JPS59135395A - Flow changing mechanism in heat exchanger included in reactor container - 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 The present invention relates to a heat exchanger built into a nuclear reactor vessel, and more particularly to a heat exchanger equipped with a primary coolant flow path changing mechanism.

Inside the reactor vessel, a main heat exchanger and an auxiliary heat exchanger are installed. and circulate. During reactor operation, coolant must flow to the primary heat exchanger and must not flow to the auxiliary heat exchanger. Furthermore, when the auxiliary cooling system is in operation, the coolant must flow through the heat exchanger of that cooling system, but must be prevented from flowing through the main heat exchanger.

For this reason, the main heat exchanger and the auxiliary heat exchanger are provided with a flow path changing mechanism. One of these flow path changing mechanisms is a liquid level control type.

As shown in FIG. 1, the liquid level control type flow path changing mechanism has a skirt 4 arranged concentrically on the outside of a primary coolant inflow window 3 formed in a shell 2 of a heat exchanger 1, and the upper end of the skirt 4. The support ring 5 of the heat exchanger 1 is fixed to the reactor lid 6, and the gas inlet pipe 7 is communicated with the inside of the skirt 4 to supply and pressurize the same gas as the reactor cover gas 8, whereby the skirt This is to lower the liquid level of the primary coolant 9 inside the coolant 4 and prevent the coolant 9 from flowing in through the inflow window 3.

Note that 6' is an outflow window.

This liquid level control type flow path changing mechanism has high reliability in operation when the heat exchanger 1 is operated.

Although the coolant has advantages such as the absence of dynamic equipment, the liquid level is easily affected by changes in temperature and pressure of the coolant in the furnace, so the liquid level must be monitored (~Gas pressure controlled by the control valve 10). need to be adjusted.

However, controlling the liquid level has problems such as the accuracy of the liquid level gauge and the control delay of the gas adjustment system, making it difficult to maintain a constant liquid level at all times. If too much gas is put into the inside of the skirt 4, the liquid level will drop to the lower end of the skirt 4, and the gas will flow out from the lower end of the skirt 4 into the furnace coolant. Gas leaks out (-11) and rises to the liquid level of the coolant in the reactor,
It is fine if the reactor cover gas 8 is mixed with the reactor cover gas, but if the main heat exchanger and the auxiliary heat exchanger are adjacent to each other, there is a risk of gas being drawn in from one heat exchanger to the other. There is. If gas gets caught in the heat exchanger during operation, it will be carried to the reactor core and have adverse effects, so this must be avoided.

The present invention was made in view of the above circumstances, and provides a flow path that prevents gas from flowing into the furnace coolant even if too much gas is put into the skirt of the liquid level control type flow path change mechanism. It is intended to provide a change mechanism.

An embodiment of the flow path changing mechanism in the heat exchanger built into the reactor vessel according to the present invention will be described below with reference to FIG. Since the same reference numerals in the figure as in FIG. 1 indicate the same parts, the explanation thereof will be omitted. Between the shell 2 and skirt 4 of the heat exchanger 1,
Piping 11 is provided as a gas relief line, and this piping 11
The upper end is opened into the reactor cover gas B, and the lower end is opened slightly above the lower end of the skirt 4.

Next, another embodiment will be described with reference to FIG.
The lower end is located slightly above the lower end of the skirt 4, the upper end is attached to the inner peripheral surface of the skirt 4 at the level of the reactor cover gas 8, and the upper end is attached to the inner peripheral surface of the skirt 4 at multiple points in the circumferential direction of the skirt 4 below the attachment position. A through hole 14 is bored to open the upper end of the gap 12 between the skirts 4 and 13 into the reactor power/gas 8.

In this way, the flow path changing mechanism of the present invention provides the piping 11 as a gas relief line within the skirt 4, or doubles it by providing the skirt 16, thereby connecting the piping 11 and the skirt 4, 13. Since the gap 12 is open into the reactor cover gas 8, in order to prevent the primary coolant from flowing into the heat exchanger 1 through the inflow window 3, the gas inlet pipe 7 is passed through the skirt 4 to prevent the primary coolant from flowing into the heat exchanger 1 through the inflow window 3. The same gas as the furnace cover gas is fed and pressurized, thereby maintaining the liquid level of the coolant 9 inside the skirt 4 at the position indicated by the solid line in FIGS. 2 and 6.
Even if excessive gas is fed into the skirt 4 due to various factors, when the liquid level of the coolant 9 drops to the lower end of the piping 11 or the skirt 13 shown by the dashed-dotted line, the excess gas is automatically removed from the distribution W.
11 and scar) 4 and 13, and can all be released into the reactor cover gas 8. Therefore, the lower limit of the liquid level of the coolant 9 in the skirt 4 can be kept constant, and excess gas introduced into the skirt 4 will never flow out into the in-furnace coolant group.

As can be seen from the above explanation, the flow path changing mechanism of the present invention lowers the liquid level of the coolant in the skirt by pressurizing the gas supply and prevents the coolant from flowing into the heat exchanger. Excessly fed gas can be released into the reactor cover gas, and leakage into the reactor coolant can be reliably prevented.

Therefore, the gas will not be drawn into other heat exchangers operating adjacently, and the gas will not be carried to the core.
There are many things that contribute to improving the safety of nuclear reactor operations.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a conventional flow path changing mechanism in a heat exchanger built into a reactor vessel, and the second factor is a schematic diagram showing an example of the flow path changing mechanism of the present invention. is a schematic diagram showing another example. 1...Heat exchanger 2...Shell 3...Next coolant inflow window 6'...Next coolant outflow window 4...Skirt 5...Support ring 6...Reactor Lid 7... Gas feed pipe 8... Reactor cover gas 9... Coolant in skirt 9'... Coolant in reactor 10... Control valve
11...Piping 12...Gap 16...Skirt 14...Through hole Applicant Kawasaki Heavy Industries Co., Ltd. Agent Patent Attorney Takashi Yujibe 1C) 'V7. vinegar

Claims (1)

[Claims] In the main heat exchanger and the auxiliary heat exchanger built into the reactor vessel, a skirt is provided concentrically outside the primary coolant inlet window of each heat exchanger, and a gas inlet pipe is installed in the upper part of the skirt. 1/, the flow path is changed by providing a gas relief line in the gap between each heat exchanger and the skirt, the lower end of which opens at a position slightly higher than the lower end of the skirt, and the upper end of which opens into the reactor cover gas. mechanism.