JPS6122920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a poison tube for power regulation and power distribution control of a nuclear reactor.

A poison tube is a device that controls the output of a nuclear reactor by raising and lowering the level of a liquid containing a neutron-absorbing substance such as B.Gd in the tube.

Until now, poison tubes have only been put into practical use for emergency reactor shutdown, and no poison tubes have been found for use in adjusting the power of a nuclear reactor or controlling power distribution. This is poison
When the tube is used for output control etc., poison
The temperature of the tube reaches its maximum due to neutron bombardment of the tube.
One of the reasons for this is that the temperature rises to about 700°C, and the deterioration of the strength of the pipe material is seen as a problem.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a poison tube with a small rise in tube temperature.

The present invention will be explained below. 1 to 4 show an embodiment of the poison tube of the present invention. The poison tube of the present invention has a double tube structure with an outer tube 1 and an inner tube 2, as shown in FIG.
Two partition plates 3 are provided on the inner tube, and the inner tube is divided into an outflow section 4 for poison liquid, an air vent section 5 when poison liquid is injected, and a cooling water outflow section 6 for cooling the inner tube. It is a structural feature. This poison tube is placed inside the calandria tube 9 to enable replacement. FIG. 2 shows the axially upper part of the poison tube of the present invention, FIG. 3 shows the axially central part, and FIG. 4 shows the axially lower part. In these figures, 9 is a calandria tube, 10 is a poison liquid outflow hole, and 11 is a poison liquid overflow hole.
Flow hole, 12 is an air vent hole, 13 is a poison liquid inflow pipe, 14 is a poison liquid outflow pipe, 15 is an air release pipe, 16 is a cooling water inflow pipe, 17 is a cooling water outflow pipe, 18 is an upper tube plate, 19 is a This is the lower tube plate. As shown in FIG. 2, the partition plate and a portion of the inner tube protrude from the inner tube to the outside of the outer tube, allowing cooling water to flow into it. The cooling water enters from the cooling water inlet pipe 16 in FIG. As a result, this poison tube is capable of cooling the outer tube and inner tube (the part where poison liquid is not injected), whose temperature has risen up to 700℃ due to the (n, α) reaction between gamma rays and poison inside the furnace. be.

Poison liquid enters from the poison liquid inflow pipe 13 in Fig. 4, rises between the outer pipe and the inner pipe (poison liquid inflow part 7), and faces the poison liquid outflow part of the inner pipe, as shown in Fig. 3. The poison liquid flows downward and circulates through the poison liquid outflow hole 10 that is opened only in that part. The liquid level of the poison liquid 7 is controlled by changing the flow rate of the poison liquid. Further, when the poison liquid is completely injected, the poison liquid also flows out through the overflow hole 11. In this case, the upper end opening portion of the air vent portion 5 is a poison liquid overflow hole 11 when poison liquid is injected, as shown in FIG.
Since it is located higher in the axial direction, the poison liquid does not need to inadvertently flow into the air vent. In this way, since the poison liquid is constantly circulating in this poison tube, it is possible to compensate for the drop in poison concentration due to neutron absorption and keep the concentration constant.
(Gray poison, which has a low concentration of neutron-absorbing substances, is used as the poison used to suppress the , a decrease in control reactivity occurs in a short period of time due to a decrease in concentration.) Also, when injecting poison, the air inside the outer tube enters through the air vent hole 12 in FIG. 3 and passes through the air vent tube 15 in FIG. 4. Get out.

By the above method, the poison tube of this example is located at a position where the liquid level of poison is close to the lower end of the core (the lowest position of the poison outflow hole drilled in the inner tube).
Since the poison solution can be waited for injection, the response is fast.Since the poison liquid is circulating, the concentration can be kept constant.It is possible to cool the outer tube and the inner tube where poison is not injected, which reduces the strength of the tube. It has the effect of preventing Further, in this embodiment, the calandria tube is provided outside the poison tube and is fixed to the upper and lower tube plates 18 and 19, so that the poison tube can be replaced.

FIG. 5 shows another embodiment of the invention, and FIG. 6 shows still another embodiment of the invention. All of these embodiments have the same structure as the previous embodiments, except that the dividing structure of the inner tube 2 is different from the above embodiments. In FIG. 5, a modified cylindrical tube 3' is used as the partition plate 3. Furthermore, in the embodiment shown in FIG.
Instead of setting an air vent part 5 in the inner pipe by the partition plate 3, a vent pipe 5' is separately installed in the inner pipe. Each embodiment has an advantage over the previous embodiments in that fewer welds are required between the diaphragm plate and the inner tube.

As described above, according to the present invention, the poison tube can be cooled without impairing the quick output control function by causing the poison to flow out from a large number of openings while venting air, resulting in low injection resistance and without impairing the quick output control function. A practical effect is obtained in that the factors that had been overlooked are resolved and it is easy to put it into practical use.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the upper end of the poison tube according to the first embodiment of the present invention, FIG. FIG. 4 is an explanatory diagram showing a partially cut out middle part of the poison tube of Example 1.
An explanatory diagram of the lower structure of the poison tube of the first embodiment, FIG. 5 is a plan view of the upper end of the poison tube of the second embodiment of the present invention, and FIG. 6 is a diagram of the poison tube of the third embodiment of the present invention. A top view of the top of the . DESCRIPTION OF SYMBOLS 1...Outer pipe, 2...Inner pipe, 3...Block plate, 4...Poison liquid outflow part, 5...Air vent part, 6...Cooling water outflow part, 9...Calandria tube.

Claims (1)

[Scope of Claims] 1. A calandria tube, an outer tube arranged inside the calandria tube concentrically with the calandria tube and whose upper end is sealed, and a calandria tube arranged inside the outer tube concentrically with the outer tube. an inner tube, the inner tube including three radially divided regions, a first region passing through the outer tube and communicating with the calandria tube, and a second and third region extending through the outer tube and communicating with the calandria tube. The upper end opens into the spatial region formed by the outer tube and the inner tube, the axially upper end of the second region is located above the axially upper end of the third region, and the third region A poison tube for nuclear reactor power control, characterized in that it has a large number of poison outlet ports on its axial side surface, and further that the space area forms a poison liquid storage tank from which the poison liquid flows out from the third area. 2. The poison tube for nuclear reactor power control according to claim 1, wherein the first region is provided in the center of the inner tube.