JPH0782104B2 - Containment vessel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a nuclear reactor, and the thermal energy released into the reactor containment vessel is extended to the outside of the system by natural force in the unlikely event of a plant failure. The present invention relates to a reactor containment vessel suitable for removal.

[Conventional technology]

As an example of a conventional technique, a reactor containment vessel of a current boiling water reactor and a residual heat removal system which is an auxiliary equipment of the vessel will be described with reference to FIG.

The reactor containment vessel 2 of a boiling water reactor is a pressure suppression type dry well 3 containing the reactor pressure vessel 1, a suppression chamber 4 containing a suppression pool water 5, and a dry well 3 further. And a vent pipe 6 for connecting the supplement pool water 5.

Assuming a coolant loss accident, the high-temperature and high-pressure steam released from the reactor pressure vessel 1 to the drywell 3 will be vent pipe 6
It is discharged to the supplement pool 5 through the passage and is condensed with pool water. This condensation suppresses a transient pressure increase in the reactor containment vessel 2. Further, the residual heat removal system 7 is installed to cope with the core decay heat generated in the long term.
After the accident of loss of coolant, after the emergency cooling system (generally abbreviated as ECCS) was activated and the core was re-submerged, the core decay heat was supplied to the dry well 3 by ECCS water, and further via the vent pipe 6. Transfer to the pool water 5. The heat of the pool water 5 absorbed by the pump 8 is removed to the outside of the reactor containment vessel by the heat exchanger 9 of the residual heat removal system 7.

As another example of the prior art, an apparatus for limiting accidental pressure overload in the confinement structure of a pressurized water reactor (Japanese Patent Laid-Open No. 50-90888) will be described with reference to FIG.

The containment vessel 2 of the pressurized water reactor is the primary reactor system 1
Of the first reactor containment wall 3, which contains the first reactor containment vessel 3, the second reactor containment vessel 4 which contains the first reactor containment vessel 3, the first reactor containment vessel 3 wall and the second reactor containment vessel It is composed of pool water 5 contained in the middle of the four walls and a coupling duct 6 connecting the space of the first reactor containment vessel 3.
A jet device 7 is installed at the tip of the coupling duct 6 in the pool water 5.

The high-temperature and high-pressure steam released from the reactor primary system 1 into the first reactor containment vessel 3 at the time of the loss of coolant is condensed by the pool water 5 through the coupling duct 6 and is stored in the reactor containment vessel 2. Suppresses transient pressure rise. Further, the core decay heat is removed by natural heat dissipation from the atmosphere in the first reactor containment vessel 3 to the pool water 5 through the containment vessel wall.

The pool water 5 is forcibly circulated by the jet device 7 installed at the tip of the coupling duct 6.
A local temperature rise of the temperature is avoided, and steam condensation at the tip of the coupling duct and natural heat radiation from the wall of the first reactor containment vessel 3 are promoted.

[Problems to be solved by the invention]

In the reactor containment vessel of a boiling water reactor, which is the former example of the above-mentioned prior art, a residual heat removal system is installed to cope with the removal of core decay heat over a long period of time, but the cost therefor Pool water containing high and fission products is routed outside the containment vessel. In addition, it was necessary to carry out regular tests to maintain reliability in order to install operating equipment such as pumps and valves.

In the reactor containment vessel of a pressurized water reactor, which is the latter example of the above-mentioned conventional techniques, the jet device 7 is installed in the pool water 5 of the suppression chamber to solve the above-mentioned problem. Although it has a structure to radiate natural heat from the wall of the reactor containment vessel to the pool water 5, there is no means for removing heat of the pool water 5 and only the natural heat radiating from the reactor containment group 4 leads to long-term core collapse heat after the accident. Is not easy to remove, and is effective only for a temporary period until the pool water 5 reaches a high temperature.

Further, although the structure is made such that the forced circulation of the pool water by the jet device further facilitates the natural heat dissipation from the first reactor containment vessel wall 3 to the pool water, there is a problem that the reactor containment vessel becomes large. is there.

An object of the present invention is to provide a reactor containment vessel suitable for greatly increasing natural heat dissipation from the wall of the reactor containment vessel.

[Means for solving problems]

The above-mentioned object is to include a reactor pressure vessel and a suppression chamber in the containment vessel, and to communicate the pool water in the suppression chamber and the suppression chamber with the drywell space in the containment vessel defined by the suppression chamber. In a nuclear reactor containment vessel having a vent pipe to be provided, an intermediate dry well space arranged around a horizontal outer periphery of the suppression chamber between the wall of the containment vessel and the suppression chamber is provided in communication with the dry well, The intermediate dry well is provided with an outer peripheral pool that is in contact with an outer outer wall surface of the intermediate dry well, and the intermediate dry pool that is in contact with an outer wall surface of the suppression chamber and an inner outer wall surface of the intermediate dry well is Provided between a well and the suppression chamber, each of the outer peripheral pool and the intermediate pool A Department communicated with the return line, in the lower than the return line, are accomplished by the peripheral pool and the intermediate pool and characterized in that the communicating by connecting lines to the reactor containment vessel.

[Action]

The space of the containment vessel (dry well, suppression chamber) during normal operation is filled with non-condensable gas (air). When the loss of coolant accident is assumed, the high-temperature and high-pressure primary system coolant is discharged into the drywell from the break point, and the pressure temperature inside the drywell is increased. As the pressure in the drywell increases, the air in the drywell space moves to the space in the suppression chamber via the vent system in a relatively short time after the accident. Therefore, the atmosphere inside the reactor containment vessel for a long time after the accident is in a mixed state of high temperature and high pressure steam in the drywell space and air and steam in the suppression chamber space.

Figure 3 shows the relationship between the ratio of the amount of air in the atmosphere to the amount of steam and the heat transfer coefficient from the atmosphere to the wall of the containment vessel. The larger the proportion of air in the atmosphere, the worse the heat transfer from the atmosphere to the containment wall.

From the above, a method of greatly promoting natural heat dissipation from the containment wall without increasing the overall surface area or increasing the size of the containment vessel (without increasing the total area of the containment wall) As one of the above, it has been found that increasing the ratio of the area of the wall of the storage container in the drywell space to the total area of the wall of the storage container improves heat dissipation.

Also in the present invention, a part of the high-temperature and high-pressure vapor released into the drywell space also enters the intermediate drywell, and the heat held by the vapor entering the intermediate drywell is passed through the outer wall surface of the intermediate drywell to the outer periphery. The liquids in the pool and intermediate pool condense, condense, become low temperature and low pressure, and efficient natural heat dissipation is achieved.The liquid in the intermediate pool circulates with the outer pool through the return line and the connection line. This contributes to more efficient natural heat dissipation.

〔Example〕

In this example, as a means for promoting natural heat dissipation from the wall of the reactor containment vessel, it is considered by some of the applicants and the inventors to install an outer peripheral pool outside the containment vessel. However, the outer pool cannot be installed because there are many pipes penetrating the containment vessel in the dry well, and the structure is installed only on the outer periphery of the suppression chamber (or the lower part of the dry well). In this case, the outer peripheral pool promotes natural heat dissipation from the suppression pool water and the atmosphere of the suppression chamber through the reactor containment vessel wall, but from the suppression pool water to the reactor containment vessel wall. Compared to the smooth heat transfer and sufficient contribution to promotion of natural heat dissipation, the heat transfer from the suppression chamber atmosphere to the reactor containment wall is not sufficient, and as a result,
Even if only the outer pool is installed outside the suppression chamber, it is not possible to radiate the core decay heat generated in the long term after the accident to the outside of the system only by natural heat radiation from the wall of the reactor containment vessel.

In the present embodiment, in order to solve the above problems, the space between the suppression chamber and the reactor containment wall becomes a drywell space so that the entire reactor containment wall becomes a drywell wall. By adopting a reactor containment structure (including a vent system), natural heat dissipation of the outer pool from the dry well atmosphere with good heat transfer coefficient through the reactor containment wall is promoted.

Further, in this embodiment, an intermediate pool is provided between the supplement chamber and the dry well space, one side of which is in contact with the supplement chamber and the other is in contact with the dry well space, which is filled with water and which is connected to the outer pool. To do. As a result, in addition to natural heat dissipation from the drywell atmosphere to the outer peripheral pool, natural heat dissipation from the suppression chamber (pool water and atmosphere) and the drywell atmosphere to the intermediate pool can be obtained. In addition, natural circulation of the pool water due to the temperature difference between the intermediate pool water and the peripheral pool water further promotes natural heat dissipation.

From the above, it is possible to radiate the core decay heat generated in the long term after the accident to the outside of the system only by natural heat radiation from the wall of the reactor containment vessel.

Examples of specific structures of the present invention will be described below with reference to the drawings. One embodiment of the present invention is shown in FIG. 1 and FIG.
For ease of explanation, one embodiment in the examination stage of the present invention is shown in FIG. 4 for reference, and the embodiment of the present invention will be described together with its comparison.

(1) One Example in the Study Stage of the Present Invention One embodiment in the study stage of the present invention will be described with reference to FIG.

A. Structure The reactor containment vessel 2 of one embodiment in the study stage of the present invention is
Similar to a boiling water reactor, it is a pressure suppression type, and includes a dry well 3 containing a reactor pressure vessel 1 and a suppression chamber 4 containing a suppression pool 5; a dry well 3; and a suppression pool 5 It is composed of a vent pipe 6 for connecting the. Further, an outer peripheral pool 11 containing water is installed outside the suppression chamber 4. Further, as auxiliary equipment for the PCV, the pool water 5 and the peripheral pool water 11 are removed of heat and sprayed into the space of the reactor PC2
Further, it has a residual heat removal system 7 composed of a residual heat removal system pump 8, a residual heat removal system heat exchanger 9, and a spray head 10 returned to the outer peripheral pool 11.

B. Action If a coolant loss accident occurs, high-temperature, high-pressure steam will be released from the reactor pressure vessel 1 to the drywell 3, and the pressure / temperature inside the drywell 3 will rise sharply, causing it to pass through the vent pipe 6. The supplement pool 5 was released into the water.
The steam completely condenses the water in the suppression pool 5 and suppresses an excessive increase in pressure in the reactor containment vessel 2. Also,
The air inside the drywell 3 is vented in a relatively short time after the accident.
6, Passing through the suppression pool 5 and moving to the space 4 of the suppression chamber 4.

Therefore, the core decay heat for a long time after the accident was
It is distributed to the space part, the suppression chamber 4 space part, and the suppression pool 5 water.

The core decay heat distributed to the space portion of the suppression chamber 4 and the water of the suppression pool 5 is naturally radiated to the outer peripheral pool 11 via the wall of the reactor containment vessel 2. Further, the core decay heat distributed to the water of the supplement pool 5 is removed by the residual heat removal system 7.

C. Evaluation Figure 5 shows an example of evaluation of core decay heat removal capacity.

As shown in FIG. 4, if the outer peripheral pool 11 is installed on the outside of the suppression chamber 4, the core decay heat after the accident cannot be removed only by natural heat dissipation from the wall of the reactor containment vessel 2. To compensate for this, the residual heat removal system 7 sprays the pool water 5 into the dry well 3 and the suppression chamber 4 space to transfer the core decay heat to the pool water 5,
The pool water is removed by the heat exchanger 9.

As described above, in the example in the study stage of the present invention, the core decay heat for a long period after the accident is caused by the natural heat dissipation from the reactor containment vessel 2 and the forced heat removal by the residual heat removal system 7. It is removed outside the system.

(2) One Embodiment of the Present Invention An embodiment of the present invention will be described with reference to FIGS.

A. Structure The reactor containment vessel 2 of the present invention is a reactor pressure vessel 1, a supplement pool water 5 installed on the outer periphery of the reactor pressure vessel 1.
And a dry well 3 containing a water-filled intermediate pool 8 installed on the outer periphery of the suppression chain 4 and a supplemental space 4 connected to the dry well 3, and an intermediate pool for connecting the dry well 3 and the suppression pool 5 A vent system 6,7 consisting of a horizontal vent pipe 7 that penetrates 8 and has one end opened in the supplement pool water 5 and the other end connected to a vertical vent pipe 6 installed in the dry well 3 on the outer periphery of the intermediate pool 8.
And a connecting line 12 connecting the outer pool 9, the intermediate pool 8 and the outer pool 9 installed on the outer periphery of the reactor containment vessel 2,
And a return line 11.

B. In the unlikely event of a loss of coolant accident, high-temperature and high-pressure steam is released from the reactor pressure vessel 1 to the drywell 3, the pressure and temperature inside the drywell 3 rises rapidly, and the atmosphere in the drywell 3 vents. It is discharged into the water of the supplement pool 5 through the system (vertical vent pipe 6, horizontal vent pipe 7). The steam is completely condensed by the water in the supplement pool 5 and suppresses an excessive pressure rise in the reactor containment vessel 2.
Further, the air in the dry well 3 passes through the vent systems 6 and 7 and the suppression pool 5 and moves into the space of the suppression chamber 4 in a relatively short time after the accident.

Therefore, in the long term after the accident, the core decay heat is distributed to the steam in the drywell 3 space, the air in the suppression chamber 4 space, and the suppression pool 5 water.

The core decay heat distributed to the drywell 3 space is transferred from the steam in the drywell 3 space to the outer pool via the wall of the reactor containment vessel 2 and to the intermediate via the wall of the intermediate pool 8. Move to the pool. Further, the core decay heat distributed to the space portion of the suppression chamber 4 and the suppression pool 5 is transferred to the intermediate pool 8 via the wall of the intermediate pool 8. Furthermore, the natural circulation of the pool water caused by the temperature difference between the water in the intermediate pool 8 and the water in the outer peripheral pool 9 prevents the heat transfer of the core decay heat to the pool water due to the local temperature rise of the pool water temperature. .

C. Evaluation Specific core collapse heat removal capacity of the naturally radiating reactor containment vessel of the present invention is shown below.

FIG. 5 shows an evaluation example. From this, in the embodiment in the study stage of the present invention in which the outer peripheral pool is installed, significant natural heat radiation from the reactor containment wall is caused by the space part of the suppression chamber and the pool water through the containment wall. It can be obtained by heat transfer to the outer peripheral pool, but this alone is not enough to naturally radiate core decay heat to the outside of the system for a long time after the accident, and a residual heat removal system is required.

In comparison with this, the reactor containment vessel of the present invention is equipped with the above-mentioned natural heat dissipation, from the vapor in the dry well space to the outer pool,
Since there is heat transfer to the intermediate pool, the core decay heat for a long time after the accident can be sufficiently removed outside the system by natural heat dissipation.

According to the present embodiment, the reactor containment vessel is such that the space between the suppression chamber and the reactor containment vessel wall becomes a drywell space so that almost the entire reactor containment vessel wall becomes a drywell wall. With this structure, the area of heat transfer from the drywell atmosphere filled with steam having a high heat transfer coefficient to the reactor containment vessel at the time of an accident is increased and natural heat dissipation is increased. Furthermore, by installing an intermediate pool connected to the outer peripheral pool between the supplement chamber and the drywell space, the heat transfer area from the drywell atmosphere is further increased to increase natural heat dissipation. We will also be able to obtain natural heat dissipation from the seon chiemba.

As described above, the economical efficiency can be improved by improving the intrinsic safety and eliminating the residual heat removing system.

〔The invention's effect〕

According to the present invention, the reactor containment vessel is designed so that the space between the suppression chamber and the reactor containment vessel wall becomes a drywell space so that almost the entire surface of the reactor containment vessel wall becomes a drywell wall. With the structure, the heat transfer area from the drywell atmosphere filled with steam with good heat transfer coefficient to the outside of the reactor containment vessel is increased in contact with the outer pool to improve the water cooling effect in the outer pool. By adding the water cooling effect of the peripheral pool and the circulating intermediate pool, natural heat dissipation can be increased more than ever before, and the inherent safety can be improved and the economical efficiency can be improved by eliminating the residual heat removal system.

[Brief description of drawings]

FIG. 1 is a longitudinal section of a nuclear reactor facility according to the present invention, in which the OA section of FIG. 2 is shown on the left half and the OB section is shown on the right half, and FIG. 2 is A of FIG. -A sectional view, FIG. 3 is a graph showing the change of heat transfer rate by the ratio of steam and non-condensable gas, and FIG. 4 is partly conceived by the applicant of the present application and the inventors of the present invention. Fig. 5 is a vertical cross-sectional view of a nuclear reactor, Fig. 5 is a graph showing changes in heat quantity after an accident over time, Fig. 6 is a vertical cross-sectional view of a conventional boiling water reactor, and Fig. 7 is a conventional pressurized water atom. It is a longitudinal cross-sectional view of a furnace. DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Reactor containment vessel, 3 ... Dry well, 4 ... Suppression chamber, 5 ... Suppression pool, 6 ... Vertical vent pipe, 7 ... Horizontal vent pipe, 8
… Intermediate pool, 9… perimeter pool, 10… perimeter pool space, 11… return line, 12… connection line, 13… reactor building.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Takahashi 3-2-1, Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi Engineering Co., Ltd. (56) References JP-A-53-8493 (JP, A)

Claims (1)

[Claims] 1. A containment vessel containing a reactor pressure vessel and a suppression chamber, and a vent pipe communicating the pool water in the suppression chamber and the drywell space in the containment vessel partitioned with the suppression chamber. In a nuclear reactor containment vessel provided, an intermediate dry well space arranged on the horizontal outer periphery of the suppression chamber between the wall of the containment vessel and the suppression chamber is provided in communication with the dry well, and the intermediate dry well is provided. The intermediate dry well and the suppression chamber are provided with an outer peripheral pool containing a liquid in contact with the outer wall surface on the outer side, and an intermediate pool containing a liquid in contact with the outer wall surface of the suppression chamber and the inner wall surface of the inner dry well. Between the outer peripheral pool and the intermediate pool A Department communicated with the return line, in the lower than the return line, the peripheral pool and the intermediate pool and characterized in that the communicating by connecting lines to the reactor containment vessel.