DE1614072C3 - Steam-cooled fast breeder reactor - Google Patents

Description

The invention relates to a steam-cooled fast breeder reactor, the core of which is from a tight Kemmantel is enclosed with a sealing and detachable superheated steam dome.

In the first generation of large power nuclear power plants, light water moderated and light water cooled reactors, e.g. B. Proven boiling water or pressurized water reactors. The disadvantages of these reactors are the poor steam conditions and poor fuel economy achieved with them. In general, only saturated steam is obtained from such reactors. The disadvantage of the bad steam conditions try z. B. can be remedied by boiling superheater fuel elements integrated into the reactor begins.

It is also known to superheat the saturated steam in a downstream, second superheater reactor (French patent specification 1244149). The gist of this Superheater reactor is enclosed with a tight core jacket on which a superheated steam dome easily detachable, but sealing, is attached. All fissile material elements are flown against from below, see above that a complex hold-down is necessary to counteract the pressure difference. Besides that it is structurally complex to lead the superheated steam pipe separately to the outside.

With this overheating, steam temperatures are obtained that are essential in modern turbine systems allow better efficiencies than pure saturated steam. But even with this technique there is a better one Fuel utilization is not possible as long as the chain reaction in the reactor only involves thermal neutrons expires. With light or heavy water as moderator, however, there is none other than thermal To achieve neutron spectrum.

However, if a fast nuclear reactor is cooled with steam, it is also possible to use steam-cooled ones to design fast reactors that are more capable than breeder reactors for their fast core To convert breeding material into fissile material than they consume themselves. In this way it is possible to see the whole To use fuel almost completely.

It is known to cool such reactors directly with steam, whereby one for the generation of the cooling steam uses part of the superheated steam. A constructive problem poses with these Reactors represent the vapor flow inside the reactor pressure vessel. The temperature of the in the reactor superheated steam is, for example, for low-cost operation of a turbine system 500 ° C. This is the temperature at which red heat is starting. The temperature of the entering the reactor Cooling steam is much lower. Because of these temperature differences that occur in the reactor itself occur, strong thermal voltages can occur; the inlets and outlets are equally at risk through the pressure vessel. It must therefore be absolutely avoided that there are breaks as a result of this Thermal stress is coming.

Furthermore, no mixing of cooling steam and superheated steam must occur within the reactor, since Otherwise, either the efficiency of the system falls sharply due to the reduced steam temperatures or, if superheated steam mixes into the cooling steam, an inadmissible high level of heating in the Core occurs.

It is the object of the invention to provide such a steam feed through internals in the reactor cause without the safety risk for the reactor operation and in terms of easy accessibility to the core of the reactor can be reached steam states that z. B. turbine systems allow with good efficiency.

This task is performed with a steam-cooled fast breeder reactor, the core of which is of a dense Kernmantel is enclosed with a sealing and detachable superheated steam dome, thereby solved that the core mantle by means of an inwardly concentrically tapering, both from the core mantle as well as from the superheated steam dome easily detachable transfer part connected to the superheated steam dome is that the transition part has passages through which a group of on the outside Fissile material elements located in the core area exclusively with the hot steam collecting room outside of the core jacket is connected, and that the superheated steam collecting space in a manner known per se

a discharge pipe that penetrates the pressure vessel and is located concentrically within the cooling supply having.

From French patent 1 345 789 it is known in a gas-cooled reactor that the Collecting space for the hot coolant, a concentric inside the pressure vessel penetrating the pressure vessel has the coolant supply lying discharge pipe. However, this device forms the core mantle and steam dome an inseparable unit, and no transition part is provided, which bushings has around a group of fissile material elements located on the outer core circumference exclusively to be connected to the superheated steam collecting room.

The invention is described in more detail below with reference to the drawing.

The breeding elements 3 are arranged in an annular zone around the crevice zone 7 of the fast reactor. the The core is closed off tightly against the space between the core and the pressure vessel wall 2 by a core jacket 5. A transition part 4 is placed on top of the core jacket, onto this transition part 4 is followed by a superheated steam dome 9. The connections between the core jacket and the transfer part as well as between Transfer part and superheated steam dome are easy to detach. The transition part 4 points laterally Penetrations through which the brood elements 3 are connected to the space 13 outside the core mantle are. The fuel elements of the fission zone open directly into the superheated steam collecting space 12. The superheated steam collecting space 12 is connected to an outflow pipe 10 through which the superheated steam flows off. The cooling steam supply 1 is placed concentrically around this outflow pipe 10. the Space around the superheated steam plenum outside the core jacket and the steam dome serves as Cooling vapor collecting space 13. There is a thermal shield between the core jacket 5 and the pressure vessel wall 2 intended. In this example it consists of steel plates 11. However, it is also possible to use a Use a water jacket for shielding. There are channels between the individual steel plates, through which the cooling steam can flow. In this way, the steel plates 11 cooled by the cooling steam. The cooling channels of the thermal shield lead down to under the support base 6 of the core jacket. At its lower point, the core mantle is well defined Passages through which the coolant, which previously cooled the thermal shield, into the Cleavage zone can occur. In addition, the absorption through which the cooling steam flows and control elements 8 from below into the core of the reactor. So you get the following steam flow:

At 1 the cooling steam flows into the pressure vessel.

Part of the cooling steam reaches the cooling steam collecting space 13, and another part of the Cooling steam flows through the steel plates of the thermal shield. From the cooling steam collecting room 13, the cooling steam first flows into the radially arranged breeding elements 3 and becomes slightly there heated. In the support base 6 of the core jacket, the cooling steam that has passed through the breeding elements 3 is deflected and now flows through the gap zone 7.

ίο In addition, the support base 6 has openings below on, through which the cooling steam that has cooled the steel plates 11 of the biological shield, also enters the core. The steam then flows from the superheated steam collecting space 12 to the consumer through the discharge pipe 10 inside the cooling steam supply. The entire reactor pressure vessel is just standing in contact with cooling steam, even at the hot steam outlet. A shield made of steel plates is beneficial when a very rapid change in reactivity leads to an explosive accident should lead. The structure of the superheated steam collection space from the superheated steam dome 9, the transition part 4 and an extension of the core jacket 5 is used for easy access to the core.

After opening the reactor cover, the connections between the core jacket and the transfer part as well as between the superheated steam dome and the transfer part can be easily released from above. Since the elements of the If the crevice zones are subjected to much higher thermal loads, there is initially a probability of failure here higher, so that it is an advantage if it can be expanded particularly easily. For this reason the diameter of the steam dome 9 was approximately adjusted to the diameter of the fast core part. Thus the brood elements of the core are indeed within the core mantle, but they will the cooling steam that surrounds the steam dome flows through it. The entire superheated steam area is from the other areas separately. Because the pressure difference between cooling steam and superheated steam is low is, namely only corresponds to the pressure loss of the flowing cooling steam medium, the needs Kernmantel 5 and the internals for the steam supply are not designed for high pressure loads.

The reactor pressure vessel does not come into contact with the superheated steam at any point. Another advantage can be seen in the fact that there is no additional core mantle between the brood mantle and the fissure zone is, the cooling steam and superheated steam area separates, because all additional fixtures in the energy-generating area of the reactor represent neutron-catching structural materials, so that unnecessarily many neutrons for nuclear reactors are lost.

In addition, the steam flowing down in the breeding elements causes a reduction in the den Core upward driving force.

1 sheet of drawings

Claims (4)

Patent claims: 1. Steam-cooled fast breeder reactor, the core of which is covered with a dense core is enclosed in a sealing and detachable superheated steam dome, characterized in that, that the core sheath (5) by means of an inwardly concentrically tapering, both from the core sheath (5) as well from the superheated steam dome (9) easily detachable transition part (4) connected to the superheated steam dome (9) is that the Überlcitungteil (4) has bushings through which a group of Fissile material elements located on the outer core circumference exclusively with the superheated steam collecting space (12) is connected outside of the core jacket, and that the superheated steam collecting space (12) in a known manner a the Pressure vessel (2) penetrating, concentrically located within the cooling steam supply (1) Has discharge pipe (10). 2. Steam-cooled fast breeder reactor according to claim 1, with a thermal shield made of steel plates, characterized in that channels for the Cooling steam are present and the core jacket has openings on its underside, which with the cooling channels are in communication with the steel plates. 3. Steam-cooled fast breeder reactor according to claim 1 or 2, characterized in that the fissile material elements connected to the space (13) outside the core shell, breeding elements (3) and form the fast core breeding zone. 4. Steam-cooled fast breeder reactor according to claim 3, characterized in that the Fuel elements of the fission zone (7) of the fast core in one of the transition part and the steam dome (9) formed hot steam collecting space (12) open and that the diameter of the steam dome (9) corresponds approximately to that of the cleavage zone (7) of the fast core.