JPS6190081A - Fast breeder 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 Field of the Invention] The present invention provides a core support mechanism that can be taken out of the reactor,
Concerning fast breeder reactors with improved maintenance and repairability.

[Technical background of the invention] FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a tank-type fast breeder reactor.

In the figure, reference numeral 1 denotes a reactor vessel, and a safety vessel 2 is provided outside the reactor vessel 1. These reactor vessels 1
The safety vessel 2 is installed in the reactor building 17A via the ring girder 17. A roof slab 3 is provided so as to close off the upper opening 1A of the reactor vessel 1. This roof slab 3 includes a fixed plug 3A and a large rotating plug 3B rotatably attached to the fixed plug 3A.
, and a small rotation plug 3C rotatably attached to the large rotation plug 3B. A reactor core 5 and a coolant 8 such as liquid sodium are housed in the reactor vessel 1, and the reactor core 5 is supported by a core support gate structure 4.

A core upper section structure 7 is provided above the core 5, passing through the small rotating plug 3C. This core upper part failure 7
A control rod drive tltFJ (not shown) is provided inside the reactor, and this control rod drive tltFJ adjusts the degree of insertion of the control ring (not shown) into the reactor core 5 to control the core output. The inside of the container 1 is divided into upper and lower parts by a partition wall 10, and the upper part is formed into a hot pool 11 and the lower part is formed into a cold boule 12.The coolant 8 that has passed through the core 5 and has reached a high temperature is transferred to the hot pool 11. The coolant 8 passes through the intermediate heat exchange detector 13, exchanges heat with the secondary coolant, and flows out into the cold boule 12.
is transferred below. Note that both ends of the discharge pipe 18 are fixed to the circulation pump 14 and the core support mechanism 4.

The core support mechanism 4 is suspended from the roof slab 3 via a hanging shell 6, and even if the roof slab 3 vibrates, both the core 5 and the upper core section structure 7 vibrate, causing their relative Prevent displacement.

Reference numerals 9 in the figure are flow holes, and the coolant 8 flowing out from the upper surface of the core 5 flows through these flow holes 9.
・Leaked to Kau Hot Bool 11.

Next, the reason for preventing displacement of the reactor core 5 during imaging will be explained. Reference numeral 20 in the figure indicates a control vertical wall, and this damping wall 20 has a cylindrical shape and is erected from the bottom inner surface of the reactor vessel 1. This damping wall 20 is composed of an outer wall 21 and an inner wall 22, and ribs 23 corresponding to the number of tanks are provided along the vertical direction between the outer wall 21 and the inner wall 22, forming a double wall structure. . The inner surface of the inner wall 22 and the core support i
For example, there is a distance of 10s to 3 between the outer peripheral surface of ff + tl
A small gap a of 0 mm is formed. In addition, a coolant flow path is formed between the outer wall 22 and the inner nitrogen 23, and the inner lower part of the damping wall 20 (lower blemish > 30 and the upper part of the core 5) is formed through this coolant flow path. It is in communication with a hot pool 11.

According to this vibration damping structure, the core support mechanism 4 and the vibration damping wall 2
Since there is no compensatory contact with 0, vertical displacement of the core support mechanism 4 due to thermal deformation etc. is released during normal operation, and excessive heating force is not generated on each structural member.

When a horizontal load acts on the core support 11+114 due to an earthquake or the like and the core support mechanism 4 attempts to displace in the horizontal direction, the core support mechanism 4 and the vibration damping v20
The small gap a between the coolant 8 and the coolant 8 in this small gap a changes
flows. The flow resistance of the coolant 8 damps the vibration of the core support mechanism 4, and prevents the core support gate structure 4 from being displaced in the horizontal direction.

In addition, when the core support gate structure 4 is vertically displaced due to vertical movement R, etc., the volume of the lower blennium 30 at the lower part of the damping wall 20 changes, but the coolant 8 inside this lower brenum 30 changes.
is released into the hot pool 11 through the small gap a and the cold FA material passage formed between the outer wall 21 and the inner wall 22 of the vibration damping wall 20, so that the pressure increase in the lower brenum 30 is prevented. It never comes to life.

Reference numeral 41 in the figure indicates a horizontal control layer member. For example, when a horizontal earthquake occurs, the horizontal load is transmitted to the reactor vessel 1 via this horizontal vibration damping member 41, and the key 4
2 and the keyway 43 to the safety container 2. The load transmitted to the safety vessel 2 is transmitted to the reactor construction 17A via the skirt portion 2A.

[Problems with Background Art] According to the above configuration, core support lj! Since the structure 4 and the circulation pump discharge piping 18 are mechanically coupled, the following problems occur. In other words, the core support gate structure 4 and the hanging shell 6
In the unlikely event that a problem should occur, the circulation pump discharge pipe 18 must be cut in order to take it out of the furnace for maintenance. In addition, thermal displacement and earthquake displacement occur in the core support structure 4, and at that time, reaction force acts on the circulation pump discharge piping 18, which may impair its integrity.

Therefore, if the structural integrity of the circulation pump discharge piping 18 is to be maintained, it is necessary to route the circulation pump discharge piping 18 or to make it have a flexible structure, which results in a double-wall configuration. . Furthermore, in order to prevent the pressure in the lower plenum 30 from becoming excessive due to vertical movement of the reactor core in the event of ground dew, it is necessary to provide a coolant passage. and ribs 23, etc., resulting in a complex structure.

In addition, there is also a problem in that the coolant 8 accumulates in the lower plenum 30 under normal conditions, which promotes the occurrence of @.

[Purpose of the Invention] The present invention has been made based on the above points, and its purpose is to create a structure in which the core support 1 can be taken out of the reactor for maintenance 7111 even in the event of a malfunction. At the same time, we simplified the configuration around the core support structure,
The object of the present invention is to provide a fast breeder reactor that can improve reliability.

[Summary of the Invention] That is, the fast breeder reactor according to the present invention includes a reactor vessel, a roof slab provided to close the upper horse 10 of the reactor vessel, and a roof slab suspended from the roof slab via a hanging song. A control wing wall having a gap between a core support mechanism accommodating the reactor core and an outer peripheral surface of the core support 1 that is erected from the bottom of the reactor vessel, and seals IXM that seal the upper and lower ends of the gap. tM, a circulation pump that penetrates the roof slab and is installed on the outer peripheral side of the core support gate structure, and a circulation pump that is arranged downward from the core and whose end is supported by the damping wall. This configuration includes an m-ring pump discharge piping.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 7. Note that the same parts as in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted. Reference numeral 120 in the figure indicates a damping wall, and the damping wall 120 has a cylindrical shape and is erected from the inner surface of the bottom of the main vessel 1 to the outer peripheral side of the core support mechanism 4. A small gap A of, for example, 10 mm to 30 mm is formed between the control wing wall 120 and the outer peripheral surface of the core support mechanism 4.

The flow resistance of the coolant 8 in this small gap A damps the vibration of the core support tlv 44 and prevents horizontal displacement of this core support mechanism.

A circulation pump discharge pipe 141 is connected to the control ff1l120, and a coolant inlet 142 is formed in the core support 1 (thickness 4) at a position corresponding to the connection position.

On the other hand, seal gate structures 143A and 143B are installed at the upper and lower ends of the small gap A, respectively. Piston rings as shown in FIG. 3 are used as these pre-seal tanks 143A and 143B. Such piston rings allow vertical and horizontal displacement. In this way, the seal gates 143A and 14
3Blff prevents the leakage of the coolant 8, and also suppresses the fluidity of the coolant 8 in the small gap A.
The aim is to create a structure that is strong against disturbances, thereby improving the vibration damping effect.

The coolant 8 leaving the circulation pump 15 flows into the small gap A through the circulation pump discharge pipe 141. Seals 15 are provided at the upper and lower ends of this small gap A as described above! ! Grooves 143A and 143B are provided. The coolant 8 that has flowed into the small gap A is supplied to the core 3 via the coolant inlet 142. Further, a flow hole 144 is formed in the lower part of the damping wall 120, and the lower plenum 22 below the core support mechanism 4 and the cold boule 13 are communicated via the flow hole 144.

The operation will be explained based on the above configuration. First, if a problem occurs in the core support r3 structure 4 or the suspension shell 6, the core support 1fFI4 and the suspension structure 6 are taken out of the reactor using the following procedure. That is, after the core 3 is taken out through the normal fuel exchange route, the small rotating plug 3C and the upper core 11 are removed.
Remove 117 upwards.

At this time, the suspension shell 6 is suspended and supported on the inner circumference of the roof slab 3, and the core support mechanism 4 is not mechanically connected to the circulation pump discharge piping 141, but simply the seal 1 (
Since it is only fitted with scraps 143A and 143B,
The suspension shell 6 and the core support gate structure (old 4) can be easily pulled together from the top surface of the roof slab 3. Therefore, maintenance and repairability can be improved. When installing the shell 6, the procedure described above may be reversed.In this case as well, the installation workability can be improved at the same time.

Further, the circulation pump discharge pipe 141 is supported by the reactor vessel 1 via the casing 14A of the circulation pump 14 on the circulation pump 14 side, and the other side is supported via the damping wall 120 instead of the core support gate structure 4 as in the conventional case. Since it is supported by the reactor vessel 1 with a The structural integrity can be greatly improved.

Also, from the wA ring pump 14, the circulation pump discharge pipe 1
41, the coolant 8 flows into the small gap A, and flows into the core 3 through the coolant inlet 142 of the core support gate structure 4.
supplied to At that time, the sealing mechanisms 143A and 1
43B flows into the lower blenheim 30 (indicated by an arrow in the figure), the leakage flow flows into the cold pool 1 through the flow hole 144 formed at the bottom of the damping wall 120.
Return to 2. That is, since the lower plenum 30 is always in a flowing state rather than in a stagnant state, the promotion of gambling is suppressed, and as a result, the reliability of the structure can be improved. When the core support 1 and 4 are vertically displaced due to vertical movement of the earth's crust, etc., the volume of the lower plenum 30117 changes. Since it flows out into the boule 12, it is possible to alleviate the pressure increase in the lower blennium 3o.

Furthermore, since the connection of the circulation pump discharge piping 141 to the damping wall +20 can be made independently of the core support structure 4, it is sufficient to connect it before bringing in the core support structure 4 and the hanging song 6. Sufficient work space can be provided and work efficiency can be improved.

[Effects of the Invention] As detailed above, the high-speed scale-up delta reactor according to the present invention includes a reactor vessel, a roof slab provided to close the upper opening of the reactor vessel, and a hanging shell from the roof slab. a core support gate structure that accommodates the desk core suspended through the
A φ damping wall that stands up from the bottom of the reactor vessel and has a gap between it and the outer peripheral surface of the core support wall, and seals that seal the upper and lower ends of the gap penetrate the skin and the roof slab. A circulation pump installed on the outer circumferential side of the core support gate structure,
The structure includes a circulation pump discharge pipe extending from the circulation pump toward the bottom of the reactor core and having its end supported by the damping wall.

Therefore, even in the unlikely event of a malfunction, the core support 151
The bridges and hanging rivers can be easily removed, greatly improving maintenance and repair work efficiency.

In addition, the configuration around the core support unit is simplified, and
Since the circulation pump discharge piping is strongly supported, the reliability of not only the circulation pump discharge piping but also the reactor internals can be improved.

[Brief explanation of the drawing]

Figures 1 to M3 are diagrams showing one embodiment of the present invention, and Figure 1 is a sectional view of a coffin of a tank-type fast breeder reactor. FIG. 2 is a sectional view showing a part of the M1 diagram in detail, FIG. 3 is a perspective view showing a piston ring, and FIG. 4 is an rI+ sectional view of a conventional tank-type fast breeder reactor. 1... Reactor vessel, 1A... Upper opening of reactor vessel, 3... Roof slab, 4... Core support 1 fJ,
5...Reactor core, 9...Hanging shell, 14...Circulation pump, 120...Control, 5 wall, 141...Circulation pump discharge piping, 143A, 143B...1 seal structure. Applicant's agent Patent attorney Takehiko Suzue Figure 1, Figure 2r1! J

Claims (2)

[Claims] (1) A reactor vessel, a roof slab provided to close the upper opening of the reactor vessel, a core support mechanism suspended from the roof slab via a suspension shell and housing the reactor core, and the above-mentioned nuclear reactor vessel. a vibration damping wall that is erected from the bottom of the reactor vessel and has a gap between it and the outer peripheral surface of the core support mechanism; a seal mechanism that seals the upper and lower ends of the gap; A fast breeding system characterized by comprising a circulation pump installed on the outer circumferential side, and a circulation pump discharge pipe arranged from the circulation pump toward the bottom of the reactor core and having an end supported by the damping wall. Furnace. (2) The fast breeder reactor according to claim 1, wherein a flow hole is formed in the lower part of the damping wall.