JPH07209478A - Reactor internal equipment temporary setting pool - Google Patents

Abstract

PURPOSE:To provide a reactor internal equipment temporary setting pool in which exposure to worker can be reduced, and working efficiency can be improved by arranging an equipment temporary setting pool in T-shape to a reactor well, and also providing a shielding door in the equipment temporary setting pool. CONSTITUTION:In a reactor internal equipment temporary setting pool 7 for temporarily setting reactor internal equipments such as a steam dryer 4 and steam separator 5 provided to communicate with a reactor well 3 in a boiling water type nuclear power plant, the steam dryer 4 and steam separator 5 temporarily set in T-shape through the passage with the reactor well 3 are never linearly arranged with the reactor well 3. The inner part of the reactor internal equipment temporary setting pool 7 is partitioned by a watertight shielding door 8, so that each of the steam dryer 4 and steam separator 5 can be temporarily arranged in water independently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temporary equipment pool for temporarily storing in-reactor equipment such as a steam dryer at the time of periodic inspection work in a boiling water nuclear power plant.

[0002]

2. Description of the Related Art In a boiling water nuclear power plant, the operation of opening and restoring a nuclear reactor is one of the main operations called critical path in the periodic inspection work. As shown in the plan view of FIG. 3, a reactor well 3 in which an unillustrated nuclear reactor is installed inside is provided with an in-reactor temporary storage pool 1 on one side and a fuel pool 2 on the other side.
Are communicated with each other and are constructed in an I-shape.

The opening and restoration work of the reactor begins with the removal and installation of the cover (not shown) from the reactor well 3.
Similarly, the upper lid of the reactor containment vessel (not shown) and the upper lid of the reactor pressure vessel, which is a reactor, are removed and attached, and the steam dryer 4 and the steam separator 5 in the reactor pressure vessel are removed, attached, and moved. Will be carried out on the 5th or 6th floor of the reactor building. Also, the radiation dose equivalent of radiation workers involved in the opening and restoration work of this nuclear reactor is always ranked high even during the entire periodic inspection work period of the nuclear power plant.

Particularly in the operation of opening the reactor, the main steam system line is filled with water after the upper lid of the reactor pressure vessel is removed, and further water filling of the reactor pressure vessel is performed while gradually raising the reactor water level. In parallel, the steam dryer 4 and the steam separator 5 are removed from the reactor pressure vessel.

Regarding the removal and movement of the steam separator 5 at this time, the work of loosening the shroud head bolt (not shown) must be performed in advance on the floor of the fuel exchanger in the reactor well 3, but at this time, The radiation dose equivalent received by the workers engaged in this work is strongly affected by the high radiation dose equivalent rate from the steam dryer 4 which has already been moved to the temporary storage pool 1 for equipment and is temporarily placed naked. Is also a factor that increases. The water filling into the equipment temporary storage pool 1 in which the steam dryer 4 is temporarily placed is performed when the steam separator 5 is moved.

[0006] Further, when the reactor is restored, dewatering the reactor well 3 after dewatering the well 3, tightening the shroud head bolts, etc., the temporary equipment pool 1 Since the well 3 and the I-shape are arranged linearly, the working environment is such that the radiation dose contribution from the steam dryer 4 is extremely large.

Therefore, in these operations, it is necessary to shield the high radiation dose equivalent rate from the steam dryer 4 as much as possible. Conventionally, when the operation in the reactor well 3 is performed, the temporary equipment pool 1 is used. Steam dryer 4 temporarily placed in the air
In order to shield the radiation from the equipment, a lead shield, which is a shielding material, was provisionally stacked on the tier 6 which is a communication portion between the reactor well 3 and the temporary equipment pool 1.

Further, as another construction method, the lead shield is suspended by an overhead crane (not shown) and shielded, or a concrete plug (not shown) that has been removed for inspection of the equipment in the furnace is used. The method of stacking again on the tier 6 was being tried.

[0009]

When the steam dryer 4 is temporarily placed in the equipment temporary storage pool 1 in the air, when the work in the reactor well 3 is performed, the reactor well is shielded for radiation. Temporary stacking of lead shields, suspension of lead shields suspended by an overhead crane, and stacking of concrete plugs on the tier 6 between the equipment 3 and the temporary equipment pool 1 are temporary vapors that are high radiation sources. Since the dryer 4 is located on a straight line with the reactor well 3 in which the worker is located,
The effect of reducing the radiation exposure by these shields is not always sufficient.

Further, it is not necessary to perform the periodic inspection work every time the in-reactor equipment is moved to the temporary equipment pool 1 or when the shield 6 is removed and arranged in the tier 6 every time the work related to the reactor well 3 is performed. Since the process is complicated and the number of processes is increased, the periodic inspection period is extended and the worker is exposed to radiation.

An object of the present invention is to arrange a temporary equipment pool in a T-shape with respect to a reactor well, and to provide a shield door in the temporary equipment pool for the operator. It is to provide a temporary storage pool for in-core equipment that reduces the radiation exposure and improves work efficiency.

[0012]

In order to achieve the above object, a temporary pool for in-reactor equipment according to the invention of claim 1 is a steam dryer provided in communication with a reactor well in a boiling water nuclear power plant, In a pool in which internal equipment such as a steam separator is temporarily placed, a steam dryer and a steam separator and the reactor well which are temporarily placed in a T-shape through a passage with the reactor well are placed. Characterized by not lining up in a straight line.

According to a second aspect of the present invention, there is provided a temporary equipment pool for temporarily storing in-reactor equipment such as a steam dryer and a steam separator provided in communication with a reactor well in a boiling water nuclear plant. In the pool, the steam dryer and the steam separator temporarily arranged by being arranged in a T shape through the passage to the reactor well are not aligned linearly with the reactor well, and It is characterized by a watertight partition door that can be opened and closed in the temporary pool.

[0014]

According to the invention described in claim 1, for the related work in the reactor well in a state where the reactor is opened and the reactor well is not filled with water, the reactor is temporarily seated in the temporary equipment pool and temporarily placed. Since the radiation from the installed steam dryer is blocked by the wall of the temporary storage pool for in-core equipment, which is arranged in a T shape with respect to the reactor well, the high radiation dose equivalent rate is high. Workers near the well are not affected.

According to a second aspect of the present invention, the radiation from the steam dryer, which is seated and temporarily placed in the temporary equipment pool in the reactor, is arranged in a T-shape with respect to the reactor well. Shut off at the wall of the temporary equipment pool. In addition, the steam dryer and steam separator temporarily placed in the temporary equipment pool inside the reactor are shielded from radiation by being shielded from radiation and submerged so that the temporary equipment pool inside the reactor and the atomizer The influence of high radiation dose equivalent rate from the in-core equipment temporarily placed in the in-core equipment temporary pool in the reactor well is blocked.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those in the above-described conventional technique are designated by the same reference numerals, and detailed description thereof will be omitted. In the first embodiment, as shown in the plan view of FIG. 1, the fuel well 2 is communicated with the reactor well 3 on one side, and the stage 6 which is a communication part on the other side.
The in-furnace equipment temporary storage pool 7 is arranged in a T-shape through the, and the steam drying equipment 4 and the steam separator 5 are individually loaded and temporarily placed in the left and right sides of the in-reactor equipment temporary storage pool 7. Secure a volume that can be easily inspected.

Next, the operation of the above configuration will be described by way of an example when the reactor is being restored. The steam dryer 4 and the steam separator 5, which have been inspected respectively, are temporarily placed in the temporary equipment pool 7 so as to be separated left and right, and the reactor well 3 has the steam dryer 4 and the steam separator 5. Since the radiation is not linearly arranged from any of No. 5, the radiation is blocked by the temporary equipment pool 7 and is not directly affected by the high radiation dose equivalent rate.

Therefore, first, after moving the steam / water separator 5 from the temporary equipment pool 7 to the reactor well 3 in a full water state by using an overhead crane to a reactor pressure vessel position (not shown) in the reactor well 3, , The reactor water level is gradually lowered to about 1 m below the flange surface of the reactor pressure vessel over time.

In the meantime, the steam-water separator 5 is gradually suspended in the reactor pressure vessel in accordance with the decrease in the reactor water level, and after being seated on the shroud head, it is removed in the reactor well 3. Dyed and tighten the shroud head bolts from the floor of the refueling machine.

At this time, the distance between the reactor well 3 and the steam dryer 4 temporarily placed in the temporary equipment pool 7 is long, and the temporary equipment pool 7 is located in the reactor well 3
Since the steam dryer 4 is arranged in a T-shape, the water level in the equipment temporary storage pool 7 is lowered due to the draining operation, and the steam dryer 4 is exposed to the air and seated. Also, the radiation from this steam dryer 4 is stored in the temporary equipment pool 7.
Since the reactor well 3 is not directly affected by the high radiation dose equivalent rate, the high radiation dose equivalent of the worker is not increased and the exposure is reduced.

That is, according to the first embodiment, in the periodic inspection work, the steam dryer 4 and the steam separator 5 are individually seated in the temporary equipment pool 7 on the left and right sides, respectively. Since the worker is not particularly affected by the high radiation dose equivalent rate from the steam dryer 4 during various operations in the well 3, there is an effect that the worker's work efficiency and radiation exposure are improved.

In the second embodiment, as shown in the plan view of FIG. 1 and the enlarged view of the essential portion of FIG. 2, the fuel pool 2 is connected to the reactor well 3 and the fuel pool 2 is connected to the reactor well 3 and the other is a communication part. The in-core device temporary storage pool 7 is arranged in a T-shape via 6 and the steam in-core device temporary storage pool 7 is independently loaded and temporarily installed on the left and right sides of the steam dryer 4 and the steam separator 5, respectively. And secure a volume that can be easily inspected.

Furthermore, a groove 7a is formed on one wall surface of the temporary equipment pool 7 and a pit 7b is formed on the other wall surface, and an inner shield plate 8a and an outer shield plate 8b are fed into the pit 7b to emit radiation. And a shielding door 8 for partitioning the inside of the furnace temporary storage pool 7 in a watertight manner is installed at two locations. The shield door 8 consisting of the inner shield plate 8a and the outer shield plate 8b has a lead plate inside and a plywood structure made of the same stainless steel plate as the temporary equipment pool 7 for the exterior, and is slid by an unillustrated hydraulic or electric drive device. The inner shield plate 8a and the outer shield plate 8b.
And are expanded and contracted in multiple stages to open and close.

Regarding the shielding door 8, if the thickness of the lead plates in the inner shielding plate 8a and the outer shielding plate 8b is selected in consideration of the shielding effect, the transmittance of gamma rays becomes smaller, and In a uniform radiation work environment, the worker's radiation exposure can be reduced and long-term work can be performed.

Next, the operation of the above configuration will be described. During the reactor opening work, the concrete plugs (not shown) stacked in the tier 6 which is a communication portion between the reactor well 3 and the temporary equipment pool 7 are removed in advance, and then the reactor well 3 is installed in the illustrated state. After removing the upper lid of the reactor pressure vessel, which is a nuclear reactor, gradually increase the reactor water level by water filling the main steam system line and water filling the reactor pressure vessel, etc. Remove it.

First, the steam dryer 4 is detached and moved to the steam dryer pit 7c in the temporary equipment pool 7 in the air,
After the seat is temporarily placed, the shielding door 8 on the side of the steam dryer pit 7c is closed to make the steam dryer 4 and the reactor well 3 in the temporary equipment pool 7 watertight and isolated from radiation, and then steam. By independently pouring water into the dryer pit 7c and submerging the steam dryer 4 in the water, the influence of the high radiation dose equivalent rate from the steam dryer 4 to the outside of the steam dryer pit 7c is blocked.

As a result, the reactor water level is adjusted to the reactor well 3
Loosening the shroud head bolts of the steam separator 5 on the floor of the fuel exchanger in the process of filling the inside with water,
It is possible to move and remove water from the reactor pressure vessel at a low radiation dose equivalent rate.

The removed water / water separator 5 moves to the air / water separator pit 7d in the equipment temporary storage pool 7 in the air, and when it is temporarily seated, the shielding door 8 on the side of the water / water separator pit 7d is closed to remove the equipment. After making the steam separator 5 and the reactor well 3 watertight in the temporary pool 7 and isolated from radiation,
By independently injecting water into the steam separator pit 7d and submerging the steam separator 5, the influence of the high radiation dose from the steam separator 5 to the outside of the steam separator pit 7d is blocked.

The steam separator 5 and the steam dryer 4 are individually drained in the steam separator pit 7d and the steam dryer pit 7c, respectively, and then checked. Since the work can be performed outside the steam separator pit 7d and the steam dryer pit 7c without being affected by the high radiation dose equivalent rate, the high radiation dose equivalent rate in the temporary equipment pool 7 is reduced. In addition, the steam dryer 4 and the steam separator 5 which have been inspected are again poured into the steam dryer pit 7c and the steam separator pit 7d, respectively, and are temporarily placed until the restoration work so that the equipment temporary storage pool 7 The influence of high radiation dose on the surroundings including is blocked.

When the reactor is restored, the shield door 8 on the steam / water separator pit 7d side is opened, and the steam / water separator 5 is moved from the temporary equipment pool 7 into the reactor well 3 using an overhead crane. After the water is moved to the position of the reactor pressure vessel (not shown), the water level of the reactor is gradually lowered from the full state in the reactor well 3 to about 1 m below the flange surface of the reactor pressure vessel over time. .

In the meantime, the steam-water separator 5 is gradually suspended in the reactor pressure vessel in accordance with the decrease in the reactor water level, and after being seated on the shroud head, it is removed in the reactor well 3. Dyeing and tightening work of the shroud head bolt from the floor of the refueling machine are carried out before moving and attaching the steam dryer 4.

Also in the case of this reactor restoration work, as in the case of the reactor opening work, the work on the floor of the fuel exchanger in the reactor well 3 is performed by the steam dryer 4 in the temporary equipment pool 7.
Since it is temporarily placed in water in the steam dryer pit 7c, it is not affected by the high radiation dose equivalent rate, so that the worker's exposure is reduced.

Also in the second embodiment, since the arrangement of the reactor well 3 and the temporary equipment pool 7 is the same T-shape as in the first embodiment, the operation and effect by this are the same. The steam dryer 4 and the steam separator 5 are respectively connected to the steam dryer pit 7c and the steam separator pit 7 of the equipment temporary storage pool 7.
When it is housed in d, it is not in a linear position in the reactor well 3 from either the steam dryer 4 or the steam separator 5, so that it is not directly affected by the high radiation dose equivalent rate.

It is to be noted that the equipment temporary storage pool 7 is seated and temporarily placed in the steam dryer pit 7c and the steam separator pit 7d,
By closing the respective shielding doors 8, the mutual equipment temporary storage pool 7
And the reactor well 3 are shielded from the high radiation dose equivalent, and water is further injected into the steam dryer pit 7c and the steam separator pit 7d, respectively, so that various operations in the reactor well 3 can be further performed. The exposure to workers can be reduced.

[0035]

As described above, according to the present invention, during the opening and restoration work of the reactor whose exposure dose equivalent of the worker is ranked higher throughout the periodic inspection construction period of the nuclear power plant, the temporary storage pool for the reactor equipment is provided. The inspection work of the equipment inside the reactor and the various work inside the reactor well are not affected by the high radiation dose equivalent rate from the equipment inside the reactor, and the safety is improved by reducing the exposure of workers and the periodic inspection work is performed. This has the effect of shortening the period.

[Brief description of drawings]

FIG. 1 is a plan view of an in-core device temporary storage pool and the like according to a first embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a main part of a shielding door according to a second embodiment of the present invention.

FIG. 3 is a plan view of a conventional in-core device temporary storage pool and the like.

[Explanation of symbols]

1, 7 ... Temporary equipment pool, 2 ... Fuel pool, 3 ... Reactor well, 4 ... Steam dryer, 5 ... Steam separator, 6 ... Stage, 7a ... Groove of temporary pool wall, 7b ... pit of temporary pool wall, 7c ... steam dryer pit, 7d ... steam separator pit, 8 ... shielding door, 8a ... inner shielding plate, 8b ... outer shielding plate.

Claims (2)

[Claims] 1. A pool in which in-reactor equipment such as a steam dryer and a steam separator provided in communication with a reactor well in a boiling water nuclear power plant is temporarily placed, through a passage to the reactor well. A temporary equipment pool for in-reactor equipment, wherein the steam dryer and steam separator, which are arranged in a V shape and temporarily placed, and the reactor well are not aligned in a straight line. 2. In a pool in which internal equipment such as a steam dryer and a steam separator provided in communication with a reactor well in a boiling water nuclear power plant is temporarily placed, a T is provided through a passage to the reactor well. The steam dryer and steam separator that are temporarily placed in a V-shape and the reactor well are not aligned in a straight line, and a shield door that can be opened and closed freely and watertightly partitions in the temporary pool of the in-reactor equipment. A temporary storage pool for in-core equipment, which is characterized by being provided.