JPH0216879B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure tube nuclear reactor, and particularly to a pressure tube nuclear reactor suitable for effectively injecting liquid poison into the reactor for emergency shutdown of the reactor.

In pressure tube reactors, such as pressurized heavy water cooled heavy water moderated reactors, the pressure tube pitch can be larger than in boiling light water cooled heavy water moderated reactors.
An injection tube dedicated to reactor shutdown equipment using liquid poison can be installed between the core tube groups.

On the other hand, in boiling light water-cooled, heavy water-moderated nuclear reactors, which are a type of pressure tube reactor, the pressure tube pitch is required to be small due to nuclear characteristics, and a special injection tube for liquid poison must be installed inside the reactor. In addition, the calandria tank is surrounded by a steel water shield, and installing a dedicated injection pipe would require creating a new penetration, which is undesirable from a structural standpoint. If a dedicated injection tube is installed in the
The control rod guide tube is also used as a liquid poison injection tube without providing a dedicated injection tube because it causes a decrease in burnup, which is undesirable.

The first conventional example of a boiling light water-cooled heavy water-moderated reactor
As shown in the figure. A calandria tank 1 filled with heavy water, which is a moderator, is surrounded by an upper iron water shield 2, a lower iron water shield 3, and a side iron water shield 4. The pressure pipe 5, which is the primary coolant boundary, is surrounded by a calandria pipe 6 and is connected to a calandria tank 1.
It is installed through the Further, the upper and lower ends of the pressure pipe 5 are provided with upper and lower extensions inserted into an upper iron-water sleeve 7 and a lower iron-water sleeve 8, respectively, which are provided by penetrating the upper iron-water shield 2 and the lower iron-water shield 3. connected to the pipe. The control rod 9 is moved up and down within a control rod guide tube 10 inserted and installed in the calandria tank 1 by a control rod drive device 11. Since the control rod guide pipe 10 is normally used as a cooling heavy water injection pipe, it is connected to a heavy water distribution header 12 via a heavy water pipe 13. The cooling heavy water flows into the calandria tank 1 through the control rod guide pipe 10. The neutron detector is housed in a neutron detector guide tube 14, and the neutron detector guide tube 14 is connected to the calandria tank upper tube plate 17.
It is housed in a sleeve 15 that is attached to the upper iron-water shield 2 above. The neutron detector is moved up and down within the neutron detector guide tube 14 by a neutron detector drive device 16 . The reactor shutdown system using liquid poison includes a liquid poison storage tank 18 pressurized with gas, an injection valve 19, a liquid injection header 20, piping that sequentially connects these, a control rod guide pipe 10, a liquid poison injection header 20, and It is composed of an injection pipe 21 that connects the

Conventional reactor shutdown equipment using liquid poison is
The injection pipe 21 has a large space in the upper part, and the injection pipe 21 is attached to the control rod guide pipe 10 which is attached to the heavy water pipe 13 in which cooling heavy water normally flows.
Because of this connection, when liquid poison is rapidly injected into the calandria tank 1, part of the liquid poison rises inside the control rod guide pipe 10, and further part flows back inside the heavy water pipe 13. I was afraid. Furthermore, since the volume inside the control rod guide tube 10 is larger than the volume of the liquid poison injection piping up to the control rod guide tube 10, this dead space causes a delay in the liquid poison injection time. An object of the present invention is to provide a pressure tube nuclear reactor that can inject a predetermined amount of liquid poison into a calandria tank in a short time.

A feature of the present invention is that an annular passage is formed around the in-furnace instrumentation guide tube inserted into the calandria tank, and the annular passage is connected to the calandria tank. A liquid poison injection pipe having an inlet facing into the calandria tank is provided through the calandria tank, and liquid poison is injected from the inlet into the calandria tank through the annular passage. Located in a pressure tube reactor.

A preferred embodiment of the present invention will be described below with reference to FIG.

The injection pipe 21 is connected to a sleeve 15 surrounding the neutron detector guide tube 14 . The lower end of the sleeve 15 is extended and passes through the calandria tank 1. Therefore, liquid poison is injected into the calandria tank 1 from the annulus formed between the neutron detector guide tube 14 and the sleeve 15. In this case, the lower end of the sleeve 15 is open in the calandria tank 1, and the opening is used as an inlet for injecting liquid poison into the calandria tank 1, and the sleeve 15 is used as a liquid poison injection pipe. Ru.

According to this embodiment, liquid poison can be injected into the calandria tank 1 with a smaller flow pressure loss than the conventional example without providing a new penetration part in the upper iron water shield 2 as in the conventional example. . Also,
A conventional control rod guide tube 10 is attached to the upper part of the sleeve 15.
As the heavy water pipe 13 is not connected, there is no backflow to the heavy water pipe 13, and since the dead space inside the sleeve 15 is small, liquid poison can be injected into the calandria tank in a short time. The number of neutron detection tubes is four times the number of conventional control rod guide tubes that can be used for liquid poison injection, and an effective injection position for reactor shutdown can be selected. In FIG. 3, a nozzle 23, a throat and a diff user part 24 are provided at the lower end of the sleeve 15 in FIG. 2 so as to have an ejector function. According to this embodiment, the liquid poison can be more effectively diffused in the calandria tank than in FIG. 2, and there is an effect that the shutdown function of the nuclear reactor can be improved.
In this case as well, the lower part 22 of the sleeve 15 is inserted into the calandria tank 1, and its lower end is open in the calandria tank 1, and the opening is an inlet for liquid poison into the calandria tank 1. The sleeve 15 is used as a liquid poison injection tube.

In FIG. 4, the sleeve 15 of FIG. 2 is extended to the lower tube plate of the calandria tank 1, and a liquid poison discharge port is provided on the side wall of the sleeve 15 within the reactor core. According to this embodiment, the neutron absorbing liquid can be injected into the reactor core, which has the effect of improving the reactor shutdown function. In this case, the lower part 22 of the sleeve 15
is inserted into the calandria tank 1, and a liquid poison discharge port provided on the side wall thereof is opened in the calandria tank 1, and the discharge port is used as an injection port for liquid poison into the calandria tank 1. The sleeve 15 is used as a liquid poison injection tube.

In FIG. 5, an outer circumferential tube 25 that houses the neutron detector guide tube 14 and the sleeve 15 is provided, an injection tube 21 is connected to this, and liquid poison is introduced into the calandria from the annulus between the sleeve 15 and the outer circumferential tube 25. It is designed to be injected into tank 1. According to this embodiment, the neutron-absorbing liquid can be injected into the calandria tank 1 with a smaller flow pressure loss than the conventional example without providing a new penetration part in the upper iron-water shield 2 as in the conventional example. Compared to the conventional example, the dead space can be reduced. Furthermore, by forming the upper part of the connection part with the injection pipe 21 into a sealed structure, there is an effect that the entire injection amount can be effectively injected into the calandria tank 1. In this case, the lower part of the outer circumferential tube 25 is the calandria tank 1.
The lower end is inserted into the calandria tank 1.
The opening is used as an inlet for injecting liquid poison into the calandria tank 1, and the outer circumferential pipe 25 is used as a liquid poison injection pipe.

According to the present invention, by using the area around the existing in-furnace instrumentation guide pipe as a liquid poison injection flow path, it is possible to reduce the amount of ineffective injection during liquid poison injection, reduce dead space, and reduce fluid pressure loss, thereby shutting down the reactor. The required amount of liquid poison can be injected in a short time, which has the effect of improving the emergency shutdown function of the reactor.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional boiling light water-cooled heavy water-moderated nuclear reactor, and FIG. 2 is a vertical cross-sectional view of a boiling light water-cooled heavy water-moderated nuclear reactor that is a preferred embodiment of the present invention.
3 to 5 are longitudinal sectional views of other embodiments of the present invention. 10... Control rod guide tube, 14... Neutron detector guide tube, 15... Sleeve, 21... Injection piping,
23... Nozzle, 25... Outer tube.

Claims (1)

[Claims] 1 A calandria tank filled with moderator,
A pressure pipe containing a fuel assembly and penetrating the calandria tank, and a control rod guide pipe and an in-core instrumentation guide pipe penetrating the calandria tank and inserted into the calandria tank. In a pressure tube type nuclear reactor, an annular passage is formed around the in-core instrumentation guide tube by surrounding the in-core instrumentation guide tube, and a passage from the annular passage into the calandria tank is provided. A liquid poison injection pipe with an injection port facing into the calandria tank,
A pressure tube nuclear reactor, characterized in that the calandria tank is provided through the calandria tank.