JP4780339B2 - Cover member of neutron source holder and method of attaching the cover member - Google Patents

Description

  The present invention relates to a lid member for a neutron source holder and a method for attaching the lid member in a boiling water nuclear power plant or the like.

  In general, in a boiling water reactor, a reactor core is housed in a reactor pressure vessel, and a set of four fuel assemblies is loaded on the reactor core.

  In addition, a control rod having a cross-shaped cross section is inserted between each set of fuel assemblies, and the control rod is inserted into and extracted from the core to control the density of neutrons inside the reactor. Start / stop and furnace power are controlled.

  In this nuclear power plant, as shown in FIG. 11, a spent fuel pool P and a storage pool such as a steam separator are connected via a water channel with the reactor Q containing the reactor pressure vessel in the center. Has been.

  Further, as shown in FIGS. 12 (a) and 12 (b), a pair of movements are provided on the operating floors on both sides along the storage pool such as the steam separator, the nuclear reactor Q, and the spent fuel pool P, respectively. A rail R is provided, and a fuel changer T is placed on the moving rail R so that it can move on a storage pool such as a steam separator, a nuclear reactor Q, and a spent fuel pool P.

  On the central side surface of the fuel changer T, as shown in FIG. 12 (b), a fuel handling portion V that can move left and right and that can be raised and lowered is provided.

  In the initial reactor start-up, a neutron emitter is placed in the reactor Q in order to create a neutron and start a fission chain reaction, and the component constituting the neutron emitter is called a neutron source.

  This neutron source is formed into an elongated rod shape having a diameter of about 1 cm and a length of about 50 cm. The neutron source is a neutron source holder having a diameter of about 2 cm and a length of about 4 m, and two neutron sources are accommodated through an insertion hole provided at the upper end thereof.

  Since the neutron source has a very strong radioactivity, even a used neutron source must be stored in the spent fuel pool P until the radioactivity is attenuated.

  Therefore, the used neutron source is stored in a state where it is stood on the neutron source holder rack installed in the spent fuel pool P while being stored in the neutron source holder.

Specifically, the fuel handling unit V that can be moved up and down of the fuel changer T grasps and lifts the annular protrusion of the neutron source holder that stores the used neutron source existing in the core in the reactor Q, In this state, the fuel changer T is moved onto the spent fuel pool P and the neutron source holder is lowered to be installed on the neutron source holder rack in the spent fuel pool P.
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  As described above, the used neutron source is stored in the neutron source holder, and this neutron source holder is installed in a standing state on the neutron source holder rack in the spent fuel pool P. Since there is a neutron source insertion hole at the top of the neutron source, the neutron source may come out of this insertion hole.

  Specifically, when the neutron source holder installed on the neutron source holder rack falls down, the neutron source spills out from the insertion hole of the neutron source holder, and the neutron source, which is a radioactive substance, cannot be properly managed. Things can happen.

In order to prevent the occurrence of such a situation, it is necessary to close the insertion hole of the neutron source holder with some kind of lid member, but with a lid member that only covers the insertion hole,
There is a possibility that the lid member easily comes off from the insertion hole.

  Therefore, the present invention was created in view of the existing circumstances as described above, and the lid member is formed by a closure plug that covers the insertion hole of the neutron source holder, and closure plug fixtures provided on both sides of the closure plug. The lid member is firmly fixed to the insertion hole of the neutron source holder by engaging the tip part of both closure plug fixtures with the annular projection of the neutron source holder, and the neutron provided at the upper end of the neutron source holder An object of the present invention is to provide a lid member of a neutron source holder capable of reliably closing a source insertion hole, and a method of attaching the lid member.

  The present invention relates to a lid member for a neutron source holder that closes the insertion hole of the neutron source provided at the upper end of the neutron source holder, a closure plug that covers the insertion hole of the neutron source holder, and provided on both sides of the closure plug. The above-described problems have been solved by engaging the annular protrusions provided on the neutron source holder with the distal end portions of the two closure plug fixtures.

  Further, the closing plug that covers the insertion hole of the neutron source holder is formed in a cylindrical shape having a ceiling portion on the upper end side and an opening on the lower end side, thereby solving the above-described problem.

  Furthermore, the closing plug fixtures provided on both sides of the closing plug are formed in a rectangular plate shape and have a length protruding from the opening of the closing plug, thereby solving the above-described problem.

  Moreover, the problem mentioned above was solved similarly by having a clearance gap between the side surface of a closing plug, and a closing plug fixing tool.

  In addition, the present invention is a method of attaching a lid member of a neutron source holder that closes the insertion hole of the neutron source provided at the upper end of the neutron source holder, the step of covering the insertion hole of the neutron source holder with a closing plug; The above-mentioned problem was solved by comprising the steps of engaging the end portions of the closing plug fixtures provided on both sides of the closing plug with the annular projections of the neutron source holder.

  The present invention relates to a lid member for a neutron source holder that closes the insertion hole of the neutron source provided at the upper end of the neutron source holder, a closure plug that covers the insertion hole of the neutron source holder, and provided on both sides of the closure plug. The neutron source insertion hole provided at the upper end of the neutron source holder is formed by engaging the annular protrusions provided in the neutron source holder with the tip portions of the two closing plug fixtures being engaged with each other. The lid member can be firmly fixed to the neutron source holder and the insertion hole of the neutron source holder can be reliably closed.

  Specifically, in the state where the closing plug is put on the insertion hole of the neutron source holder, the end portions of the closing plug fixtures provided on both sides of the closing plug are engaged with the annular protrusion of the neutron source holder. The closure plug can be firmly fixed in the insertion hole of the neutron source holder.

  Therefore, even if the neutron source holder falls off the neutron source holder rack in the spent fuel pool, the plug is removed from the neutron source insertion hole provided at the upper end of the neutron source holder. Therefore, the insertion hole is reliably closed by this closing plug, and the occurrence of a situation where the neutron source spills out from the insertion hole of the neutron source holder is prevented.

  In addition, the closure plug that covers the insertion hole of the neutron source holder has a ceiling portion on the upper end side and is formed in a cylindrical shape having an opening portion on the lower end side. By lightly pushing the plug, the insertion hole portion of the neutron source provided at the upper end of the neutron source holder can be completely covered with the closing plug.

  For this reason, it is extremely easy to attach the closing plug to the insertion hole of the neutron source holder, and the insertion hole portion is completely covered by the attached closing plug, and the neutron source spills out of the insertion hole. Can be surely stopped.

  Furthermore, the closing plug fixtures provided on both sides of the closing plug are formed in a rectangular plate shape and have a length protruding from the opening of the closing plug. The insertion hole portion of the source holder is completely covered with the closing plug, and the distal end portions of the both closing plug fixtures can be advanced along the neutron source holder to be engaged with the annular protrusion of the neutron source holder.

  At this time, the opening of the closing plug is positioned above the annular protrusion of the neutron source holder, the tip ends of both closing plug fixtures are in contact with and engaged with the lower surface of the annular protrusion, and the neutron source holder is attached by the attached closing plug. The state of completely covering the insertion hole portion of is maintained.

  In addition, since there is a gap between the side of the closure plug and the closure plug fixture, both the closure plugs can be fixed by inserting a pair of left and right expansion arms provided on the mounting jig into this gap. The tool can be expanded.

For this reason, the double-closed plug fixing tool provided on the closed plug can be removed by pressing the closed plug lightly by placing the double-closed plug fixing tool in the expanded state and placing it on the insertion hole of the neutron source holder. After proceeding along the neutron source holder, pulling out the expansion arm returns the both plug closures to their original positions, and the tip of both closure plug fixtures can be easily moved into the annular projection on the neutron source holder. Can be engaged.

  In addition, the present invention is a method of attaching a lid member of a neutron source holder that closes the insertion hole of the neutron source provided at the upper end of the neutron source holder, the step of covering the insertion hole of the neutron source holder with a closing plug; And the step of engaging the tip of the closure plug fixture provided on both sides of the closure plug with the annular projection of the neutron source holder, and the closure plug can be easily installed in the insertion hole of the neutron source holder. After the mounting, the distal end portions of both closing plug fixtures engage with the annular protrusions of the neutron source holder, and the closing plug can be firmly fixed to the insertion hole of the neutron source.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  The present invention is the lid member 1 of the neutron source holder H that closes the insertion hole H1 of the neutron source S provided at the upper end of the neutron source holder H.

  As shown in FIGS. 1 and 2, the neutron source holder H is formed of, for example, a SUS stainless steel tube having a diameter of about 2 cm and a length of about 4 m. The neutron source holder H is provided with an insertion hole H1 for the neutron source S at the upper end. Further, the neutron source holder H is provided with an annular projection 4 below the insertion hole H1.

  The neutron source holder H is loaded with two neutron sources S formed into an elongated rod shape having a diameter of about 1 cm and a length of about 50 cm through the insertion hole H1, and the lid member 1 is attached to the insertion hole H1. The neutron source S is stored.

  As shown in FIG. 10, the neutron source holder H is installed in a neutron source holder rack L installed as a temporary mount on the side in the spent fuel pool P.

  In each of these neutron source holder racks L, as shown in FIG. 9, for example, five neutron source holders H are mounted, and the neutron source holders H are always stored.

  Moreover, the insertion hole H1 provided in the upper end of the neutron source holder H is closed by the lid member 1 made of, for example, SUS stainless steel.

  As shown in FIGS. 3A and 3B, the lid member 1 includes a closing plug 1A that covers the insertion hole H1 of the neutron source holder H, and closing plug fixtures 2a and 2b provided on both sides of the closing plug 1A. It consists of and.

  As shown in FIGS. 3A and 3C, the closing plug 1A has a ceiling portion 1a on the upper end side and is formed in a cylindrical shape having an opening 1b on the lower end side.

  The plate-like closing plug fixtures 2a and 2b extend from the ceiling portion 1a side of the closing plug 1A toward the opening 1b side.

  Specifically, as shown in FIG. 3A, a laterally long through hole 6 penetrating in the lateral direction is provided on the upper peripheral surface of the closing plug 1A. Then, as shown in FIG. 3 (b), a pair of plate pieces is formed on the side surface 1c of the closing plug 1A by inserting a band plate bent into a substantially U-shaped downward frame into the through hole 6. -Shaped closing plug fixtures 2a and 2b are extended downward.

  As shown in FIGS. 3A and 3B, the pair of closing plug fixtures 2a and 2b has a length protruding from the opening 1b of the closing plug 1A.

  Further, the distal end portions of the two closing plug fixtures 2a and 2b are configured to engage with the annular protrusion 4 provided below the insertion hole H1 of the neutron source holder H.

  Specifically, as shown in FIGS. 3 (b) and 3 (c), locking portions that are bent in a substantially L-shape toward the inside as shown in FIGS. 3a and 3b are provided.

  When the lid member 1 is attached to the insertion hole H1 of the neutron source holder H, as shown in FIG. 6, the annular protrusion 4 existing below the insertion hole H1 is connected to the outer side of the closing plug fixtures 2a and 2b. It will be in the state which is pinched from.

  Further, the locking portions 3a and 3b provided at the distal end portions of the two closing plug fixtures 2a and 2b are brought into contact with and engaged with the lower edge and the lower surface of the annular protrusion 4, so that the annular protrusion 4 is grasped from below. It becomes a state. Therefore, the upward movement of the both closing plug fixtures 2a and 2b is prevented, and the lid member 1 is fixed to the insertion hole H1 of the neutron source holder H.

  Further, as shown in FIGS. 3A and 3B, a groove portion 5 is provided on the outer periphery of the ceiling portion 1 a in the closing plug 1 </ b> A constituting the lid member 1. This groove portion 5 is a portion into which a substantially U-shaped cutout recess 12a provided on the inner side of the U-shaped arm 12 for attaching / detaching the lid member in the mounting jig 11 described later (FIG. 4B). (See FIGS. 5A and 5B).

  Further, as shown in FIG. 3 (b), both the closing plug fixtures 2 a and 2 b are arranged so as to have a slight gap from the side surface 1 c of the closing plug 1 A constituting the lid member 1. This gap is a portion into which a pair of left and right expanding arms 13 provided in the mounting jig 11 described later is inserted (see FIGS. 4B, 5A, and 5B).

  Below, the attachment jig | tool 11 used when the insertion hole H1 located in the upper end of the neutron source holder H is obstruct | occluded with the cover member 1 is demonstrated.

  As shown in FIGS. 4A and 4B, the mounting jig 11 includes a cylindrical body 17 made of, for example, SUS stainless steel. A hook groove 15 for inserting and fixing the tip of an operation pole (not shown) from the fuel changer T is provided in the cylindrical receiving portion 14 at the upper portion of the cylindrical body 17.

  As shown in FIGS. 4 (a) and 4 (b), the hook groove 15 is notched in the left and right symmetrical positions in the cylindrical receiving portion 14 in the upper part of the cylindrical body 17 in the L-shape opposite to each other. Then, projections (not shown) provided on both sides of the tip of the operation pole are inserted into the hook groove 15 and the operation pole is twisted to fix the cylindrical body 17 of the mounting jig 11 to the tip of the operation pole. I can do it.

  Further, as shown in FIG. 4B, a planar T-shaped base portion 16 is suspended from the lower surface of the mounting jig 11. On the upper side of the base portion 16, a U-shaped arm 12 protrudes horizontally. The U-shaped arm 12 is inserted into the groove portion 5 of the ceiling portion 1 a of the lid member 1, and has a substantially U-shaped cutout recess 12 a inside the U-shaped arm 12.

  Further, corresponding to the U-shaped arm 12, a pair of left and right strip-shaped expanding arms 13 having a tapered end are provided on the lower side of the base portion 16. As shown in FIG. 5A, the expansion arm 13 is inserted into a gap formed between the both closing plug fixtures 2a and 2b and the side surface 1c of the closing plug 1A constituting the lid member 1. It is something to wear.

  When the expanding arm 13 is inserted into the gap, as shown in FIG. 5 (b), the closing plug 1A is sandwiched between the pair of left and right expanding arms 13, and the closing plug fixtures 2a and 2b are sandwiched. Is expanded.

  As shown in FIGS. 7 (a), (b), (c) and FIG. 9, the neutron source holder rack L has a rectangular frame shape on one side of a vertically long mounting plate 21 having an angled fastening portion 22 at the upper end. The gantry 23 is attached by pin / hole fitting portions 24 at four corners.

  And, as shown in FIGS. 8 (a) and 8 (b), five substantially L-shaped hook portions 26 are arranged side by side on the upper side of the pedestal 23 through lateral angles 25. The front side of the inserted neutron source holder H is held.

  At this time, as shown in FIG. 8B, the hanging portion 26 is fixed at the upper end with a bolt 27 so as to face obliquely downward from the angle 25. Further, the angle 25 is provided with a U-shaped guide portion 28 located in parallel below the hanging portion 26 so as to support the inserted neutron source holder H from both the left and right sides.

  On the other hand, as shown in FIGS. 7 (a), (b), (c) and FIG. 9, five bottomed cylindrical pipe portions 29 are attached to the lower side of the pedestal 23 so as to face the hanging portion 26. It has been. As shown in FIG. 9, the piping portion 29 supports the inserted neutron source holder H from below.

  Below, the process of fixing the cover member 1 to the insertion hole H1 of the neutron source holder H using the attachment jig 11 will be described.

  First, the cylindrical body 17 of the mounting jig 11 is fixed to the tip of an operation pole (not shown).

  Then, as shown in FIGS. 5A and 5B, a U-shaped arm 12 for attaching / detaching the lid member of the mounting jig 11 is mounted in the groove portion 5 of the closing plug 1 </ b> A constituting the lid member 1. Specifically, the substantially U-shaped notch recess 12a existing inside the U-shaped arm 12 is matched with the groove 5 of the closing plug 1A.

  At the same time, as shown in FIG. 5 (b), the mounting jig 11 is placed in the gap formed between the both closing plug fixtures 2 a and 2 b and the side surface 1 c of the closing plug 1 A constituting the lid member 1. The expansion arm 13 is inserted and the both closed plug fixtures 2a and 2b are expanded.

  Next, the operation pole is lowered into the spent fuel pool P (see FIG. 10) by the fuel handling unit V, and the lid member 1 attached to the attachment jig 11 is stored in the neutron source holder rack L. Attached to the insertion hole H1 of the neutron source holder H.

  After mounting the lid member 1, the U-shaped arm 12 of the mounting jig 11 is pulled out from the groove portion 5 of the lid member 1. At the same time, the expansion arm 13 of the mounting jig 11 is pulled out from the gap formed between the both closing plug fixtures 2a and 2b and the side surface 1c of the closing plug 1A constituting the lid member 1.

  As a result, as shown in FIG. 6, the two closed plug fixtures 2a and 2b that have been expanded return in the direction of the side surface 1c of the closure plug 1A, and the distal ends of the two closure plug fixtures 2a and 2b Engages with the annular protrusion 4 of the neutron source holder H.

  Specifically, as shown in FIG. 6, the locking portions 3 a and 3 b provided at the distal ends of the two closing plug fixtures 2 a and 2 b are brought into contact with and engaged with the lower edge and the lower surface of the annular protrusion 4. In this state, the annular protrusion 4 is grasped from below. And the upward movement of both the closing plug fixtures 2a and 2b is prevented, and the lid member 1 is firmly fixed to the insertion hole H1 of the neutron source holder H.

  The lid member of the neutron source holder according to the present invention and the method of attaching the lid member are as follows: Attaching the lid member by remote control in a spent fuel pool in various facilities such as a neutron source holder of a boiling water nuclear power plant It can be widely used as a method.

It is a perspective view which shows the structure of the neutron source holder stored in the neutron source holder rack in a spent fuel pool. It is a front view which shows the state which loads a neutron source in a neutron source holder. The structural example of a cover member is shown, (a) is a front view, (b) is a side view, (c) is a bottom view. The structural example of an attachment jig is shown, (a) is a top view, (b) is a side view. The use state of an attachment jig is shown, (a) is a perspective view of a state before attaching an attachment jig to a lid member, (b) is a perspective view of a state after attaching an attachment jig to a lid member. . It is a perspective view of the state where the lid member was installed in the insertion hole of the neutron source holder. The structural example of a neutron source holder rack is shown, (a) is the whole front view, (b) is a side view of a mount, (c) is a top view of a mount. The structural example of the hanging part of a mount frame is shown, (a) is an enlarged front view which shows the principal part of a hanging part, (b) is a side view of a hanging part. It is a disassembled perspective view which shows the structure of a neutron source holder rack. It is a top view which shows the example of arrangement | positioning of the neutron source holder rack in a spent fuel pool. It is a perspective view explaining the installation in the nuclear power plant in a prior art example. BRIEF DESCRIPTION OF THE DRAWINGS The installation in the nuclear power plant in a prior art example is demonstrated, (a) is a top view of the whole, (b) is a top view of a fuel replacement machine periphery.

Explanation of symbols

P ... spent fuel pool Q ... nuclear reactor R ... rail T ... fuel changer V ... fuel handling part H ... neutron source holder H1 ... insertion hole L ... neutron source holder rack S ... neutron source 1 ... lid member 1A ... closed Plug 1a ... Ceiling part 1b ... Opening 1c ... Side 2a ... Closed plug fixture 2b ... Closed plug fixture 3a ... Locking portion 3b ... Locking portion 4 ... Annular projection 5 ... Groove 6 ... Through hole 11 ... Mounting jig DESCRIPTION OF SYMBOLS 12 ... U-shaped arm 12a ... Notch recessed part 13 ... Expansion arm 14 ... Cylindrical receiving part 15 ... Hook groove 16 ... Base part 17 ... Cylindrical body 21 ... Mounting plate 22 ... Fastening part 23 ... Mount 24 ... Pin and hole Fitting part 25 ... Angle 26 ... Hanging part 27 ... Bolt 28 ... Guide part 29 ... Piping part

Claims (5)

  A lid member of the neutron source holder that closes the insertion hole of the neutron source provided at the upper end of the neutron source holder, and a closure plug that covers the insertion hole of the neutron source holder, and fixing of the closure plug provided on both sides of the closure plug A lid member for a neutron source holder, wherein the end portions of both closing plug fixtures engage with an annular projection provided on the neutron source holder.   2. The lid member for a neutron source holder according to claim 1, wherein the closing plug that covers the insertion hole of the neutron source holder is formed in a cylindrical shape having a ceiling portion on the upper end side and an opening on the lower end side.   The lid member for a neutron source holder according to claim 1 or 2, wherein the closure plug fixtures provided on both sides of the closure plug are formed in a rectangular plate shape and have a length protruding from the opening of the closure plug.   The lid member of the neutron source holder according to any one of claims 1 to 3, wherein a gap is provided between a side surface of the closing plug and the closing plug fixture.   A method of attaching a lid member of a neutron source holder that closes the insertion hole of the neutron source provided at the upper end of the neutron source holder, the step of covering the insertion hole of the neutron source holder with the step of placing the closure plug on both sides of the closure plug A method of attaching a lid member of a neutron source holder, comprising the step of engaging a distal end portion of a closed plug fixing tool with an annular projection of the neutron source holder.

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