DE2505532C2 - Nuclear reactor power plant with coolant supply in the event of an accident-related loss of reactor coolant - Google Patents

Description

The invention relates to a nuclear reactor power plant with a .Reaktorbaugruppe that a nuclear fuel containing reactor core, at least one steam generator, which has a first connection connected to the reactor assembly and from a reactor coolant of high temperature and high operating pressure, which under normal conditions is essentially! is constant, as well as with at least one container for cooling liquid, which is connected to the reactor assembly via first pipelines connected, exposed to a pressure below the operating pressure of the reactor coolant and with the reactor and the steam generator is arranged within a sealing enclosure, the always supply the pressurized cooling liquid to the first pipelines of the reactor assembly, if the operating pressure is sufficiently reduced due to the loss of reactor coolant due to an accident and a second predetermined pressure difference between the cooling liquid and the reactor coolant In the Reactor assembly that is smaller than the first pressure difference between the coolant and the one under normal operating pressure Reactor coolant.

Such a power plant is known (DE-OS 23 16 066). The intended measures serve to in the event of industrial accidents, to prevent water, steam and carried fission products from escaping into the environment. The supply of coolant kept in reserve means that in the event of a line break with outflowing reactor coolant,

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encountered excessive increases in temperature and pressure. There is then no longer any need a so-called dry protective device in the form of a reactor building made of steel and / or concrete to provide that can withstand the full pressure with which in a corresponding reactor accident reckon is.

Be! the well-known nuclear reactor power plant an open one to secure the coolant supply in the event of a leak within the enclosure Elevated tank with coolant and a closed one Pressure accumulator provided with cooling liquid which is pressurized by a gas cushion. These Amounts of liquid stored within the enclosure can be lost to replenishment gone reactor coolant can be used, but in the event of a reactor accident this alone not yet guaranteed the necessary security. Rather, that which has emanated and becomes in a sump of enclosure collecting coolant is reused. A pump is provided for this purpose, which is operated with external electrical energy. Although the static energy of the coolant in the elevated tank as well as the pressure of the gas cushion KOhliquid is available, it is therefore because of the sump assigned and from externally operated pump around an at least partially active system whose effectiveness requires that the power to drive the pump does not fail. However, this cannot be done under all circumstances be guaranteed, so that the known power plant is burdened with a certain slcherheltirislko.

ίο Incidentally, it is also with the known system already critical to achieve the desired inlet pressures for the coolant kept in reserve, well on the one hand that provided for a gravity feed open elevated tanks because of its location within the enclosure only with a limited volume executed and can only be arranged at a comparatively low height and because on the other hand the pressure accumulator works with an elnleltungsdrucck that with increasing emptying and corresponding Expansion of the gas cushion drops sharply.

The invention is based on the problem of the security of a generic system Improve accidents with leakage of reactor coolant.

This object is achieved in that the steam generator with the second pipelines Connect cooling liquid container and that after reaching a third predetermined pressure difference between the cooling liquid and the steam in the steam generator under a relatively high Pressurized steam is supplied to the cooling liquid tank through the second pipelines in order to to apply a pumping force to the cooling liquid, so that the one containing the fuel of the reactor core Part of the reactor assembly is completely filled.

In this way a completely passive safety system arises in the sense that there is no dependency from the use of electric pumps or similar devices with external Energy driven. This also eliminates the risk that the required external energy fails. At the same time, however, a safe supply of the cooling liquid is also ensured Exploitation of the existing steam pressure within the system. This passive security system, which is applicable to both pressurized water reactors and boiling water reactors. also has the The advantage that after an accident the reactor is accessible again after a comparatively short time and can be made ready for operation, because with active systems it is to be expected that the for Active parts such as pumps, electrical cables and the like required for operation are damaged and need to be replaced.

Thus, in the subject of the application, the energies generated within the reactor system are used to to reduce the internal pressures to safety values To prevent the reactor core from melting down, to reduce internal temperatures to safety values and prevent leakage of radioactive material into the environment. This takes place within a few minutes after an accident occurred.

Appropriate refinements and developments of the invention emerge from the subclaims.

The system according to the invention, in which with a high pressure and high temperature cooling medium and / or A moderator such as light water or heavy water is worked on, has several interconnected

Cells or chambers. In which the ingredients the nuclear reactor facility are housed, for example the reactor vessel, steam generator, pressure generating devices, a regenerative heat exchanger and piping. Inside the protective device cells encloses a first container or a main container, which is made up of interconnected Steel jackets composed of the entire cooling system of the reactor. A second container made of steel forms an enclosure immediately adjacent to the first container or the main container. This second Enclosure is in turn arranged in a further enclosure made of reinforced concrete or prestressed concrete. Between the first and the second enclosure there is an annulus that is filled with water is filled.

The flood tank and tank for refilling the reactor vessel are under complete enclosure In the cells of the protective device In a arranged at a certain height above the reactor cooling system and the associated pipelines and with water filled. The first enclosure and also the second enclosure are pressure relief devices assigned, which make it possible to establish a connection to a deep well.

The deep well surrounds the protective cell for the Reactor vessel and extends down below the reactor vessel. The one with a lining Steel-lined deep well, which contains a coupling fluid. Is with an enclosure made of reinforced concrete and / or prestressed concrete. In the deep wells are two separate sets of heat exchanger assemblies immersed and separated from each other by a flow guide device that practically extends over extends the entire depth of the deep well. One of the heat exchanger arrangements is in communication with the space containing the reactor vessel, while the second heat exchanger arrangement is in connection with a body of water in the open air. Heat exchanger arrangements are also available for the coupling fluid, with v-elcher the annular space between the first Container and the second container is filled. These heat exchanger assemblies are located in the named waters in the open air.

The water that is in the refill containers the reactor vessel, the flood tanks, the annulus between the first and the second Enclosure, as well as located in the deep well, is treated in a special way to get the desired To ensure protective effect. The water is degassed and it contains chemicals in solution that as a neutron poison, anti-corrosive agent !, getter for Oxygen and getter for radionuclides come into effect. The water filling is done with the help of Steam jet cooling devices or kept by heat exchanger assemblies in the cooled state.

The passive protection device is usually housed in a reactor building. The order the cell construction also allows the spaces to contain spent nuclear fuel and to accommodate a fuel feed chamber in the reactor building. The heat exchanger arrangements, which are assigned to the rooms for the storage of burned nuclear fuel are open Connection with the open water.

When the passive protection device according to the invention is typically due to a loss of coolant responds, causes the decompression of the reactor coolant caused by a burst pipe becomes that in the first enclosure, where a high vacuum is normally maintained, there is steam is produced. This steam pressurizes the enclosure, and when it reaches a predetermined level Under pressure, the steam causes the sealing disks assigned to the flood tanks to be torn open will. This has the consequence that steam flows into the flood tank, that a thermal expansion of the steam takes place and that the flood tanks fill completely with water. By this filling of the flood tanks with water becomes the space enclosed by the first tank exposed to increased pressure until the coolant is blown off through the in the container Counter pressure is interrupted. The first container is designed so that the blowing off of the coolant through the counterpressure created in the container is interrupted, while there is still another in the reactor vessel There is an amount of water that is sufficient to effectively cool the nuclear fuel.

Before the reactor coolant is stopped by the back pressure in the enclosure, causes the hydrostatic pressure that prevails in the containers for refilling the reactor vessel that the Non-return valves associated with connecting lines are opened, whereupon pretreated water In the reactor cooling system is injected. The decompression of the refill container leads to the fact that Closing disks are torn, which are assigned to the steam distributors, which between the Secondary side of the steam generator and the refill containers are arranged. By tearing open the Shutters initiate the flow of steam from the steam generators to the steel injectors; the steam flowing through these injectors pulls pre-treated water with it from the refill containers. The steam and the water are intimately mixed with each other as they pass the diffuser plate of the injector flow through, so that a homogeneous solution is created from the pretreated water, with which the reactor vessel is refilled.

The chilled water in the elevated flood tanks frightens the mind while it is being blown off of the coolant overflowing vapor, while the counter pressure in the container increases, to stop blowing off. As soon as the coolant has been blown off, the Gravity pulls the chilled water, which contains neutron poison in solution, to act around the pipelines completely flooding the reactor and the reactor cooling system Above the pipe smear leading to the loss of coolant has led to refill. All of the energy stored in the reactor system is used by the Flood water added. The amount of flooded water has a heat absorption capacity that sufficient to bring the temperatures down, so that the atmosphere in the main container is brought back to the normal high vacuum by the flooding. All substances that come from the The main tank during the blowdown and flooding will escape from the water in the second Container added. Any overpressure that occurs in the first vessel during blowdown, is drained to the water in the deep well.

The energy that continues to be given off as decay heat by the nuclear fuel is generated by conduction and natural convection passively emitted to the environment

ben. This heat is first given off by convection from the nuclear fuel to the reactor coolant and then gets through heat conduction within the non-insulated metal walls of the reactor system to the Flood water In the first container. Coolant lines connected to the heat exchanger assembly In the Deep wells are connected, transfer the heat by conduction and convection from the the reactor vessel containing space to the water In the deep well. The thermal convection causes a Circulation of the water in the deep well around the deflector and in the second one Deep well existing heat exchanger arrangement over. In the area of the second heat exchanger arrangement the heat of decay is given off by conduction to water, which flows through the pipes and through natural convection is caused to flow through the pipes from the outdoor body of water.

Furthermore, energy becomes passive through the water in the second container discharged into the open. Here, heat is generated by conduction through the steel jacket transferred from the flood water in the first container to the water in the second container. That Water in the second container then flows through the heat exchanger arrangements as a result of natural convection, that are outdoors in a body of water. The water of this body of water is thermal Convection causes at d;: n heat exchange crane arrangements to circulate past to absorb the heat contained in the water from the second container.

The structure of the passive protection device makes it possible to use the spaces for storing the spent nuclear fuel and to accommodate the auxiliary equipment of the reactor in the reactor building. This arrangement also enables the use of passive heat exchange circuits connected to heat exchanger assemblies which are the rooms for the storage of spent nuclear fuel and the auxiliary equipment of the reactor are assigned. These passive heat exchanger arrangements give heat to the Im From open waters.

The invention is hereinafter carried out with further Details are explained with reference to schematic drawings of an exemplary embodiment. It shows

Flg. 1 a vertical section through a reactor building for receiving a passive protection device according to the invention, the section through a Flood tank cell, a reactor coolant pump cell, the reactor vessel cell, a steam generator cell, a refill cell and cells to hold Verblndungsrotirlelungen for the Reactor coolant is generally along broken line I-I in Figure 4;

2 shows a vertical section through the reactor building, which is substantially along the line H-II in Fig. 4 through two spaces for receiving spent nuclear fuel runs, between which the space for loading the nuclear reactor with Nuclear fuel located;

F1 g. 3 a vertical section through the reactor building along the line HI-III in Fig. 4, by a Pressure generator cell, one accessible shaft, the cell containing the reactor vessel, a second accessible cell Well and cell runs that contain the regenerative heat exchanger;

FI g. 4, 5, 6 and 7 each have a horizontal cut through the reactor building along the relevant lines IV-IV, V-V, VI-VI and VII-VII in Flg. 2;

Flg. 8 and 9 each show a schematic representation of containers for refilling the reactor vessel, wherein in Fig. 8 a typical pipeline arrangement for a refill is shown while Flg. 9 shows the general arrangement of the refill containers in a pressurized water reactor with four cooling loops reveals; and

Flg. 10, 11, 12 and 13 are each a graphical representation of a particular aspect involved in a protective device is to be considered, the Im In the event of a loss of coolant in a pressurized water reactor to come into effect, which for a electrical output of 1000 MW is designed.

Here, Flg. 10 shows the relationship between the total required free volume and the highest pressure occurring in an industrial accident with one that can withstand full pressure. Protective device to be operated in the dry state, which is normally at atmospheric pressure, (1.01 bar) or at a high vacuum of about 0.138 bar or at a full vacuum of 0 bar is working.

Flg. 11 illustrates the relationship between the Amount of reactor coolant maintained in the liquid phase, d. H. of the total amount that In the reactor cooling system and the first protective container is available, and the one that occurs in the event of an industrial accident highest pressure, d. H. the back pressure in the protection device, in case of full pressure withstanding protective device that can be operated dry, whereby the amount of coolant is also shown, which remains in the reactor vessel alone.

Fig. 12 illustrates the relationship between the amount of the reactor coolant alone contained in the reactor vessel Remains in the liquid phase, and that with one Highest pressure occurring during an industrial accident, d. H. the back pressure in the first enclosure in case a passive protection device; wherein steam is introduced into the flood tank, and wherein the first container or the main container overall has a free volume that is approximately 2830 or approximately 2125, respectively or about 1410 or about 990 m '.

Flg. Fig. 13 illustrates the relationship between the pressure in the first container after flooding prevails, and the amount of flood liquid that In the passive protection device at a temperature of 16 ° or 10 ° or 4 ° C is saved; for this comparison, the total available is free Volume of the first container is set at about 990 m ', and it is assumed that before the Construction underlying industrial accident in the container a pressure of about 0.138 bar absolute is maintained will.

In Flg. 1 to 7 a passive protection device for a four-loop pressurized water reactor is shown. The first enclosure is made up of interconnected cells that enclose the various parts of the reactor cooling system. According to Flg. 1, the reactor vessel 102 is accommodated in a reactor vessel cell 101. There are four steam generator cells 103, each of which contains a steam generator 104 . Furthermore, the building shown has four reactor coolant pump cells 105, and a reactor coolant pump 106 is arranged in each of these cells. In a further cell 107 there is a device 108 (Fig. 3)

for applying pressure. According to FIG. 3, the regenerative high-pressure heat exchanger 110 is accommodated in a cell 109 (FIG. 5). Further cells 111 contain the pipelines 112 from which the plant containing the reactor coolant is composed.

The containers 114 for refilling the reactor vessel are located in further cells 113. The lower end of each cell 113 containing a refill container is welded with a sealing effect to a load-bearing jacket which forms part of the first enclosure. The cells 115 (FIG. 1), which contain the pipelines connected to the refill containers 114 , connect these supporting jackets to the adjacent steam generator cells 103.

In further cells 116 are shown in FIG. 1 the flood tank 117 is arranged. The lower end of each flood tank is welded with a sealing effect to a load-bearing jacket, which also forms part of the first enclosure. The cells 118, in which the pipelines connected to the flood tank are located, connect these supporting jackets to the adjacent steam generator cells 103.

The cells of the enclosures are made of steel and concrete. A gapless lining 119 made of steel (FIG. 3) determines the shape of the interconnected cells. The free space within the cells allows access to the maintenance of the parts of the reactor. The cylindrical steel jackets 119 are provided with stiffening rings on their inside to give the jackets the section modulus necessary to enable them to withstand the external pressure to which the cells forming the first enclosure are subjected. There are also reinforcement rings at the junctions between the cells containing the pipelines and those cells. In which the main parts of the plant are located.

The cells 111 for receiving the pipelines for the reactor cooling system make it easy to install pipeline supports and brackets that serve for this purpose. To prevent damage to the first enclosure and other components in the event that a broken pipe executes peltschschllagähnllche movements when a coolant leak occurs. These piping supports and brackets are three-point brackets separated from the stiffening rings and reinforcing rings associated with the steel liner 119 of the first enclosure in the piping cells. The stiffening rings are also spaced at small intervals to provide additional protection for the steel lining. The larger components are against movements that z. B. earthquakes could occur, protected by vessel stabilizers.

The steel lining 119 is double-walled in a manner not shown. The annular spaces between the steel sheets are filled with water. In which a neutron gifi is dissolved. The space enclosed by the inner sheet metal forms the first enclosure for the reactor cooling system. During the power operation of the reactor, a high vacuum is maintained in this free space so that there is no need for thermal insulation on the outer surfaces of the reactor cooling system. When the reactor is taken out of service to allow maintenance to be carried out, air at atmospheric pressure is circulated in the first enclosure; for this purpose, the vacuum or suction lines that are connected to the interior of the first enclosure are used.

Avoiding the use of thermal insulation on the outer surfaces of the reactor cooling system, the Secondary parts of the steam generator and the auxiliary piping represents a decisive improvement represent the protection devices known up to now, in which operated at high or low temperature Facilities and the surfaces of certain components within the first enclosure with a Thermal insulation must be provided. In particular, this improvement offers the following advantages:

A reduction in the volume of the enclosure, a shortening of the construction tent, a saving Material costs, eliminating the risk of stress corrosion as a result of the presence of Chlorides that act as impurities in thermal insulation are in place, enabling constant remote monitoring of the critical parts of the exposed Outer surfaces made of steel on the pipelines for the reactor coolant, the reactor vessel and other larger components, furthermore a shortening of the tent, during which the maintenance and testing personnel is exposed to radiation, which is due to the saving of the tent needed to keep the Removing and reinstalling thermal insulation, as well as avoiding the hazards arising from the Presence of eroded thermal insulation in the event of a coolant leak.

In the protective devices known up to now, the jet causes when the coolant is blown off when a leak occurs, the insulation is eroded, that the insulation material in Water is suspended so that spray nozzles and air filters are clogged that lead to the spray and Air circulation devices are included, and that also includes heat exchangers and the screens at the pump inlets the emergency circulation device, which is used to dissipate the decay heat.

The water-filled annular space between the first and the second enclosure forms a "water jacket", with the exception of the passages of the enclosure as a "cold wall" for the first enclosure Effect comes. The coolant escaping from the first enclosure is taken from the water in the second enclosure added. The distance between the sheets of the "cold wall" can vary between a few inches (around 25 mm) and several feet (around 300 mm), depending on the constructive details of the passive protection device.

Almost all of the cells of the first enclosure are enclosed by a concrete structure 120 (FIG. 4) which is prestressed or reinforced as required, but with the exception of the upper end of the reactor vessel. According to FIG. 1, a dome 121 provided with a flange is provided which encloses the drive devices for the control rods. These control rod actuators are accessible via a manhole 122 provided with a flange at the upper end of the pressure vessel.

The concrete structure that is the second enclosure immediately surrounds, forms a support for both the second and the first enclosure as well as for the reactor cooling

location. The concrete structure has sufficient wall thickness at all points to act as a biological shield to come into effect. Thus, the people who are in the reactor building are against penetrating radiation, both during normal reactor operation and at all industrial accidents that take place within the first containment, and those too Loss of coolant belong.

Some of the cells of the first enclosure are divided. The cell containing the reactor vessel sets consists of two chambers, an upper and a lower one. The upper chamber is shown in FIG. 1 formed by the steel dome 121 provided with a flange. This is in the lower chamber Reactor vessel 102. According to FIG. 1, the two chambers are separated from one another by a membrane 123 made of steel separated. If the reactor is to be charged with fresh fuel, the one provided with a flange Head piece 124 is removed from the reactor vessel, a sealing ring with the help of Screws attached to a second seal against water penetration between the upper and the lower Bring about chamber. This in Flg. 1, not shown, the second seal bridges the annular space between the flange of the reactor vessel 102 and the steel lining of the protective device in the area of the cell 101 containing the reactor vessel.

Each of the four cells 105 for accommodating the reactor coolant pumps has two chambers, and one chamber for the pump motor and one chamber for the pump. The free space that the Surrounds the pump housing 106 directly, forms according to Flg. 1 each the lower chamber. The pump motors 126 are housed in associated chambers 125. The motor chambers 125 can either be air or a an atmosphere consisting of an inert gas can be supplied. At the same time, the remaining part can of the free space or volume inside the first enclosure either on a high vacuum or atmospheric pressure.

1, a steel membrane 127 divides each pump cell into two chambers. The membrane 1st welded with a sealing effect to the pump housing and the lining of the cell, around the Upper chamber 125 containing engine delimit.

The steel lining of the motor chamber 125 is with a sealing effect with a plate-shaped end part 128 welded. This end piece can easily be cut out so that it is possible to replace the relevant pump motor via an opening arranged directly above it. After the pump has been renewed, the plate-shaped head piece 128 is welded in again.

The four reactor vessel refill tanks 114 and the four flood tanks 117 contain dissolved neutron poison. The contents of this container are kept at a deep level with the help of mechanical cooling devices Temperature held. An amount of liquid is kept ready in any three refill containers 114 that sufficient to prevent the reactor vessel 102 from being refilled after a loss of coolant has occurred To bring overflow.

The flood tank 117 contain an amount of liquid that is sufficient to the free volume of the first containment to a level that is higher than any broken pipe that occurs in the primary cooling system. At the lower ends of the flooding tank 117 are tear-openable Discs 12!> Available. A pipe section 130 is arranged immediately above each tearable disc, which acts as a diffuser to quench the steam with flooding liquid, while steam overflows in the event of a loss of coolant.

In conduits 131 leading to the upper ends of the flood tank 117 are connected, pressure relief valves are switched on. Will occur when a The excess pressure fluid is discharged through these pressure relief valves when there is a loss of coolant Coolant diverted to a 20L deep well.

There are drainage lines with two in series at all the low points of the first enclosure arranged shut-off valves and a waterproofing device, namely at the Steam generator cells, in the lower and the upper chamber of the cell containing the reactor vessel as well in the upper and lower chambers of the cells, in which the pumps for the reactor coolant are located are located. All of these drain lines lead to a leak monitoring container. The top The chambers of the pump cells are connected to a separate container. The two containers are in turn connected to a room for storing radioactive waste.

These drain lines can be used to clear the system after a coolant leak has occurred to make it operational again. After all nuclear fuel from the reactor vessel into the Spaces for the storage of nuclear fuel has been transferred, the flood liquid is, with which the first enclosure was flooded, gradually withdrawn via the leak monitoring container, whereupon the liquid with the help of a facility for processing liquid radioactive waste is treated. After all the flooding liquid Once it has been peeled off, the steel inner surfaces of the first enclosure can be seen spray using the steam lines, which are primarily present for the purpose are to expel the atmospheric air and the equipment for the normal start-up of the reactor prepare. After performing several operations to spray detoxification solutions the facility can, to a limited extent, wash away the possibly radioactive surfaces be made available to carry out the detox in full. After performing this Detoxification can be used to estimate the damage caused by the loss of coolant and the Carry out repair work as required are to bring the system back into a state in which the power operation can be continued.

The enclosure 201 of the deep well is filled with highly borated water, in which the Boron concentration of that of the reactor coolant during the work for charging new Nuclear fuel is equivalent. After the reactor has been shut down for the purpose of introducing it again Nuclear fuel is the boron-containing water from the deep well to the room 202 for loading with Pumped nuclear fuel. After the completion of the loading work, the boron-containing water is removed the room 202 again drained to the deep well.

The deep well has an inner zone 203 and an outer zone 204 . according to Flg. 1 are separated by a concentric cylinder 205 made of steel, which extends from a point near the bottom of the deep well to a point which is slightly higher than the normal level of the boron-containing water during operation. The outer zone 204 serves as a heat sink for a high temperature fluid that is delivered directly to the deep well, e.g. B. when blowing off too high a pressure from the pressure generating device of the cooling system for the reactor, from the steam generators, from the first or second protective container or from secondary enclosures.

In the inner zone 203 of the deep well, the boron-containing water serves as a heat transfer medium for the decay heat during the period following a loss of coolant. This heat is given off to the cooling pond by the boron-containing water from the primary protective container. In the inner zone, a guide element 206 divides this zone into two ring channels. Cooling pipes 207 are arranged in the inner channel , which are connected to lines 208 which extend from the cells for the pipes of the reactor cooling system to the lower chamber of the cell 101 containing the reactor vessel 102 . The biological shielding under the reactor vessel 102 is graduated and provided with an annular space through which a flow can flow. Cooling coils 209 are assigned to the outer ring channel and are connected to lines 210 which lead to a cooling hole located in the open air.

In the event of a loss of coolant, the cell 101 containing the reaction vessel fills with the coolant vented from the reactor, the liquid overflowing from the refill containers, and the liquid discharged from the overflow containers. The heat circulation in the cooling tubes 207 causes sensible heat to be given off to the boron-containing water in the deep well. The thermal circulation of the water in the deep well causes the sensible heat to be transferred to the water in the cooling chamber, which is caused by thermal means. To circulate in the cooling coils 209.

The cooling coils also serve to transfer the sensible energy, which is transferred directly to the outer zone 204 of the deep well when the reactor system blows off at overpressure or if the steam generator is caused to blow off by too high a pressure. The thermal circulation of the water in the deep well through the cooling coils 209 then causes the heat to be transferred to the water of the cooling pond.

The deep well is provided with walls made of reinforced concrete, which offer additional biological protection while the reactor is in operation. The deep well is lined with sheet steel 211 , and a high negative pressure can be maintained in this during normal reactor operation.

Secondary protective enclosures 212 are arranged according to FIG. 1 directly above the cells 125 which contain the pumps for the reactor coolant. Manholes 213 with screwed-on double flanges make it possible to make the chambers 125, in which the pump motors are located, accessible for carrying out inspections, investigations and maintenance work. The required pipelines, electrical lines and control lines extend from the motor chambers through special openings in the enclosure above the pump motors 126.

The motor chambers 212 are supplied with air or an inert gas atmosphere via pipelines from the overlying enclosure. If the motor chambers are to be made accessible to personnel, air is supplied to them. To enable the reactor to operate, the air is replaced by an inert gas. The inert gas not only improves the transfer of heat from the pump motors to the fluid contained in the annulus, but it also prevents any other possible burning of the electrical lines for measuring devices and the control lines. In addition, the inert gas provides protection against burning of the lubricating oil of the pump motors both during normal operation and in the event of a loss of coolant. To prevent industrial accidents, the chambers for the pump motors are provided with armor 214 , which provides protection against flying parts of the pump flywheels in the event that the pumps are damaged.

According to Flg. 3 A secondary protective enclosure 215 is placed unnoticeably over the cell 107 in which the device for increasing the pressure is located. A manhole 216 with screwed double flanges makes it possible to make the cell 107 accessible for carrying out test, investigation and maintenance tasks. The required pipelines and the electrical lines for measuring and regulating devices extend from the cell 107 through special openings to the second. enclosure 215.

The pipelines 217 assigned to the pressure increasing device 108 and provided with safety valves are shown in FIG. 3 arranged so that the valves are accessible for maintenance from a platform arranged immediately above the manhole 216. The delivery lines that connect to the safety valves run via special openings 228 that surround them to the deep well 201.

The cell for receiving the pipelines which connect the reactor cooling system to the pressure regulating device 108 make it possible to keep the free space within the cells 107 under a high negative pressure. If the primary protective container is filled with air under atmospheric pressure when the repair reactor is switched off, the pipeline cell makes it possible for the personnel to make the neighboring facilities accessible, i.e. the steam generator, the pump housing, the container for refilling the reactor vessel, the flood tank and the like Reactor vessel 102.

According to Flg. 3 A second protective enclosure 218 is arranged immediately above the cell 109 in which the regenerative heat exchanger is located. This includes a manhole 219 with screwed double flanges, through which the enclosure for the regenerative heat exchanger is accessible so that test, investigation and maintenance work can be carried out.

Pipe connections between the regenerative heat exchanger and the non-regenerative heat exchanger extend through the secondary enclosure. The electrical lines for measuring and control devices also extend from the cell 109 through special openings to the second enclosure 218.

A stirring cell. which the reactor cooling system with

connects the regenerative heat exchanger HO, causes that the free space in this cell is kept at the same pressure as the other free spaces in the first enclosure. This pipeline cell, which is arranged on the side of the cell 101 for the reactor vessel facing away from the cell 107 for the pressure control device, makes it possible to make the adjacent devices accessible when the reactor is shut down; this includes the remaining steam generator, pump housing, refill tank for the reactor vessel, flood tank and the reactor vessel itself.

The secondary enclosures above the pumps for the reactor coolant are shown in FIG. 1 accessible via covers 220. Unauthorized opening of the first enclosure is thus impossible made that a high negative pressure between the bolted double flanges in the area of the manholes is present at the entrances to the cells.

If the reactor remains shut down for a longer period of time, it is possible for the personnel to use the primary To make the protective enclosure accessible for carrying out inspection and maintenance work. Before this happens, the free space within the Enclosure flushed through high-performance filters and beds made of activated charcoal. Between the vacuum lines the primary enclosure and the associated ventilation system, pipe sockets are installed, to establish a connection to the atmosphere for ventilation purposes.

Compared to the previous state of the art, the reduction in the volume and the high negative pressure in the primary enclosure lead to a considerable reduction in the air mass, over a factor of 400, which contains radioactive particles emitting gamma rays and which must be flushed out of the enclosure, when the reactor is shut down for fuel loading and / or other maintenance work. Operation under a high vacuum after a preliminary steam purging practically eliminates the remaining air which is subject to activation by neutrons which escape from the reactor vessel and in the atmosphere within the enclosure cause argon 41, oxygen 19, nitrogen 16 and tritium are formed.

The In Flg. The secondary enclosure 221 shown in FIG. 3 serves as a pipeline tunnel and Venillstatlon for pipelines that are connected to the steam generator in the associated cells. These include steam lines 222 and feed water lines 223. These pipelines emerge from the. Tunnel 221 to Flg. 3 using a set of the round pipeline enclosure. According to Flg. 2 there are intermediate walls 224 through which the relevant pipelines are led out of the reactor building to the outside. From the secondary enclosure 221 , ventilatation pipelines 225 extend to the deep well 204. These ventilation lines protect the pipe tunnel 221 from excessively high pressure in the event that a vapor distribution air is released. κ. These ventilation lines have in the vertical direction according to Flg. 7 such a length that they come into effect like parts of a U-tube barometer.

Also shown in Fig. 6 are vacuum lines 226 connected to the primary containment vessel.

laid in the pipe tunnel 221 . According to FIG. 2, there are steam injectors 227 with barometric legs and vacuum pumps which are connected to the vacuum lines 226 which lead out of the cells containing the steam generator. These devices are housed in a shaft that accommodates auxiliary devices and forms part of the reactor building.

According to Flg. 2, shut-off valves 229 are switched on in the steam and feed water lines in an extension of the pipe tunnel 221. The vacuum lines are similarly equipped with shut-off valves.

According to Flg. 6, safety valves and quick release valves are switched on in branch lines 230 of the steam lines 222 and distributed in suitable catfish in the pipe tunnel 221. The delivery lines for these valves lead to the deep well 201.

According to Flg. 6 there are locks 231 that can be used by the personnel, by means of which the pipe tunnel 221 can be made accessible. These locks 231 are located higher than the bottom of the pipe tunnel 221. If a pipe rupture occurs within the enclosure 221 , all of the liquid in this enclosure is retained and the resulting vapor is conveyed to the deep well 201 via pipes 225 (FIG. 6) submitted.

A protective effect is also brought about by the reactor building 301 , which is designed in such a way that there is a slight negative pressure in it during normal operation. The cells of the first enclosure, together with the associated secondary enclosures, the auxiliary equipment operating at low pressure, the equipment for disposing of radioactive waste, the rooms for introducing nuclear fuel and the equipment for operating the reactor are all housed inside the reactor building.

According to Flg. 4 to 6 have a circular plan and are made of reinforced concrete. The building has a roof 302 which is supported by the exterior walls of the building, the four steam generator cells 103, the four cells 113 for the refill tanks and the four cells 116 for the flood tanks.

A crane system 303 with a rectangular plan shape is also supported by the surrounding wall of the reactor building and the steam generator cells. According to Flg. 3, recesses in the cells in question, which are set back to the outside, form platforms for receiving crane rails 304.

Outside the round part of the reactor building there are two shafts intended to accommodate auxiliary equipment, which are, however, connected to the actual building and have the same strength. According to Flg. 2, a shaft 305 for receiving water pipes is arranged on the north side of the system. A further shaft 306 for auxiliary equipment is available diametrically opposite this shaft 305. The facilities supplied with water include the heat exchangers used to cool certain parts, the pumps and the feed water pumps. In addition, the shaft 305 according to FIG. S a passenger elevator 307 and a staircase 308.

A freight elevator 309 is present in the auxiliary equipment shaft 306 , and this shaft also contains a second staircase 308 as well

various operating and auxiliary devices.

The reactor building is accessible via the personnel lock 310 , which according to FIG. 4 is assigned to the shaft 305 for the water pipes. According to FIG. 4, the reactor building is also accessible via a lock 311 for introducing devices. This lock forms part of the shaft 306.

There are three floors or levels for the various facilities, which are separated from one another by intermediate floors made of reinforced concrete. Special openings are used to accommodate all pipelines, electrical lines, measuring and control lines, etc., which extend between the various floors and are led out of the reactor building. There are no passages for personnel between the different floors. Inside the reactor building, the different floors are accessible via the elevator shafts. On each floor there are mechanically interlocked double doors 310 so that the building is accessible to personnel from the passenger elevators. The device locks 311 make it possible to establish a connection between the freight elevators and the reactor building on each floor.

There are separate heating, ventilation and air conditioning facilities on each floor Air present. These devices are designed so that they constantly circulate the air, the The amount of supplementary air used is kept as small as possible. All of these facilities are designed to that they make it possible. In the area of the concerned Devices to maintain a low negative pressure. Any radioactive material that happened to be released and get into a room containing devices, are under regulated conditions via high-performance filters and beds of activated carbon removed after a sufficient decay period has expired Is.

According to the invention, attention is paid to the appropriate use of the free space which surrounds the "reactor island" within the reactor building. According to Flg. 4 and 5 there are spaces for charging the reactor with nuclear fuel. The free space according to FIG. 6 is used to accommodate equipment not endangered by radioactivity, and it can be used to carry out maintenance work. Electrical cables as well as measuring and control lines are from the chamber 121 . In which the device for driving the fuel rods is located, guided by steel pipes up to the floor of Figure 6; these steel pipes are cast in the concrete which forms the base of the space 202 for charging the reactor with fuel and the base of the spaces 313 and 314 (Fig. 2) for receiving spent nuclear fuel. Correspondingly, electrical cables and measuring and control lines are led out of the enclosures above the pump cells 212, above the cell 215 for the pressure increasing device and above the cell 218 for the regenerative heat exchanger via steel pipes which are cast into the concrete and which are themselves extend to the third floor. The one from Flg. 7 visible free space serves to accommodate reactor auxiliary devices and operating devices, including the devices for handling chemicals, ion exchange columns, cooling devices for shutting down the reactor, devices working with boric acid and other devices where a risk from radioactivity cannot be ruled out. The pipelines connecting these facilities to the reactor coolant system via the secondary enclosures are laid in tubular enclosures that are cast in concrete. The mentioned free spaces are also used to store radioactive liquid and to accommodate the facilities for handling radioactive waste materials. This includes facilities for the treatment of gaseous and liquid radioactive substances. There is also a room for storing solid radioactive substances.

According to FIG. 4, the zone for charging the reactor with nuclear fuel includes space 202 for introducing fuel, space 313 for receiving used fuel and a standby area 314. Gates 315, which are arranged on both sides of the space for introducing fuel, separate rooms 313 and 314 from room 202. Rooms 202, 213 and 314 are filled with water that is highly enriched in boron.

If the reactor is to be shut down for the purpose of populating it with fuel, the boron-containing water is drained from the space containing the reactor into containers which are present in the storage room for boron-containing water. After the flanged dome 121 has been removed, the flanged head 124 of the reactor vessel 102 is made ready for removal. The chamber containing the reactor is filled with the boron-containing water from the deep well 201 , while the head 124 of the reactor vessel is raised in accordance with the rise in the water level.

According to Flg. 2 Is a space 316 for holding new nuclear fuel appropriately arranged. After the completion of the loading operations, the top of the reactor vessel is lowered back onto the reactor vessel, while the boron-containing water is drained from the cell 101 in order to fill the deep well 204 again. After the head of the reactor vessel and the dome 121 have been reinstalled, the boron-containing water is pumped back into the reactor cell 101 from the storage containers for the boron-containing water. When the reactor is restarted, during which the reactor coolant is heated, the excess water is drained from the reactor part and stored in the containers for storing water containing boron until it is subjected to a treatment.

The space 313 for spent nuclear fuel and the standby space 314 are dimensioned overall so that they can accommodate at least 1-2 / 3 fuel fillings for the reactor. The spent fuel space 313 is used during normal loading operations, while the standby space 314 is used when all of the fuel supply is to be removed from the reactor core.

The spent fuel space 313 is connected to an adjacent cast pit 317 by a duct. In which a slide 315 is installed. Pit 317 can be emptied and used as a decontamination pit after the spent fuel is enclosed in a shipping container. After the detoxification, the shipping container is continuously removed from the reactor building on rails after opening doors 334 (panel 4). It is a

There is a track connection, not shown, which extends through the openings of the gates 334 into the reactor building.

According to FIG. 4, the charging chamber 202 and the fuel chambers 313 and 314 are assigned overflow positions s 318 , which serve to maintain a certain level of the liquid. The escaping liquid is directed to containers in the zone for storing the boron-containing water.

According to FIG. 4, there is a movable pressure 319 on the charging level, by means of which the used fuel can be handled and the reactor charged with new fuel. It is also possible to assign such a mobile bridge to each of the three rooms mentioned. is

There is sufficient space in the reactor cell 202 so that the core container 320 of the reactor and the internals 321 of the reactor can be stored underwater while new fuel is being introduced; the dome 121 and the head piece 124 of the reactor vessel are stored in a storage zone which is formed by the armor that was transferred from the space above the loading space 202 to the ready space 314 before the loading process.

Thermal convection cooling is provided for each of the three rooms mentioned so that the fission or decay heat that is given off by the used fuel in the room in question can be removed. According to FIG. 4, pipes 322 arranged in pairs are provided, which are in communication with the cooling chamber and extend in the vertical direction for each container. According to Flg. 4 there are horizontally arranged cooling tubes with wide ribs 323 , which connect the inlet and outlet lines connected to the cooling pond with one another. In order to increase the thermal circulation, the cooling tubes have a slight slope from the inlet in the direction of the outlet. The return lines leading to the cooling pond are also arranged higher than the lines by means of which water from the cooling chamber is fed to the lines for cooling the three rooms mentioned. Each of the three spaces is assigned a deflection element 324 which is adjacent to the cooling tubes. The deflection members are opposite the cooling pipes and extend almost over the entire height of the rooms in question, ie from a point near the floor of the room in question to a point which is slightly lower than the level of the boron-containing water. The water in the space in question, which is located in the channel between the deflection element and the wall of the space, is cooled, and the resulting increase in the specific gravity of the water causes thermal circulation to take place.

The level of the water in the cooling chamber is higher than that of the boron-containing water in the rooms mentioned. The water resistance will monitored by the concentration of boron In the water in the named rooms from tent to tent through an analysis.

According to Flg. 4, there are normally locked shutoff valves 322 in the open position to allow the cooler to be monitored. After closing these valves and after loosening the flanges on the lines that are above the water level in the rooms mentioned. Is it possible to raise the cooler and check and clean it? Since the water in the rooms mentioned has a high heat absorption capacity, there is enough tent available for such maintenance work without the risk of overheating of the rooms mentioned. The spaces 313 and 314 for used fuel can be provided with transparent covers in order to prevent the evaporation of trltium-containing water as long as no loading work is in progress. In addition, a shield acting as an armor is arranged over the space 202 for charging the reactor with fuel; this shield is used during power operation of the reactor in order to protect the reactor cooling system.

Flg. 6 and 7 show the supporting structure for the reactor part. This includes a foundation 325, which carries the reactor vessel 102 , as well as a reinforced concrete structure, which is assigned to the fuel charging space 202 . The cylindrical reinforced concrete wall 32fi, which encloses the deep well 201 , the foundation 327 for equipment, and the cylindrical wall 328 of the reactor building made of reinforced concrete form a supporting structure for all cells of the protective device and the parts arranged therein.

Inside the protective cell construction 120 made of concrete according to Fig. 3 alternate channels are each formed through which the primary protective cells are accessible, in addition to the manhole 216 of the cell 107 for the pressure raising means and the manhole 219 of the regenerative heat exchanger containing cell 109. The the deep well 204 accessible solubilizing shafts 232 to Flg . 6 show according to FI g. 5 manholes 233 , through which the four steam generator cells 103 are directly accessible. Stairs (not shown) are arranged in the shafts 232 in order to facilitate access via the manholes 233.

The access shafts 232 according to Flg. 5, 6 and 7 not only serve as access points to the primary enclosure and the deep well, but they also have other tasks to perform. During the operation of the reactor, the steel-lined shafts are used, which extend into the liquid in the deep well and end at a distance of a few feet of about 300 mm each from the bottom of the deep well, as can be seen from Flg. 3, serve as drainage lines for the numerous safety and pressure relief valves that belong to the reactor cooling system, the secondary side of the steam generator and the first and second protective enclosures. The pipelines 217 of the pressure control system, equipped with safety valves, according to Fig. 3 extend through an opening 228 to the adjacent access shaft 232. Overpressure valves 141 are arranged on the containers 114 for refilling the reactor vessel connected to the deep well. The pressure relief valves, which are connected in the pipelines 131 , which extend from the upper ends of the flood tank 117 , are also in connection with the access shafts and serve to protect the primary protective container against excessive pressure. Also an overpressure of the liquid in the annulus between

the first and second protective container can be eliminated by e i compound which leads via the access shafts to the deep wells.

According to Flg. 2 are access tunnels 329 at the top Ends of the vertically arranged cells are available to make the safety and pressure relief valves accessible make, which are arranged above the parts to be protected. The tunnels 329 are over tight locked doors 330 and stairs 331 (wing 4) easily accessible. According to Flg. 5 are tightly sealed Breakthroughs 332 present, which differ from the said tunnels extend down to the rooms containing certain facilities. the Tunnels 329 are protected against excessively high pressure in that ventilation ducts are present that are too closed lead to the deep well.

The reactor building can be completed with all internal concrete structures before the Parts of the reactor cooling system are delivered to the construction site. For erecting the reinforced cylindrical Concrete structures inside that make up the reactor building form, one can use slipforms. In addition to the openings in all floors lead to the reactor building in order to make the relevant facilities accessible to the staff make the roof of the reactor building too Provide openings. These roof openings, which are provided with closures 333 according to FIG. 3, are the Reactor vessel, the four steam generators, the four refill tanks, the four flood tanks and the assigned to both shafts making the deep wells accessible. The reactor building and the roof are designed in such a way that it is possible to accommodate a crane which is used to lift the parts of the reactor cooling system to be installed and, if necessary, to remove and replace defective parts.

The protective cells are made of factory-made steel jackets according to certain grid dimensions built up. The connections between the different cells are welded on the construction site manufactured so that a coherent first protective container is created, which is in a second protective container Is included. The plate-shaped head pieces at the upper ends of the upright jackets made of steel in the area of the protective cells and the roof locks are welded on the construction site after the parts of the reactor cooling system have been installed. Schadhaue parts can also be removed, if you open the roof locks in question by cutting off the plate-shaped heads. To When the part in question is renewed, the plate-shaped head is welded in again and checked.

At each roof opening, a steel-sheathed lock made of reinforced concrete is installed. the Matching flanges of the closures are for sealing with O-rings as well as with devices for applying a pressure and for tracking leaks. The closures are connected to the matching flanges by screws.

The passive protection device according to the invention is designed so that the critical parts of the system remain in place in the event of earthquakes and other acts of God. It is a sufficient one Strength guaranteed so that the system can withstand the forces of inertia that occur; to this The purpose is with the concentric cylindrical foundations, which are the base and roof panels connect with each other, as well as reinforced concrete or prestressed concrete for the ceilings of the various floors used on such a catfish that a monolithic Construction arises. The stability of the construction is also due to the massive concrete construction increased which the cells of the first enclosure, the second enclosures and the Form walls of the spaces for charging the reactor with fuel. The strength of the structure can if necessary, can be increased by the fact that between the cylindrical walls radial Arranges walls.

In the passive protection device according to the invention it is practically not necessary to have any Connect parts to sources for emergency water. Such connections from which in active protective devices to a large extent use is made, as is the state of the art are particularly at risk from faults such as those that occur in strong earthquakes. The only ones Connections that are used in the passive protection device of the invention are those to the pipes carrying out in the open water. However, these lines need after an industrial accident In the form of a loss of coolant inoperable for a period of several hours to be. Even if a pipe burst should occur in one of the feeding devices, the thermal The circulation would continue and the pipe tunnel would only fill with water that was added to the Im Has been taken from open water.

Furthermore, the passive protection device is protected against sabotage. This is due to the fact that the passive devices form an integral part of the overall structure and during normal operation are not accessible because there is a high negative pressure in the primary protective container.

The passive protective device can be designed in such a way that It is possible to arrange the reactor building underground, to embed it, to mount it on watercraft to store it or to arrange it submerged like an iceberg. In any case, the system is given a profile shape, which has a more pleasing appearance than a protective device that is almost completely over the Is arranged on the ground.

Flg. FIG. 8 shows a typical piping arrangement for a reactor vessel refill container, such as is used in a Pressurized water reactor is assigned to each of the four existing loops. Each container 114 for refilling The reactor vessel is connected to the reactor vessel 102 by reactor coolant lines 112. In the one or several safety spray lines 132 switched on are. Each of the safety valves 132 is equipped with two non-return valves 133 and one that can be remotely controlled Valve 134 equipped, which are connected in series. In the refill 114 are a or several jet injectors 135 installed so that they are below the liquid level. The diffuser part each jet injector 135 is arranged at the lower end of the respective refill container 114 and connected to a safety injection line 132. The suction chamber of each jet injector 135 is in Open towards the treated water in the refill container so that it is flooded by the water 1st. The nozzle portion of each jet injector 135 is connected to a manifold 136 which is in communication with a steam supply line 137, which the secondary side of the steam generator 104 with the

Refill container connects so that the pressure medium required for your operation can be fed to the jet injectors. In the steam supply line 137 , a flow restriction throttle 138, a rupture disk 139 and a remotely controllable valve 140 are interconnected. Instead of the tear disk 139 , a safety pressure valve can be switched into the steam supply line 137.

In order to protect the refill container 114 against excessively high pressure, pressure relief valves 141 are provided which are in communication with the deep well 201 via the access shafts 232 . A low power, positive displacement pump, not shown, maintains hydrostatic pressure acting on the treated water in each refill tank 114. A cooling device, also not shown, with cooling coils is used to keep the treated water in each refill container at a low temperature.

Furthermore, according to FI g. 8, a steam discharge line 142 is present, which leads from the secondary side of the steam generator 104 to the lower part of the refill container 114 , so that steam can be blown out of the steam generator. The quick release valves 143 connected to the vapor release lines 142 are actuated by the reactor control device. The pressure relief valves 141 prevent the refill container 114 from being subjected to excessive internal pressure during any steam venting operation that occurs when a pressure change is caused by a stepped or linear change in load.

F1 g. 9 shows the piping arrangement for the vessels 114 for refilling the reactor vessel 102 in relation to the steam generators 104 and the reactor coolant lines 112 in a pressurized water reactor with four coolant loops. It can be seen that the piping is arranged so that each steam generator 104 is connected to a refill tank 114 by a steam line 137 . Furthermore, the pipelines are arranged so that each refill container 114 is connected to the two reactor coolant lines 112 via safety injection lines 132; two refill containers 114 are connected to the four associated inlets of the reactor vessel 102 , and the two remaining refill containers 114 are connected to the associated four outlets of the reactor container 102 .

The containers 114 for refilling the reactor vessel 102 together with the flooding containers 117 form a device for storing the entire amount of radioactive coolant that is given off by the reactor during the life of the plant. When operating a nuclear reactor, it must be taken into account, among other things, that the concentration of tritium in the reactor coolant is constantly increasing. Tritium is an isotope with a long half-life, which is produced in considerable quantities in the coolant, mainly because neutrons react with soluble boron, lithium 6 and deuterium, and because some of the tritium diffuses generated in nuclear fuel by ternary fission. If the concentration of tritium in the coolant increases according to the operating time of the reactor, the concentration of tritium in the humid air, which is above the space 202 for introducing nuclear fuel and the space 313 for spent fuel during the work for loading the reactor, also increases Fuel increases with each such operation. As a result, the length of time personnel can be exposed to the ambient air is shortened, so it is important that the reactor coolant be diluted to lower the tritium concentration before the reactor is charged with fresh fuel. The tanks 114 for refilling the reactor vessel, the flood tanks 117 and the deep well 201 provide enough storage space within the protective device to repeatedly take up all the turbid water that has to be processed during the service life of the system. Thus, very effective shielding is required for the storage of the cloudy water, which is also subjected to a chemical treatment so that it can be used in the event of a loss of coolant. Long-lasting fission products that are in the liquid phase do not need to be released into the environment.

Flg. Figures 10 through 13 graphically illustrate the response of reactor protection devices and illustrate the advantages of the embodiment described above. In these graphical representations it is assumed that the volume of the reactor cooling system is about 337 m ³ , that there is a coolant quantity of about 240,000 kg in this room, and that the Köhlmift.e! a heat quantity of 77! χ! Ο ⁶ kcal is stored. An additional amount of energy of 25.95 χ 10 'kcal is available for delivery to the protective device within the first 5 minutes after the occurrence of an industrial accident for which the device is calculated. The operation of the protective device in the event of an industrial accident is described below; this is followed by a more detailed explanation of the graphic representations.

The response of the passive protection device of the invention to loss of coolant will be described below with respect to a first enclosure that for a back pressure of about 6.9 bar is designed absolutely. As an example is a pressurized water reactor selected with four coolant loops, the output of which in normal operation is 1000 MW amounts to. The stated values on which the construction is based are in a range that is suitable for the selected nuclear power plant is typical. Similar numerical considerations of a passive protection device They sat near all the other pressurized water reactors employ two or three coolant loops are available, as well as for all types of boiling water reactors:

In the reactor system chosen as an example, the coolant absorbs heat while it flows through the reactor vessel 102 , the coolant releases the absorbed heat to generate steam while it flows through the steam generator 104 , and finally it is again used by the coolant pump 106 for the reactor coolant circulated through said parts. The pressure generating device 108 maintains the reactor coolant at a pressure of approximately 145 bar absolute in order to suppress boiling of the coolant in the reactor coolant. In the chemical treatment and volume control of the coolant in the reactor system, the regenerative heat exchanger 110 is used as a preheater, by means of which the coolant entering is heated with the aid of the coolant exiting. This reactor plant, whose

Parts connected by the pipelines 112 contain about 240,000 kg of the coolant, and an amount of energy of about 77 χ 10 * kcal is stored in the coolant at a weighted average temperature of about 302 ° C.

The primary protective container is designed in such a way that there is a free space in it on the order of 2830 m '. The air present in this space is initially expelled with the aid of steam injectors, and a total pressure of less than 0.138 bar is maintained in said space with the aid of the vacuum pumps connected to the deep well 201.

The flooding tank 117 within the first enclosure containing a total of about 1,365x10 'kcal liquid held by cooling to a temperature of about 10 ⁰ C. At a total pressure of less than about 0.138 bar absolute, a total freeboard is maintained, which is a little over 140 m ^{J in} the case of the flood tanks.

Each of the containers for refilling the reactor vessel Is dimensioned so that it can hold about 136,000 kg of treated water at a temperature of about 10 ° C and under a hydrostatic pressure of about 24 bar absolute. The secondary side each steam generator contains a liquid quantity of about 45 450 kg, the energy content of which is about 12.6 χ 10 ' kcal. The steam generators are operated with the nominal load at a pressure in the range of approx 62 bar absolute operated. The tear discs in the Steam supply lines are designed so that they are torn open when the pressure In the relevant steam generator on the secondary side is about 45 bar higher than the pressure in the containers for refilling the reactor vessel. If there are safety pressure relief valves instead of the tear-off disks, are these designed so that they are also at respond to a pressure difference of about 45 bar and open. The slide valves in the water injection systems and the steam supply lines remain during power operation of the reactor opened.

Under the stated conditions on which the construction is based, the tear discs or hold the safety overpressure «5 used in their place valves withstand the pressure fluctuations that occur with a stepwise or linear change in the load, without tearing or opening taking place. The hydrostatic pressure of about 24 bar absolute, the in the refill containers prevents it from reaching Chen the pressure difference of about 45 bar to which the tear disks brw. the safety overpressure valves set sln.J, but with the exception of cases In where there is a loss of coolant.

The construction described is based on the assumption that a loss of coolant is caused by the rupture of the largest pipeline 112 of the reactor cooling system. In the event of such a pipe break, the coolant is blown off unhindered at the two open ends of the broken pipe. Most of the coolant is blown off within less than 10 seconds.

Blowing off the coolant at the pipe break causes the free space inside the first protective container to be pressurized. When a pressure of approximately 3.45 bar absolute is reached, the tear disks 129 are likely to burst, whereupon steam flows over into the flooding container 117 . The openings that can be exposed by the tear-off disks 129 are designed in such a way that they act as ejector nozzles, and they are arranged at such a distance from the diffuser pipes 130 that suction chambers are present at the ends of the pipes, the pipes 130 themselves acting as diffusers Effect come to condense the overflowing steam.

The existing freeboard of about 140 m ^J enables a quantity of steam of about 68,200 kg to flow over into the flood tank 117 . The substances in the primary protective container that are absolutely non-condensable at the low pressure of less than 0.138 bar are entrained by the steam and likewise transferred to the flooding container 117. While the flood tanks are filled by the transferred fluid and the thermal expansion of the existing fluid, the continuing blow-off of the coolant causes the pressure in the first protective enclosure to continue to increase.

As soon as the continued venting from the reactor cooling system leads to a reduction in the pressure of the In Cooling system still carries existing coolant to below a value of about 24 bar absolute, The non-return valves of the safety spray lines are activated automatically as a result of the pressure difference opened. The hydrostatic pressure of about 24 bar absolute, which is used in the containers for refilling the Reactor vessel prevails is quickly reduced that treated water from the refill Is injected into the reactor.

Blowing off from the reactor system over the pipe break point causes a further reduction in the pressure of the coolant that is still present. If the If the pressure in the reactor falls below a value of about 17.25 bar absolute, the also decreases Pressure on the jet injectors in the containers to refill the reactor vessel on one below this Worth lying value. As a result, a build-up occurs on the rupture discs in the steam supply lines Pressure difference of about 45 bar absolute, so that the tear-off disks burst.

The rupture of the rupture discs causes steam to flow from the secondary side of the steam generator to the Jet injectors flows. The steam flowing through the injector nozzles pulls treated water out of the Refill containers with; the steam and water are intimately mixed together while they are the Flow through the diffuser, so that a homogeneous solution is created, which consists of treated water and composed of neutron poison dissolved in it. The openings of the flow restriction throttles are like this sized to control the supply of steam to the injectors during most of the Steam blow-off process the speed of sound is reached. This regulation of the steam flow the injector nozzle ensures the required efficiency of injecting treated Water from the refill containers into the reactor system.

The further easing of the pressure of the still Im The coolant present also causes the back pressure in the free space within the reactor first enclosure increases. As soon as a counter pressure of about 6.9 bar absolute in the first enclosure is reached, the further venting from the reactor is terminated by a pressure equalization. After When the coolant has been blown off, the jet injectors, which are designed for a filling speed

speed of about 150 mm / s are designed, continued until the reactor vessel. is filled again and excess Liquid appears at the pipe break point. The steam generators cause on their secondary side that the required pressure medium is available for the operation of the jet injectors until the pressure on the Secondary side of the steam generator is approximately equal to the counterpressure prevailing in the enclosure. After the pressure equalization has been established, the refill containers Im still contain a small one Amount of treated water.

Alternatively, the safety pressure relief valves, which are present instead of the tear-off disks, can be used to the amount of fluid available on the secondary cable of the steam generator for the safety injection to limit. The supply of steam to the injectors continues until the flud is on the secondary side of the Steam generator has been reduced to the return pressure to which the safety pressure relief valves are set. This reset pressure is chosen so that the injectors have a sufficient amount of steam is supplied to the reactor vessel again at the reduced back pressure in the enclosure to fill.

The termination of the reactor coolant venting also terminates the overflow of vapor from the enclosure into the flood tank 117. The static pressure gradient of the liquid in these containers causes the direction of flow at the exposed by the tear disks Orifices reverses as soon as the overflow of steam is stopped. The enclosure is thereby filled with liquid that liquid under the action of gravity from the flood tanks exit; here the flood tanks emit a volume of liquid that is almost equal to the free volume Volume of the first enclosure is. To these catfish the coolant lines of the reactor are completely submerged so that they are with the flooding liquid be filled again.

After flooding, and after the temperatures in the primary enclosure and the reactor vessel have approximately equalized, the weighted average temperature of the total amount of liquid is about 71 ^° C. This temperature gives the total energy stored in the coolant of about 77 χ 10 'kcal and the energy of about 50x10 'kcal stored on the secondary side of the steam generator plus an amount of energy of about 26x10' kcal, which is stored energy that comes from the nuclear fuel, the internal structural parts and the components of the reactor, as well as the decay heat which is released during the first 5 minutes after the accident at work. At around 71 ° C, the vapor pressure in the reactor cooling system is lower than the sum of the pressure of the atmosphere in the enclosure and the static gradient of the liquid above the pipe rupture point; therefore, liquid can flow into the reactor in order to fill the system again up to the level of the flooding liquid.

Since in the event of a loss of coolant, the nuclear fuel is continuously cooled, and since the one described Safety injection takes place, through which the reactor vessel within a few minutes after When the broken pipe is refilled, the nuclear fuel is prevented from melting. The amount of from the Fission products escaping from fuel are limited to the amount that is released for a short time when a mechanical cladding is damaged. This releases the fission products limited, which are walled into the empty space between the fuel and the cladding. the short-term release is limited to a few percent of the In the form of noble gases and iodine compounds available fuel. This released amount turns out to be small when compared to the amounts compares which are considered permissible according to the current state of the art.

If a loss of coolant occurs, the primary reservoir is only for a brief period Tent less than 5 min at an elevated pressure. All substances that escape from the first container are for the most part retained by the liquid in the second container. All fabrics that are about the openings in the containers escape remain trapped in the secondary enclosures. In addition, there is enough in the primary container Amount of flooding liquid is present so that essentially all of the fission products are dissolved which escape from the fuel for a short time.

After flooding, the liquid, which has a temperature of around 71 ° C, is now the first Container flooded, a heat absorption capacity that is sufficient to absorb the heat of decay that is generated during the first hour after the industrial accident without the pressure in the first Container increased above atmospheric pressure. During this period of time, the The rate at which failure heat is generated is significant. The passive heat transfer device is designed in such a way that it absorbs the decay heat at the rate of generation transmits that is available after the first hour has elapsed, d. H. with about 47.4 χ 10 'kcal / h. This requirement of heat transfer In fact, it is even less if one takes into account the heat transfer to the environment, which takes place during the first hour. The passive heat transfer devices, in which with the Coupling flows in the deep well as well as in the annulus of the container are worked accordingly the rate of transfer of the decay heat in the event that the flooding liquid In the primary container at a maximum temperature of about 93 ° C and the water in the The maximum outside temperature is around 38 ° C. Under these conditions the Vapor pressure In connection with the pressure of the non-condensables in the primary container below maintained at atmospheric pressure, so that an escape of substances from the protective device after Industrial accident is prevented.

In the stored flooding liquid, the liquid for refilling the reactor vessel and in the liquid in the annulus between the first and second protective containers are different Chemicals released as neutron poisons, oxygen getters. Getter for fission products and means for Lowering of the freezing or freezing point come into effect. As neutron poisons z. B. Boron, cadmium and hafnium in question. In addition to operating the primary tank under a high Negative pressure and the degassing of the liquids can be used as oxygen gel additives such. B. Hydrazine and sodium sulfite. As a getter for SoaltDro-

dukie are ζ. B. Sodium Hydroxide and Sodium Thlosu! - fat suitable. In order to lower the freezing or freezing point, one can use numerous together related alcohols,:. B. Ethylene glycol, use.

These chemical additives have to perform a specific task in the event of an industrial accident. the Neutron poisons prevent the nuclear fuel from reaching the low liquid temperatures after the Accident at work becomes "critical".

The oxygen gels are used to remove the radiolytic oxygen, the after the industrial accident as a result of the decomposition of water. By eliminating the oxygen prevents an explosive concentration forms with hydrogen produced by radiolytic means. One can do one of the liquid celts Add amount of absorbent sufficient to bind all the oxygen that is released after Industrial accident is generated, so that practically the discharge of radiolytically released Oxygen to the atmosphere in the containment is prevented. It also turns the fuel on a temperature which is considerably lower than the temperature for spontaneous ignition of a Hydrogen-oxygen mixture, so that also a hydrogen combustion by the flooding of all possible ignition sources is prevented.

The flooding liquid and the liquid for refilling the reactor vessel can almost all Pick up fission products in dissolved form. In addition, dissolved chemicals can be used that combine with the fission products, so that stable Connections arise. This gives additional security that after the industrial accident no fission products can develop from the enclosure.

The means of lowering the freezing or freezing point make it possible to keep the liquids used in the protective device at low temperatures to hold without the danger of solidification into a massive block of the Elbe. By lowering the freezing point is the heat absorption capacity of the liquid brought to a greater density increased, so that after the industrial accident there is an even lower pressure in the enclosure adjusts.

The special features of the passive protection device according to the invention and the superiority of the protection device over known reactor protection devices are shown below with reference to the graphs shown in Figs explained in more detail.

If the highest pressure intended for an industrial accident is set higher, the result is accordingly Flg. 10 a considerable reduction in the free volume that is available in the first container got to. If the pressure to be allowed in the enclosure in the event of an industrial accident, i. H. the back pressure In the first container, raised, according to Flg. 11 a considerable increase in mass of the reactor coolant, which is kept in the liquid phase

As mentioned, the invention is intended to provide a protective device be created, which with the help of passive facilities enables a sufficient To bring about cooling, so that if there is a loss of coolant, overheating and possibly the Melting of the nuclear fuel is avoided. at a protective device that is exposed to full pressure and that works in dry mode is required an excessively high back pressure for this purpose.

The transfer of steam into the overflow tank serves, according to the invention, in comparison to a device operating under full pressure to achieve a reduction in stress. The overflow of steam provides Compared to the Energy transfer in devices working with steam known type has the advantage that per unit weight of the coolant, about twice as much energy can be transported on average. at the use of overflowing steam remains in the reactor vessel with the protective device according to the invention passively back an amount of coolant sufficient to cause the fuel to overheat impede.

The known protective devices require active coolant injection devices which are used to refill the reactor vessel with coolant . If these active devices fail, the fuel will melt to a significant extent within a few minutes of the occurrence of a pipe rupture and refrigerant leak.

If you compare Flg. 12 with wing. 10, it can be seen that when steam overflows to the Überflulungsbehäliem gets by with a significantly lower print volume. To get the coolant Im To hold back the area of fuel, moderate back pressure is applied, thus excessive Blowing off from the reactor vessel is prevented. In addition, the free Voluii.jn In is the primary Enclosure limited so that the coolant mass in the first container at the highest pressure at an industrial accident is not excessively large.

With regard to the illustration of the blow-off of coolant in FIGS. 11 and 12, it is assumed as a precaution that that in the first container the ratio between liquid and vapor is the same as In the reactor vessel. In practice, however, most of the coolant that is blown off consists of a liquid and a vapor phase together, se that a larger amount of liquid is retained in the reactor than one would have to assume from FIGS. 11 and 12. In Flg. 12 are thus the pressure and Volume values that are required when using coolant To be retained in the reactor, carefully prepared.

In the case of the passive protective device described, all substances that are not required are located outside the primary container, so that the dimensions of the container can be kept as small as possible to the required relationship between the pressure and the volume to be achieved at the coolant In the case of a Loss of coolant Maintained near fuel will. These measures include the extraction of air in addition to the relocation of all auxiliary equipment and supporting constructions to the outside. The suction of air up to the generation of a high Vacuum makes it possible to provide the outer surfaces of the reactor cooling system with thermal insulation. All of these auxiliary devices, e.g. B. the means for quenching the pressure increasing device, the Equipment for spraying the container, the water pipes, the outlets for hot and cold Flude and the equipment for the containers which blowers, filters, dryers, cooling coils, pipe

lines, measuring devices and control devices are either located outside the primary container, or their use can be dispensed with. Other auxiliary equipment, e.g. B. the reactor construction crane, the fuel charging bridge and the Facility Cart For handling fuel as well as the facilities for operating the reactor vessel are removed from the first enclosure arranged that they are accessible at all times for maintenance purposes within the reactor building. Outside of the first container, the structures made of solid concrete are also arranged, for. B. interior walls, False ceilings, supporting structures for devices, e.g. for parts of the reactor cooling system, the biological shields, the armor to protect against flying debris, the walls of the Space for charging the reactor with fuel, the walls of the channels for fuel transport, etc. and there are also the openings of large diameter for exchanging equipment parts outside the first enclosure. The facilities just mentioned are among those known up to now Protective devices for pressurized water reactors usually arranged inside the protective device. The arrangement of these parts outside the primary container forms a further feature of the invention passive protection device.

In that the said devices are arranged outside the primary container. Is it possible, to reduce the volume of the interior of the protective device so much that you can use the passive protective device Small-diameter rows forming part of the primary enclosure can connect. The cell diameters are compared to the corresponding diameters at known protective devices for pressurized water reactors reduced to about a fifth to about a tenth. With such a reduction in the cylinder diameter of the protective device to a fifth or less, it is possible to five times or more the maximum pressure permitted in the event of an accident at work to increase the wall thickness of the protective device without the need for the same materials to enlarge.

The savings achieved by applying the invention to a passive protection device can be readily seen when one looks at the free spaces within the protective devices known type for nuclear power plants that im same Working power range, compare with the free space that is available with a passive protection device is needed according to the invention. The values of the space requirements are below for various Constructions put together.

Full pressure (dry operation)

Eliminate steam with the help

of ice

Eliminate the steam with help

of water

Passive protection device

(Back pressure 6.9 bar absolute)

73 900 m ^!

34 00OrV ¹ 7 87On '2 83On ^J

55

This considerable reduction in the dimensions of the protective device leads to a considerable relief the construction of a passive protection device. That included in the first enclosure small air volumes can be achieved with the help of the steam jet

60

65 tors easily within voh two hours drive out. Low pressure steam can be used for this purpose. A high vacuum of less than about 0.138 bar absolute can easily be maintained with the aid of a vacuum pump, the delivery rate of which is about 57 l / min; the leakage losses that can be compensated by such a pump are higher than the current range of 0.1 to 0.5 * per day. The delivery side of the vacuum pump is in connection with the deep well. Furthermore, the first container can easily be ventilated for carrying out maintenance work by using pipe fittings to connect the ventilation system of the reactor building to the vacuum lines which lead out of the first container.

The presence of a small enclosed space in the first container makes it easier to retain the liquid coolant in the reactor plant. If the enclosed free space is reduced, only a correspondingly smaller amount of the coolant can be accommodated in the first container, and this increases the amount of the coolant which is retained in the reactor. If the counterpressure prevailing in the container is increased, the amount of coolant that is present in liquid form also increases; this applies to both the reactor and the first container, in which the volume cannot be changed. Since there is provision for steam to overflow into the flood tank during the blow-off of coolant in the event of an industrial accident, there is greater latitude with regard to the definition of the tank size and the back pressure. The overflow of steam into the flood tank also reduces the enthalpy of the remaining coolant. Such a reduction in enthalpy leads to a greater part of the coolant being retained in liquid form at the set back pressure than would be the case with a greater enthalpy. These basic facts also lead to an increase in the latitude in the design of the protective device, and they allow an optimization of the transfer of steam, the free space within the container and the back pressure so that the nuclear fuel is always effectively cooled even if a loss occurs Coolant enters. These constructional aspects are the graphic representation in Flg. 12 is based.

Among the other points to consider for laying down the free space in the container and the design pressure are decisive, include accessibility to carry out inspection and maintenance work when the vehicle is switched off Reactor, the passage cross-sections required for blowing off coolant and flooding the Protective device with flooding liquid in such a way that the reactor cooling system passively again is filled with coolant. When dimensioning the primary protective container, it may be desirable to have more Provide space for testing and maintenance work than can be agreed with the requirement that the Nuclear fuel should be kept flooded by the coolant. For a larger size container the amount of coolant blown off may prove to be insufficient. According to the invention Passive safety injectors Inside the first container used to add make-up liquid To be injected directly into the reactor.

Furthermore, it may be desirable to design the first container for a pressure which is lower than that Design allows to ensure that the fuel remains submerged in liquid coolant. According to of the invention, the device for refilling the reactor vessel is also used to the To increase the amount of coolant that is kept available at the lower back pressure to keep the fuel completely submerged.

The treated liquid in the containers for refilling the reactor vessel is degassed with the aid of an excess chemical deaerating agent which is in solution and serves to remove the υ oxygen generated by radololytic routes when the flooding liquid is used. This is a decisive improvement over the prior art, according to which an inert gas is used to inject liquid. A liquid that is pressurized by means of an inert gas becomes saturated with the gas. During an injection process to achieve a protective effect, degassing takes place, which impairs the process of refilling the reactor vessel. In particular in that the density of the liquid 25 · ⁸ Celtic changed in the area of leading to the reactor vessel FaIIeI-tung.

The use of the treated liquid under the hydrostatic pressure in the refill containers offers a further advantage. The hydrostatic pressure in the refill containers and the bursting pressure of the rupture disks in the steam lines that are connected to the secondary side of the steam generator can vary between the different refill containers, so that the reactor vessel can be refilled better. This feature also represents a decisive advantage over the previous state of the art, according to which an inert gas is used for the passive injection of liquid into the reactor vessel. Every change in the electrical spray pressure or the pressure loss in the pipelines leading to the reactor vessel leads to changes in the injection speed and the duration of the injection process. Any change in the injection tent further adversely affects the liquid density or the static pressure gradient in the fall line leading to the reactor vessel, while the various accumulators empty and the gas bubble in each container above the liquid passes through the fall line to the reactor vessel.

The passive protective device according to the invention offers the required protection which makes it possible to prevent an inadmissible increase in the temperature of the nuclear fuel in the event of a loss of coolant. In summary, it should be noted that the protective device works in such a way that a back pressure is maintained in it which is high enough to stop the blow-off of the coolant under conditions under which an amount of coolant remains in the area of the fuel which is sufficient for effective heat transfer. A rapid passive injection of treated liquid takes place through all nozzles leading to the reactor vessel with the exception of the broken pipeline in order to fill the reactor vessel so that the removal of heat is not interrupted. Passive heat transfer cels are used to eliminate the decay heat after the occurrence of an industrial accident. The optimization of the counterpressure to be provided constructively forms part of the design on which the nuclear power plant is based.

In the protective devices known up to now, in which active safety devices are present, the following phenomena occur, which are due to the fact that the nuclear fuel exposed to an excessively high temperature rise for a prolonged period of time:

Embrittlement of the lining from a Zlrkonleglerung;

Fuel swelling as a cause of pipe blockages;

Melting of brazed joints and alloys with a low melting point, e.g. B. Silber-Indlum-Kad.-nlum; Swelling of elements made of boron carbide; Exothermic reactions between metals and Water or steam;

Burning of the hydrogen released by reactions between metals and water; Reactions between uranium oxide and the zirconium alloy;

S: melting the nuclear fuel with the release of large amounts of fission products; and sagging of molten nuclear fuel.

The passive protective device offers protection against processes taking place in the reactor at high speed , which lead to a sudden increase in pressure, which the numerous overpressure and safety valves of the pressure increasing device are unable to cope with. Such a process can be caused by faults of a known type that make automatic shutdown of the reactor impossible. This educational effect is provided by tear-off disks, which are arranged in accessible channels in the area of the inlets of the steam generator. These tear-off disks are designed in such a way that they burst at a certain pressure which is 10% higher than the maximum permissible operating pressure of the safety valves specified for nuclear power plants by the relevant regulations.

For example, a pressure surge leads to the maximum operating pressure of the reactor cooling system by 15 to Exceeds 20%, causing the rupture discs In the accessible canals. This process leads to a regular loss of coolant in those parts of the reactor plant in which this is the least likely to cause disruption. Of the The reactor is protected by steam-receiving spaces in the area of the reaction zone, and it becomes complete turned off by the liquid containing the neutron poison, which In the reactor vessel from the Refill container is injected. The remaining parts of the passive protection device come during the total duration of the malfunction In the same way as in the case of a loss of coolant.

It is possible to mimic a burst pipe for experimental purposes in order to determine the effectiveness of the passive Proof of protective device. For this purpose a tear disk, which is sized so that it can makes it possible to imitate a broken pipe to the desired extent, in a walk-in channel of a Built-in steam generator. The tear disk is designed in such a way that it is torn open when it is pressed.

which is the normal operating pressure of the reactor coolant exceeds, but is lower than the pressure to which the pressure relief and safety valves are normally set are set. While the reactor is in operation, a tear disk is torn open at an inlet port to imitate one Loss of coolant in a hot leg, while the bursting of a tear disk in an outlet channel serves., a cooling medium loss in a? to imitate the cold leg.

The passive protection device according to the invention also offers protection against other types of Industrial accidents that occur according to the current state of the art in the construction of protective devices must be taken into account.

Firstly, there are operational disruptions, which lead to excessively high pressure in the area of the reactor cooling system. This includes an uncontrolled Retraction of the control rod assembly, a sudden seizure of the rotor of a reactor coolant pump, which leads to failure of this pump, disappearance of the external load, and the like. Power operated Pressure relief valves, the pressure relief valve are assigned, allow a blowdown to the deep well for the purpose of a Bring about pressure reduction. The heat sink formed by the deep well is so dimensioned that you The heat absorption capacity is sufficient for the assumed industrial accidents.

Secondly, this includes malfunctions on the secondary side of the steam generator for a short time can lead to an excessive increase in pressure. This includes the loss of the external load, the breakage a steam generator pipe, the breakage of a steam pipe and the like. Enable quick steam release valves it, the too high pressure by blowing off to the deep well, to the containers for refilling the To eliminate the reactor vessel and the turbine condenser. Blowing off steam into the environment, in which possibly radioactive substances are released is just as unnecessary as in the to now common constructions.

The passive protection device offers complete protection against all types of burst pipes where the refill-Lelstung of the filling pumps is exceeded, the to the facilities for handling of Chemicals and volume control. Furthermore, the passive protection device offers protection Leaks that change in the course of the tent, and where there are e.g. B. is a hairline crack, through which initially only small amounts of liquid escape, which however may quickly become too grows out of a complete burst pipe.

The primary container includes facilities to enable loss to occur Quickly detect coolant and the location of the leak before the break can enlarge. These devices serve, among other things, the fluid sucked out of the enclosure at the inlet of the Vacuum pump to condense and filter. The evacuated fluid is checked for the presence of Radioactivity as well as of carried liquid monitored; a method is used here in which an electrode or spark plug is used.

The coolant escapes in the form of steam, and the greater part of this steam is carried by the cold Wall condenses, which is formed by the cooling water in the annulus of the enclosure. That Condensate flows to one of several low-lying drains with which the Steam generator cells, the upper and lower chambers of the ZsIIe for the reactor vessel and the lower ones and upper chambers of the pump cells are provided. At each drainage point there are electrodes for Follow-up of leaks.

Constant monitoring of the protective device for leaks is ensured by the ring-shaped Water space between the first and the second protective container made possible, also by the water seals on the pipelines leading out of the protective device and in that the various Breakthroughs in the protective device are acted upon by an inert compressed gas. Every escape of coolant in the free space within the first container is demonstrated by the facilities which are available to track losses of reactor coolant.

The imminent occurrence of damage to the reactor cooling system can be determined more easily if the outer surfaces of the parts of the cooling system are not provided with thermal insulation. When the reactor is shut down, these external surfaces can therefore be checked quickly. Since there is no thermal insulation, it is also possible to carry out remote monitoring with the aid of television cameras, borescopes and the like while the reactor is in operation.

It should be noted that the presence of a small, externally closed free space in the first protective container facilitates flooding of the reactor in that it is possible to the first To completely fill the protective container, whereby there is a guarantee that the reactor cooling system is completely again is filled. Since the reactor cooling system has no thermal insulation, the ones made of metal form Walls effective heat conduction paths to transfer the stored energy, which after the Blowing off is still present in the reactor, and in addition, the heat can be removed here, which is during Shutting down the reactor is generated by gamma radiation. The chosen arrangement of the flood tanks makes it possible to keep a sufficient amount of liquid ready and the flow at a low level Maintain temperature so that the flood liquid has sufficient heat absorption capacity possesses and makes it possible according to FIG. In the first Protective container to restore a high vacuum or a low vapor pressure. That fact stands in contrast to the protective devices known up to now, in which within the protective device increased pressure is maintained for several days after an industrial accident.

The presence of a small, externally closed space in the first protective container leads to an increase in the operational safety of the passive protection device, in which the combustion of hydrogen released by radiolytical pathways is prevented. This hydrogen is created by the Decomposition of water due to the high intensity gamma radiation in the reactor vessel. That Burning of the hydrogen is prevented by the removal of the oxygen; the little first Protective container is brought to a high negative pressure by pumping out air, leaving only traces left behind by oxygen; the concentration of oxygen in the flood and top-up liquid is released, a mechanical vent

treatment as well as by chemical ventilation, as this also removes the last traces of dissolved oxygen are eliminated; Besides, the flood liquid gets a lot of the chemical Venting agent added sufficient to keep the flooding fluid completely off the Radolytlschem way to free released oxygen; for example, sodium sulfite is used for this purpose Present at 400 ppm. It also prevents the low temperature of the coolant after the flooding, the boiling of the coolant, and the stripping off of the radiolytic route Oxygen and hydrogen are prevented from causing an opposite reaction to occur promote, be! which the rad! o! yt! sch generated gases are bound again; continues to cause the low Temperature that the radiolytically formed hydrogen is kept below its ignition temperature will.

The overflow liquid contains chemical additives to dissolve the decomposition products promote so that there is assurance that they will be withheld. An alkaline borate solution called sodium thlosulfate contains, causes iodine compounds to be retained. An added benefit of the The use of alkalis consists in adjusting the pHh value so that corrosion is limited will.

The alkaline borate solution also acts as a neutron poison. There is a sufficient one Amount of boron available so that after flooding and refilling the reactor cooling system the Boron concentration in the entire liquid filling of the primary protective container and the reactor 2000 ppm. With this relatively low boron concentration, there is no danger of crystallization.

The invention can be applied to nuclear reactors, where light or heavy water, liquid metal and / or molten salts are used. Since there is more experience available with regard to light water breeder reactors, and since it turns out to be has proven necessary to build such power plants near cities, there is an important one The feature of the invention is that it enables such systems to be built in an economical manner and use them in the way you want for cities within to build a radius of about 15 km. Such light-water breeder reactors arranged underground or under water can be easily created using the invention.

According to the invention, particular care is taken to prevent the escape of radioactive substances. With the novel use of a high vacuum in accordance with the invention, it is now possible to close a reactor both during normal operation and during a loss of cooling medium protect and, in particular, remove the heat generated after an accident at work. The invention allows. To train nuclear reactors in a particularly expedient way, since the free space that is inside of the device required between the inner and outer chambers is very small. what made Is very desirable for reasons of economy. At the same time allows the device according to the invention the necessary biological protection.

In accordance with the foregoing description, the invention has its full scope; As part of the Various modifications can be made in the invention.

For example, you can train the cells of the primary protective container so that one through concrete There is a supported steel primary tank; In this case it is not necessary to do a second one Provide a protective container and an annular space filled with water.

With the development of water-cooled engines, it is possible to reduce the number of chambers. In which a gaseous atmosphere must be present for the transfer of heat; this applies e.g. B. for the motors that drive the reactor coolant pumps.

It is possible to have all the steam generator cells In To subdivide chambers in order to further reduce the free space in the first protective container considerably; a steel membrane is used here, which is sealed with Effect is welded to the pipe wall of the steam generator and the lining of the cell, in addition, To divide each steam generator cell into two chambers.

One could design the deep well so that the second set of heat exchanger assemblies would not be in the deep well, but rather in a cool tale located in the open air.

It is also possible to go to the deep well the use of a coupling fluid for heat transfer and the second set of To dispense with heat exchanger arrangements; If there is a loss of coolant, then sensible heat is generated the flood fluid flows directly through the first set of heat exchanger assemblies to the Water released in the cooling pond.

Finally, it is possible with the flood tanks to reduce the freeboard considerably by making sure that when too high a The non-condensable substances carried along by the overflowing gas via the pressure relief valves the flood tank will be delivered to the deep well.

In addition 12 sheets of drawings

Claims (15)

Patent claims: 1. Nuclear reactor power plant with a reactor assembly which has a reactor core containing nuclear fuel, at least one steam generator which is connected to the reactor assembly via a first connection and through which a reactor coolant of high temperature and high operating pressure can flow, which is essentially constant under normal conditions , as well as with at least one container for cooling liquid, which is connected to the Rsaktorbaugruppe via first pipes, is exposed to a pressure below the operating pressure of the reactor coolant and is arranged with the reactor and the steam generator within a sealing enclosure, the first pipes of the reactor assembly being under pressure Always supply standing coolant when the operating pressure is sufficiently reduced due to an accident-related loss of reactor coolant and a second predetermined pressure difference between the coolant and the reactor coolant in the Reactor assembly is brought about, which is smaller than the first pressure difference between the cooling liquid and the reactor coolant under normal operating pressure, characterized in that second pipes (137 ) connect the steam generator (104) to the Kühlfiüsslgkeltbehälters (114) , and that after reaching a third predetermined pressure difference between the cooling liquid and the steam In the steam generator (104) under a relatively high pressure steam is supplied to the Kühliquidlgkeltsbehaiter (114) through the second pipelines (137) in order to apply a pumping force to the cooling liquid so that the fuel of the reactor core containing part of the reactor assembly (102) is completely filled. 2. Nuclear reactor power plant according to claim 1, characterized in that the cooling liquid tank (114) is normally closed and contains water with a neutron poison as the cooling liquid. 3. Nuclear reactor power plant according to claim 2, characterized in that the neutron poison is present in such a concentration that, when the steam from the steam generator (104 ) displaces the cooling liquid from the cooling liquid container (114) by the volume of the reactor assembly ( 102), which contains the fuel and the reactor core, must be completely filled with a sufficient concentration of neutron poison. 4. Nuclear reactor power plant according to claim 2, characterized in that with the Kühlflußlgkeltsbehaiter (114), the first pipes (132) and the second pipes (137) steam jet injector nozzles (135) are in connection, so that when steam flows through the second pipelines and the steam jet injector nozzles, cooling liquid flows out of the container (114) and is supplied to the first pipelines (132) through the steam jet injector nozzles (135). 5. Nuclear reactor power plant according to claim 1, characterized in that between the cooling liquid container (114) and the steam generator (104) third pipelines (142) are provided which supply steam to the container (114) when a predetermined maximum pressure of the steam in the steam generator is exceeded. 6. Nuclear reactor power plant according to claim S, characterized in that the third pipelines (142) are kept closed by valves (143) responsive to changes in pressure, as long as the vapor pressure does not exceed the predetermined maximum pressure. 7. Nuclear reactor power plant according to claim 1 or 5, characterized in that the second pipelines (137) are kept closed by devices (139) responsive to pressure changes until the aforementioned third pressure difference is reached. 8. Nuclear reactor power plant according to spoke 7, characterized in that the devices responsive to pressure changes have tear disks (139) . 9. Nuclear reactor power plant according to claim 1 or 5, characterized in that the maximum throughput of the steam generator (104) through the second pipelines (137) to the cooling liquid tank (114) flowing steam through operating in the range of the speed of sound, in the second pipelines (137) activated throttles (138) is determined. 10. Nuclear reactor power plant according to claim 1, characterized in that the cooling liquid in the Kühliquidlgkeltsbehaiter (114) is cooled to a low temperature at which, however, it is still liquid. 11. Nuclear reactor power plant according to claim 1, characterized in that the cooling liquid vented and thus essentially of free oxygen supporting a hydrogen explosion is completely exempt. 12. Nuclear reactor power plant according to claim 1, characterized in that within the enclosure (116, 101, 103, 105, 107, 109, Ul, 113, 115, 118 and 119) there is a flood tank (117) with a second cooling liquid , which is connected by third lines to the interior of the enclosure, that the third lines are assigned devices responsive to pressure changes which establish a flow connection whenever a predetermined increased pressure as a result of an escape of reactor coolant into the interior of the enclosure Enclosure occurs so that the second coolant flows out into the interior of the enclosure and enters into heat exchange with the reactor group (102). 13. Nuclear reactor power plant according to claim 12, characterized in that the volume of the enclosure (116, 101, 103, 105, 107, 109, 111, 113, 115, 118 and 119) and the reactor assembly (102) and the amounts of the first cooling liquid and the second cooling liquid are chosen so that there is negative pressure inside the enclosure after the first and second cooling liquids have flowed out. 14. Nuclear reactor power plant according to claim 1, characterized in that a plurality of separate cooling liquid containers (114), which are each connected by first pipes (132) to the reactor assembly (102) , and a plurality of steam generators (104) are present, each through the second pipe lines (137) with the associated coolant container (114) are connected. 15. Nuclear reactor power plant according to claim 14, characterized in that the reactor assembly (102) Inlet and outlet means through which the reactor coolant flows during normal operation (112) to which the first pipelines (132) are connected.