JPS5913988A - Boric acid solution injecting system - 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 growing mature log injection system (SLC) system, and in particular to equipment suitable for mixing sodium pentaborate and reactor water.

The crawling water injection system (C3LC system) assumes that the reactor cannot be shut down at a low temperature due to control rod insertion failure.
It has the ability to inject an IJ solution from the bottom of the reactor core, give negative reactivity to the reactor core, and gradually bring the reactor to a low-temperature shutdown.

In FIG. 1, sodium pentaborate is injected into the bottom of the reactor core from one boron water injection nozzle 7 provided in the lower plenum 4, mixed with reactor water, and then transported to the reactor core 6 together with the coolant. .

The growing tree injection system is a backup system for reactivity control, not a backup system for one Scrum function.

Therefore, the sodium pentaborate solution injected into the reactor is designed to gradually diffuse into the coolant. Preliminary calculations indicate that the time required for the growing adult tree injection system to inject the negative reactivity necessary for cold shutdown is approximately 30 minutes.

The ATWS phenomenon, which assumes that control rods cannot be inserted, requires reactor shutdown by using the sodium pentaborate liquid injection function. For this reason, there is currently a movement centered in the United States calling for strengthening the capabilities of the SLC system.

The object of the present invention is to provide reliable water borax that allows the sodium chloride injected into the furnace to quickly and evenly mix with the coolant, mitigating the hypothetical form Ili of kTWs. Our goal is to provide injection equipment.

It also aims to further improve the safety of nuclear reactors.

The conventional crawling water injection nozzle uses only one standpipe sparger as shown in 7 in Figure 1, so the mixing of sodium pentaborate and reactor water in the lower plenum 4 is difficult. It wasn't even.

On the other hand, by using a C-ring type sparger as a creeping mature tree injection nozzle, it is possible to equalize and speed up the mixing of sodium pentaborate and reactor water.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 8.

In FIG. 2, the S]JC ring sparger 9 is provided at the bottom of the core support plate and supported by the core shroud 2, and this is the first plan. Figure 3 shows the presence of halogens in reactor water.)
In consideration of sinking of the IJ, an 8L CIJ song sparger 9 was installed on the upper part of the core support plate, and this is the second plan. Sodium pentaphosphate, stand pipe 8
After that, it is injected into the reactor water from the SLC ring sparger 9.

First, consider the first option. Figure 3 shows the line AA' in Figure 2.
FIG. The SLC ring sparger 9 surrounds the control rod guide tube 11 and is provided inside the core shroud.

This shape is called type l.

(The control rod guide tube is omitted in Figures 1 to 3.)
FIG. 4 is a side view of the SLC system. The SLC ring sparger is vertically connected to the SLC standpipe 8 by a Tm connecting pipe. In order to increase the amount of injection of hydrolic acid, an SLC cloth was installed in the 5LCI injection sparger 9.
It is also possible to provide a sparger 12. This is the 6th
As shown in the figure.

The SLC cross sparger 12 is installed through the control rod guide tube gap.

Next, we will consider the second option. There are no particular problems with type 1. For Type 2, the SLC cross sparger will pass between the fuel supports as shown in FIG. (The fuel support and fuel assembly are omitted in FIGS. 1 to 3.) FIG. 8 is an enlarged view of section B in FIG. 3.

Approximately 10 to 20 SLC nozzles 14 are attached to the SLC ring sparger 9 at equal intervals.

As a third option, it is conceivable to use the core sparger sparger 5 as the water injection nozzle. This means that when considering the bank facilities for existing plants, R
, there is an advantage that there is no need to install a new nozzle in the PV.

According to this embodiment, there are the following effects.

(1) The time required for the IJum to reach the prescribed #key is 1/10 to 20 times that of the conventional method.

(2) In the past, it took several minutes for the sodium pentaborate@stable to become uniform, but in this case, a circular sparger is used, so the mixing is even.

According to the present invention, when the control ring cannot be inserted, sodium gold pentaphosphate and reactor water can be mixed evenly and quickly as a neutron absorbing material, resulting in the following effects.

(1) The virtual influence of ATWS can be alleviated by the crawling water injection C3LC> system.

(2) The reliability of the SLC system can be improved by (1).

(3) (2) will improve the safety of nuclear reactors.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional reactor pressure vessel, FIG. 2 is a longitudinal sectional view of a reactor pressure vessel according to an embodiment of the present invention, FIG. 3 is a longitudinal sectional view of another embodiment, and FIG. The figure is a sectional view taken along line A-A in Figure 2 (Type 1), and Figure 5 is SLC! Fig. 6 is a sectional view taken along line A-A in Fig. 2 (type 2).
), Figure 7 is an enlarged view of part C in Figure 3, and Figure 8 is an enlarged view of part B in Figure 4.
It is an enlarged view of the part. 2... Core shroud, 8... SLC stand sparger, 9... SLC/Gesvasha, 10...
T Hoyoshi 1 Figure 2 Figure 3 Figure 7-472-

Claims (1)

[Claims] 1. A creeping mature tree injection system in a boiling water nuclear reactor, characterized by having an SLC ring sparger as a liquid neutron injection sparger.