DE1539677B2

DE1539677B2 - Nuclear reactor with high pressure gas circulation cooling

Info

Publication number: DE1539677B2
Application number: DE19661539677
Authority: DE
Inventors: Der Anmelder Ist
Original assignee: Benzler, Dr.-Ing. Hartwig, 3180 Wolfsburg
Priority date: 1959-02-10
Filing date: 1966-03-19
Publication date: 1970-10-15
Also published as: DE1539677A1

Description

Die Erfindung bezieht sich auf einen Kernreaktor mit Hochdruckgasumwälzkühlung, bei dem das primäre Druckgassystem in einem Sekundärbehälter angeordnet ist, wobei im Sekundärbehälter ein Gasdruck von mindestens einigen Atmosphären aufrechterhalten wird. Ein derartiger Kernreaktor ist aus der belgischen Patentschrift 561 780 bekannt.The invention relates to a nuclear reactor with high pressure gas circulation cooling, in which the primary Compressed gas system is arranged in a secondary container, with a gas pressure in the secondary container is maintained by at least some atmospheres. Such a nuclear reactor is from the Belgian patent 561 780 known.

Die Erfindung befaßt sich daher mit Kernreaktoren, bei denen die durch Kernspaltung freigesetzte Wärme mittels Umwälzens eines unter hohem Druck stehenden gasförmigen Kühlmittels aus dem Reaktorkern an eine Wärmesenke abgeführt wird. Unter hohem Druck stehende Gase werden auch als reale Gase oder Dämpfe bezeichnet. Insofern bezieht sich die Erfindung auch auf dampfgekühlte Kernreaktoren. Im besonderen betrifft die Erfindung schnelle Reaktoren mit Hochdruckgasumwälzkühlung. .The invention is therefore concerned with nuclear reactors, in which the heat released by nuclear fission by circulating a gaseous coolant under high pressure from the reactor core a heat sink is dissipated. High pressure gases are also called real gases or vapors designated. In this respect, the invention also relates to steam-cooled nuclear reactors. In particular The invention relates to fast reactors with high pressure gas recirculation cooling. .

Reaktoren, die durch Umwälzen von unter hohem Druck stehenden Gasen gekühlt werden, haben bisher den Nachteil, daß bei einem durch Störung bedingten Abfall des Gasdruckes die Kühlleistung stark zurückgeht. Man hat daher bisher nicht gewagt, den Kühlgasdruck auf verhältnismäßig hohe Werte anzuheben, weil sonst im Falle eines Druckverlustes die Reaktornachwärme, d. h. die nach der Beendigung der Kettenreaktion im Reaktorkern frei werdende Wärme, nicht mehr sicher und ohne größere Beschädigungen der Anlage abzuführen wäre. Unter Umständen kann es sogar zum Schmelzen des Brennstoffs kommen.Reactors that are cooled by circulating high pressure gases have heretofore been used the disadvantage that if the gas pressure drops due to a malfunction, the cooling capacity is greatly reduced. So far, no one has dared to raise the cooling gas pressure to relatively high values, because otherwise, in the event of a pressure loss, the reactor post-heat, d. H. those after the chain reaction has ended Heat released in the reactor core, no longer safe and without major damage to the Plant would be discharged. Under certain circumstances, the fuel can even melt.

Die Reaktornachwärme beträgt nach Auslaufen der Kettenreaktion in vielen Fällen etwa 6°/o der vollen Leistung und geht danach nur langsam zurück. In gewisser Annäherung ist bei gleichbleibender Gebläsedrehzahl und vorgegebener Aufwärmspanne die Kühlleistung des umgewälzten Gases angenähert proportional dem Gasdruck. Demnach dürfte der Kühlgasdruck eines Reaktors im Störungsfall nicht weiter als auf 6% des vollen Wertes absinken, wenn eine sichere Abfuhr der Nachwärme gewährleistet sein soll. Da die normale Grenze für den Druckabfall die Außenatmosphäre ist, errechnet sich der zugehörige volle Gasdruck zu theoretisch etwa 17 ata. Das heißt, bis herauf zu 17 ata Primärgasdruck wäre im Falle von störungsbedingter Druckentlastung eine sichere Abfuhr der Reaktornachwärme noch möglich. Wegen der geringen Wahrscheinlichkeit für einen vollständigen Druckverlust im Primärsystem läßt man in der Praxis für diesen Störfall jedoch gewisse Temperaturanstiege und auch begrenzte Schädigungen zu und geht bis auf Höchstwerte von 40 bis 60 ata für den Primärgasdruck.After the end of the chain reaction, the reactor heat after the end of the chain reaction is in many cases about 6% full power and then only slowly decreases. To a certain approximation is with a constant fan speed and the predetermined warm-up period approximates the cooling capacity of the circulated gas proportional to the gas pressure. Accordingly, the cooling gas pressure of a reactor should not be used in the event of a malfunction fall further than 6% of the full value if a reliable dissipation of the residual heat is guaranteed should be. Since the normal limit for the pressure drop is the outside atmosphere, the associated one is calculated full gas pressure to theoretically about 17 ata. That is, up to 17 ata primary gas pressure would be In the event of a failure-related pressure relief, safe removal of the reactor residual heat is still possible. Because of the low probability of a complete pressure loss in the primary system, one leaves in practice, however, certain temperature rises and also limited damage occur for this incident and goes up to maximum values of 40 to 60 ata for the primary gas pressure.

Auf jeden Fall ist festzustellen, daß Druckverluste bei gasgekühlten Reaktoren bisher einen der schwersten Störungsfälle dieses Systems darstellen und dieses Risiko entscheidend für dessen derzeitige Leistungsbegrenzung ist. In any case, it should be noted that pressure losses in gas-cooled reactors have been one of the most severe to date Represent malfunctions of this system and this risk is decisive for its current performance limitation.

Um diesen Nachteil zu umgehen, hat man vorgeschlagen, Druckbehälter zu bauen, die nicht explosionsartig zerstört werden können. Eine derartige Eigenschaft haben beispielsweise gewisse Spannbetondruckbehälter oder aus Einzelelementen aufgebaute Behälter, bei denen jedes Element für sich und unabhängig von den anderen Elementen Belastungskomponenten aufnimmt. Solche Behälter sind zwar gegen schlagartige Zerstörung geschützt, nicht jedoch gegen mehr oder weniger schnelles Gasausströmen.In order to circumvent this disadvantage, it has been proposed to build pressure vessels that are not explosive can be destroyed. Certain prestressed concrete pressure vessels, for example, have such a property or containers made up of individual elements, in which each element is separate and independent absorbs load components from the other elements. Such containers are true Protected against sudden destruction, but not against more or less rapid gas leakage.

Man hat weiter vorgeschlagen, gasgekühlte Reaktoren mit einem dichten Containment zu umgeben, in dem sich bei einem Entweichen des Primärgases ein gewisser Druck aufbaut, der die Notkühlung des Reaktorkerns erleichtern soll. Eine derartige Maßnahme ist in ihrer Wirksamkeit sehr begrenzt und hat vor allem den großen Nachteil, daß das Containment im Falle der gefährlichsten Störung schlagartig beansprucht wird, was seine Sicherheit ungünstig beeinflußt.
Besonders kritisch ist der Störungsfall eines Gasdruckverlusts bei schnellen Reaktoren, wo man große Wärmeleistungsdichten erreichen will und deshalb in verstärktem Maße auf hohe Betriebsdrücke angewiesen ist.
Der Erfindung liegt die Aufgabe zugrunde, die durch unvorhergesehene Druckverluste des primären Kühlkreislaufes bedingte Leistungsbegrenzung von gasgekühlten Reaktoren zu beseitigen.It has also been proposed to surround gas-cooled reactors with a tight containment in which a certain pressure builds up when the primary gas escapes, which pressure is intended to facilitate emergency cooling of the reactor core. Such a measure is very limited in its effectiveness and, above all, has the great disadvantage that the containment is suddenly stressed in the event of the most dangerous disturbance, which has an unfavorable effect on its safety.
The failure case of a loss of gas pressure is particularly critical in fast reactors, where one wants to achieve high heat output densities and is therefore increasingly dependent on high operating pressures.
The invention is based on the object of eliminating the power limitation of gas-cooled reactors caused by unforeseen pressure losses in the primary cooling circuit.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß der Gasdruck im Sekundärbehälter um mindestens einige Atmosphären unter dem Primärgasdruck liegt. In besonderer Ausgestaltung der Erfindung wird vorgeschlagen, den Gasdruck im Sekundärsyslem so hoch zu legen, daß bei einem Ausgleich mit dem Primärsystem dessen Druck nicht unter einen Wert absinkt, bei dem die durch die Primärgebläse umgewälzte Gasmenge nicht mehr zur Abfuhr der Reaktornachwärme ausreicht.This object is achieved in that the gas pressure in the secondary container to is at least a few atmospheres below the primary gas pressure. In a special embodiment of the invention it is proposed to put the gas pressure in the secondary system so high that there is an equalization with the primary system, the pressure of which does not drop below a value at which the pressure generated by the primary fan circulated amount of gas is no longer sufficient to remove the residual heat from the reactor.

Eine weitere Ausgestaltung der Erfindung besagt, daß das Volumen des Sekundärbehälters erheblich größer als das des Primärsystems ist, so daß bei einem Druckausgleich zwischen beiden Systemen der Druckanstieg im Sekundärbehälter nur unbedeutend ist.Another embodiment of the invention says that the volume of the secondary container is considerable is greater than that of the primary system, so that when the pressure between the two systems is equalized, the pressure increase is insignificant in the secondary container.

Durch diese Maßnahmen wird erreicht, daß um das primäre Drucksystem eine künstliche Atmosphäre geschaffen wird, deren normaler Druck wesentlich höher liegt als der äußere Atmosphärendruck. Da das Verhältnis des Primärdrucks zum umgebenden Druck aus Sicherheitsgründen einen bestimmten Wert nicht übersteigen darf, kann der absolute Primärdruck entsprechend dem in Atmosphären ausgedrückten Druckniveau der künstlichen Atmosphäre gegenüber den bisherigen Anlagen angehoben werden. Ein Druckverlust des Sekundärbehälters ist für die Sicherheit nicht nachteilig, weil das Primärsystem davon nicht beeinflußt wird. Sobald man ein Nachlassen des Sekundärdrucks feststellen sollte, kann man die Anlage vorschriftsmäßig abfahren und den Schaden beheben.These measures ensure that an artificial atmosphere is created around the primary pressure system is created whose normal pressure is much higher than the external atmospheric pressure. There the ratio of the primary pressure to the surrounding pressure is a certain one for safety reasons Value, the absolute primary pressure can correspond to that expressed in atmospheres Pressure level of the artificial atmosphere can be increased compared to the previous systems. A Pressure loss of the secondary tank is not detrimental to safety because the primary system is affected by it is not affected. As soon as you notice a decrease in the secondary pressure, you can use the Shut down the system in accordance with regulations and repair the damage.

Im Prinzip könnte man für einen vorgegebenen Primärgasdruck den Sekundärdruck mehr oder weniger hoch auslegen, doch ist es häufig zweckmäßig, ihn aus technischen oder wirtschaftlichen Gründen nur so hoch anzusetzen, daß nach einem eventuellen Ausgleich beider Drücke die Primärgebläse gerade noch die Reaktornachwärme sicher abführen können. Die Zweckmäßigkeit, das Volumen des Sekundärbehälters erheblich größer als das des Primärsystems zu bemessen, folgt daraus, daß dann die Gasmenge im Primärsystem trotz des dort höheren Drucks klein bleibt gegenüber der Gesamtgasmenge nach der Mischung. Somit ist kein größerer schlagartiger Druckaufbau im Sekundärbehälter möglich.In principle, the secondary pressure could be more or less for a given primary gas pressure interpret it high, but it is often expedient for technical or economic reasons should only be set so high that after a possible equalization of the two pressures, the primary fan will be straight can still safely dissipate the residual heat from the reactor. The convenience, the volume of the secondary container To be dimensioned considerably larger than that of the primary system, it follows that the amount of gas then in the primary system, despite the higher pressure there, remains small compared to the total amount of gas after mixing. This means that no major sudden pressure build-up is possible in the secondary container.

Eine weitere Ausgestaltung der Erfindung besagt, daß der Sekundärbehälter in an sich bekannter Weise als Sicherheitscontainment dient. Ein Sicherheitscontainment hat die Aufgabe, eine Ausbreitung von unzulässigen Mengen radioaktiver Stoffe in die Umgebung zu verhindern. Es wird daher mit besondererAnother embodiment of the invention says that the secondary container in a known manner serves as a safety containment. A security containment has the task of preventing the spread of to prevent inadmissible amounts of radioactive substances in the environment. It will therefore be special

Claims

3 43 4

Manufactured with care and continuously cheaper constructions for gas tightness. Is regulated in the event of a waste being monitored. Furthermore, containment containers are often built up to the primary gas pressure evenly the water pressure from two shells, one of which is back, so bursting loads can also be made of non-concrete and the other can consist of steel, whereby stationary operating conditions and accidents include gas suction from the space in between. You can also avoid it. The design of the secondary container according to the pressure loads of the steam generator in the case of known aspects of a safety container malfunction on the water side, the gas pressure allows the nuclear reactor to constructively regulate blow-off into the secondary container,
just as easy to design as previous systems. An embodiment of the above

In another further development of the invention, the nuclear reactor can, for example, according to the following

it is proposed that the secondary container be constructed with a scheme: In a vertical cylindrical

gas other than the primary system. Example of a steel pressure vessel with an internal diameter of 2 m

As the primary coolant, an expensive gas such as knives can be arranged from top to bottom:

Helium or a vapor with a high saturation temperature - a fast reactor core with a brood jacket on all sides

temperature such as water vapor can be selected during 15 of a total of 2 m height, a reactor support grate ,, a

the secondary tank with an inexpensive gas such as radiation shield, a continuous steam generator for

Carbon dioxide is charged, which at room temperature 300 ata operating pressure of 12 m height, six sym-

temperature, a sufficiently high vapor pressure and good metrically mounted circulation fans. Primary cooling gas is

Has cooling properties. The advantage of this measure CO ₂ , the reactor core, support grid with shield

lies in the cost savings as well as in the technical 20 and steam generator sucked in by the fans

Adaptability of the concept. and through an annular space between internals

Finally, it is proposed that the heat from the container and the container flows back upwards. The primary circuit via a heat exchanger by means of CO ₂ -temperatures lie between 250 and 600 ⁰ C, water of 100 to 400 dissipate ata, wherein the reactor thermal output is 1100 MW for water circulation under the same pressure as the primary 25,500 MW power generation. The pressure vessel can be gas cycle. In this case, it can also be set up for changing the fuel and at the bottom for the purpose of opening when the primary fan expansion drops. The cylindrical prigas pressure is reduced to the same extent as the water pressure abmär container rests in an annular support and is lowered. Shielding concrete structure of 2.5 m thick, the above

The proposed reactor makes it possible to use the 30 and below demountable shielding plates.

Primary gas pressure is closed to values of 100 to 400 ata. Reactor block and nuclear secondary

and possibly more to go. This is a pressure area, attachments are in a vertical cylindrical

the secondary container with a diameter of 12 m, which is used by modern high-pressure steam processes

is known. There is therefore the possibility of being _{filled with CO 2} of around 20 ata and 20 ° C

35 is also for such high-performance steam conditions. The steam generator supply and discharge lines are through

Primary system pressure on the secondary cooling circuit - primary and secondary tanks to the conventional one

adjust pressure. This has the following advantage: The power plant part is out.

Experience has shown that the most difficult problems in the drawing is such a nuclear reactor in

of the modern reactor construction in fast reactors of an embodiment shown schematically. Included

and for high temperature thermal reactors on 40 the details are labeled as follows:

the area of the steam generator, which is used as a heat reactor core 1

act as a sink for the primary system. This is where the support grid with radiation protection 2

namely large thermal loads with large heat exchangers for water of 300 ata

Pressure loads together. Pressure is therefore required on the secondary side 3

special efforts, reasonably usable 45 circulation fans 4

To develop steam generator designs, with fan motor 5

an absolute break resistance is not achieved anyway pressure vessel cover 6

can be. If, according to the invention, the shielding plates 7 are placed

Primary gas pressure at the same level as the steam concrete structure 8

process pressure, the ₅ o steel pressure tank (primary tank) 9 is not required during operation

pure compressive stress in the heat transfer surrounds of the built-in containers 10

areas. Their exposure to water is therefore reduced 11

- as far as one of the low flow gas density through 12

ignores the residual amounts caused by pressure losses - vapor discharge 13

on the purely thermal component, and a bursting 55 secondary container with inner part of the

as well as sudden overflow of the water into the safety containment 14

Gas or gas in water is excluded - suction area of the safety container -

sen. The advantage over the previous steam units 15

generating systems is thus clear. For example, the outer wall of the security container

in current high-temperature gas reactors an over- 60 ments 16

critical pressure difference between water and gas, space for CO ₂ of 300 ata as primary

in the case of reactors cooled with liquid metal, cooling gas 17

In the event of a pipe burst, the vapor pressure increases over the space for secondary gas of 20 ata 18

Intermediate, inactive liquid metal circuit affect the primary coolant. 6 ₅ claims:

The proposed reactor closes the previous 1st nuclear reactor with high pressure gas circulating cooling

Difficulties with the steam generators from, increased development in which the primary pressurized gas system in

the operational safety and allows simpler and a secondary container is arranged, with im

Secondary tank a gas pressure of at least a few atmospheres is maintained thereby characterized in that the gas pressure in the secondary container by at least some Atmospheres below the primary gas pressure.

2. Nuclear reactor according to claim 1, characterized in that the gas pressure in the secondary system is so high that when the pressure is equalized with the primary system, its pressure will not fall drops to a value at which the amount of gas circulated by the primary fan is no longer available Removal of the residual heat from the reactor is sufficient.

3. Reactor according to claim 1 or 2, characterized in that the volume of the secondary container is significantly larger than that of the primary system.

4. Nuclear reactor according to one or more of the

preceding claims, characterized in that the secondary container is known per se Way is designed as a safety containment.

5. Nuclear reactor according to one or more of the preceding claims, characterized in that that the secondary container is filled with a different gas than the primary system.

6. Nuclear reactor according to one or more of the preceding claims, characterized in that that the heat from the primary system through a heat exchanger with water from 100 to 400 ata is discharged, which is under the same pressure as the primary gas.

7. Nuclear reactor according to claim 6, characterized in that when the primary gas pressure drops the water pressure in the heat exchanger system is reduced to the same extent.

1 sheet of drawings