JPS5957189A - Lmfbr type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Portion of the Invention] The present invention is directed to a tank-type waste metal cooling type high-speed blasting reactor.

Technical Problems with the Invention] Conventionally, liquid metal cooled fast breeder reactor 1-1: A core support structure is placed at the lower part of the reactor valley, and this core support structure It was constructed to support the reactor core. death〃·
However, in the case of a reactor vessel with a large diameter, such as a tank-type high-speed iQ breeder reactor, there is a possibility that the reactor vessel and the roof slab may vibrate up and down in different modes in addition to the expansion. and,
In such a case, the reactor core installed on the reactor vessel side and the 1ffiJ installed on the roof slab side.

Due to the relative displacement of the control rod drive mechanism, the control rod gripped by the control rod drive mechanism moves up and down with respect to the reactor core, causing a problem in which reactivity control is not determined. .

In order to prevent such problems, it has been devised that a cylindrical suspension shell is suspended from the lower surface of the roof slab, and the reactor core is supported by this suspension shell. In such a system, both the core and the control rod drive mechanism are supported by the roof slab, so the relative displacement of the two during an earthquake is small, and stability during an earthquake is improved. However, in such a reactor, it is necessary to form a flow path through which the still-temperature coolant that has flowed from the upper surface of the reactor core into the inside of the suspension shell flows out to the outside of the suspension shell. Such a flow path must be able to always ensure a stable flow of the coolant even if the flow rate of the coolant changes or the liquid level of the coolant changes. In addition, the related breeder reactor is configured so that even if the circulation pump is stopped, the coolant is circulated by natural convection and heat can be removed from the reactor core. There must be.

As such a flow path, a system in which a pipe was provided passing through the peripheral wall of the hanging cylinder, and another one in which a 70-hole was provided in the peripheral wall of the hanging cylinder was considered. The former is suspended each time the pipe is bent.
Since the position of Qj='2 openings and the 11 openings on the outside of the suspension shell can be set freely, it is possible to predict the λ point such that the flow of coolant during operation and the circulation by natural convection are less likely to be hindered. However, it is expected that the structure will be complicated. Further, although the latter type has a simple structure, it may have a negative effect on the viU of the flow leg material during operation and on the circulation of the coolant due to natural convection.

[Purpose of the invention]

The present invention is a liquid metal solution that forms a flow hole as a flow path for the coolant in the peripheral wall of the suspended cylinder, and that does not adversely affect the circulation of the coolant due to 01 shear or natural convection of the coolant during operation. 1 to obtain a legged fast breeder reactor.

[Sail rigging of invention]

The core is suspended from the roof slab through a circular suspension shell, and a flow hole is formed on the peripheral wall of the suspension shell, and the upper edge of this flow hole is used to fuel the fuel. At the time of exchange? ) ↑ Position it below the liquid level of the leg material, and place it at 70
- The lower edge of the hole is located p below the expected lowest liquid level. Therefore, a coolant passage is created that does not cause gas entrainment during normal operation and during refueling, and that can falsely maintain circulation by natural convection even when the coolant liquid level drops to the lowest expected level. It can be easily formed and has a simple structure.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is a nuclear reactor vessel, and this reactor vessel 1 is surrounded by a safety vessel 2. The upper end of this reactor vessel 1 is closed by a roof slab 3. A reactor core 4 is housed within this reactor vessel 1, and this reactor core 4 is supported by a core support structure 5.

6 is a hanging body which is cylindrical in shape.

The suspension shell 6 is suspended from the lower surface of the roof slab 3, and the core support structure 5 is attached to the lower end of the suspension shell 6. Therefore, the core 4 is suspended from the roof slab 3 by the -C suspension shell 6 via the core support (I'4 structure 5).

Further, 7 is a core upper mechanism, and the roof slab 7'
It is provided to penetrate through 3. A control rod drive mechanism (not shown) is provided in the core upper mechanism 7 to insert and withdraw the control rods into the core 4.lpf
has been completed. Further, a plurality of intermediate heat exchangers 8... and circulation pumps 9... are provided between the outer peripheral surface of the suspension shell 6 and the inner peripheral surface of the reactor vessel 1. The intermediate heat exchanger 8... and the circulation cylinder... are mutually arranged in the circumferential direction. Reference numeral 10 denotes a steady rest member that supports the lower end of the hanging trunk 6 and prevents the lower end of the hanging trunk 6 from swinging horizontally in the event of an earthquake or the like. Further, this steady rest member 10 has a partition wall made of wood, and divides the inside of the reactor vessel 1 into upper and lower parts.

A plurality of flow nails 11 are formed on the peripheral wall of the suspension barrel 6. These flow holes 11 are arranged in the same direction.

The circumferential positions of these flow holes 11 are arranged to correspond between the intermediate heat exchangers 8 and the circulation bonders 9, as shown in FIG. Further, a thermal resistor 12 made of a material with low thermal conductivity is attached to the surface of the suspension barrel 6 and the inner surface of the flow hole 1. The coolant at a temperature of 70°C that flowed from the upper surface of the reactor core 4 into this suspended shell 6 as described in +jiJ is 70°C.
- Hole 11...flows to the outside of this hanging shell 6, flows into the intermediate heat exchanger 8..., exchanges heat with the secondary coolant, and cools the coolant to the reactor. It is configured to flow into the lower part of the container 1. And this reactor vessel 1
The low-temperature coolant flowing to the lower part of the reactor core 4 is sent to the lower part of the reactor core 4 by circulation pumps 9 .

The vertical positions and dimensions of the flow holes 11 are set as follows.

That is, the shape of these flow holes 1 is approximately oval. The upper edge is located below the liquid level L1 of the leg material at the time of four fuel exchanges, and the position of the lower edge is the expected lowest liquid level L2 of the fuel leg material, which is the reactor vessel. The leg material leaks from the bottom of the safety container 2 and is positioned below the level of the liquid in the glass, which is equal to the liquid level in the safety container 2. In this embodiment, the upper edge of the flow hole 11 is located at approximately the same position as the liquid level Ll at the time of fuel exchange, and the expected lowest liquid level L2 is 70.
- It is configured to approximately coincide with the center of hole 1. Further, the dimensions of the flow holes 11 are set as follows, where the sieve size of the flow holes 11 is 11 and the width is X. In other words, the difference between the coolant liquid level Lo during normal operation and the expected minimum liquid level L2 is calculated as H2: the coolant liquid level Lo during normal operation and the coolant liquid level L during fuel exchange.
The difference from 1h is 1h, the thickness of the thermal resistor 12 is tn, the limit value for the earthquake load stress of the suspension shell 6 is 1.28m, the suspension 9 shell 6 is
, the number of flow holes 1 is n, the load that acts on this hanging shell 6 during an earthquake is P, the thickness of the peripheral edge of the flow hole 1 of the hanging 9 shell 6 is t, and the cooling The flow rate of the material is Q,
When the coolant passage speed through the 70-hole determined from the gas entrainment limit is V.

y≦2 (H-h -tn) --------
--...-CL)) J・2”””ni, 28m・n(?
(D-2t)2-o)・・・・・・・・・・・・(2
' x 2+ x (y-x )-=-"-= 0
,,,-・・-river (3) 4
It is set to be n'V.

The operation of the above embodiment will be briefly explained. First, during normal operation, the liquid level Lo of the coolant is high, and the noro hole 11
It is located above the upper edge of...

In this case, since the entire flow hole 1... is completely immersed in the coolant, this flow hole 11... Even if it flows, it will not cause gas entrainment.

- Furthermore, since the output of the reactor is reduced during fuel exchange, the cooling of the coolant is reduced, and the volume is reduced, so that the liquid level of the coolant drops to yji L 1 . However, flow hole 1
The upper edge of 1... is at this liquid level LtJ:,! l) Since the upper part of the flow hole 11... does not come out above the liquid level, there is no possibility that gas will be drawn in when the coolant passes through this flow hole 11... There isn't. Note that during this fuel exchange, the flow rate of the coolant is small, so if flow hole 1 is even slightly below the liquid level, there is no risk of gas being drawn in.

In addition, coolant leaks from the lowest expected liquid level L2 of the coolant ridge surface, that is, from the bottom of the reactor vessel 1, and the safety vessel 2
Even if the liquid level drops to the same level as the liquid level inside, the lower edges of the flow holes 11 are below this lowest liquid level, so the coolant passes through the flow holes 11. can flow. Therefore, in such a case, the circulation ports 9... are stopped and the coolant can also be circulated through natural convection. Note that when the coolant circulates through natural convection, the flow rate becomes extremely small, so the high-temperature coolant flowing out from the top of the core 4 and the low-temperature coolant are not sufficiently mixed, resulting in high-temperature The material may form a layer near the liquid surface, impeding natural convection and creating a large temperature gradient at the interface between this high-temperature coolant layer and the coolant below, causing damage to the furnace. A problem occurs in which excessive thermal stress is generated in the member. However, in this embodiment, the liquid level of the coolant in such a case is 70-hole 1 no.
It is located in the center of , that is, between the upper and lower edges, so
Since the layered high-temperature coolant accumulated on the liquid surface of the coolant efficiently flows out of the hanging cylinder 6 through these flow holes 11, the above-mentioned problems can be prevented.

In addition, in this embodiment, the thermal resistor 12 is attached to the surface of the suspension body 6 and the inner surface of the flow hole 1, so that the thermal stress generated in the suspension body 6 can be reduced. can.

In addition, the above-mentioned equations (1), (2), and (3) satisfy the conditions in the above-mentioned embodiment, and the suspension cylinder 6
It is possible to give a general range of the dimensions of 70-hole 1 for ω, stress 1 during an earthquake, and conditions for preventing gas entrainment during normal operation.

That is, in the above-mentioned embodiment, in order to efficiently perform natural convection under the worst condition in which the liquid level of the cold comb 1'' material has decreased to the lowest level L2 and the circulation bonders 9... have stopped, this L2
The position of the flow hole 1 is set between the upper edge and the lower edge of the flow hole 1, and since the thermal resistor 12 is attached, the flow pole 11 is formed by this thermal resistor 12.
Considering the actual opening size of Kaede, H-4-t ≧h ・・・・・・・・・
...(1) 2 n − . Therefore, if this formula 01 is modified, the above y≦2
(H-h-tn) ・・・・・・・・・
...(1) is obtained.

In addition, the suspension shell 6 is an essential structure that supports the reactor core 4, and the stress Pm generated in the suspension shell 6 due to the load during an earthquake is limited by the earthquake load stress regulated by laws and regulations, design policies, etc. The value must be less than 1.28m. Since the cross-sectional area of the hanging body 6 is reduced by forming the flow holes 1, the residual rate of this cross-sectional area is expressed as η. And since this η is, the above equations (2') and (2")...
......(2") Therefore, from this (2///) formula, the above...
・・・・・・・・・(2) is obtained.

Also, when the coolant passes through the flow hole 11... of the coolant leg, the static pressure in the vicinity of this 70-hole 1 decreases, and the gas curls from the free surface of the coolant. There is a possibility that the Of course, as in this embodiment, the flow hole 1
If the upper edge of the fuel is below the liquid level when changing the fuel,
During fuel exchange, the flow rate of coolant is small, so if the upper edge of this flow hole 1 is even slightly below the liquid level during fuel exchange, gas will not be trapped, and during normal operation. Since the liquid level of the coolant rises, the head pressure of the coolant acts on the flow holes 11, and gas entrainment does not occur even if the flow rate of the coolant increases. Therefore, in normal cases, gas entrainment will not occur if the opening areas of the flow holes 11 are sufficiently closed. but,
If the opening area of the flow holes 11 is made too small, gas entrainment may occur.

Since the area of the d openings necessary to prevent this gas entrainment is q, if there are n flow holes 11...
One flow hole 11... is 2x2-1-x(y-
x)≧9− ・・・・・・・・・・・・(
3') 4 n-v. Therefore, by transforming this, the above fang x 2+x (y-x) -Q''≧0
......(3) -v is obtained. Therefore, in order to satisfy formula (1), the dimensions of this flow hole 11... should be below the straight line Fl in FIG.
To satisfy equation (2), the area to the left of straight line F2 is sufficient, and to satisfy equation (3), the area above curve F3, that is, the area marked with diagonal lines in FIG. 5, is sufficient.

Note that the scales of the x and y axes in Fig. 5 are constants, and H=
2.3tn, h==i, Om r tn=0.2m
p 1.2 Sm=1.2X10'kg/m2. D=
10m, n=12, P=1.18X107k
g, t ==0.1 m, Q = 18.17 m
/gee.

This is when v = 1.5 m/lhe c.

In addition, the above-mentioned 70-hole 11... is an intermediate heat exchanger 8.
..., circulation pump 9..., so that the heat source coolant flowing out from these flow holes 1... is circulated through these intermediate heat exchangers 8... and circulation? f
9..., and these intermediate heat exchangers 8
...and circulation 4? Excessive thermal stress is not generated in the engine 9.

〔Effect of the invention〕

As described above, the present invention suspends the reactor core from the roof slab via a cylindrical suspension shell, and forms a flow hole in the peripheral wall of the suspension shell, so that the upper edge of the flow hole is used during fuel exchange. The flow hole is located below the liquid level of the coolant, and the lower edge of this flow hole is located below the expected lowest liquid level. 2) Gas entrainment does not occur during normal operation or during refueling, and (6) the cooling system ensures circulation by natural convection even when the liquid level of the waste material drops to the lowest expected level. Its advantages include being able to form a passage for materials and having a simple structure.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, with Figure 1 being a longitudinal sectional view and Figure 2 being a longitudinal sectional view.
The figure is a cross-sectional view taken along the line ■-■ in Figure 1, Figure 3 is a schematic vertical cross-sectional view near the flow hole, Figure 4 is a schematic cross-sectional view near the flow hole, and Figure 5 is a cross-sectional view along the line ■-■ in Figure 1. 0 is a diagram illustrating restrictions on the dimensions of flow holes. 1... Reactor vessel, 3... Roof slab, 4...
Core, 7... Core upper mechanism 58... Intermediate heat exchanger,
9... Circulation port/), 11... Flow hole, 12.
・Thermal resistor. Figure 1 Figure 2 Figure 3 O Figure 4

Claims (2)

[Claims] (1) A reactor vessel, a roof slab that closes the upper end of the reactor vessel, a reactor core housed in the reactor vessel, and a cylindrical reactor that is suspended from the roof slab and supports the reactor core. At the same time, a hanging shell has a 70-hole on its peripheral wall for discharging high-temperature coolant flowing from the upper surface of the reactor core to the outside, and a space between the outer circumferential surface of the hanging shell and the inner circumferential surface of the reactor vessel. The upper edge of the flow hole is located below the liquid level of the coolant during fuel exchange, and the lower edge of the flow hole is as expected. A liquid metal cooled fast breeder reactor, characterized in that the reactor is located below the lowest liquid level of the coolant. (2) A patented fast breeder reactor characterized in that the second side of the suspended shell and the inner surface of the flow hole are covered with a thermal resistor. <3) The dimensions of the flow hole are as follows: where the height of the flow hole is y, the width is X, the difference between the coolant liquid level during normal operation and the expected lowest liquid level is H, and during normal continuous operation The difference between the coolant liquid level and the coolant liquid level at the time of fuel exchange is h, the thickness of the thermal resistor is tn, and the limit value for the seismic id type stress of the suspended shell is ``f''.
:1. 2 8 m, the inner diameter of the hanging shell is D, the number of flow holes is n, the load acting during an earthquake is k P p, the plate thickness around the flow hole of the hanging shell is t, the current of the coolant is Q, the gas entrainment. When the coolant passage speed through the 7-hole hole determined from the ilflJ limit of 3. The liquid metal cooled fast breeder reactor according to claim 2, wherein the reactor is nIIv.