CN105427900B - A reactor melt retention system after a severe accident - Google Patents

Abstract

The present invention relates to reactor safety system designing techniques, and in particular to reactor fusant out-pile gaseous-waste holdup system after a kind of major accident.Its structure includes fusant arresting device and cooling line, the fusant arresting device being located at below pressure vessel as key equipment, including the porous sacrificial layer and high-temperature crucible construction package for allowing fusant layering diffusion and coolant to pass through, high temperature resistant support column is distributed between each layer as support；Cooling line can continue the cooling water in supplement reactor pit, guarantee flooding and persistently cooling down completely for fusant.When nuclear power station generation reactor core melts the major accident ruined, the present invention can be realized reactor core fusant utmostly and quickly and effectively dispersion cooling, so that reactor pit bottom burn through risk is reduced, the safety under raising reactor disaster.

Description

A reactor melt retention system after a severe accident

technical field

The invention relates to the reactor safety system design technology, in particular to a reactor melt retention system outside the reactor after a severe accident.

Background technique

Most of the large-scale second-generation improved nuclear power plants currently under construction and in operation in my country do not have an effective external melt retention system. After the Fukushima accident in Japan, the safety issues of nuclear power plants, especially the prevention and mitigation of severe accidents, are more urgent. At present, for severe accidents, the cooling and retention strategies of the core melt can be mainly divided into two types: 1) The cooling and retention (IVR) of the melt in the pressure vessel is obtained in the design of the AP-1000 model of the Westinghouse Company in the United States. Application; 2) Cooling and collection of melt outside the pressure vessel (EVR), which is applied in the VVER-1000 model designed in Russia and the advanced pressurized water reactor EPR model designed by ANP in France. For the out-of-core cooling strategy, Russia's VVER-1000 "crucible" trap combines the design features of the AP600 passive water supply to cool the metal surface of the molten material inclusion and the European advanced pressurized water reactor core trap improves melting by sacrificial materials The technical characteristics of material characteristics and heat flux reduction; the design idea of the French ANP "extended" core catcher is to make the melt flow directly into the reactor pit, and the melt reacts chemically with the sacrificial concrete of the pit under the action of high temperature. The reaction gradually melts the sacrificial concrete to achieve the functions of preliminary cooling and collecting the melt, and the entire chemical reaction process is carried out under the protection of the pile pit protection layer to ensure that the melt will not penetrate the pile pit and enter the structural concrete to control the spread of nuclear radiation . Domestic research on core traps has also been published in relevant patents, such as Shanghai Nuclear Engineering Research and Design Institute Type I, II, and IV type bottom opening steam pipe wall core melt retention devices (CN103377724A, CN103377723A, CN103377720A), with integrated cooling Channel core catcher (CN103081023A), large passive nuclear power plant core catcher with bottom water injection and external cooling (CN103177778A) and large passive pressurized water reactor nuclear power plant core catcher with melt expansion chamber (CN103165198A) etc.

However, none of the technologies disclosed in the above patent applications involves the design of a coolant-permeable stagnation plate, nor does it realize the design of layer-by-layer cooling of the melt under controllable conditions. Therefore, based on the above ideas, a stronger cooling capacity can be developed , Core melt retention technology with higher safety retention efficiency.

Contents of the invention

The purpose of the present invention is to meet the needs of nuclear power plant safety design, to provide a system for the retention of reactor melt outside the reactor after a severe accident, which can realize the maximum, fast and effective recovery of the core melt when a serious accident of core meltdown occurs in a nuclear power plant. Decentralized cooling, thereby reducing the risk of melt-through at the bottom of the reactor pit and improving safety in the event of a reactor accident.

The technical scheme of the present invention is as follows: a reactor melt retention system after a serious accident, comprising a melt retention device arranged at the bottom of the reactor pit below the reactor pressure vessel and a cooling pipeline from a safe water source, the melt retention The device is capable of receiving all falling melt jets within the projection range of the reactor pressure vessel, wherein the melt retention device includes multiple layers of high-temperature-resistant crucibles that allow the melt and coolant to penetrate, and each layer of high-temperature-resistant crucibles is equipped with A porous sacrificial layer that can be melted through by the melt.

Furthermore, in the reactor melt retention system after a serious accident as described above, a high-temperature-resistant support column is provided between two adjacent layers of high-temperature-resistant crucibles for connection and support.

Furthermore, in the reactor melt retention system after a severe accident as described above, there is a free space with a height of 40-60 cm between two adjacent layers of high-temperature-resistant crucibles.

Furthermore, in the reactor melt retention system after a serious accident as described above, the high temperature resistant crucibles on each layer except the bottom layer are provided with flow holes distributed in an array and criss-crossed, and the porous sacrificial The layers are tiled on the upper surface of each layer of high temperature resistant crucible with a thickness of 20-30 cm.

Furthermore, in the reactor melt retention system after a serious accident as described above, the high-temperature-resistant crucible has a disc-shaped structure, the middle part is a flat collection area, and the outer edge is tilted by 10-30 degrees to form a weir, The flow holes are arranged in the central collection area of the high-temperature-resistant crucible, and the flow holes on two adjacent layers of high-temperature-resistant crucibles are staggered.

Further, in the reactor melt retention system after a serious accident as described above, the porous sacrificial layer is a sponge structure processed by a sintering process with a porosity of 0.1-0.3; There are retention holes and retention pits distributed in an array.

Furthermore, in the reactor melt retention system after a serious accident as described above, the melting temperature of the porous sacrificial layer is 1500-2000°C, and the melting temperature of the high-temperature-resistant crucible and the high-temperature-resistant support column is 2800°C. ℃ or more.

Further, in the reactor melt retention system outside the reactor after a serious accident as described above, the cooling pipelines are arranged in two rows and equipped with pump valves, which are respectively external water injection pipelines and internal reactor water injection pipelines; The outlet of the water pipeline is located at the bottom of the reactor pit, and is used to supply water to the reactor pit; the outlet of the water injection pipeline in the reactor is connected with the pressure vessel, and is used to supply water to the reactor pressure vessel.

Furthermore, in the reactor melt retention system after a severe accident as described above, the coolant provided by the cooling pipeline flows through the melt retention device, and the coolant quickly penetrates into the voids of the porous sacrificial layer to realize the cooling function .

Furthermore, in the reactor melt retention system after a serious accident as described above, when the melt interacts with the coolant in the reactor pit and the temperature and pressure exceed a certain threshold, the configured overpressure blasting device of the pit ventilation system will Automatic blasting and pressure relief to prevent damage to the concrete partition wall of the pile pit.

The beneficial effects of the present invention are as follows: (1) The disc-shaped high-temperature-resistant crucible designed by the present invention can thin the high-temperature molten material received, thereby increasing the heat exchange area, and sharing the cooling layer by layer, reducing the risk of heat flow concentration; 2) The present invention adopts the design of multi-layer crucible through-hole staggered arrangement, which can effectively divide and distribute the molten material; (3) The present invention simultaneously cools the molten material inside and outside the reactor through two columns of cooling pipelines, and cools the reactor. The retention device outside the melt pile realizes two cooling methods: bottom-up submersion and top-down spraying at the same time, which increases the reliability of the system.

Description of drawings

Figure 1 is a layout diagram of the reactor melt retention system outside the reactor;

Fig. 2 is a structural schematic diagram of a melt retention device;

Fig. 3 is a sectional view of the melt retention device (schematic diagram of the position of the sacrificial layer and the through hole of the high temperature resistant crucible).

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The present invention provides a reactor melt retention system outside the reactor after a serious accident. The cooling lines 1, 2. The melt retention device includes a multi-layer high-temperature-resistant crucible 9 (except the bottom layer 11) that allows the melt and coolant to penetrate. On the high-temperature-resistant crucible 9, components such as a porous sacrificial layer 8 and a high-temperature-resistant support column 10 are arranged. Directly below the reactor pressure vessel 5 can receive all the molten jets falling within the projected range of the reactor pressure vessel. The two columns of cooling pipelines are equipped with pump valves, both of which take water from the safe water source provided by the power station. Under accident conditions, the external water injection pipeline 2 and the internal reactor water injection pipeline 1 supply water to the reactor pit 7 and the reactor pressure vessel 5 respectively, and the external reactor water injection pipeline 2. Water is injected from the bottom of the reactor pit 7 to gradually submerge the melt retention device; the water injection pipeline 1 in the reactor directly injects water into the reactor pressure vessel 5 for cooling the core and providing a spray-like spray to the top of the melt retention device cooling form. When the melt interacts with the cooling water in the pit and the temperature and pressure exceed a certain threshold, the configured overpressure blasting device 3 of the pit ventilation system will automatically blast and release the pressure to prevent damage to the concrete partition wall 4 of the pit.

The melt retention device provided by the present invention is a multi-layer structure, as shown in Figure 2 and Figure 3, each layer of structural units is connected and supported by high temperature resistant support columns 10, leaving 40 between adjacent two layers of structural units -60cm free space. The melting temperature of the porous sacrificial layer 8 is 1500-2000 degrees, and it is tiled on the upper surfaces of the high-temperature-resistant crucibles 9 and 11 with a thickness of 20-30 cm; the melting temperature of the high-temperature-resistant crucible 8 and the high-temperature-resistant support column 10 is 2800 degrees Above, high temperature ceramic materials can be used. Each layer of the high-temperature-resistant crucible 9 except the bottom layer is provided with flow holes 12 distributed in an array and interlaced with each other. The flow holes 12 on two adjacent layers of high-temperature-resistant crucibles are arranged in a staggered position. The high-temperature-resistant crucible at the bottom A non-porous crucible. The main body shape of the high temperature resistant crucible and the porous sacrificial layer on it is a disc structure, the outer edge is raised by 10-30 degrees to form a weir, and the middle part is a flat collection area, and the flow hole 12 is set in the middle part of the high temperature resistant crucible collection area. The central part of the porous sacrificial layer has retention holes 13 and retention pits 14 distributed in an array. The porous sacrificial layer is processed by a sintering process and has a porous sponge structure with a porosity of 0.1-0.3, which allows the coolant to quickly penetrate into the pores of the porous sacrificial layer's sponge structure to achieve cooling.

The reactor molten matter retention system outside the reactor after a severe accident provided by the present invention, when a serious nuclear power plant accident occurs, the cooling system operates according to the operator's instructions, and the molten material can be formed by injecting water into the reactor and outside the reactor respectively. The double cooling of the upper and lower parts promotes its solidification retention and eventual long-term cooling.

As shown in Figure 1, after the core molten material melts through the lower head 6, it falls into the top layer retention unit of the reactor molten material retention device outside the reactor, and the high-temperature molten material will be diluted in the disc-shaped receiving device under the action of gravity, Thereby increasing the heat exchange area, making the cooling effect and solidification retention function easier to achieve efficiently.

As shown in Figure 2, when a large amount of high-temperature molten material first falls into the retention device, it first contacts the porous sacrificial layer 8. On the one hand, the cooling water permeated in the spongy porous sacrificial layer 8 can effectively cool the molten material. , to promote its solidification crust, on the other hand, in the local area where excessive high-temperature melt is accumulated, the sacrificial layer material (such as iron oxide or aluminum oxide or a mixture of the two) will absorb a large amount of heat by melting itself, and ensure the temperature It is lower than the design temperature of the high temperature crucible to ensure its structural strength and the integrity of the geometric form of the device.

As shown in FIG. 3 , when the sacrificial layer 8 on the top is melted through, the excess melt at its corresponding position will flow into the sacrificial layer of the next layer of unit structure through the melted channel, and be flattened and cooled for the second time. Since the porous sacrificial layer of the lower layer is designed with retention holes 13 and retention pits 14 arranged in an array, the melt is distributed to the top of the high-temperature-resistant crucible 9 in this layer in a controlled manner. If it is fully cooled and retained, the corresponding portion of the melt will continue to melt through the sacrificial layer 8 and migrate to the next extended structure along the preset flow holes 12 of the high temperature resistant crucible 9 . By rationally designing the cladding thickness of the sacrificial layer and the opening position and diameter of the through-holes on the high-temperature-resistant crucible, with the help of the up-and-down dislocation through-hole arrangement, the molten material accumulated in each layer will be controllably distributed to the next layer , this design of multi-layer retention not only prolongs the residence time, but also provides a feasible way for the uniform redistribution of the heat source in three-dimensional space. In this way, the melt can be solidified and retained safely and efficiently, and long-term cooling can be provided.

In addition, in the multi-layer retention device, the high-temperature-resistant crucible 11 equipped with the lowest structural unit is non-porous to ensure that in extreme cases, even if the melt breaks through the barriers and reaches the last layer of the retention structural unit, it can still be absorbed. All contained within the designed melt retention device without interacting with the concrete floor of the containment and creating additional safety risks.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (9)

1. reactor fusant out-pile gaseous-waste holdup system after a kind of major accident, including setting is below reactor pressure vessel (5) The fusant arresting device of reactor pit (7) bottom and cooling line from stand-by water source, the fusant arresting device energy Enough accept all fusant jet streams fallen in reactor pressure vessel (5) drop shadow spread, it is characterised in that: the fusant Arresting device includes the high-temperature crucible (9,11) that multilayer allows fusant and coolant to penetrate, two layers adjacent of high-temperature crucible Between be equipped with connection and supporting role high temperature resistant support column (10), on every layer of high-temperature crucible be equipped with can be melted object The porous sacrificial layer (8) of burn through, the porous sacrificial layer (8) are the cavernous structure being process by sintering process.

2. reactor fusant out-pile gaseous-waste holdup system after major accident as described in claim 1, it is characterised in that: adjacent two There are the free spaces that height is 40-60cm between layer high-temperature crucible.

3. reactor fusant out-pile gaseous-waste holdup system after major accident as described in claim 1, it is characterised in that: remove the bottom The every layer in addition high-temperature crucible (9) is equipped with array distribution and the staggered recirculation hole of interlayer (12), and described is porous Sacrificial layer is laid in the upper surface of every layer of high-temperature crucible with the thickness of 20-30cm.

4. reactor fusant out-pile gaseous-waste holdup system after major accident as claimed in claim 3, it is characterised in that: described is resistance to High-temperature crucibles (9,11) are disk-like structure, and middle part is smooth collecting region, and outer rim tilts 10-30 degree and forms shield weir, the stream The middle part collecting region in high-temperature crucible (9) is arranged in through-hole (12), recirculation hole (12) dislocation on adjacent two layers high-temperature crucible Arrangement.

5. reactor fusant out-pile gaseous-waste holdup system after major accident as described in claim 1, it is characterised in that: described is more The porosity of hole sacrificial layer (8) is 0.1-0.3；The delay hole (13) of array distribution is equipped at the middle part of porous sacrificial layer (8) (14) are cheated with being detained.

6. reactor fusant out-pile gaseous-waste holdup system after major accident as described in claim 1, it is characterised in that: described is more The fusion temperature of hole sacrificial layer (8) is 1500-2000 DEG C, the high-temperature crucible (9,11) and high temperature resistant support column (10) Fusion temperature is at 2800 DEG C or more.

7. reactor fusant out-pile gaseous-waste holdup system, feature exist after major accident as claimed in any one of claims 1 to 6 In: two column are arranged altogether and are equipped with pump valve for the cooling line, respectively waterflood-transmission line (1) in out-pile waterflood-transmission line (2) and heap； The outlet of the out-pile waterflood-transmission line (2) is located at reactor pit (7) bottom, for supplying water into reactor pit (7)；Water filling in the heap The outlet of pipeline (1) is connected with pressure vessel (5), for supplying water into reactor pressure vessel (5).

8. reactor fusant out-pile gaseous-waste holdup system after major accident as claimed in claim 7, it is characterised in that: the cooling Through fusant arresting device, coolant rapid osmotic enters among the gap of porous sacrificial layer to be realized the coolant flow that pipeline provides Refrigerating function.

9. reactor fusant out-pile gaseous-waste holdup system after major accident as described in claim 1, it is characterised in that: work as reactor pit (7) fusant occurs in and coolant interacts, when temperature and pressure are more than certain threshold value, the reactor pit ventilating system of configuration is super It presses demolition set (3) by automatic-explosion pressure release, prevents reactor pit concrete partition (4) from damaging.