A reactor head-top air cooling system

Abstract

The present application relates to the technical field of pressurized water reactor top structure, and provides a reactor top air supply cooling system, which comprises a surrounding cylinder, which surrounds a control rod drive mechanism inside and forms a cooling ventilation flow channel, and a separate air supply pipeline, the bottom of the surrounding cylinder is provided with an air inlet, the top of the surrounding cylinder is provided with an air outlet, the inlet end of the separate air supply pipeline is installed on the top of a reactor pit, the outlet end of the separate air supply pipeline is opposite to the air inlet, and a gap is left between the outlet end of the separate air supply pipeline and the air inlet. Compared with the prior art, the air flow is changed from air extraction to air supply, the connecting structure between the air pipe and the surrounding cylinder is cancelled, most of the cooling air is ensured to enter the inside of the surrounding cylinder, the disassembly and assembly of the connecting structure is avoided to increase the reactor refueling and maintenance period, the fan is avoided from being directly installed on the surrounding cylinder to cause the reactor top structure to be complex, and the risk that the vibration of the fan directly acts on the reactor is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of the reactor head structure of the pressurized water reactor, in particular to a reactor head air supply cooling system. BACKGROUND

[0002] The reactor head structure is one of the important components of the reactor, and one of its main functions is to take away the heat generated by the coil of the control rod drive mechanism (CRDM) with the help of cooling air to ensure that the temperature of the CRDM does not exceed the limit value. The CRDM is an important component that drives the control rod assembly to move and accurately adjusts the reactivity change in the reactor, and has important safety functions such as starting the reactor, increasing power, maintaining power, load tracking, normal shutdown and emergency shutdown. Nuclear reactor operation experience and related research show that the main factors affecting the service life and performance of the control rod drive mechanism include operating temperature, working pressure and working load. If there is no appropriate cooling measures, the temperature of the coil of the control rod drive mechanism may exceed the maximum temperature that the coil assembly can withstand, which will cause the coil assembly to degrade or fail, or even cause the coil to burn out. Therefore, ensuring that the CRDM operates within the temperature limit is crucial to the safe and stable operation of the reactor.

[0003] At present, the ventilation cooling system in the existing reactor head structure mainly uses a fan to forcibly exhaust air to take away the heat from the surface of the drive mechanism. There are mainly two types of structural forms: one is a duct connection type air exhaust cooling system, as shown in FIG. 1, which arranges the fan in a room (not shown in the figure) of the reactor building, connects the air exhaust pipe 9 to the surrounding cylinder 7 to exhaust air, and the main problem is that the connection structure between the air exhaust pipe 9 and the surrounding cylinder 7 needs to be removed each time the reactor is refueled or maintained, which takes a long time and is located on the main line of the reactor disassembly, increasing the reactor refueling or maintenance cycle, reducing the effective operation time of the reactor, and reducing the economy of the reactor. The other is a direct connection type air exhaust cooling system, as shown in FIG. 2, which directly installs the direct connection type air exhaust fan 11 to the surrounding cylinder 7, and the direct connection type air exhaust fan 11 is hoisted together with the reactor head structure, so that the connection structure between the air exhaust pipe 9 and the surrounding cylinder 7 does not need to be removed, saving the refueling or maintenance cycle, but the main problem of this scheme is that the direct connection type air exhaust fan 11 is directly installed on the surrounding cylinder 7, greatly increasing the complexity of the reactor head structure, and also greatly increasing the weight and volume, increasing the difficulty of disassembly and maintenance of the reactor head structure, and the vibration of the fan also directly acts on the reactor, which brings risks to the reactor structure. Figure 1 Figure 2 The present application relates to the technical field of the reactor head structure of the pressurized water reactor, in particular to a reactor head air supply cooling system.

[0004] The present application relates to the technical field of the reactor head structure of the pressurized water reactor, in particular to a reactor head air supply cooling system.

[0005] ​​The application achieves the technical scheme as follows:

[0006] The reactor top air supply cooling system comprises a surrounding cylinder which surrounds the control rod drive mechanism inside and forms a cooling ventilation flow channel, and a separate air supply pipeline, the bottom of the surrounding cylinder is provided with an air inlet, the top of the surrounding cylinder is provided with an air outlet, the inlet end of the separate air supply pipeline is installed on the top of the reactor pit, the outlet end of the separate air supply pipeline is opposite to the air inlet, and a gap is left between the outlet end of the separate air supply pipeline and the air inlet.

[0007] Optionally, the size of the outlet of the separate air supply pipeline is completely same as the size of the air inlet.

[0008] Optionally, the height of the center of the outlet of the separate air supply pipeline is greater than the height of the center of the air inlet, so as to compensate the expansion amount of the position of the air inlet in the height direction when the reactor operates.

[0009] Optionally, the gap is 500 mm.

[0010] Optionally, the air inlet is provided with one, and the air outlet is provided with a plurality of in the circumferential direction.

[0011] Optionally, the outer wall of the surrounding cylinder is provided with a cable channel, and a heat insulation gasket is arranged between the cable channel and the surrounding cylinder.

[0012] Optionally, the temperature that the coil of the control rod drive mechanism can withstand is greater than or equal to 400 DEG C.

[0013] Optionally, the cooling air delivered by the separate air supply pipeline has a target flow rate and pressure, and the temperature of the cooling air is lower than the temperature of the air near the surrounding cylinder.

[0014] The technical scheme of the application has at least the following advantages and beneficial effects: in the application, the cooling air is delivered by the separate air supply pipeline, the cooling air enters the inside of the surrounding cylinder from the air inlet to cool the control rod drive mechanism, and the cooling air flows out from the air outlet after being heated, compared with the prior art, the air flow is changed from air extraction to air supply, the connection structure between the air pipe and the surrounding cylinder is cancelled, most of the cooling air enters the inside of the surrounding cylinder, the disassembly and assembly of the connection structure is avoided to increase the refueling and maintenance period of the reactor, the fan is directly installed on the surrounding cylinder to avoid the complexity of the top structure of the reactor, and the risk that the vibration of the fan directly acts on the reactor is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those of ordinary skill in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0016] Figure 1 A structural schematic diagram of a duct connection type air extraction cooling system in the prior art;

[0017] Figure 2 A structural schematic diagram of a direct connection type air extraction cooling system in the prior art;

[0018] Figure 3 A structural schematic diagram of a reactor top air supply cooling system provided by the present application;

[0019] Figure 4 A schematic diagram of a cooling air flow mode;

[0020] Figure: 1 - separate air supply pipeline, 2 - air outlet, 3 - cable channel, 4 - pressure vessel top cover, 5 - reactor pit, 6 - control rod drive mechanism, 7 - containment vessel, 8 - air inlet, 9 - air extraction pipeline, 10 - connection structure, 11 - direct connection type air extraction fan. DETAILED DESCRIPTION

[0021] REFERENCE Figure 3 A reactor top air supply cooling system, comprising a containment vessel 7 and a separate air supply pipeline 1. In actual application, the containment vessel 7 is bolted to the pressure vessel top cover 4, the containment vessel 7 surrounds the control rod drive mechanism 6 inside and forms a cooling ventilation flow channel, the bottom of the containment vessel 7 is provided with an air inlet 8, the top of the containment vessel 7 is provided with an air outlet 2, the inlet end of the separate air supply pipeline 1 is installed on the top of the reactor pit 5, and the outlet end of the separate air supply pipeline 1 is opposite to the air inlet 8, that is, the separate air supply pipeline 1 is introduced from the top of the reactor pit 5, sinks along the pit wall to the position of the air inlet 8 of the containment vessel 7, and a gap is left between the outlet end of the separate air supply pipeline 1 and the air inlet 8, preferably, the gap is 500 mm, which leaves a space for the up and down movement of the top structure of the reactor for refueling or maintenance.

[0022] In operation, cooling air is delivered through the split air supply pipeline 1, enters the inner part of the containment 7 from the air inlet 8, and cools the control rod drive mechanism 6. The cooling air is heated and flows out of the air outlet 2. Compared with the prior art, the air flow is changed from exhaust to supply, the connecting structure 10 between the air duct and the containment 7 is cancelled, most of the cooling air enters the inner part of the containment 7, the disassembly and assembly of the connecting structure 10 is avoided, the reactor refueling and maintenance period is shortened, the fan is not directly installed on the containment 7, the complexity of the reactor head structure is avoided, and the risk of the vibration of the fan directly acting on the reactor is avoided.

[0023] The cooling air delivered by the split air supply pipeline 1 has a certain flow rate and pressure, so that most of the cooling air can be smoothly pushed into the inner part of the containment 7. The temperature of the cooling air is lower than the temperature of the air near the containment 7, and is preferably 16℃.

[0024] The size of the outlet of the split air supply pipeline 1 is the same as that of the air inlet 8, and further, the height of the center of the outlet of the split air supply pipeline 1 is greater than the height of the center of the air inlet 8, so as to compensate for the expansion of the position of the air inlet 8 in the height direction during the operation of the reactor. It is easy to understand that in actual application, the height difference between the center of the outlet of the split air supply pipeline 1 and the center of the air inlet 8 is determined according to the actual expansion of the position of the air inlet 8 in the height direction.

[0025] In this embodiment, only one air inlet 8 is provided, and a plurality of air outlets 2 are provided in the circumferential direction, so that the cooling air entering the containment 7 flows upward (as shown in Figure 4 Fig. 2) for cooling the drive mechanism. As an option, eight air outlets 2 are provided in the circumferential direction in this embodiment.

[0026] It is worth noting that, by using the structure provided by the present application, only the control rod drive mechanism 6 is arranged in the inner part of the containment 7, and the cooling baffle and the air duct between the containment 7 and the control rod drive mechanism 6 in the prior art can be cancelled. Since the cooling baffle and the air duct in the inner part of the containment 7 are cancelled, the uniformity of the air flow through each group of control rod drive mechanisms 6 is reduced. In order to reduce the requirement for the air volume of the cooling air supply system, the control rod drive mechanism 6 is a high-temperature-resistant drive mechanism, and the temperature that the coil of the control rod drive mechanism 6 can withstand is greater than or equal to 400℃. By using the high-temperature-resistant drive mechanism, the temperature resistance level of the drive mechanism is improved, and the requirement for the air volume of the cooling air supply system is reduced.

[0027] The outer wall of the containment 7 is provided with a cable passage 3 for laying the in-core measurement cable led out from the pressure vessel top cover 4. On this basis, a heat insulation gasket (not shown in the figure) is arranged between the cable passage 3 and the containment 7 to prevent the cable from being accelerated aging due to high temperature. The thickness of the heat insulation gasket is determined according to the heat insulation effect of the material thereof, and the preferred value is 20mm.

[0028] The above merely describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A reactor head forced air cooling system comprising a containment cylinder that encloses a control rod drive mechanism inside and forms a cooling air flow channel, characterized in that, The reactor further comprises a separate air supply pipeline, an air inlet is arranged at the bottom of the containment, an air outlet is arranged at the top of the containment, the inlet end of the separate air supply pipeline is installed at the top of the reactor pit, the outlet end of the separate air supply pipeline is opposite to the air inlet, and a gap is left between the outlet end of the separate air supply pipeline and the air inlet. The size of the outlet of the separate air supply pipeline is completely same as the size of the air inlet, and the height of the center of the outlet of the separate air supply pipeline is greater than the height of the center of the air inlet, so as to compensate the expansion of the air inlet in the height direction during the operation of the reactor.

2. The reactor head-air cooling system of claim 1, wherein, The gap is 500mm.

3. The reactor head-air cooling system of claim 1, wherein, The air inlet is one, and the air outlet is multiple in the circumferential direction.

4. The reactor vessel top air cooling system of claim 1, wherein, The outer wall of the containment is provided with a cable channel, and a heat insulation gasket is arranged between the cable channel and the containment.

5. The reactor vessel top air cooling system of claim 1 wherein, The temperature that the coil of the control rod drive mechanism can withstand is greater than or equal to 400℃.

6. The reactor vessel top ventilation cooling system in accordance with claim 1, wherein, The cooling air delivered by the separate air supply pipeline has a target flow rate and pressure, and the temperature of the cooling air is lower than the temperature of the air near the containment.

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