JP2000137091A - Nuclear reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a core tank from thermal influence of emergent cooling water by fitting a nearly conical shaped core tank protecting pad on the outer wall of a core tank, and opposing the extreme end to the injection nozzle of emergent cooling water. SOLUTION: A pressurized water reactor provided with a emergent cooling water injection nozzle jetting emergent cooling water toward the outer wall 4a of a core tank 4, is provided with a core tank protecting pad 10. This protecting pad 10 is formed out of weldable materials to the core tank. into a nearly conical shape, and it is fitted to the outer wall 4a of the core tank 4 so that the extreme end part 10a is opposed to the injection nozzle 7. Further the conical face is, for example, formed into recessedly curved circular-arc-shape, for smoothly introducing the emergent cooling water from the nozzle 7 to the outer wall 4a. By the above-mentioned, a part of the emergent cooling water is avoided from flowing toward a reactor vessel 1 side, and further because the flow of the emergent cooling water does not become unstable by breakaway or the like, an important factor generating temperature fluctuation is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear reactor such as a pressurized water reactor having an emergency cooling water injection nozzle for jetting emergency cooling water toward an outer wall surface of a core vessel provided in a reactor vessel. About the furnace.

[0002]

2. Description of the Related Art Conventionally, this type of reactor has a structure as shown in FIG. 3, and a reactor vessel 1 is provided with a plurality of cooling water inlet nozzles 2 and cooling water outlet nozzles 3. . These cooling water inlet nozzles 2 and cooling water outlet nozzles 3 are alternately arranged at intervals in the circumferential direction of the reactor vessel 1, and the primary water flowing into the reactor vessel 1 from the cooling water inlet nozzle 2 The cooling water is supplied to a core tank 4 provided in the reactor vessel 1.
The reactor 1 descends in a downcomer 5 formed between the reactor vessel 1.

[0003] The core tank 4 is a steel cylindrical structure having an open lower end, and primary cooling water that has descended in the downcomer 5 flows into the core tank 4 from the lower end of the core tank 4. The core tank 4 has an outlet nozzle 6 communicating with the cooling water outlet nozzle 3 of the reactor vessel 1. The primary cooling water flowing into the core tank 4 is supplied from the outlet nozzle 6 to the cooling water outlet nozzle 3.
And is sent from the cooling water outlet nozzle 3 to a steam generator provided outside the reactor vessel 1.

FIG. 4 is a sectional view taken along the line AA of FIG. 3, and the reactor vessel 1 is provided with an emergency cooling water injection nozzle 7 as shown in FIG. The emergency cooling water injection nozzle 7 is disposed between the cooling water inlet nozzle 2 and the cooling water outlet nozzle 3, and when an accident such as loss of primary cooling water occurs in the reactor, the emergency cooling water injection nozzle 7 is provided. High-pressure emergency cooling water is injected into the reactor vessel 1 from the injection nozzle 7.

Incidentally, the emergency cooling water injected into the reactor vessel 1 from the above-described emergency cooling water injection nozzle 7 is:
Since the temperature of the primary cooling water in the reactor vessel 1 is considerably lower than that of the primary cooling water (approximately 20 ° C.), when the emergency cooling water jetted from the emergency cooling water injection nozzle 7 hits the outer wall of the core tank 4, the core Excessive thermal stress may occur in the tank 4. For this reason, in the above-mentioned nuclear reactor, as shown in FIG.
The core tank protection pad 8 as shown in FIG. 1 is attached, and receives the emergency cooling water jetted from the emergency cooling water injection nozzle 7 to protect the core tank 4 from the thermal influence of the emergency cooling water. I am trying to do it.

[0006]

However, when the emergency cooling water jetted from the emergency cooling water injection nozzle 7 hits the core tank protection pad 8, the emergency cooling water is partially atomized as shown in FIG. Since the flow is directed toward the reactor vessel, large temperature fluctuations occur on the inner wall side of the reactor vessel 1, and there is a concern that the soundness of the reactor vessel 1 may be impaired by the temperature fluctuations. Further, when the above-mentioned core tank protection pad 8 is attached to the outer wall surface 4a of the core tank 4, the core tank 4
A step is generated between the outer wall surface 4a and the core tank protection pad 8, and the step causes the flow of the emergency cooling water to become unstable due to separation or the like, thereby causing a large temperature fluctuation.

The present invention has been made in view of the above points, and provides a nuclear reactor capable of protecting a reactor core tank from the thermal influence of emergency cooling water without generating large temperature fluctuations on the reactor vessel side. It is intended to provide.

[0008]

In order to solve the above-mentioned problems, an invention according to a first aspect of the present invention is to provide an emergency cooling water jetting jet toward an outer wall surface of a core tank provided in a reactor vessel. In a reactor equipped with a cooling water injection nozzle, a substantially conical core tank protection pad is attached to an outer wall surface of the core tank, and a tip of the core tank protection pad is opposed to the emergency cooling water injection nozzle. It is characterized by. According to a second aspect of the present invention, in the nuclear reactor according to the first aspect, the reactor core tank protection pad has a circle for guiding the emergency cooling water spouted from the emergency cooling water injection nozzle to the outer wall surface of the reactor core tank smoothly. An arcuate conical surface is formed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a part of a reactor vessel and a core vessel of a pressurized water reactor according to an embodiment of the present invention. As shown in FIG. 7 are provided. The emergency cooling water injection nozzle 7 is connected to the cooling water inlet nozzle 2 of the reactor vessel 1 (FIG. 4).
And the cooling water outlet nozzle 3,
A core tank protection pad 10 is attached to the outer wall surface 4a of the core tank 4 facing the emergency cooling water injection nozzle 7.

The core tank protection pad 10 protects the core tank 4 from the thermal influence of the emergency cooling water injected into the reactor vessel 1 from the emergency cooling water injection nozzle 7.
It is formed of a material that can be welded to the core vessel 4. The core tank protection pad 10 has a substantially conical shape as shown in FIG.
And attached to the outer wall surface 4a of the core tank 4. Further, the core tank protection pad 10 has a conical surface 10 b facing the emergency cooling water injection nozzle 7, and the conical surface 10 b discharges the emergency cooling water ejected from the emergency cooling water injection nozzle 7 into the core tank 4. Has an arcuate surface curved in a concave shape in order to smoothly guide it to the outer wall surface 4a.

In the above-described embodiment of the present invention, when the emergency cooling water ejected from the emergency cooling water injection nozzle 7 collides with the core tank protection pad 10, the emergency cooling water as indicated by an arrow in FIG. The flow changes from a linear flow to a curved flow, and eventually flows along the outer wall surface 4a of the core vessel 4.

Therefore, in one embodiment of the present invention, a part of the emergency cooling water colliding with the reactor core tank protection pad 10 does not flow toward the reactor vessel side, so that a large temperature fluctuation occurs on the reactor vessel side. Without this, the core tank 4 can be protected from the thermal influence of the emergency cooling water. Also, since there is no step between the outer wall surface 4a of the core tank 4 and the core tank protection pad 10, the flow of the emergency cooling water does not become unstable due to separation or the like, and the temperature fluctuation does not occur. The cause of occurrence can be eliminated.

[0013]

As described above, according to the present invention, a substantially conical core tank protection pad is attached to the outer wall surface of the core tank,
By making the tip of the core tank protection pad face the emergency cooling water injection nozzle, the core tank can be protected from the thermal effects of the emergency cooling water without generating large temperature fluctuations on the reactor vessel side. Can provide a nuclear reactor capable of operating.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a part of a reactor vessel and a core vessel of a pressurized water reactor according to an embodiment of the present invention.

FIG. 2 is a view showing a core tank protection pad attached to a core tank of the pressurized water reactor according to one embodiment of the present invention;
(A) is a front view, (b) is a side view.

FIG. 3 is a longitudinal sectional view of a pressurized water reactor.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a longitudinal sectional view showing a part of a reactor vessel and a core vessel of a conventional pressurized water reactor.

FIG. 6 is a view showing a core tank protection pad attached to a core tank of a conventional pressurized water reactor, (a) is a front view,
(B) is a side view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Reactor vessel 2 Cooling water inlet nozzle 3 Cooling water outlet nozzle 4 Core tank 6 Outlet nozzle 7 Emergency cooling water injection nozzle 10 Core tank protection pad

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Nakajima 1-1-1 Wadazakicho, Hyogo-ku, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. 1-1-1 Tazakicho Mitsubishi Heavy Industries, Ltd., Kobe Shipyard

Claims (2)

[Claims] 1. A reactor equipped with an emergency cooling water injection nozzle for jetting emergency cooling water toward an outer wall surface of a core tank provided in a reactor vessel, wherein the outer wall surface of the core tank has a substantially conical shape. A reactor having a core vessel protection pad having a shape, and a front end of the core vessel protection pad facing the emergency cooling water injection nozzle. 2. An arc-shaped conical surface which guides the emergency cooling water spouted from the emergency cooling water injection nozzle to the outer wall surface of the core tank is formed on the core tank protection pad. A nuclear reactor according to claim 1, characterized in that: