The interstitial structure that is used for nuclear reactor pressure vessel
Technical field
The present invention relates to the formation of a kind of gap and keep structure, in core melt down accident, be not damaged in order to protection nuclear reactor pressure vessel lower end.
Technical background
The present invention is relevant with nuclear reactor, introduce a kind of formation structure of gap in the lower end of this reactor core pressure vessel, and remain on a kind of geometric configuration that is easy to cool off with this, be implemented under the situation of core melt down accident, prevent to make the overheated and ultimate failure of this lower end housing because of the accumulation of reactor core fragment of fusing.Within this lower end, add the housing of a spill parabola or garden cylinder and constitute the liquid phase boundary line of this reactor.If when a kind of like this major accident will take place, the core pressure vessel of this reactor was because overheated, its inner reactor core material may melt, and transfers to the lower end of this core pressure vessel subsequently downwards.In this case, the reactor core material of fusing will directly contact with this core pressure vessel lower end, thereby make this heating of metal reactor core pressure vessel lower end and distortion, and cause that it breaks, thereby face the danger that a large amount of radioactive materials leak.This structure of the present invention has formed a predetermined gap, directly contact with the inside surface of this pressure vessel with the reactor core material that prevents to melt, so: at first, prevented the rapid intensification of this reactor core pressure vessel lower end, secondly, by guaranteeing the water-cooled effect in this gap, help to realize preventing major accident and therefore prevent the damage of the core pressure vessel lower end of this reactor.
Traditional water-cooled reactor does not prevent this interstitial structure of serious meltdown accident, therefore, just in case take place that major accident and molten core material shift downwards and when this core pressure vessel lower end accumulation, perhaps can produce a little gap naturally, and this gap may be too little, too irregular, cooling to this fragment may be insufficient, and the amount of cooling water of this fragment is decided according to the scope of accident.In No. 2 units in three miles islands (TM1-2) accident in 1979, prove once serious accident at last, comprising core meltdown, the reactor core fragment of fusing directly contacts the extreme that has caused this core pressure vessel inwall with the lower end of this core pressure vessel and is heated near its melting temperature.Yet because some unaccountable mechanism, this core pressure vessel was cooled off again afterwards and had been avoided the damage of this core pressure vessel.In order to explain this rapid cooling, set up following theory: limited chilled water has been added among the gap that forms between the reactor core fragment of fusing and this core pressure vessel lower end inside surface, but its inhomogeneous and random distribution has caused being created in the TM1-2 accident of focus, although in fact the quantity of the reactor core fragment of Zhuan Yiing is 19 tons, the less than 1/5th of having only reactor core material, but the breakage of separating with unconspicuous border is still left in this reactor core pressure vessel lower end.Therefore, if an accident that has bigger fusing degree takes place, it is not enough that this reactor core pressure vessel lower end only depends on natural cooling mechanism to cool off, and its potential result is breaking of reactor core pressure vessel, and the reactor core fragment of this fusing subsequently releases.Its consequence is that a large amount of high-temperature materials will release and build interior structure with containment and further excite chemical reaction and thermal response from this core pressure vessel.Owing to this high temperature and high pressure threatens the integrality of this containment, may produce one even more serious accident.
Designed the outside catcher (ex-vesse catcher) (U.S. Patent number 4,113,560) of a kind of core pressure vessel by M.J.Driscoll and F.L.Bowman (Massachusetts Institute of Technology (MIT)).In the outside catcher of this core pressure vessel, the reactor core fragment of this container is solidified by the structure (graphite, sand etc.) of core pressure vessel outside.The outside catcher of this core pressure vessel can seal and be isolated in its inside separately with the reactor core fragment of fusing, to stop itself and containment building further reaction takes place.It is intended that will avoid producing heat and gas when the concrete reaction of reactor core fragment that melts and containment terrace, and prevents that a large amount of radioactivity molten core fragments from overflowing from this concrete base.Yet this special device is designed to; only after a reactor core pressure vessel breaks; and, therefore, need a kind of additional security system to cool off and protect this containment to build no matter may have a large amount of heat and radioactivity radiation leakage within the containment building.In quick breeder reactor, adopted the reactor core below trap structure of reactor with the liquid metal cooling.But in Fermi's type heap, because design defect,, will facilitate a core melt down accident when this connection loosing and when blocking ANALYSIS OF COOLANT FLOW.In addition, the horizontal reactor core below catcher design that Fermi's type heap and SUPERPHENIX reactor are used can not produce effect to water-cooled reactor, because it is very abominable with the cooling condition of obstruction below this steel plate of bubble to be seethed with excitement.
A kind of core pressure vessel external refrigeration mode has been proposed, and proving it has the ability external refrigeration is carried out (referring to T.G.Theofanos in this core pressure vessel lower end, C.Liu, S.Addition, S.Angelini, O.Kymaelaeinen and T.Samassi show " core pressure vessel inside is to the cooling and the maintenance (In-vessel coolability and Rention of aCore-melt) of molten core ", DOE/ID-10460, in November, 1994).This method be considered to limited several be in operation or design in factory its rationality is arranged, but it has a shortcoming, will expend a large amount of time and water resource exactly and the cavity of reactor is flooded in a large number.In addition, the excess of this core pressure vessel is flooded or floods out of turn, may just have the danger that radiation heat impacts and make this pressure vessel generation annular region embrittlement.
The content of invention
In first embodiment, disclose a kind of formation of gap and kept structure, this structure is used in to be had one the reactor core apparatus is arranged on reactor core pressure vessel lower end top, and have in this reactor core pressure vessel in the nuclear reactor pressure vessel of cooling back installation, described structure comprises:
A concave surface housing, be arranged on the below of described reactor core apparatus and the lower end of close described reactor core pressure vessel, its effect is under the situation of heap core melt down accident that reacts, and will and hold from the collection of the molten core fragment in the described reactor core apparatus; With
A kind of device is used for separating and keeps described concave surface housing to be in respect to described reactor core pressure vessel lower end and separates on the position of certain intervals, between described concave surface housing and described reactor core pressure vessel lower end, form and keep a gap with this, under the heap core melt down accident situation that reacts, this gap can make the circulating coolant circulation in the middle of described gap in the described reactor core pressure vessel, thereby what prevent described fusing heap reactor core fragment and described reactor core pressure vessel lower end directly contacts and take away heat from the heap reactor core fragment of described fusing, so, the integrality of described reactor core pressure vessel lower end its structure of maintenance during utilizing described concave surface housing collection and holding described molten core fragment.
In one second embodiment, disclose the formation of a kind of gap and kept structure, be used in one have be arranged on the reactor core apparatus reactor core pressure vessel lower end top and nuclear reactor pressure vessel that in this reactor core pressure vessel, have cooling back installation in, described structure comprises:
A concave surface housing, be installed in the below and the close described reactor core pressure vessel lower end of described reactor core apparatus internally, be used for when reacting the heap core melt down accident, collecting from the reactor core fragment of described reactor core apparatus fusing and holding;
One group of brace summer that is fixed on the described concave surface housing is used for keeping this concave surface housing to be in respect to described reactor core pressure vessel lower end and separates on the position of certain intervals when reacting the heap core melt down accident;
One group of structural bead that is fixed on this concave surface housing is used for limiting the distortion and the vibration of the relative described concave surface housing that separates with described reactor core pressure vessel lower end under normal running and generation core melt down accident situation; With
One group of deformation constrain leg that is fixed on this spill housing, be used for when the reactor core meltdown accident takes place, keeping the planform of described concave surface housing, described thus support beam group and described limit deformation pin group form between described concave surface housing and described reactor core pressure vessel lower end and keep a gap, so that react the heap core melt down accident situation under make described in reactor core pressure vessel coolant circulating can in described gap, circulate, thereby prevented direct contact of described molten core fragment and described reactor core pressure vessel lower end, and from described molten core fragment, be with sufficient heat, thereby make described reactor core pressure vessel lower end collect and hold the integrality that can keep its structure in the process of described molten core fragment at described concave surface housing.
In one the 3rd embodiment, disclose a kind of formation of gap and kept structure, be used for one and have the reactor core pressure vessel that its reactor core apparatus is arranged on the top of reactor core pressure vessel lower end, and described reactor core pressure vessel lower end has an outer surface, and have circulating coolant in this reactor core pressure vessel, described structure comprises:
A concave surface housing is installed in from the outside below the described outside surface of described reactor core pressure vessel lower end, and separated certain intervals;
A kind of lower end outside surface of separating and keeping described concave surface housing to be in respect to described reactor core pressure vessel that installs separates on the position of certain intervals, thereby between the described outside surface of described concave surface housing and described reactor core pressure lower end, form a gap, in case the heap core melt down accident that reacts; And
A coolant delivery device, be used under the situation of heap core melt down accident that reacts to described gap supply coolant, the heat that will produce in described reactor core pressure vessel lower end because of the molten core fragment heating that described reactor core apparatus produces is taken away, so that can be under the situation of heap core melt down accident that reacts, collecting by described reactor core pressure vessel and holding the structural intergrity of keeping described reactor core pressure vessel lower end in the described molten core fragment process.
Design of the present invention comprises that a structure constitutes a tangible gap, and this gap is with the geometric configuration that keeps being convenient to cool off, and the bottom of close this reactor core pressure vessel is to stop its fusing.The present invention can be applied in all water-cooled reactors, is connected and plays effectiveness with the circulation line of passive (Passive) mode and existing engineering safety facility and nature.
Brief description of drawings
Now will be in conjunction with the accompanying drawings and later detailed description, described advantage and other advantages of the preferred embodiments of the present invention are done further explanation.Wherein:
Fig. 1 illustrates a kind of pressurized water reactor (PWR) core pressure vessel that has interstitial structure of the present invention.
Fig. 2 illustrates a core pressure vessel that has the blast groove type pressurized water reactor (VVER-type) of interstitial structure of the present invention.
Fig. 3 illustrates boiling water reactor (BWR) core pressure vessel that has interstitial structure of the present invention.
Fig. 4 illustrates pressure heavy water reactor (CANDU-type) core pressure vessel that has interstitial structure of the present invention.
Fig. 5 illustrates a multilayer interstitial structure that is arranged on the inside, reactor core pressure vessel lower end of interstitial structure of the present invention.
Fig. 6 illustrates the example of a present invention in this reactor core pressure vessel lower end inner support interstitial structure.
Fig. 7 illustrates a present invention to be installed in the interstitial structure of this outside, reactor core pressure vessel lower end.
Fig. 8 A and 8B are being not intended to of a major accident development in the nuclear reactor of band gap structure not.
Fig. 9 A and 9B are synoptic diagram that major accident is prevented from having the nuclear reactor of interstitial structure of the present invention.
Figure 10 A, 10B and 10C illustrate one can be applied in top view, sectional view and planimetric map in pressurized water reactor (PWR) and blast groove type pressurized water reactor (VVER-type) and the boiling water reactor (BWR), interstitial structure of the present invention respectively.
Figure 11 A, 11B and 11C illustrate one can be applied in view, sectional view and planimetric map in the pressure heavy water reactor (CANDU-type), interstitial structure of the present invention respectively.
Realize optimal mode of the present invention
Shown in Fig. 1,2,3 and 4, this centre reactor core (1) is a nuclear fuel zone, and here cooling medium stream is taken away the heat of nuclear reaction.Descend if a fault and cooling power have taken place, this reactor core and structure on every side may melt and accumulate in its lower end.In this case, this interstitial structure (3) will prevent that this molten core from directly contacting with the inside surface of this lower end (2).In addition, detection/control nozzle inserts this reactor core pressure vessel lower end (2) and is welded on its inside surface.This interstitial structure of the present invention (3) will be installed in down the bottom of reactor core supporting construction, form a suitable gap or a distance with the bottom of this reactor core pressure vessel, and have enough intensity and thermotolerance and keep the geometric configuration that is easy to cool off, also bear the reactor core net weight that during the reactor core material meltdown accident, melts simultaneously.Consider boiling heat transfer and structural behaviour, the minimum dimension in this gap is decided to be about 2 centimetres.This interstitial structure (3) is parabola or concave, and is furnished with vertical pod apertures (6).This structure (3) preferably covers entire reaction heap core pressure vessel lower end (2) and flows into this gap with the reactor core that prevents to melt.Cooling medium in the pressure cavity of bottom flow distribution because the variation that causes of interstitial structure of the present invention (3), in course of normal operation or be in must be as much as possible little under the transition state of designed light-water reactor (LWRS).
Fig. 6 is shown in the middle of this core pressure vessel lower end, and this interstitial structure of the present invention (3) goes up welding or fixing situation at bottom core structure or detection/control insert structure (4).This structure (3) can add that adhering to supporting construction stops the overweight distortion that causes of carrying.This device is used for this concave surface housing being separated with the lower end of this reactor core pressure vessel and remaining on the position that separates certain intervals with it, under the situation of reactor core fusing, between this concave surface housing and this reactor core pressure vessel lower end, form and keep a gap like this.These devices make can circulate this reactor core pressure vessel coolant circulating, thereby prevent that the reactor core fragment of this fusing from directly contacting with the lower end of this reactor core pressure vessel, and take away heat from the molten core fragment in the middle of this gap.This circulate coolant guarantees that this reactor core pressure vessel lower end keeps its structural intergrity during being collected by this concave surface housing and holding this molten core fragment.Be used for this concave surface housing being separated with this reactor core pressure vessel lower end and keeping this device embodiment of separated certain intervals position to comprise, one group of brace summer (10A) is fixed on limit deformation leg (9) and structural bead (10b) on this concave surface housing.
If this high-temperature reactor reactor core material fusing and being deposited in the bottom high-pressure space of this reactor core pressure vessel (Fig. 9), this interstitial structure of the present invention (3) will be caught this molten core material, to avoid it directly to contact with this core pressure vessel, and can utilize coolant circulating in the gap (5) between this core pressure vessel and this fragment, the heat in the reactor core material that drops is eliminated.
As shown in Fig. 1,2,3 and 4, every kind of interstitial structure (3) all is illustrated as an individual layer, but also may wish to use a kind of multilayer interstitial structure herein.As shown in Figure 5, in this case, this gap forms and keeps in the structure, this concave surface housing is confirmed as one first concave surface housing (3A) and one second concave surface housing (3B), and wherein this first concave surface housing (3A) separates certain intervals and forms first gap (3AA) with this reactor core pressure vessel lower end (2); This second concave surface housing (3B) separates certain intervals and forms second gap (3BB) with this first concave surface housing.Preferably the diameter of this second concave surface housing (3B) is less than the diameter of this first concave surface housing (3A), and gap (3BB) between two concave surface housings and the gap (3AA) between this first concave surface housing and this reactor core lower end, be even or equal interval separately separately.If the concave surface housing can be provided with following mode in this reactor core pressure vessel, first the most close this reactor core pressure vessel lower end and back more up, its diameter is more little in succession.
In Fig. 5, (3A is to be fixed on the structure of pilot sleeve (7) 3B) to this first and second concave surfaces housing, and this jacket casing the (not shown) of this detection/control insert structure (4).In each interstitial structure (3), be distributed with pod apertures (6), can be used for being reduced in during the normal running and in the transient process of design, the water temperature in this gap in this bottom high-pressure space and the water temperature in this reactor poor.Length one diameter of this pod apertures is than greatly, so that the reactor core fragment of this fusing can not therefrom pass.This molten core that drops may detect this/control and insert device (4) generation thermal shock, thereby further causes the difficulty of reactor core condition diagnosing.Fig. 6 illustrates a pilot sleeve structure (7), and it projects upwards and form a vertical gap (8) from this interstitial structure, and this gap has similar cooling effect, protects this detection/control to insert device.This interstitial structure of the present invention (3) should adopt durable and can bear made hot and that mechanical load impacts.Corrosion resistant metal wrapped into as much as possible just can have the endurance quality that needs among pottery and/or the compound substance.This interstitial structure (3) can also additional heat sink to increase its cooling power.
Illustrated the interstitial structure of this core pressure vessel inside among Fig. 1,2,3 and 4, and Fig. 7 illustrates a core pressure vessel outer gap structure (3) that is installed in outside, pressure vessel lower end (2).In this case, required cooling medium will be supplied with from a coolant reservoir tank (5).During accident, this jar is by an operation valve (16) and cooling medium input pipe 17 input cooling mediums.The inside and outside interstitial structure of core pressure vessel can be installed with a kind of mode of the examination and maintenance of this core pressure vessel of can not disturbing.If desired, can adopt with reactor core pressure vessel in the same quadrat method of multilayer interstitial structure, use the multilayer interstitial structure (in order to shorten length, not signal) of core pressure vessel outside.
The formation of this outer gap and maintenance structure applications are in a nuclear reactor pressure vessel, this core pressure vessel has a reactor core apparatus that is arranged on top, reactor core pressure vessel bottom, and, in this reactor core pressure vessel, have coolant circulating.This outer gap structure comprises the concave surface housing of a below that is arranged on this outside surface outside, reactor core pressure vessel lower end and separated certain intervals, thus between the outside surface of this anti-reactor core pressure vessel lower end and this concave surface housing gap of formation.Coolant delivery device in this gap, and is taken away the heat of this reactor core pressure vessel lower end with coolant feed under the situation of heap core melt down accident that reacts; This heat is to be produced by the molten core fragment that falls from this reactor core apparatus in the reactor core meltdown accident, therefore can during collecting by this reactor core pressure vessel and holding this molten core fragment, keep the structural intergrity of this reactor core pressure vessel lower end.
Better is that this coolant delivery device further comprises an operation valve, is used for controlling the flow that this cooling medium flows into this gap.Also can help cooling medium at the lower end of reactor core pressure vessel installation heat radiator dispels the heat when flowing to the gap.
The not expansion of major accident during this interstitial structure of Fig. 8 signal, and Fig. 9 is shown in interstitial structure of the present invention and assists down and check accident.In Fig. 8 and Fig. 9, label 12,13 and 14 is represented water coolant (12) respectively, molten core fragment (13) and the core pressure vessel lower end of damaging (14).Figure 10 (A) illustrates the top view of this interstitial structure (3), Figure 10 (B) signal one sectional view, and Figure 10 (C) illustrates an one planimetric map, this structure can be used among PWR, blast groove type PWR (VVER-type) and the BWR.The planimetric map of this interstitial structure among this Figure 10 (C) is illustrated it to have mesh lines and is strengthened the 3-D display effect.This figure has also illustrated to be used for inserting the structure of the pilot sleeve (7) of detection/control device.
Figure 11 (A) has illustrated to be applied to a top view of the interstitial structure of the present invention (3) of a pressure heavy water reactor (CANDU-type), Figure 11 (B) signal one sectional view, and Figure 11 (C) illustrates an one planimetric map.The planimetric map of this interstitial structure among this Figure 11 (C) is illustrated it to have mesh lines and is strengthened the 3-D display effect.This figure has also illustrated to be used for inserting the structure of the pilot sleeve (7) of detection/control device.The design of follow-on nuclear reactor need provide the protection to major accident.Under the situation of light-water reactor, be the design of this goal programming, comprise the performance of two attentions: promptly the reactor cavity floods method and advanced containment cooling means.These methods that prevent major accident will need a large amount of and valuable device.Contrast therewith, interstitial structure of the present invention is installed with simple relatively structure, the protection to core pressure vessel is provided, and can have cut much ice in a kind of passive mode.The explanation that we are detailed this interstitial structure.Obviously, in the field of the invention, the existing knowledge that whoso has all can make the present invention be used for various uses easily, thus we will be not only will be in the claim scope, interior and in various uses, use the present invention.