JPH0143919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for assembling a fuel assembly with measurement lines that is installed in a nuclear reactor to continuously examine the behavior of core fuel. [Technical Background of the Invention] The schematic structure of a conventional fuel assembly with measurement lines and its assembly method will be described with reference to FIG.
In the figure, 1 indicates a drive section, and 2 indicates a fuel section. This fuel section 2 is suspended by a finger 4 attached to the tip of an inner extension tube 3 disposed within the drive section 1. Inside the fuel section 2,
A fuel 5 incorporating UO ₂ and PuO ₂ , a FP gas measurement pipe 6, a fuel pin 9 containing a neutron detector 7, a temperature measurement sensor 8, etc., and a plurality of flow meters 10, etc. are accommodated. . And these FPs
The measurement cables for the gas measurement pipe 6, neutron detector 7, temperature measurement sensor 8, and flowmeter 10 are as follows:
It becomes a bundle and passes through the inner extension pipe 3 that passes through the fuel part 2 and the drive part 1, and the external measuring instrument 11
It is connected to the. Note that 12 in the figure indicates a cutter, which is provided at the tip of the outer extension tube 13. A cutter drive mechanism 14 is provided at the upper end of this outer extension tube. In general, a fuel assembly with a measurement line has a short life span of the measurement part, so it is necessary to replace it with a new fuel assembly with a measurement line every two to three years. However, the drive section 1 and the fuel section 2 incorporating fissile material are integrated via the inner extension tube 3. If handled as a whole, the cask that is stored during maintenance for radiation protection will be thicker, heavier, and more difficult to handle. Furthermore, handling work becomes difficult due to radiation exposure. Therefore, the cutter drive mechanism 14 lowers the outer extension pipe 13, the cutter 12 cuts the measurement cable and the measurement pipe, and the fuel part 2 and drive part 1 are cut off.
This is a configuration that separates the Further, in the figure, 15 indicates an upper guide pipe on the drive section 1 side, and 16 indicates a lower guide pipe on the fuel section 2 side. A sealing mechanism 17 and a bellows 18 are provided between the upper guide tube 16 and the outer extension tube 13. Furthermore, a bellows 19 is provided between the outer extension tube 13 and the inner extension tube 3. Next, a method of assembling the fuel assembly with measurement lines having the above configuration will be explained. First, the inner extension tube 3 of the drive section 1 is assembled. On the other hand, fuel 5 is contained in the fuel part 2,
A fuel pin 9 containing an FP gas measurement pipe 6, a neutron detector 7, a temperature measurement sensor 8, etc., a flow meter 10, etc. are installed. and the inner extension tube 3
The measurement cables and measurement piping for each of the above-mentioned measuring instruments are routed inside. Then, the outer extension pipe 13 is assembled and installed, the bellows 19 is connected, and the cutter drive mechanism 14 is assembled. Next, the upper guide tubes 15 are installed, and at the same time, the seal portions 17 and bellows 18 are installed or connected. Then, the fuel section 2 is suspended by the finger 4 attached to the tip of the inner extension tube 3 and installed at a predetermined position, and the measurement cable and measurement pipe are connected to the measuring instrument 11. [Problems with the background art] According to the above configuration and assembly method, during assembly,
Although the working time is limited due to the exposure dose from UO ₂ and PuO ₂ built into the fuel section 2, the measurement cables and measurement piping routed inside the inner extension pipe 9 are several meters long. There was a risk of damage when passing through the dovetail inner extension tube 8, and since the inside of the inner extension tube 8 was very narrow, it was difficult to carry out routing work. [Object of the Invention] The object of the present invention is to separate the measurement cable and gas measurement piping on the drive section side from the measurement cable and measurement piping on the fuel section side, and to connect them via a connector at the final assembly stage. A fuel assembly with measurement wires that can shorten the length of measurement cables and pipes by connecting them, making routing work easier and preventing damage to measurement cables and measurement piping. The objective is to provide an assembly method for the. [Summary of the Invention] The method for assembling a fuel assembly with a measurement line according to the present invention includes the steps of respectively assembling a drive section inner extension tube and a fuel section inner extension tube, and a step of assembling a drive section inner extension tube and a fuel section inner extension tube, respectively. a step of passing a measurement cable and a gas measurement pipe; a step of connecting the drive part inner extension pipe and the fuel part inner extension pipe via a connecting part; and a measurement cable passed through the drive part inner extension pipe. a step of connecting the measurement cable passed through the fuel part inner extension pipe, the gas measurement pipe passed through the drive part inner extension pipe, and the gas measurement pipe passed through the fuel part inner extension pipe through connectors, respectively; This is a fully equipped configuration. In other words, the inner extension tubes are provided separately for the drive section and the fuel section, and are connected to each other via the connection section during assembly, and the measurement cable and gas measurement piping are connected to the drive section and the fuel section.
Each fuel section is separate and connected via a connector during assembly. Therefore, the measurement cable and gas measurement pipe can be shortened, which makes routing work within each extension pipe easier and prevents damage to the measurement cable and gas measurement pipe during routing work. Furthermore, since the drive part side and the fuel part side can be assembled separately, when assembling the drive part side, the radiation dose from the fuel contained in the fuel part side will not be affected. Safety can be improved without any problems. [Embodiment of the Invention] An embodiment of the present invention will be described with reference to FIGS. 2 and 3. In FIG. 2, 101 indicates a reactor vessel. Inside the reactor vessel 101, a reactor core 102 is arranged which includes a plurality of fuel assemblies (not shown), control rods (not shown), and the like. Upper opening 101 of the reactor vessel 101
A is closed by a shielding plug 103.
A fuel assembly 104 with measurement lines is inserted into the core 102 through the shielding plug 103. Next, the structure of the fuel assembly 104 with measurement lines will be explained with reference to FIG. The fuel assembly with measurement line 104 is composed of a drive section 105 and a fuel section 106. This fuel section 106 is suspended from the drive section 105 via a finger 108 provided at the lower end of the inner extension tube 107. The inner extension tube 107 is the drive section inner extension tube 107.
A and a fuel part inner extension pipe 107B, which are connected by a connecting part 109. Inside the fuel section 106, there is a fuel 110 incorporating UO ₂ and PuO ₂ , a FP gas measurement pipe 111A,
Neutron detector 112 and temperature measurement sensor 1
A fuel pin 114 containing a fuel pin 13, etc., and a plurality of flow meters 115, etc. are accommodated therein. and these
FP gas measurement piping 111A, neutron detector 11
2. Temperature measurement sensor 113 and flow meter 115
The measurement cable 126A is a bundle, passes through the fuel section inner extension pipe 107B, and is connected to the connector 116. On the other hand, inside the drive section inner extension tube 107A, the fuel section inner extension tube 10
Measurement cable 126B and FP gas measurement pipe 11 corresponding to measurement cable 126A and FP gas measurement pipe 111A passing through 7B
1B is arranged, and one end side is connected to the connector 11.
6 and the other end thereof is connected to a measuring instrument 117 provided outside. That is, the measurement cable 126B and FP gas measurement piping 111B on the drive section 105 side, which are provided separately, and the measurement cable 126A and FP gas measurement piping 111A on the fuel section 106 side are connected via the connector 116. The configuration is as follows. Furthermore, 118 in the figure indicates a cutter. This cutter 118 is provided at the tip of the outer extension tube 119. And this outer extension tube 1
A cutter drive mechanism 120 for driving the cutter 118 is provided at the upper end of the cutter 19 . As explained in the conventional example, the cutter 118 is connected to the fuel section 106 and the drive section 104 when replacing or maintaining the fuel assembly 104 with measurement lines every 2 to 3 years.
It is provided to handle the measurement cable 126A and the FP gas measurement pipe 111A as separate parts. That is, the outer extension tube 119 is lowered by driving the cutter drive mechanism 119. As the outer extension tube 119 descends, the cutter 118 also descends to cut the measurement cable 126A and the FP gas measurement pipe 111A. In addition, 121 in the figure is the drive unit 1
Reference numeral 122 indicates an upper guide pipe on the 05 side, and a lower guide pipe on the fuel section 106 side. This upper guide pipe 1
21 and the outer extension tube 119, a sealing mechanism 123 and a bellows 124 are provided. Further, a bellows 125 is provided between the outer extension pipe 119 and the fuel section inner extension pipe 107B. Next, a method of assembling the fuel assembly with measurement lines having the above configuration will be explained. First, drive section inner extension pipe 0
7A and the fuel section inner extension pipe 107B are assembled separately. On the other hand, fuel 1 is contained in the fuel section 106.
10. Install the FP gas measurement pipe 111A, the neutron detector 112, the temperature measurement sensor 113, and the flow meter 115. Next, the measurement cables 126B, 126A and the FP gas measurement pipes 111B, 111A are routed inside the drive section inner extension tube 107A and the fuel section inner extension tube 107B, respectively. The connecting portion 109 connects the drive section inner extension pipe 107A and the fuel section inner extension pipe 107B.
Connect. Next, the drive section inner extension tube 107A
Then, the measurement cables 1266B, 126A and the FP gas measurement pipes 111B, 111A, respectively routed to the fuel section inner extension pipe 107B, are connected via the connector 116. Now the drive unit 10
The 7A side and the fuel part 107B side are connected and integrated. Next, the outer extension pipe 119 is assembled and installed, and the bellows 125 is connected. At the same time, the cutter drive mechanism 120 is assembled. Next, each upper guide pipe 1
21 is assembled and installed, and at the same time, the seal portion 123 and the bellows 124 are installed or connected. Finger 1 at the tip of the fuel section inner extension pipe 107B
At step 08, the fuel part 106 is suspended and installed in the lower guide pipe 122 at a predetermined position, and the measurement cable 1
26B and the FP gas measurement pipe 111B are connected to the measuring instrument 117. That is, the conventional inner extension tube is separated into a drive section inner extension tube 107A and a fuel section inner extension tube 107B, which are connected via the connecting section 109, and are connected to the measurement cables 126B, 126A and the FP gas measurement piping 111B. 111A has a configuration in which the driving part 105 side and the fuel part 106 side are each separated, and connected through a connector 116 during assembly. Therefore, there is no need to handle measurement cables and FP gas measurement piping that are several meters long as in the past, and the measurement cables and measurement piping can be shortened.
Routing work within 7A and 107B is facilitated, and the measurement cable and measurement piping are not damaged during the routing work. Further, since the working time can be shortened, the problem of radiation exposure from UO ₂ and PuO ₂ incorporated in the fuel section 106 can also be solved. [Effects of the Invention] The method for assembling a fuel assembly with measurement lines according to the present invention includes the steps of assembling the drive section inner extension tube and the fuel section inner extension tube, and the step of assembling the drive section inner extension tube and the fuel section inner extension tube, respectively. a step of passing a measurement cable and a gas measurement pipe; a step of connecting the drive part inner extension pipe and the fuel part inner extension pipe via a connecting part; and a measurement cable passed through the drive part inner extension pipe. a step of connecting the measurement cable passed through the fuel part inner extension pipe, the gas measurement pipe passed through the drive part inner extension pipe, and the gas measurement pipe passed through the fuel part inner extension pipe through connectors, respectively; This is a fully equipped configuration. In other words, the inner extension tubes are provided separately for the drive section and the fuel section, and they are connected through the connection section during assembly, and the measurement cable and gas measurement piping are connected to the drive section and the fuel section.
Each fuel section is separate and connected via a connector during assembly. Therefore, the measurement cable and gas measurement piping can be shortened, which makes routing work within each inner extension pipe easier.
This prevents the measurement cable and gas measurement pipe from being damaged during routing work, and the drive part side and fuel part side can be assembled separately, so when assembling the drive part side, the fuel part This has great effects, such as being able to improve safety without being affected by radiation exposure from the fuel stored on the side.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a fuel assembly with measurement lines showing a conventional example, FIGS. 2 and 3 are views showing an embodiment of the present invention, and FIG. FIG. 3 is a longitudinal sectional view of the fuel assembly with measurement lines assembled by the assembly method according to the present invention. 104 ... Fuel assembly with measurement line, 105... Drive section, 106... Fuel section, 107A... Drive section inner extension tube, 107B... Fuel section inner extension tube, 10
9... Connection part, 111A, 111B... FP gas measurement piping, 115... Connector, 126A, 1
26B...Measurement cable.

Claims (1)

[Claims] 1. Assembling the drive section inner extension tube and the fuel section inner extension tube, respectively, passing the measurement cable and gas measurement pipe through the drive section inner extension tube and the fuel section inner extension tube, respectively; and the step of assembling the drive section inner extension tube and the fuel section inner extension tube, respectively. A step of connecting the pipe and the fuel section inner extension tube via a connecting part, and a measurement cable passed through the drive section inner extension tube, a measurement cable passed through the fuel section inner extension tube, and the inside of the drive section inner extension tube. 1. A method for assembling a fuel assembly with a measurement line, comprising the step of connecting a gas measurement pipe passed through the fuel section and a gas measurement pipe passed through the inside extension pipe of the fuel section through connectors, respectively.