JPS61294396A - Treater for control rod - 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 control rod handling device for transporting control rods, for example, from inside a nuclear reactor into a solid waste transfer container (hereinafter referred to as a cask).

[Technical Background of the Invention] Generally, in a boiling water reactor (hereinafter referred to as BWR), a coolant and a reactor core are housed in a reactor pressure vessel. The reactor core is composed of a plurality of fuel assemblies, control rods, and the like. That is, one control rod is installed for every four fuel assemblies, and for example, 185 control rods are installed in an atomic coupler of 1100 MW class. By inserting and withdrawing these control rods into the reactor core, the output of the reactor core is controlled.

゛The above control rod has the configuration as shown below.

A plurality of poison tubes are housed within the blade, which has a cross-shaped cross section. This poison tube is filled with porongarite as a neutron absorbing material. A lifting handle is fixed to the upper end of the blade, and a lowering handle is attached to the lower end.

゛ The lifespan of a control rod with the above configuration is generally 4 years,
Therefore, every year some control rods reach the end of their lifespan and become used. Control rods that have reached the end of their lifespan and are no longer used are transferred from the reactor pressure vessel to a dedicated storage rack in the fuel pool. Here, a predetermined cooling period is allowed. It is then transferred into a cask and transported to a waste storage facility.

When transferring control rods to the above cask, a dedicated 11
This is done using a w rod handling device.

Therefore, with reference to FIGS. 5 and 6, a conventional control rod handling device and control rod transportation using the handling device will be described. The reference numeral 101 in FIG.
It is hanging down. Reference numeral 103 in the figure is a wire rope. The traveling/type auxiliary hoist 102 travels along a hoist rail 105 via a hoist traveling section 104. Further, the control rod gripping tool 101 is a control rod 106.
is grasping. The control rod gripper 101 has a configuration as shown in the sixth factor. A hook 111 is installed on the control rod gripper 101, and this hook 111 is connected to an air cylinder 112. An air hose 113 is connected to this air cylinder 112, and the air cylinder 1
Air is supplied to 12, and air cylinder 112 is driven. This causes the hook 111 to operate.

According to the above configuration, first, the traveling auxiliary hoist 102 is operated to position the control rod gripping tool 101 above a desired control rod 106 and lower it to a predetermined position.

Then, the hook 111 is driven by air, and the tsvH
Grasp the handle 106A of the sleeve. Next, the control rod 106 is raised by the traveling auxiliary hoist 102. Then, it travels along the rails 105 and is transferred to a desired position within the reactor or fuel pool.

[Problems with the background art] Normally, when the control rods 106 are handled in a fuel pool, they are all carried out underwater, with sufficient water depth secured, so radiation exposure can be avoided without installing any particular shield. Although it is possible to provide a shield, there is a concern that workers may be exposed to radiation if the water is not deep enough to provide adequate shielding. This applies even if the water is deep enough or the work is prolonged. Conventionally, in such cases, methods have been taken such as moving workers away from the vicinity of the transfer site or speeding up the rotation of workers, but the work becomes complicated and improvements are required.

[Object of the Invention] The present invention has been made based on the above points, and its purpose is to provide a solution that can be used even if the water depth is insufficient or if the work is prolonged. The object of the present invention is to provide a control rod handling device that can reduce radiation exposure to workers and greatly improve safety.

[Summary of the Invention] That is, the control rod handling device according to the present invention includes a hoist mechanism that is attached to a fuel exchanger distributed with electricity on the operation floor of a nuclear reactor building and runs along a traveling rail;
a control rod grip that is suspended from the hoist mechanism and moves up and down; a shield that is suspended from a traveling portion of the hoist mechanism and is arranged to surround the control rod grip from above;
The present invention is characterized by comprising a hoisting mechanism interposed between the traveling section and the shield.

In other words, the shield is arranged to surround the control rod grip from above, so that it can reliably function as a shield even in the unlikely event that the pool water is not deep enough or the work is prolonged. At this time, the position of the shield can be adjusted as appropriate by interposing a winding mechanism.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. Reference numeral 1 in FIG. 1 indicates a fuel exchange machine, and a traveling auxiliary hoist 2 is installed in this fuel exchange machine 1. This traveling type auxiliary hoist 2 runs along traveling type auxiliary hoist rails 3.

The fuel exchanger 1 has a floor 5 at the upper edge of the fuel pool 4.
It is installed in The traveling type auxiliary hoist 2 suspends a control rod gripper 6, and this 1ilJm rod gripper 6
grip the control rod 7. On the other hand, a shield 8 is suspended from the traveling section 2A of the hoist 2 located on the traveling auxiliary hoist rail 3.

As shown in FIG. 2, this shield 8 is installed so as to surround the control rod grip 6 from above. A through hole 8A is formed in the center of the shield 8, and this through hole 8A
A stud 9 is arranged at. The control rod gripper 6
is connected to the wire 0-710 via this stud 9, and is further suspended from the traveling auxiliary hoist 2 via this wire loaf 10.

Next, the mounting state of the shield 8 will be explained.

A truck 12 is attached to the traveling portion 2A of the traveling auxiliary hoist 2 via a connecting rod 11. A hanging lug 13 is attached to the lower part of this truck 12, and a hoisting mechanism 14 is attached to this hanging lug 13.

On the other hand, a pair of hanging ears 15 are attached to both sides of the upper end of the shield 8, and a wire row 116 having a turnbuckle 17 is connected to each of these hanging ears 15. A ring 18 is fixed to the tip of the wire 〇, 16. Also, from the winding mechanism 14 side, the wire lobe 1
9 is extended, and a hook 20 is attached to its tip. By hanging the ring 18 on this hook 20, the winding mechanism 14 side and the shielding body 8 side are connected.

Next, the configuration of the control rod gripper 6 will be explained. That is, as shown in FIG. 3, the control rod gripper 6 has a hook 2.
1 is attached to the hook 21, and an air cylinder 22 is connected to this hook 21. An air hose 23 is connected to this air cylinder 22 . air hose 23
The air cylinder 22 is driven by the air supplied through the air cylinder 22, which operates the hook 21 and connects the control rod 7.
grasp or release the handle 7A.

Note that the air hose 23 is guided by a guide roller 31 fixed to the shield 8, and is configured so as not to come into contact with the shield 8.

Next, the dimensions of the shield 8 will be explained. Dimensions are 4th
It is determined by the gamma ray distribution of spent control rods shown in the figure. FIG. 4 is a diagram showing the gamma ray distribution in the axial direction of the 1% JIIl rod, with the horizontal axis representing the gamma ray dose and the vertical axis representing the axial position of the control rod. , and the thickness of the upper part of the shield 8 is determined from the gamma ray dose from the upper surface of the IIJIll rod. Specifically, the value is approximately 150 am+, taking into consideration the water depth during movement. Next, the length of the 11 sides of the shielding body 8 is determined by the amount of gamma rays that are refracted from the side of the control rod and reach the pool water surface. For example, in the case shown in Fig. 4 above, the upper part of the control rod is Since the amount is large, 7 from the top.
The shield 8 is required up to a position of approximately 50 to 100 feet. However, in that case, the thickness should be 50jw+, and a lead plate should be used. When determining the length of the side surface, in addition to the amount of gamma rays, the handling of the l11m rod and the operation of the traveling auxiliary hoist 2 are also taken into consideration. Incidentally, the dimensions of each part of the shielding body 8 are shown in FIG. Moreover, it goes without saying that these dimensions are just an example.

The operation will be explained based on the above configuration. First, fuel exchange I
The control rod gripper 6 and the shield 8 are positioned above the desired control rod 7 by the movement of the ll itself and the movement of the traveling auxiliary hoist 2. Note that when the traveling auxiliary hoist 2 travels, the trolley 12 also moves together, so the shield 8
and the control rod gripper 6 always move together. After moving to a predetermined position, the traveling auxiliary hoist 2 is operated to lower the control rod grip 6. At this time, the air hose 23 also descends at the same time. This lowering operation continues until the lower end of the control rod gripper 6 comes into contact with the control rod 7.

Next, air is supplied to the air cylinder 22 via the air hose 23 to drive it. As a result, the hook 21 grips the handle 7A of the control rod 7. After gripping the control rod 7, the traveling auxiliary hoist 2 is operated to raise and move the control rod gripper 6, and the rod is housed in the cask 41 shown in FIG. Note that this cask 41 is placed on an octopus dumper 42.

According to this embodiment, the following effects can be achieved.

(1) In other words, since the shielding body 8 is installed to surround the control rod gripping tool 6 from above, the radiation shielding function is greatly improved, and even if the pool water in the fuel pool 4 is not deep enough, Even in such cases, the shielding function can be sufficiently exerted, and the radiation exposure of workers can be effectively reduced. The same can be said when the work is prolonged, and there is no need for complicated procedures such as expediting the rotation of workers or moving workers away as in the past.

(2) Next, the shield 8 is suspended by a hoisting mechanism 14, so by appropriately operating the hoisting mechanism 14, the shield 8 can be stacked at a desired location, making it easy to handle. .

(3) Furthermore, since the dimensions of the shielding body 8 are determined based on the gamma ray distribution of the control rod, its shielding effect is reliable.

According to the ``Radiation Shield'', when handling spent control rods in a fuel pool, even if the pool water in the fuel pool is not deep enough or the work is prolonged, radiation shielding must be ensured. This can significantly improve safety. Also, since it has a winding mechanism,
The shield is also easy to handle.

[Brief explanation of drawings]

Figures 1 to 4 are views showing an embodiment of the present invention, with Figure 1 showing the entire fuel and control rod handling device, and Figure 2 showing the installation state of the shield and control rod grips. Figure shown, 3rd
The figure shows the configuration of the control rod gripper and the shield, and Figure 4 shows the gamma ray dose distribution in the axial direction of the spent control rod.
5 and 6 are diagrams showing a conventional example, where FIG. 5 is a diagram showing an attached state of a control rod gripping tool, and FIG. 6 is a diagram showing the configuration of the control rod gripping tool. 1... Fuel exchange machine, 2... Traveling auxiliary hoist,
3... Traveling auxiliary hoist rail, 4... Fuel pool, 6... Control rod grip, 7... Control rod, 8...
Shielding body, 14... winding mechanism. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Column dose □ Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) A hoist mechanism that is attached to a fuel exchanger located on the operation floor of the reactor building and runs along a travel rail, a control rod grip that is suspended from this hoist mechanism and moves up and down, and the above-mentioned hoist mechanism The control rod gripping device is characterized by comprising: a shield suspended from the running portion of the control rod gripper and arranged to surround the control rod grip from above; and a hoisting mechanism interposed between the running portion and the shield. Control rod handling equipment. (2) The control rod handling device according to claim 1, wherein the size of the shield is determined based on the gamma ray dose distribution in the axial direction of the spent control rod.