, openings 12 are provided distributed in the circumferential direction to communicate the space 11 between the inner periphery of the standby pipe 9 and the heat shielding tube 10 to the low temperature plenum 3c.

Note that the lower half of the stand pipe 9 has a larger diameter than the upper half.

In the standpipe device having the above configuration, the coolant from the low-temperature plenum 3c enters the space 11 between the standpipe 9 and the heat shield cylinder 10 through the opening 12. The space 11 is in contact with the coolant of the low temperature plenum 3c rising into the heat shield cylinder lo via the heat shield tube 10, and is in contact with the coolant of the high temperature plenum 3a via the stand pipe 9. The coolant in 11 is high temperature Blenheim 3
The temperature is maintained at an intermediate temperature between the temperature of the low temperature plenum 3c and the temperature of the low temperature plenum 3c.

Therefore, even when the coolant in the low-temperature plenum 3c flows into the standpipe 9 when the coolant flow rate decreases and the liquid level inside rises, the temperature difference between the coolant that has risen and the inner surface of the standpipe 9 is small. Yes, thermal shock is greatly alleviated. Furthermore, in the above embodiment, since the lower half of the standpipe 9 has a large diameter, the rise in the liquid level in the standpipe due to the coolant flowing into the standpipe 9 when the coolant flow rate decreases is absorbed by the lower half. , it is possible to prevent the rise in the liquid level from spreading to the upper end of the stand pipe 9, and it is possible to alleviate thermal shock.

[Effects of the Invention] As is clear from the above, the standpipe device of the present invention has a simple structure in which a heat shield cylinder is provided on the inner periphery of the standpipe, and the thermal shock of the standpipe when the coolant flow rate decreases is alleviated. be able to.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of an embodiment of the present invention;
The second $$Wf diagram is a vertical cross-sectional view showing a schematic configuration of a conventional tank-type high-speed breeder reactor. 1...Reactor vessel 2...Reactor core 3...
... Coolant 3a ... High temperature plenum 3b.
...Middle plenum 3C...Low temperature plenum 4...Roof slab 5...Upper bulkhead 6...Lower bulkhead 7... Primary coolant circulation pump 8...Intermediate heat exchanger 9...
...Standpipe 10 ...Heat shield tube
11... Space 12... Opening

Claims (1)

[Claims] The outer periphery is joined to the inner periphery of the reactor vessel that houses the primary coolant and the reactor core, the inner periphery is joined to the outer periphery of the reactor core, and the lower end is joined to the lower bulkhead, which forms a low-temperature plenum between it and the bottom of the reactor vessel, and the upper end is connected to the inside of the reactor vessel. A standpipe is provided with an opening therein, a heat shielding tube having a lower end joined to the lower partition wall is provided on the inner periphery of the standpipe, and a space between the inner periphery of the standpipe and the heat shielding tube is defined by the heat shielding tube. A standpipe device characterized by communicating with a low-temperature plenum.