JPS607386A - Upper mechanism of core of 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 relates to a high-speed expansion "1 reactor core" part 12M 4 using solid metal such as liquid sodium as a coolant.
Regarding f4.

[Technical background of the invention and its problems] A fast breeder reactor uses a liquid (a liquid metal with a high heat conversion rate such as honalium) as a coolant.

FIG. 1 is a longitudinal sectional view of a conventional fast breeder reactor. As shown in the figure, the reactor vessel '1 is equipped with a cold JJI 444 feed pipe 2 and a cold fJI material outflow pipe 3. It is accommodated in -C. There are 111 supports in this 1 Prince reactor vessel 1.
When the core 6 is installed supported by the Ii4 structure 5, b
(,Z, An intermittent plug 7 is provided at the upper opening of the reactor vessel 1 (), and a core upper mechanism 8 is superimposed above the core 6 through the rotary plug 7. The upper machine (148 includes multiple till control drive structure internal tubes 9, outlet flow of each burner assembly of the core 6!i), a flow rate for measuring the outlet temperature, and a thermometer. A large number of 51 wells 10 are installed 5 times.The space between the plug 7 and the coolant 4 is filled with cover gas 12. A rectifying grid plate 11 is disposed at the lower end of the guide tube 9 to rectify the cold Nj flow at the outlet.

In addition, the core upper part 11<M8 has a flat guide plate 1 inside the cylindrical main body 13, as shown in an enlarged view in FIG.
5 is provided, to which a control rod guide tube 9 that houses a control rod drive machine (111) is attached, and a cylindrical main body 13
The shielding lid 16 is fixed to the upper edge of the large-diameter joint body 14 connected to the upper part of the body by means of a plurality of attachment parts (117).

The instrumentation wells 1o are bundled into several sets within the cylindrical body 13 from the lower end of the core upper mechanism 8, and each instrumentation well has a certain inner pipe 1.
8 and is guided above the core upper mechanism 8.

In such an upper core structure 8, if the instrumentation well 10 or the like is damaged, for example, it is necessary to remove the entire lateral 8 of the upper core from the rotating plug 7 for repair. The quality meter can normally be removed from the instrumentation well 19 for replacement in the event of a failure, but in the unlikely event that it fails to pull out, the entire center upper mechanism 8 can be removed. It's going to be a big deal. In this way, in the event of equipment damage or failure, the upper 1 m i
When the entire M8 is pulled out and maintenance work is performed, the work size increases and it takes a long time to repair it, which affects Plan 1 - operation availability v! In addition to this, there are also problems such as high radiation exposure during work.

[Objective of the Invention] The present invention has been made C'+1 in view of the above circumstances, and its purpose is to significantly improve the maintainability of instrumentation wells, etc. Core-1 part 1m
We offer 4ft1+.

[Summary of the Invention] In order to achieve the above object, the present invention provides a Hatake breeder reactor that is installed vertically above a core in a reactor vessel through a rotary plug that closes the upper opening of the reactor vessel. In the upper core mechanism of the reactor, the core is composed of a large number of instrumentation well guide tubes iJ3 and control rod drive machines 4ia guide tubes corresponding to the core arrangement consisting of fuel assemblies and control rods arranged in the reactor vessel. An upper main body is provided above the reactor core, and a shielding plug is provided above each of the guide tubes and is detachable from each guide tube. Each of the guide tubes has a hexagonal cross section, a circular cross section, or a columnar tube having an appropriate shape.

[Embodiments of the invention] An embodiment of the present invention will be described with reference to the drawings.

The same 1 sushi place as in Figures 1 and 2 is designated with the same code.
jjJ l, I will explain.

FIG. 3 is a longitudinal sectional view of the upper core mechanism according to the present invention. In the same figure, the rotary plug 7 is connected to a reactor core (not shown), a cold I
It is installed in the upper opening of the reactor vessel (not shown) that accommodates J material 4, cover gas 12, etc., and penetrates through the center of this rotary plug 7 to connect the upper core BM Ji/+ 8.
is installed vertically above the reactor core (not shown).

This core upper mechanism 8 has a plurality of control rod drives (several IM
Control rod drive mechanism guide tube 9 for supporting and guiding 19
Flow m it (13
J-L guide tube 1 equipped with H1 for supporting, guiding and covering a large number (usually several hundred) of welding wells 10 that accommodate thirsty wells.
8, the core upper body 20, etc., the flow rate, the core L required from the thirst 1α measurement conditions; (1) the rectifying plate 11 installed to rectify the cold flow; There are 114 shielding plugs 21, each of which is individually installed in the space above the pipe 18.

FIG. 4 is a partial sectional view of a part of the main body of the reactor core 1 taken along the line 8 in FIG. A combination of circular tubes and hexagons, respectively! (In addition, this cross-sectional structure can be changed to a hexagonal shape as shown in FIG. Both may have a circular ?τ configuration.

FIG. 6 is an enlarged cross-sectional view of the area around the plug 21 in FIG.
A b-hole plug 21 is provided, and an instrumentation well 10 passes through the Ib-hole plug 21.

FIG. 7 is an enlarged cross-sectional view of the rectifying grid plate 11 portion in FIG.
It is constructed.

In the upper core mechanism of the present invention configured as described above, when the instrumentation well 10 is damaged, repair or replacement work is carried out using a drain plug provided above the damaged instrumentation well guide 18. Since only the instrument 21 can be handled as one unit with the instrument 10, the maintenance area can be limited to this part ().

Moreover, the radiation protection cask used when pulling out the shield plug 21 is small and can be used for any shield plug.

In addition, since the instrumentation well guide pipe 18 is vertically installed above each fuel assembly in one-to-one correspondence, other instrumentation systems, such as those used to detect fuel bottle damage, can also be used to detect damaged combustion. If a meter is installed, damage can be detected independently for each fuel assembly, making it effective for specialized applications i1.

Furthermore, it is necessary to minimize the phase shift of one end of the upper core 1a lf4 from the ridged ground during an earthquake when the control rods are inserted in the horizontal direction. For this reason, it is necessary to increase the rigidity of the core upper mechanism against the water\11 direction load, and the core upper body of the core upper mechanism according to the present invention has a combination structure of hexagonal tubes and circular tubes over the entire cross section. Because of this, it is possible to make the rigidity much higher than the conventional outer 161-yen (14-jen).

[Effects of the Invention] According to the present invention, since the maintenance department is localized and the radiation exposure of the workers is reduced, the amount of work during maintenance of each part is reduced by 9 hours or less. Therefore, it is possible to significantly increase the plant operating rate by 41'.

In addition, because the upper core mechanism has high rigidity against horizontal loads, the control frame insertion performance during earthquakes is highly reliable, and the four independently installed J-structure guide pipes are It has various effects such as being able to be effectively used as is for other cutting tool systems such as a damaged fuel detector.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional fast breeder reactor, FIG. 2 is a partially enlarged sectional view of FIG. 1, FIG. 3 is a longitudinal sectional view of an embodiment of the present invention, and FIG. FIG. 5 is a cross-sectional view of another embodiment shown in FIG. 4, FIG. 6 is an enlarged n-side view of the shielding plug shown in FIG. 3, and FIG. 7 is a cross-sectional view taken along line A-A. FIG. 3 is an enlarged cross-sectional view of the rectifying grid plate portion shown in the figure. 1...Nuclear J vessel 4...Coolant 6...Core
7... Rotating plug 8... Core upper mechanism 9... Control rod drive □ Structure guide tube 10... Instrumentation well 11... Rectifier grid plate 12...
・jj bargas 13...Cylindrical upper body 1 G...
1 shielding lid 18...Instrumentation 1 guide 19...Control rod drive 1 number 20...Core upper body 21...Shieling plug cost (J Figure 1 or 1 person) Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7/(? -1//

Claims (2)

[Claims] (1) In the upper core machine 4j4 of a fast breeder reactor, which passes through a rotating plug that closes the upper opening of the reactor vessel and is installed vertically above the reactor core in the reactor vessel, A core upper body consisting of a large number of guide tubes corresponding to the array of the installed fuel assemblies and control rods is provided above the reactor core, and each guide tube can be individually removed at the upper part of the guide tube. An upper core mechanism of a fast breeder reactor, characterized in that it is configured to be provided with a possible shielding plug. (2) The upper core mechanism of a fast breeder reactor according to claim 1, wherein the guide tube is a cutting tool well guide tube and a control rod drive mechanism guide tube. 3) The upper core mechanism of a fast breeder reactor according to claim 1, wherein the guide tube is a columnar tube with a hexagonal or circular cross section.