JP2965635B2 - Inspection method in fast breeder reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention is to inspect a reactor internal structure installed in a reactor vessel of a liquid metal cooled fast breeder reactor during a service period. The inspection method in the fast breeder reactor.

2. Description of the Related Art Conventionally, a fast breeder reactor of this type has a core 2 inside a reactor vessel 1 and a core supporting the core 2 and forming a flow path for core coolant as shown in FIG. 5, for example. A support structure 3,
A core support skirt 4 for transmitting the load of the core support structure 3 to the reactor vessel 1, a boundary between the hot plenum 5 and the cold plenum 6 of the coolant, and a horizontal load of the core are transmitted to the reactor vessel 1. Lower partition 7 and primary pump 8
, An intermediate heat exchanger 9 and an upper core mechanism 10. The primary pump 8, the intermediate heat exchanger 9, and the core upper mechanism 10 are provided with a roof slab 11 for forming a lid of the reactor vessel 1.
It is supported by. The core support structure 3 further includes two core support plates 3a for supporting the weight of the core 2, a lower reinforcement 3b for reinforcing the rigidity of the core support plate 3a, and a high-pressure coolant discharged from the primary pump 8 for the core 2. It is composed of an inlet plenum 3c leading to the entrance.

In the fast breeder reactor thus configured, important welds that form a boundary or support the core 2 among the welds of the structures in the reactor vessel 1 are shown in FIG. In the figure, the crosswise joints of the important welds are marked with x and the longitudinal joints are marked. Indicated by.

The following three methods are conceivable for performing the inspection during the service period of these important welds.

(1) A method of disassembling the inspection target equipment and taking it out of the furnace.

(2) A method in which the coolant inside the reactor vessel is pumped down to lower the liquid level, and the inspection target equipment is exposed to the gas.

(3) A method of connecting and observing images with a coolant see-through device using an ultrasonic transmitter.

(Problems to be Solved by the Invention) However, in the method (1), the inspection target is extremely limited, and the important welded portion cannot be covered. In the method (2), preparation work such as evacuation of the core in advance and In the method (3), there is a problem that minute image information cannot be obtained due to the limitation of the resolution capability of the current technology level.

Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to enable detailed observation of an important welded portion that forms a boundary or supports a core in a welded portion of a reactor vessel internal structure. Another object of the present invention is to provide an inspection method in a fast breeder reactor configured so as not to hinder the operation of the reactor after the inspection.

[Constitution of the Invention] (Means for Solving the Problems) The present invention relates to a nuclear reactor vessel, a nuclear reactor vessel, a core support structure for supporting a core provided in the nuclear reactor vessel, and A control rod drive mechanism for inserting a control rod into the reactor vessel, a lid covering the upper part of the reactor vessel, an upper core mechanism supported by the lid to support the control rod drive mechanism, and a coolant in the reactor vessel In a method for inspecting the inside of a fast breeder reactor, a circulating section for forcibly circulating the inside of the lid and an upper part being fixed to the lid and being installed on the upper part of the fast breeder reactor, the primary pump is removed and the installation position of the primary pump is removed. A partition plate having an in-reactor inspection device installed therein, storing an inert gas near a welded portion of a reactor internal structure disposed in the reactor vessel, and having an inert gas space extinguishing hole at an upper portion thereof. To create an inert gas space, A monitoring camera provided in the in-furnace inspection device is inserted into a gas space to monitor the vicinity of the weld and inspect the soundness.After the inspection, the inert gas filled in the inert gas space from the small hole is inspected. After flowing out to the outside to eliminate the inert gas space, the in-furnace inspection device is withdrawn, and the primary pump is returned to the withdrawal point.

(Operation) In the present invention, the partition plate is provided in the coolant immersion portion in the nuclear reactor vessel, so that an inert gas is fed into a region surrounded by the partition plate to form an inert gas space. Next, the tip of the in-furnace inspection apparatus is put into this inert gas space, and the inspection target is observed with a fiber scope or a CCD camera installed at the tip. On the other hand, among the welded portions of the internal structure of the reactor vessel, the important welded portions that form the boundary or support the core are all pre-boarded so as to be located in the inert gas space. All inspections can be performed by the furnace inspection device. Further, after the inspection, the inert gas in the inert gas space flows out through the small holes to the outside, and the inert gas space is extinguished, so that the subsequent operation of the reactor is not hindered.

(Embodiment) An embodiment of an inspection method in a fast breeder reactor according to the present invention will be described with reference to FIGS.

In FIG. 1, a reactor core 2 is provided inside a reactor vessel 1,
A core structure 3 that supports the core 2 and forms a flow path for the core coolant, forms a boundary between the hot plenum 5 and the cold plenum 6 of the coolant, and transmits the horizontal load of the core to the reactor vessel. The lower partition 7, the primary pump 8, the intermediate heat exchanger 9, and the core upper mechanism 10 are housed therein. The primary pump 8, the intermediate heat exchanger 9, and the core upper mechanism 10 are supported by a roof slab 11 that forms a lid of the reactor vessel 1.
The core support structure 3 further includes two core support plates 3a (one of which is an extremely thick forged plate) 3a for supporting the weight of the core 2, and an inlet plenum 3c for guiding the high-pressure coolant discharged from the primary pump 8 to the core. It is composed of A first partition plate 12 is provided outside the inlet plenum 3c, and a second partition plate 13 having a function of a pedestal for the primary pump is provided at a connection portion with the primary pump 8. A standpipe 7a for accommodating the primary pump 8 and the intermediate heat exchanger 9 is provided in the lower partition wall 7. The standpipe 7a for the primary pump is extended downward to form a third partition plate 14. .

In the fast breeder reactor configured as described above, important welds that form a boundary or support the core 2 among the welds of the structures in the reactor vessel 1 are shown in FIG. In the figure, the crosswise joints of the important welds are marked with x and the longitudinal joints are marked. Indicated by.

At the time of inspection, the primary pump was pulled out, and the furnace inspection device 15 (the third
(See FIG. 4 and FIG. 4). The apparatus has a support leg 15a at an intermediate portion, and an articulated structure 15b below the intermediate portion.

 Next, the operation of the present embodiment will be described.

At the time of inspection, the primary pump 8 of the roof slab 11 shown in FIGS.
As shown in FIG. 3 (a), the furnace
Is installed, and the articulated structure 15b is inserted into the reactor vessel 1. At this time, after extending the support legs 15a to the left and right to contact the primary pump stand pipe 7a and fix the position of the intermediate portion,
By moving the articulated structure 15b, its tip is inserted downward into a region surrounded by the third partition plate 14 in the coolant in the reactor vessel 1.

When an inert gas is supplied from above in this state, as shown in an enlarged manner in FIG. 3 (b), the inert gas flows out as bubbles from the tip of the articulated structure 15b, and the third partition plate 14 and the lower partition 7 The inert gas is accumulated in a region surrounded by the above and the inert gas space 16 is formed.

A third small hole 14a is provided at the upper end of the third partition plate 14, from which the inert gas flows to the outside. Therefore, an inert gas space 16 is formed in a region surrounded by the third partition plate 14 and the lower partition.

Next, as shown in FIGS. 4 (a) and 4 (b), the tip of the multi-joint structure 15b is inserted into the inert gas space 16, and the inert gas is supplied from the tip of the multi-joint structure. Observe the inspection target using a fiberscope or CCD camera installed at the tip.

The inert gas space 16 surrounded by the first partition plate 12 or the second partition plate 13 can also be observed by the same procedure as described above. As a result, all the important welds shown in FIG. Can be observed.

When the supply of the inert gas is stopped after the completion of the in-reactor inspection, the inert gas is discharged from the first small hole 12a, the second small hole 13a, and the third small hole 14a to the outside, that is, the cooling inside the reactor pressure vessel. It flows into the upper plenum of the inert gas reservoir above the material. As a result, the inert gas space disappears, and the reactor is returned to an operable state again by pulling out the furnace inspection device 15 and inserting the primary pump 8.

The above embodiment is an application example assuming a case where an important weld in a reactor vessel of a tank type fast breeder reactor is inspected.
The method of forming a gas space in the coolant and performing the in-core inspection is applicable to other types of nuclear reactors or other inspection targets. For example, application to observation of a damaged state, deformation, and vibration of the surface of the device, search for foreign matter, and the like can be considered.

The embodiments of the present invention are as follows.

(1) A reactor vessel, a core support structure for supporting a reactor core installed in the reactor vessel, a control rod drive mechanism for inserting a control rod into the reactor core, and covering an upper part of the reactor vessel A lid, a core upper mechanism supported by the lid and supporting the control rod drive mechanism, and a circulating unit for forcibly circulating a coolant in the reactor vessel penetrates through the lid and the upper part is fixed to the lid. In the inspection method in the fast breeder reactor comprising a primary pump installed in the reactor, the primary pump is removed, an in-core inspection device is installed at a position where the primary pump is installed, and the nuclear reactor installed in the reactor vessel is installed. An inert gas space is formed by storing an inert gas near the welded portion of the furnace internals and installing a partition plate having an inert gas space extinguishing hole at the top to form an inert gas space. Insert the surveillance camera provided in the internal inspection device and After monitoring the vicinity of the contact portion and inspecting the soundness, after the inspection, the inert gas filled in the inert gas space flows out to the outside from the small hole to extinguish the inert gas space, and then the furnace The internal inspection device is withdrawn, and the primary pump is returned to this withdrawal point.

(2) An inert gas supply device for sending an inert gas into a region surrounded by the partition plate is installed on the roof slab via a door valve.

(3) Install a fiberscope or a CCD camera for in-furnace inspection to guide the CCD camera into the inert gas space on the roof slab via a door valve.

(4) An inert gas supply / inspection device having the functions of the above inert gas supply device and the in-furnace inspection device is provided.

(5) Of the welded portions of the internal structure of the reactor vessel, all the important welded portions that form the boundary or support the core are trimmed so as to be located in the inert gas space.

[Effects of the Invention] According to the present invention, a partition plate for forming an inert gas space inside a reactor vessel primary coolant is provided, and an inert gas is provided at a place where a primary pump is installed on a roof slab. Since the supply device and the in-furnace inspection device are installed, the area surrounded by the partition plate should be replaced with an inert gas space to observe it in detail and efficiently with a fiberscope or CCD camera. Can be. In addition, since a small hole is provided at the upper end of the partition plate, if the supply of the inert gas is stopped after the end of the inspection, the inert gas space is extinguished by gas outflow from the gas space, and the operation state is easily returned to the operating state. be able to.

Further, in the present invention, among the welded portions of the reactor vessel internal structure, since the boundary is formed or all the important welded portions supporting the core are plate-cut so as to be located in the inert gas space, All of these important welds can be observed in detail and efficiently.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state before an inspection in an embodiment of an inspection method in a fast breeder reactor according to the present invention, and FIG.
FIG. 3A is a longitudinal sectional view showing an important welding portion to be inspected, and FIG. 3A is a longitudinal sectional view showing a state in which a primary pump is removed from the state shown in FIG. 1 and an in-furnace inspection apparatus is installed, FIG. (B) is an enlarged view of a main part of FIG. 3 (a), and FIG. 4 (a)
3 is a longitudinal sectional view showing the operating state of the furnace inspection apparatus during the inspection from the state of FIG. 3, FIG. 4 (b) is an enlarged view of a main part of FIG. 4 (a), and FIG. FIG. 6 is a longitudinal sectional view showing a furnace, and FIG. 6 is a longitudinal sectional view showing an important welding portion to be inspected in FIG. 1 ... Reactor vessel, 3 ... Core support structure, 3c ... Inlet plenum, 7 ... Bottom bulkhead, 7a ... Stand pipe, 12
... First partition plate, 12a First small hole, 13 Second partition plate, 13a Second small hole, 14 Third partition plate, 14a
... third small hole, 15 ... furnace inspection device, 15a ... support leg, 15b ... articulated structure, 16 ... inert gas space.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁶ , DB name) G21C 17/00 G21C 1/00 G21C 13/00 G21C 17/08 G21C 15/02 G21C 19/02

Claims (1)

(57) [Claims] 1. A reactor vessel, a core supporting structure for supporting a core disposed in the reactor vessel, a control rod driving mechanism for inserting a control rod into the core, A lid covering the upper part, a core upper mechanism supported by the lid to support the control rod drive mechanism, and a circulating unit for forcibly circulating the coolant in the reactor vessel penetrates through the lid and the upper part is the lid. In a method for inspecting a fast breeder reactor comprising a primary pump fixed and installed in a reactor, the primary pump is removed, an in-core inspection device is installed at the installation position of the primary pump, and the primary pump is disposed in the reactor vessel. Inert gas is stored in the vicinity of the welded portion of the reactor internal structure, and a partition plate having an inert gas space extinguishing hole is installed on the upper portion to form an inert gas space. Into the monitoring camera provided in the furnace inspection device After monitoring the vicinity of the welded portion and inspecting the soundness, after the inspection, the inert gas filled in the inert gas space is discharged from the small hole to the outside and the inert gas space is extinguished. A method for inspecting the inside of a fast breeder reactor, wherein the in-furnace inspection apparatus is withdrawn and the primary pump is returned to the withdrawn point.