JPH03102296A - Incore strong back - Google Patents

Abstract

PURPOSE:To enable prevention of falling-off of an incore monitor IM by constituting an incore strong back to hold the IM with a plurality of supporting members arranged longitudinally along the strong back and with hooks working with the members. CONSTITUTION:A pin 17 for locking is withdrawn by a submerged remote handling, each hook 14 is released by a handling axis 15 rotated by a handle 16, an IM 7 is placed along a main part 12 so that a lower end of the IM 7 may be engaged with a setting guide 19 and a ring 7a may be engaged with a bracket 20 for prevention of falling-off, and the handle 16 is made to turn reversely to hold the IM 7 between each hook 14 and support member 13. Then, an incore strong back 10 is made to stand vertically and the IM 7 is loaded to a reactor core by handling of each the hook 14 and handling rope. Those handling can be executed firmly and rapidly by a remote handling and the handle 16 is fastened by the pin 17 and therefore the hook 14 is not released unintentionally. Even if the hook 14 is released by an erroneous handling, the guide 19 and the bracket 20 hold the IM 7 and therewith falling-off of the IM is prevented.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a method for transporting a neutron instrumentation tube (in-core monitor) into and out of a nuclear reactor core during periodic inspection of a nuclear reactor in a nuclear power plant. This relates to the in-core strongback (instrumentation tube transport device) used when

(Prior art) Generally, in a boiling water reactor, a rod-shaped neutron flux instrumentation tube (hereinafter referred to as in-core monitor ) is inserted and installed to monitor the distribution of neutron flux.

The above in-core monitor is usually installed as follows. That is, a locking piece with a spring is attached to the upper end of the in-core monitor, and the upper end is supported by the spring force of the locking piece at the intersection of the upper lattice plate in the furnace,
Further, the lower end portion thereof is installed by being connected to a flange having a shape of a seat that supports the lower end portion against impact.

On the other hand, the fuel assembly is made up of a metal sheath, that is, a fuel channel, in which a fuel bundle, in which a large number of cylindrical low-enriched uranium dioxide pellets are loaded into a fuel cladding tube, is removably housed. is loaded into the gaps between the four adjacent fuel assemblies.

In addition, when loading the in-core monitor into the reactor core, the in-core monitor has a length of about 10 meters and is prone to bending and deformation. (called a bag) to prevent deformation.

The in-core monitor is loaded into the core as shown in Figure 7. Figure 7 is a schematic cross-sectional view showing the overall configuration of a boiling water reactor. In this figure, a reactor pressure vessel 2 is stored in an H reactor containment vessel 1 while being supported by a reactor pressure vessel pedestal 3, and the outer circumferential surface of the reactor pressure vessel 2 is It is surrounded by a heat shielding wall 4 placed and fixed on top. In addition, the reactor containment vessel 1 is provided integrally with the reactor building structure 5, and is provided with an in-core monitor in the previous stage thereof, 8 is a floor for fuel exchange,
Reference numeral 9 indicates a refueling platform that is movable on the refueling floor 8 and is placed above any arbitrary position of the reactor core 6. In addition, a strong back 10 is attached to the in-core monitor 7 in the stage before loading into the reactor core 6. Furthermore, although omitted in this figure, a steam separator, steam dryer, etc. are installed above the core. Loading of the π in-core monitor 7 into the reactor core 6 is performed as follows. That is, the strongback 10 is suspended horizontally from a hook of an overhead crane in a nuclear reactor building using a hanging rope lla. Note that an operating rope 7a is attached to the end of the in-core monitor 7 on the core 6 side so as to be detachable as appropriate. The strong back 10 is lowered toward the reactor core while changing direction from a horizontal state to a vertical state by the operation of an overhead crane and the operating rope 7a by the worker W1, and when it has been lowered to an appropriate position, the in-core monitor 7 is lowered to the strong back. 10 and inserted into the reactor core 6. At this time, the worker W1 operates the operating rope 7a to prevent the in-core monitor 7 from falling rapidly and falling off. Also,
The worker W2 on the refueling platform 9 gently lowers the in-core monitor 7, which has been detached from the strong back 10, into the reactor core using the operating rope ←a.

(Problems to be Solved by the Invention) The reactor components explained above are all required to have high dimensional accuracy, and if a core component falls for some reason, only the fallen equipment will be damaged. Failure to do so may damage surrounding equipment, impairing their functionality and causing a serious accident. Furthermore, since the in-core monitor 7 is arranged adjacent to the fuel assembly as described above, if the in-core monitor 7 is bent or deformed, it may interfere with the fuel channel and cause damage due to vibration or the like. Therefore, when loading the in-core monitor 7, there is a risk that the strong back 10 may shake in a vertical position at the top of the core 6, causing the in-core monitor 7 to fall off or fall, and extremely careful work is required. It will be done. In addition, in order to prevent the above-mentioned dropping and falling, it is necessary to have a large number of monitors monitoring the product. The present invention has been made based on the above circumstances, and has a strong back system that eliminates the risk of accidents such as dropping or dropping of in-core monitors and reduces the number of workers and monitors required for loading the reactor core. The purpose is to provide. [Structure of the Invention] (Means for Solving the Problems) The strongback of the present invention includes a main part made of long steel, and a plurality of parts distributed in the longitudinal direction on one side of the main part. a support member, a plurality of hooks each cooperating with the support member, an operating shaft fixed to one end of these hooks and extending in the longitudinal direction of the main length, and attached to the upper end of the operating shaft. a removable locking pin for fixing the handle to the main part; a mounting guide provided at the lower end of the main part to engage the lower end of the in-core monitor; It is characterized by having a fall prevention bracket provided approximately in the center and engaged with a ring provided in the axially central portion of the in-core monitor.

(Function) In the strongback of the present invention having the above configuration, a plurality of hooks are opened and closed at the same time by rotating the handle, and the Incore monitor can be gripped and opened reliably and quickly by remote control. Further, since the handle is fixed by a locking pin, there is no possibility of the hook being unintentionally opened. Furthermore, even if the hook is released due to some kind of erroneous operation, the installation guide and fall prevention bracket will hold the Incore Monitor, so the Incore Monitor will not fall. (Embodiment) Fig. 1 is a side view showing the overall configuration of one embodiment of the present invention, and Fig. 2 is a side view showing the overall configuration of an embodiment of the present invention.
The figure is a view taken along the A-A arrow in Figure 1, Figure 3 is a view taken along the B-B arrow in Figure 1, Figure 4 is a view taken along the C-C arrow in Figure I, and Figure 5 is the view taken in the Figure 1. FIG. 6A is an enlarged plan view of a portion surrounded by an ellipse D indicated by a dashed line in FIG. 1;
Figure 6B is a partially cutaway side view. First, in FIG. 1, the main part 12 of the strong back 10 is constructed by joining a plurality of shaped steels 12a, and on one side of the main part 12 there are a plurality of supporting members 13 for the in-core monitor (6 in the figure). Clause) It is fixed. These supporting members 1
3 are each provided with a hook 14 for gripping the in-core monitor in cooperation with the support member. Each hook 14 has a longitudinal operating shaft 15 in the main part 12 at one end thereof.
The handle l6 is connected to the upper end of this operating shaft.
is installed. The relationship between the hook 14 and the operating shaft 15 is best shown in FIG. That is, a pin 15a passing through the hook and the operating shaft is driven into the operating shaft 15 passing through one end of the hook 14 to connect the hook 14 and the operating shaft l5. In addition, as shown in FIGS. 4 and 5, the handle 16 has a handle and a main part 12.
A plurality of pins (17 shown in the figure) are inserted into and removed from the upper end plate.
18), it is locked except during operation.

Furthermore, a mounting guide 19 is provided at the lower end of the main portion 12 for positioning the in-core monitor when it is mounted. This mounting guide not only facilitates the installation of the in-core monitor, but also prevents the in-core monitor from falling toward the reactor core even if the handle 16 is unintentionally opened.

A fall prevention bracket 20, which will be described in detail with reference to FIGS. 6A and 6B, is provided approximately in the longitudinal center of the side surface of the main portion 12 of the strongback 10.

FIG. 6A is a plan view of the portion shown in FIG. 1 surrounded by a dot-dashed ellipse D, and FIG. 6B is a partially cutaway side view thereof. In these figures, the fall prevention bracket 20 is approximately U
It is shaped like a letter and protrudes from the side surface of the main part 12, and the upper surface thereof is provided with a recess for receiving a ring 7a provided at approximately the center of the in-core monitor 7. In addition, in the figure, 21 indicates a hanging metal fitting provided on the opposite surface of the side surface of the main part, and 22 indicates its pedestal. The in-core monitor 7 is attached to the strongback 10 of the present invention having the above configuration as follows.

In other words, the locking pin 17 can be operated remotely underwater.
, 18 and operate the handle 16 to open the operating shaft 15.
Rotate to release each hook 14 and attach the in-core monitor 7.
Align the in-core monitor 7 along the main part 12 so that the lower end of the in-core monitor 7 is engaged with the mounting guide 19 and the ring 7a is engaged with the fall prevention bracket 20, and rotate the handle 16 in the opposite direction from the front. The in-core monitor 7 is held between each hook l4 and the support member 13. Each of the above operations is simple and can be performed reliably and quickly even when remotely operated underwater.

After attaching the in-core monitor 7 to the strong back 10 as described above, set the strong back 10 vertically 7 in the same manner as explained with reference to FIG. The in-core monitor 7 is loaded into the reactor core 6 by the operation. [Effects of the Invention] According to the strongback of the present invention having the above configuration, the in-core monitor is held by the plurality of support members distributed in the longitudinal direction of the strongback and the hooks that cooperate with the support members, so that the in-core monitor is There is no risk of the Incore monitor falling even if the strongback shakes when loaded. Furthermore, since the handle for operating the hook is locked, there is no risk of the hook being unintentionally opened. Even in the unlikely event that the hook is released due to some kind of erroneous operation, the installation guide and fall prevention bracket will hold the Incore Monitor in place, so the Incore Monitor will not fall and the various accidents that result from this will not occur. In addition, as mentioned above, the in-core monitor can be reliably and quickly attached and detached and loaded into the reactor core even by remote control underwater, making it possible to significantly reduce the radiation exposure of workers.

[Brief explanation of drawings]

FIG. 1 is a side view showing the overall configuration of one embodiment of the present invention, and FIG.
The figure is a view taken along the line A-A in Figure 1, Figure 3 is a view taken along the line B-B in Figure 1, Figure 4 is a view taken along the line C-C in Figure 1, and Figure 5 is the view taken as seen in Figure 1. FIG. 6A is an enlarged plan view of a portion surrounded by an ellipse D indicated by a dashed line in FIG. 1;
FIG. 6B is a partially cutaway side view of the reactor, and FIG. 7 is a schematic cross-sectional view of the reactor illustrating the loading work of the in-core monitor into the reactor core. 7...Incore monitor 10...Strongback E2...Main part 12a...
...Shape steel l3...Support member 14...
...Hook 15...Operating shaft 15a. 17, 1
8...Pin 16...Handle 19.
...Mounting guide 2o...Fall prevention bracket

Claims (1)

[Claims] A main part made of elongated steel, a plurality of support members provided longitudinally distributed on one side of the main part, a plurality of hooks that respectively cooperate with the support members, and the like. an operating shaft fixed to one end of the hook and extending in the longitudinal direction of the main body; a handle attached to the upper end of the operating shaft; and a removable locking pin for fixing the handle to the main part. , a mounting guide provided at the lower end of the main part and engaged with the lower end of the in-core monitor; and a drop prevention device provided at approximately the longitudinal center of the main part and engaged with a ring provided at the axial center of the in-core monitor. An in-core strongback characterized by having a bracket.