JPS58173490A - Reactor facility - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a high temperature miniature nuclear reactor, a plurality of steam generators housed together with the high temperature miniature reactor in a cylindrical steel pressure vessel surrounded by a concrete safety envelope, and a The circulation blower is located after the steam generator when viewed in the direction and is arranged within the safety envelope.

It concerns a nuclear reactor installation consisting of a natural circulation concrete cooling system connected to a secondary cooling water system for recooling.

The prior art is an installation in which a high-temperature nuclear reactor for nuclear heat generation and a device for the utilization of the generated heat are installed together in a pressure vessel.

In this case, the removal of heat is carried out by cooling gas, which is passed by blowers in a closed circuit through the core and heat exchangers (
- next circuit). Special devices such as auxiliary heat exchangers and auxiliary blowers can be provided for removal of residual heat. Additionally, by special arrangement and design of secondary circuit components, it is also possible to eliminate auxiliary equipment.

For example, in the case of a tri+7 high-temperature sub-furnace (T) ITR300), the heat exchanger, blower and secondary system and their parts are installed so that all the residual heat is discharged to the heat exchanger via the primary operating system. It is configured. The flow path of cooling gas from top to bottom through the reactor core and from bottom to top through one exchanger is the flow path during normal operation. However, for a reliable discharge of the residual heat, provision must be made for the blower to be operated at any time, so that the hot gas rising by free convection does not endanger the cold gas area.

In another nuclear reactor installation with a gas-cooled high-level reactor, namely an experimental reactor installation, a heat exchanger is placed above the reactor, and the cooling gas is supplied to both the core and the heat exchanger. It also flows from bottom to top. The blower below the reactor core stopped, and the air flow began to flow due to natural convection along the steam generator installed above the reactor core and the accessories placed around the reactor core.
Residual heat is exhausted. In addition to the graphite reflective jacket, the accessories also include a carbon brick jacket surrounding the graphite jacket for screening and thermal insulation. In order to ensure the containment of the liberated fission products, the above-mentioned accessories are surrounded by a double gas-tight steel pressure vessel.

The basis of the invention is the nine reactor installation mentioned at the outset, which surrounds a steel pressure vessel with a safety envelope consisting of a double concrete shell.

A natural circulation concrete cooling system is installed within the inner concrete shell, through which cooling water circulates in a closed circuit. A second cooling water system is provided for recooling the concrete cooling system and discharging the absorbed heat to the outside. Heat absorption from the steel pressure vessel takes place essentially by thermal radiation, and heat removal from the concrete takes place by direct contact.

Normally - when the equipment responsible for removing residual heat fails and is shut down, the operational concrete cooling system described above is also used for removing residual heat.

The first thing to consider as a residual heat exhaust system is the heat exchanger/blower unit, the secondary circuit for operation, and the auxiliary cooling system. Even if the circulation blower stops, residual heat discharge on the negative side can be guaranteed. The prerequisite for this is that the cooling gas pressure in the secondary circuit is sufficiently high so that sufficient natural convection is generated and maintained. - When the downstream heat absorber is shut down, residual heat is released into the steel pressure vessel by natural convection, conduction and radiation, from where it is substantially radiated.
Heat is transferred to the concrete cooling system within the inner concrete envelope.

The object of the present invention is to provide a nuclear reactor equipment having the nine structures mentioned at the beginning, in order to ensure discharge of residual heat even if the circulation blower stops in the event of a failure, by means of a special arrangement and structure of the following circuit components. The goal is to ensure sufficient natural convection.

The objective of the present invention is achieved as follows. That is, a steam generator is arranged in a manner known per se above the high-temperature small nuclear reactor, and a first hole is placed between the steam generator and the high-temperature small nuclear reactor.

A second hot gas collection chamber is provided, into which a second hot gas collection chamber is fed, which is guided in a manner known per se from below to the top of the reactor core, and above the steam generator a second hot gas collection chamber is provided. A chamber is disposed and communicates with a first hot gas collection chamber by a central hot gas passage, a steam generator is gathered around said hot gas passage, and a circulating air flow is arranged in a first hot gas collecting chamber.

In the area between the gas collecting chamber and the lower edge of the steam generator, it is mounted on the side of the steel pressure vessel in a horizontal position in a manner known per se, and the steel pressure vessel is usually without thermal insulation. It is composed.

In the reactor equipment according to the present invention, cooling gas flows through the core from the bottom to the top even during normal operation, in order to minimize the component design for hot gas temperatures required for normal operation and residual heat removal operations. . In this case, in reactors using spherical fuel elements, care must be taken to avoid lifting of the spheres when flowing upward through the pile of fuel elements. This is achieved by means of a gas that limits the mass velocity of the gas. In the case of upward flow within the core, the core cross-section is limited because the absorber rods inserted into the core are eliminated in the hot upper region, and control and isolation must therefore be provided by discrete reflector rods. At the same time, the exit direction and core dimensions of the reactor at a given gas temperature and desired power density are
It is determined in relation to the permissible mass velocity of the cooling gas.

The operating pressure of the primary circuit, i.e. the wear pressure, is sufficient for starting and maintaining the natural circulation 11fi of the primary circuit and ensures the removal of residual heat even when all circulation blowers are stopped.

The hot gas flowing upward from the core is the first.

After gathering in the hot gas gathering room, go through the central hot gas passage,
The fact that it is led into a second hot gas collection chamber above the steam generator and fed into the steam generator from above greatly contributes to a good natural convection lick. The steam generator is thus flowed through from top to bottom, increasing the buoyancy forces that cause natural convection, ie the density difference between the upward and downward gas flows.

Additionally, the flow from above to the steam generator facilitates upward-evaporating steam generator operation. This allows favorable process control requirements (minimum throughput) for part-load and low-load operation.

The above-described arrangement of the steam generators also makes it possible to avoid direct entry of water into the reactor core even if the steam generator tubes fail due to failure.

The circulating blower, which is placed in a horizontal position, is located in the immediate vicinity of the steam generator. Since it is preferable that the amount of cooling gas passing through the steam generators can be individually controlled and adjusted completely, one circulation blower is assigned to each steam generator.

The result is that the steam generator is mounted on the side of the steel pressure vessel. With this arrangement of blowers, leakage through the side reflector is prevented because the outer chamber around the side reflector that encloses the fuel element deposit has a higher cooling gas pressure during normal operation than the fuel element deposit. It only occurs in the direction from this low-temperature outer chamber to the high-temperature core.

By not insulating the steel pressure vessel too much, a good heat extraction from the next circuit is achieved. This allows the external concrete cooling system and the NW
When discharging residual heat to the A system, the primary side temperature can be kept low even when the container is insulated. Also, since the container is not insulated, the cooling gas is more strongly chilled in this area, thereby increasing the buoyancy forces that create natural convection.

According to the invention, the natural convection can be further improved by equipping each circulation blower with one connecting device and one shaft device.

This makes it possible to reduce the flow resistance in the secondary circuit, so that there is no risk that the circulation blower will be threatened by hot gases if the steam generator is shut down and natural convection takes place.

In a nuclear reactor installation with the arrangement and design of the primary circuit components according to the present invention, after a failure, the circulation of cooling gas can be discontinued for exhaustion of residual heat.

The presence of cooling gas pressure in a high temperature small nuclear reactor provides sufficient natural convection in the secondary circuit to cause heat transport from the reactor core to the steam generators.

Normally, that is, when the circulation blower is activated.

After reactor shutdown, residual heat is discharged to the main water tank via the operating water-steam circuit (system 1). If this operating system is not in operation, several auxiliary cooling systems (system 2) can be used if necessary, in which case only one of these systems is responsible for all residual heat removal. be able to.

When the circulation blowers that are powered independently from each other stop, is there residual heat? - It is possible to reach the steam generator via primary natural convection and also to one of the auxiliary cooling systems.

When the primary heat absorber, that is, the steam generator and its water supply cap, is shut down, residual heat generated in the core is transferred to the steel pressure vessel by natural convection, conduction, and radiation. From there, heat is transferred essentially by radiation to the cooling system of the safety envelope. If necessary, make the concrete cooling system higher heat removal capacity. In case of loss of coolant (hypothetical accident "pressure relief in the next circuit") and - complete cessation of cooling in the next circuit, residual heat is transferred by radiation and conduction to the surface of the steel pressure vessel and from there to concrete cooling. There is no significant increase in the release of fission products from the fuel elements into the system.

Even assuming that recooling of the concrete cooling system and water supply to this system were stopped, the temperature in the steel pressure vessel was clearly below 400°C, which would prevent the release of large amounts of fission products from the fuel element. The core temperature will not be reached for a long period of time.

An embodiment of a nuclear reactor installation according to the invention is schematically shown in the drawing.

Figure 1 shows reinforced concrete 13-t safety jacket (see Figure 2)
A steel pressure vessel 1 disposed within is clearly shown. The steel pressure vessel @1 consists of a lower cylindrical part 2, an upper cylindrical part 3 and two curved ribbed parts 4, 5. All container parts are connected to each other by seven lances 6, the cuts are sealed and monitored for leaks. The lid parts 4, 6 are configured as an elliptical arch floor. The lower flank a of the pressure vessel member 2 is configured so as to be able to receive a support structure 16 (described below) and an external bearing 7.

The lower pressure vessel 2 is used to support the high-temperature small nuclear reactor 10, and the upper pressure vessel 3 houses four steam generators 11 and a circulating blower J2 as a heat class storage stomach, as described below. .

The high temperature small nuclear reactor 10 has a core 13 consisting of a stack 14 of fuel elements and a graphite reflective material 15 surrounding the entire circumference of the stack 14.
has. A graphite reflector consisting of a ceiling reflector 15m, a bottom reflector 15b, and a bottom reflector 15c has a central extraction pipe 17 for a zero-spherical fuel element sitting on a metal support structure 16 inserted through the metal support structure 16. It will be done.

A metal heat shield 18 consisting of a ceiling, sides and bottom is disposed around the graphite reflector 15.

The side reflector 15b is provided with a heat shield 180 by the support member 19.
It is supported by the side part 11m. A twist stop (not shown) provided in the upper area prevents the two components from shifting in orientation with respect to each other. Attached to the inner surface of the side reflector 15b are four graphite protrusions spaced 90' apart and protrude into the stack of fuel elements. An annular gap 24 between the side heat shield 18a and the pressure vessel lower part 2,! It is provided.

The bottom of the heat shield 18 rests on a flexure bearing 21 which rests on the support structure 16 . Bottom part and support structure 16
There is a coal P gas collection chamber 22 in communication with the fuel element stack 14 by means of a bottom heat shield and a number of holes in the bottom reflector 1f5e. Between the ceiling reflector 15&, which also has a gas passage, and the ceiling part of the heat shield I8.

There is a first hot gas collection chamber 23 that forms the upper part of the high-temperature small reactor 10 (Dlk). Helium is used as a cooling gas and is sent upward through the reactor core 13. As a result of the upward flow, the steam generator 11 The transfer of cooling gas to can be configured very simply.

Two different disconnection devices are provided for shutting down the high-temperature small nuclear reactor 1o. The first shutoff device, which is used for both immediate shutoff and long-term shutoff in the event of an accident, consists of a plurality of absorption rods 25. The absorption rod 25 is inserted from below into a hole in the side reflector 11ib and a hole in the graphite protrusion 2o in the core I3.

A small absorption sphere is used as the second isolation device.

The absorption spheres can be pumped into the fuel element deposit 'I4' under the action of gravity. The absorption sphere is responsible for long-term shut-off when the shut-off device of the hook l does not work. The charge of small absorption spheres is stored inside the upper part 3 of the pressure generator at the height of the steam generation tsxz.

As mentioned above, the heat absorption device consists of four steam generators 11. A vertical hot gaff passage 28 runs upwardly through the center of the pressure vessel upper part 3, and this e.g.

Four steam generators 11 are arranged around the gas passage so as to be shifted by 90 degrees. The center hot gas is insulated inside the passageway zsFi, and is connected to the hot gas collecting chamber 23 through a nape joint zyyc. The hot gas passage 28 is connected to a second hot gas collecting chamber 31 via a second slip joint 30 .

A second hot gas collection chamber 31 is arranged above the steam generator 11 and distributes hot gas to the steam generator 11 . Each steam generator 11 is connected to a hot gas collection chamber 31 by a pipe joint 32 .

A suction pipe 33 of the circulation blower 12 is connected to the lower low temperature end of the steam generator 11 . One blower 12 for each steam generator 11
will be assigned. uII311 blower 12 is steam generator 1
1 and is installed in a horizontal position on the outside of the lower part 3 of the pressure vessel.

Therefore, the pressure in the coal P chamber is higher than that in the furnace 13, so
Leakage through the graphite reflector 15 can only pass in the direction of the reactor core 13; the blower 12 blows air directly into the steel pressure vessel 1.

The water supply pipe 34 and the live steam discharge pipe 35 enter the steam generator 1111C next to the lower end of the steam generator 11.

If the flow direction of the cooling gas is from above the steam generators 11, the generated steam is led downwards again in an unheated straight tube bundle arranged in the six tubes of each steam generator 11.

The steam pipes are arranged in a loop and have nine elastic bands.

Connect each to the straight pipe bundle. To avoid heat loss from the live steam to the cold gas, this compensation area is surrounded by an internally insulating iron plate jacket 37 that largely isolates the cold gas.

The load of the steam generator 11 is on the one hand due to its jacket,
On the other hand, it is transferred by a support volume structure 36 attached to the pressure vessel upper part 3 in the area of the conduits 34,35.

Next, the cooling gas circuit passing through the high-temperature small nuclear reactor 10 and the steam generator 11 will be explained in its entirety.

Helium flows upwardly over the fuel element stack 14 at a working pressure of 70 par, heating it to a trap of 7()0°C. After passing through the ceiling reflector 15a, N @ l hot gas collection room 2
3 and from there enters the hot gas passage 28. Here it flows upwards and after turning around in the second hot gas collection chamber 31 the four steam generators 11 are evenly distributed. Helium is cooled to 250° C. in the steam generator 11 and further flows to the microvolume blower 12 via the blower suction pipe 33. 7 more
The cold helium, compressed to a pressure of 0 par, then enters the annular gear, De 24, between the side heat shield IIIm and the lower part of the pressure vessel 2, flowing downwards and thoroughly filling the two components. Cooling. A small portion of the cold gas is channeled into the sphere extraction tube 17 for cooling of the fuel elements in the sphere extraction tube 17 in the area of the support structure 160 and is added back into the main cooling gas stream through the core bottom. The cold gas then reaches the cold gas collection chamber 22 and enters the fuel element stack 14 again via the bottom shield and the bottom reflector 15e.

To avoid flotation of the spherical fuel elements as they flow upwardly through the stack 14, the helium mass velocity is limited to a predetermined value.

The service water enters the steam generator at 190°C, and the live steam generated leaves the steam generator at a temperature of 530 t::. The live steam is sent to a steam turbine facility for further use.

As shown by the second @, a safety jacket 3o is disposed closely around the steel pressure vessel 1. The safety envelope 30 consists of two approximately cylindrical concrete shells, an inner concrete shell 4o and an outer concrete shell 4no, and a concrete ceiling 42 joined together with these two concrete shells. The steel pressure vessel 1 is also integrally connected to the two concrete shells 4θ, 41, with the zero cantilever support ring 38 supported on the concrete cantilever support ring 38.

An annular chamber 43 is formed between the two concrete shells 4o, 4no. This room 43 is accessible within a limited range and can be used as a work room.

In order to protect the inner concrete shell 4o from excessive heat, the safety envelope 39 has a concrete cooling system 43. This cooling system 43td is also used to discharge residual heat when the primary side residual heat exhaust cover of the nuclear reactor equipment is stopped. When concrete cooling system 43 utilizes natural circulation.

The concrete cooling system 43 includes an annular elevated tank under atmospheric pressure and a pipe system consisting of a large number of ascending pipes 45 and descending pipes 46, and this pipe system forms a closed circuit in which cooling water circulates. The elevated tank 44 communicates with the elevated tank 44. An elevated tank 44 containing approximately 100 ms of water is mounted on top of the inner concrete shell 40. The elevated tank 44 also communicates with a second cooling system 47 in which cooling water circulates. The second cooling system discharges heat generated in the elevated tank 44 to the outside.

The riser pipe 46 is installed on the side of the inner concrete shell 40 facing the steel pressure vessel 1 . The downcomer pipe 46 is provided on the side facing the outer concrete shell 41.

A blowout pipe 48 leading out from the safety jacket 39 and equipped with an overpressure valve 49 communicates with the elevated tank 44 . Water can be replenished into the elevated tank 44 at any time by a water supply system # (not shown).

- When discharging residual heat from the next circuit, heat is transferred from the steel pressure vessel 1 primarily by radiation to the concrete shell 40 inside the safety envelope 39. Heat absorption by the water rising in the riser pipe 45 is performed by thermal conduction. The heat is transferred to an elevated tank 44 where it is transferred to a second cooling water system 47.
sent to.

When the cooling water system 47 is stopped, the water in the elevated tank 44 is heated and evaporated. Even under these conditions, residual heat discharge can be maintained for 2 hours to 3 days without any active measures being taken. If a period longer than that is required, the elevated tank 441C can be filled with water using the water supply equipment.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the reactor equipment excluding the safety envelope, Figure 2
The figure shows a reduced schematic diagram of the reactor equipment including the safety envelope and concrete cooling system. 1...Steel pressure vessel, 10...High temperature small nuclear reactor, 1
1...Steam generator, 12...Circulating air fan, 14...
・Reactor core, 23...First hot gas collection chamber, 28...
-Hot gas passage, 31...second hot gas collection chamber.

Claims (2)

[Claims] (1) A high-temperature small reactor, a plurality of steam generators enclosed by a concrete safety envelope and housed together with the high-temperature small reactor in a nine-cylindrical steel pressure vessel, and the steam generators as viewed in the flow direction. In a nuclear reactor installation consisting of a circulating blower downstream of the steam and a natural circulation concrete cooling system located within the safety envelope and connected to the secondary cooling water system for recooling, A generator is disposed above the high-temperature small nuclear reactor, and a first hot gas collection chamber is provided between the steam generator and the high-temperature small nuclear reactor, and a first hot gas collection chamber is provided that penetrates the reactor core from bottom to top. A second hot gas collection chamber is arranged above the steam generator to which the guided cooling gas is sent. A central hot gas passage communicates with a first hot gas collecting chamber, a steam generator is gathered around said hot gas collecting passage, and a circulation blower is connected between the first hot gas collecting chamber and the lower edge of the steam generator. A nuclear reactor installation, characterized in that the steel pressure vessel is installed horizontally on the side of a steel pressure vessel in the area of tl, and that the steel pressure vessel is constructed with almost no thermal insulation. (2) Claim No. 1, characterized in that each circulation blower is equipped with one shutoff device and one piston device.
Nuclear reactor equipment described in section 1).