JPH03105289A - Reactor container - Google Patents

Abstract

PURPOSE:To reduce the area of heat transfer necessary for removing a heat from a container by a construction wherein a channel enabling natural draft of air is provided along the outer wall of the container and a partition is provided between the outer wall of the container and a wall surface opposite to the outer wall in this channel. CONSTITUTION:A partition 5 is installed in a channel formed by the wall surface 3 of a container and a wall surface 4 opposite to the outer wall. In this case, air flowing in from below the container is heated by a heat transferred from the wall surface and rises and it is released upward along the container. According to this constitution, the area of heat transfer required when a decay heat generated on the occasion of long-term cooling after LOCA is removed from the container by convective heat transfer of the air can be reduced by about 15%.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a containment vessel for a nuclear reactor, and in particular, a containment vessel having a structure suitable for radiating decay heat generated in the reactor core to the outside by natural forces during an accident. Regarding containment vessels.

[Conventional technology]

In the containment vessel of a boiling water reactor, a pressure suppression method is adopted in which steam ejected into the containment vessel when a pipe ruptures is guided to a subrepression pool in the pressure suppression chamber and condensed, thereby suppressing the rise in pressure within the containment vessel. are doing. During a blowdown immediately after a pipe rupture accident, a large amount of steam energy stored in the reactor pressure vessel is released into the containment vessel, raising the temperature of the subreduction pool. When the temperature of the sub-retention pool rises, heat is radiated outside the containment vessel due to the temperature difference between it and the peripheral pool installed outside the containment vessel. In this case, when the temperature of the outer pool exceeds 100°C, the outer pool water evaporates and the water level gradually decreases. An example of a containment vessel having such a structure is, for example, Japanese Patent Application Laid-Open No. 63-1
There is a publication No. 91096.

A concrete example of this is shown in FIG. In such a structure, there is a clear space that is unique to the structure and ensures the heat dissipation ability of the outer pool, and within this time, it is assumed that decay heat can be removed by natural forces alone without any external operations. has been done.

[Problem to be solved by the invention]

Conventional containment vessels assume that after the outer pool water has evaporated, water must be replenished or a residual heat removal system must be activated. Now, we will go further and consider a system that can achieve heat removal without any external operations even after the water in the outer pool has evaporated. One example of this is a method of removing heat using natural convection of air. However, natural convection of air cannot be expected to have a very high heat transfer coefficient, so in order to remove the heat equivalent to decay heat from the outer wall of the containment vessel, it is necessary to increase the heat transfer area, making the containment vessel larger. There is a problem with doing so.

In order to avoid increasing the size of the containment vessel, it is necessary to proactively improve its heat dissipation characteristics.

An object of the present invention is to provide a reactor containment vessel with good heat dissipation characteristics by increasing the amount of heat dissipated by natural convection outside the containment vessel.

[Means to solve the problem]

The above object is achieved by installing a partition wall made of a material with good thermal conductivity in an air flow path provided along the outer wall of the containment vessel.

[Effect]

The operation of the present invention will be explained below with reference to FIG.
(a) shows a cross section of an air flow path provided along the outer wall of the containment vessel. The temperature of the outer wall of the containment vessel (wall L) is Twt, and the temperature of the wall facing the outer wall (wall 2) is T.
112, it is assumed that the mainstream temperature of the air is T a r r. Now, the amount of heat Q transferred from wall 1 to wall 2 by radiation
r is Q, = tσA ((T-1)' (T w2)'
) − (1) Here, ε is the emissivity, and σ is the Stefan Boltzmann constant. In a steady state, the amount of heat given to the wall surface 2 is given to the air from the wall surface 2 by convection heat transfer. The amount of heat transfer Q2 at this time is Q2= h A (TwZ Tagr)
-(2) From the energy balance relationship, the amount of radiant heat transfer and the temperature of the wall surface 2 are determined so as to satisfy the relationship Q, -Qz.

Here, consider the case where a partition wall is installed in the flow path as shown in (b). In this case, the relational expression between radiant heat transfer and convective heat transfer is approximately Q, = εa A((Tvt)'(T-a)')
-(3)Q3:hA(Tw3-Tatr)
...(4)Q3'"h' A(Tw3
Tair''・(5) At this time, from the relationship of energy balance, Qr=03+Q3' Also, since the heat transfer coefficient can be considered to be almost equal on both sides of the partition wall, the amount of radiant heat transfer and The temperature of the bulkhead is determined. In other words. In case (b), compared to case (a), the heat transfer area has doubled, and the temperature of the partition wall is balanced at a lower value by that much, so the amount of radiant heat transfer increases. I understand that. Note that the total amount of heat radiation from the containment vessel is determined by convective heat transfer Ji from the outer wall of the containment vessel.
Q1 = h A (Twt Tair)
−(6), it is determined as Q ” Q 1 + Q r .

FIG. 4 is a diagram showing the results of evaluating the effect of the partition wall of the present invention, and it can be seen that by installing the partition wall of the present invention, the amount of heat dissipation is improved by about ↓5% compared to the case without a partition wall.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. A partition wall 5 is installed in a flow path formed by a containment vessel wall surface 3 and a wall surface 4 facing the outer wall thereof. Air flowing in from below the containment vessel is heated by heat transfer from the walls, rises, and escapes upward along the containment vessel.

FIG. 5 shows another embodiment of the present invention, in which a pool 7 is provided outside the containment vessel, and the bottom of the pool communicates with the outside. In this case, at the beginning of the cooling process of the containment vessel, heat is removed by evaporation of the outer pool water, the water level of the outer pool decreases, and after the communication hole 8 is cursed, convection heat transfer by air becomes possible. .

〔Effect of the invention〕

According to the present invention, it is possible to reduce the heat transfer area necessary for removing decay heat during long-term cooling after LOCA from the containment vessel by air convection heat transfer by about 15%.

[Brief explanation of drawings]

The upper figure is a sectional view of an embodiment of the present invention, Figure 2 is a sectional view of a containment vessel with a pool on the outer periphery, Figure 3 is an explanatory diagram showing the principle of the present invention, and Figure 4 is an effect of the present invention. FIG. 5 is a sectional view of another embodiment of the present invention. 1...Reactor core, 2...Reactor pressure vessel, 3...Containment vessel outer wall, 4...Wall surface, 5...Partition wall, 6...Subpression 2nd figure completed W1 Tll/2 T wide 7Q TWt TW3Tw'2 To-il''L Fig. 4 Ita, character 21 hill h view 1 A (7n2) Fig. 5

Claims (1)

[Claims] 1. In a reactor containment vessel containing a nuclear reactor, a flow path that allows natural ventilation is provided along the outer wall of the containment vessel, and the outer wall of the containment vessel and the outer wall within the flow path are provided. A nuclear reactor containment vessel characterized in that a partition wall made of a material with good thermal conductivity is installed between the wall surface facing the reactor containment vessel. 2. The nuclear reactor containment vessel according to claim 1, wherein a pool is provided on the outer periphery of the containment vessel, and a bottom of the outer pool communicates with the outside of the containment vessel. Reactor containment vessel.