JP6091784B2 - Reactor pressure vessel nozzle cleaning and decontamination equipment - Google Patents

Description

  The present invention relates to a cleaning decontamination apparatus for a reactor pressure vessel nozzle, and in particular, a reactor pressure vessel capable of safely and effectively cleaning and decontaminating a narrow overflow portion of a nozzle having a thermal sleeve with a simple configuration. The present invention relates to a cleaning / decontamination apparatus for a nozzle portion.

  As a decontamination apparatus for a reactor pressure vessel nozzle part, there is a decontamination apparatus for the purpose of reducing exposure during the operation of removing a safe end provided with a thermal sleeve (see, for example, Patent Document 1). This decontamination apparatus has an apparatus main body suspended in a reactor pressure vessel body so as to be movable up and down, a position detection means for detecting the position of the apparatus main body, and this apparatus main body adsorbed on the inner wall surface of the reactor pressure vessel body. And a decontamination means for removing the clad accumulated in the annular narrow portion formed between the reactor pressure vessel nozzle main body and the thermal sleeve.

JP-A-10-123292

  The nozzle part decontamination device described in Patent Document 1 approaches the nozzle part in a state where there is no riser pipe or sparger pipe or the like inside the reactor pressure vessel connected via the thermal sleeve. It is a decontamination device that can function in a state where the device is adsorbed on the furnace wall surface.

  However, during regular inspection of a nuclear power plant, a water supply sparger, a core spray line, and the like are present, and the decontamination apparatus described in Patent Document 1 is difficult to access to the nuclear pressure vessel nozzle. In addition, there is a fatal problem that the piping part becomes an interference and the thermal sleeve cannot be decontaminated. In addition, this decontamination device is a very effective decontamination device in large-scale improvement work that removes the connection pipe inside the container, such as nozzle safe end replacement work, but there is a method of fixing the device body. Since it is a method of adsorbing with a negative pressure between the furnace wall surface, there is a problem that the main body of the apparatus is complicated and large, and more cables are required for the control system. In addition, it is expected to be extremely difficult to operate in in-reactor water with many in-reactor structures.

  On the other hand, unlike the large-scale decontamination apparatus as described above, ISI (In-Service Inspection) or IHSI (Induction Heating Stress Improvement) that is performed during a regular periodic inspection period is residual due to high-frequency induction heating. As a measure to reduce radiation exposure mainly during inspection work (such as stress improvement), a horseshoe-shaped high-pressure water jet nozzle (cleaning head) that matches the outer circumference of the nozzle is seated on the top of the nozzle to be inspected and directed toward the narrow part of the thermal sleeve A decontamination apparatus that reduces the nozzle surface dose rate by removing the clad staying inside by jetting high-pressure water has also been developed.

  According to the above decontamination apparatus, unlike the decontamination apparatus described in Patent Document 1, there is no need for large-scale preparation such as adsorption / fixing work to the furnace wall surface of the apparatus body, and the decontamination work process is shortened. The configuration of the cleaning device can be simplified. The operation of the water injection device (cleaning device) is a simple device that can be easily operated using the auxiliary hoist of the fuel changer. The decontamination (cleaning) mechanism of the clad staying in the narrow part of the thermal sleeve is not based on the impact breaking force of high-pressure water, but high-speed fluid in which surrounding water is entrained by high-pressure water (high-speed flow is generated in the gap) The water jet nozzle (water jet head) has a horseshoe that matches the outer shape of the nozzle thermal to be cleaned so that the high-speed fluid flows uniformly in the gap and the cleaning effect is improved. It is formed into a shape.

However, the water injection device (cleaning nozzle) used in the above decontamination device is suspended from the auxiliary hoist of the fuel changer and is held by its own weight in the reactor water. There is a concern that the horseshoe-shaped head at the tip vibrates in the furnace due to the reaction force and damages the internal structure of the furnace. Therefore, in order to cancel the reaction force caused by the water injection, the water injection is also performed in the direction opposite to the injection direction.
At this time, the force F (impact force = cleaning force) received by the thermal sleeve which is a decontamination (cleaning) target nozzle is expressed by the following equation (1).
F = γQ / g · ν [kgf] ν = √ (20 · g · P) (1)

Here, Q is the injection flow rate (m ³ / s), γ is the liquid specific weight (kg / m ³ ), ν is the fluid velocity (m / s), and g is the acceleration (m / s ² ) And P is the pressure (kgf / cm ² ).

  The detergency in the water injection device used in the decontamination device is increased by increasing the injection pressure by increasing the flow rate of the injection water. And if the injection flow rate is large, stronger cleaning power can be applied. However, as described above, the reaction force also acts against the cleaning force at the same time. Therefore, in order to stabilize the cleaning head at the tip, the reverse injection (reaction force) having the same force as the cleaning force is required.

  For this reason, in order to increase the cleaning power, it is necessary to prepare a high-pressure pump vehicle having a large capacity and a high output in anticipation of the impact energy being halved. In the cleaning operation using this high-pressure pump vehicle, a yard operation (preparation operation for securing a MUW (make-up water system) water supply source) occurs, a through hole (spare sleeve) of the reactor building is required, or the reactor building 1 There are many incidental work such as laying a high-pressure water transfer line from the floor to the operation floor of the reactor building, and the washing work by the high-pressure pump car is a factor that increases time, labor cost and material cost. The conventional horseshoe-shaped water injection device (cleaning nozzle) is a decontamination device applicable to the water supply nozzle (N4) and the core spray nozzle (N5) among the double tube structure nozzles provided with the thermal sleeve. However, for low pressure water injection nozzles (N6 nozzles) existing in BWR reactor pressure vessels with a power generation of 1.1 million kW, there is a feature in the connection structure between the low pressure water injection nozzle and the shroud side in the reactor Therefore, there is a problem that the decontamination apparatus of the preceding example cannot be applied.

  The present invention contributes to the reduction of radiation exposure in the construction where work is performed on the surface of the nozzle portion such as ISI of the reactor pressure vessel nozzle portion. Therefore, the low pressure water injection nozzle (N6 It is an object of the present invention to provide a reactor for cleaning and decontaminating a reactor pressure vessel nozzle that can safely and effectively clean the gap in the thermal sleeve.

In order to achieve the above object, a cleaning decontamination apparatus for a reactor pressure vessel nozzle part according to the present invention comprises:
In the reactor decontamination device for the reactor pressure vessel nozzle that performs water jet cleaning of the narrow part between the nozzle body provided in the reactor pressure vessel and the thermal sleeve provided concentrically, the reactor pressure vessel is moved up and down. a suspension is the apparatus body freely, and high-pressure water header provided at a lower portion of the apparatus main body, a plurality of injection nozzles for injecting high pressure water toward the narrow portion is branched from the high-pressure water header, the high-pressure water header A plurality of high-pressure pump units for supplying high-pressure water to the high-pressure hose for supplying high-pressure water from the high-pressure pump unit to the high-pressure water header, and the narrow portion depth direction of the injection nozzle attached to the high-pressure water header and a angle adjusting mechanism for the mounting angle is adjustable, and wherein the high-pressure pump unit of the plurality groups are operated in parallel.

  According to the reactor pressure vessel nozzle part cleaning and decontamination apparatus having the above-described configuration, the width of the plurality of injection nozzles can be made smaller than the gap width between the half clamp fixed to the thermal sleeve and the inner wall surface of the reactor pressure vessel. Therefore, even when there is a clamp joint or bellows connected to the thermal sleeve, the injection nozzle can easily approach the nuclear pressure vessel nozzle part, and high pressure water can be injected from the injection nozzle to the narrow part. The cleaning and decontamination work can be performed efficiently. Moreover, since a plurality of high-pressure pump units that supply high-pressure water to the injection nozzle are installed and operated in parallel, high-pressure water supply is provided in comparison with the case where a single high-pressure pump vehicle is provided as in the prior art. The equipment configuration can be greatly reduced in size and simplified.

The cross-sectional view which shows the assembly state of the low pressure water injection nozzle provided in a nuclear reactor pressure vessel. It is a figure which shows the coupling structure of a low pressure water injection nozzle and a bellows, (a) is sectional drawing, (b) is IIb-IIb arrow line view of Fig.2 (a). The top view which shows the structure of one Example of the high pressure water supply part of the washing | cleaning decontamination apparatus of the reactor pressure vessel nozzle part which concerns on this invention. It is a figure which shows the structure of one Example of the apparatus main-body part of the washing | cleaning decontamination apparatus of the reactor pressure vessel nozzle part which concerns on this invention, (a) is a top view of an apparatus main-body part, (b) is an apparatus main-body part. Front view, (c) is a side view of the apparatus main body. It is a figure which shows the washing | cleaning operation state of the low pressure water injection nozzle which uses the washing | cleaning decontamination apparatus of the reactor pressure vessel nozzle part which concerns on this invention, (a) is a top view, (b) is a longitudinal cross-sectional view.

  First, the decontamination cleaning apparatus according to the present invention is suitable for cleaning a low-pressure water injection nozzle that cannot be cleaned by a conventional cleaning apparatus. The structure will be described with reference to FIGS.

  The nuclear power plant has an emergency core cooling system (ECCS) in preparation for an accident (LOCA: Loss of coolant accident) in which the reactor cooling system piping breaks and the reactor coolant is lost from the core. The emergency core cooling system is composed of a high pressure core spray system, an automatic decompression system, a low pressure core spray system, and a low pressure water injection system.

  As shown in FIGS. 1 and 2, the low-pressure water injection nozzle 1 has a water injection pipe 5 connected to the end of a nozzle body 3 welded to the trunk of the reactor pressure vessel 2 via a safe end 4. Inside the nozzle body 3, a cylindrical thermal sleeve 6 extending from the safe end 4 side is coaxially arranged via a narrow portion 7 having an appropriate width.

  The thermal sleeve 6 of the low-pressure water injection nozzle 1 is coupled to the upper part of the in-furnace shroud 9 via a bellows 8 as shown in FIGS. 2 (a) and 2 (b). The opposing flange of the thermal sleeve 6 and the flange of the bellows 8 are sandwiched and fixed by an upper half clamp 10 and a lower half clamp 11 as clamp joints.

  And the half clamps 10 and 11 which are connecting joints exist in the annular opening front surface of the narrow part 7 of the nozzle body 3, and the inner wall surface of the reactor pressure vessel (RPV) and the half clamps 10 and 11 A narrow structure in which the gap W1 is an opening of about 43 mm is formed.

  Further, as shown in FIG. 1, even in the single-piece shape of the thermal sleeve 6, since the tip portion inside the reactor is expanded in a tapered shape, the thermal sleeve 6 is also confirmed by visual confirmation with a reactor underwater camera. It is extremely difficult to confirm the position of the narrow portion 7 that is a gap between the nozzle body 3 and the nozzle body 3.

  On the other hand, the water injection device (cleaning device) having the horseshoe-shaped water injection header (cleaning nozzle) described above is a suitable decontamination device for the water supply nozzle and the core spray nozzle. Further, the horseshoe-shaped water jet header employs a structure in which a decontamination apparatus is fixed by being seated on a water supply sparger or a core spi pipe header.

  However, when the clamp joints 10 and 11 are interfering objects as in the low-pressure injection nozzle portion 1, it is impossible to bring the cleaning nozzle head (injection nozzle) close to the narrow portion 7, so that the dedicated low-pressure injection nozzle 1 is used. It was necessary to develop a cleaning device and cleaning system for thermal sleeves.

  In addition, it is possible to confirm the front of the annular narrow portion by removing the clamp joint (a pair of half clamps) in advance before starting cleaning and temporarily removing the bellows and the sleeve. However, if complicated processes such as the recovery / confirmation inspection work of the coupling after cleaning are taken into consideration, there is a problem that the influence on all processes in the periodic inspection is also increased. Accordingly, it has been desired to realize a cleaning device and a cleaning system that can safely and easily perform decontamination of the thermal sleeve without removing the bellows and the coupling.

Example 1
Example 1 of the high-pressure water supply part and the apparatus main body of the cleaning / decontamination apparatus for the reactor pressure vessel nozzle part according to this embodiment will be described with reference to FIGS.

  That is, the reactor pressure vessel nozzle part cleaning and decontamination apparatus 1 according to the present embodiment is a narrow part 7 between the nozzle body 3 provided in the reactor pressure vessel 2 and the thermal sleeve 6 provided concentrically. In the cleaning and decontamination apparatus for the reactor pressure vessel nozzle that performs water jet cleaning, an apparatus main body 30 that can be lifted up and down in the reactor pressure container, a high-pressure water header 31 provided at a lower portion of the apparatus main body 30, A plurality of injection nozzles 32 that are branched from the high-pressure water header 31 and inject high-pressure water toward the narrow portion 7; and two portable high-pressure pump units 21 and 21 that supply high-pressure water to the high-pressure water header 31; A high-pressure hose 22 for supplying high-pressure water from the portable high-pressure pump units 21 and 21 to the high-pressure water header 31, and the plurality of portable high-pressure pump units 21 and 21 are operated in parallel. It is configured to.

  Further, as shown in FIG. 3, two high-pressure pump units 21 and 21 which are supply sources of high-pressure washing water are connected in parallel, and high-pressure washing water is installed in the apparatus main body 30 shown in FIG. The high pressure water header 31 and the plurality of spray nozzles (cleaning nozzles) 32 are supplied. As shown in FIG. 3, a high-pressure water operation unit 23 for controlling the washing operation on the refueling machine is arranged on the high-pressure water supply route, and the high-pressure water operation unit 23 has a pressure on the high-pressure hose 22 route. A total 24, a handle operation type stop valve 25, and a foot operation foot valve 26 are arranged.

  A plurality of (two) portable high-pressure pump units 21 and 21 and a high-pressure hose 22 provided in the area indicated by arrows AA in FIG. 3 are vacant beside the reactor well pool on the top floor (operating floor) of the reactor building. It is installed in a space (not shown). On the other hand, on the fuel exchanger platform (not shown), an operation mechanism such as a foot valve (stepping valve) 26 for monitoring the pressure of the high-pressure water and turning on / off the high-pressure water injection is disposed as the high-pressure water operation unit 23. . The tip of the foot valve 26 on the secondary side (B-B arrow region) is sunk in the reactor pressure vessel, and the high-pressure water header provided in the apparatus main body 30 shown in FIG. 31 and the injection nozzle 32 are connected. The apparatus main body 30 is configured to be suspended to the low-pressure water injection system nozzle 1 to be cleaned in the reactor pressure vessel (reactor water).

  The cleaning technique employed in the reactor pressure vessel nozzle section cleaning and decontamination apparatus according to the above embodiment is a water jet method, in which high-pressure water is injected into the narrow portion 7 of the thermal sleeve 6 and high speed is introduced into the narrow portion 7. In this decontamination method, the clad accumulated and staying in the narrow portion 7 is washed away by generating a flow. The washed-out clad moves to the core side and is purified and removed with the operation of the reactor coolant purification equipment (CUW system).

  The cleaning force (impact force) by this water jet method is represented by the product of the jet flow rate and the fluid velocity (fluid pressure). Therefore, as described above, the cleaning power can be improved by increasing the flow rate and pressure of the injected high-pressure water. In the cleaning and decontamination apparatus shown in FIG. 3, all the devices used can be arranged on the same reactor building floor where the work is performed, and the line length for supplying high-pressure water, that is, the high-pressure hose from the high-pressure pump unit 21 to the injection nozzle 32 is used. What is necessary is just to prepare the total length of 22 as the minimum necessary length.

  The high-pressure water passing through the high-pressure hose 22 is subjected to various resistances such as pipe resistance, passage resistance such as gauges and valves, and therefore a pressure drop inevitably occurs. However, in this embodiment, since the pressure drop in the injection nozzle 32 is suppressed to the minimum by the minimum necessary high pressure hose length, the cleaning force (impact force) is also less reduced.

  For the required flow rate of high-pressure water, prepare a high-pressure pump with specifications that meet the design requirements. When using small portable electric high-pressure pump units 21 and 21 as in the present embodiment, the pump unit itself is limited to a small flow rate specification, and therefore, a plurality of discharge pressures and discharge flow rates having the same specification. The required flow rate is secured by parallel operation (simultaneous operation) of the high-pressure pump units. In the embodiment shown in FIG. 3, a configuration example in which two portable small high-pressure pump units are connected in parallel is shown, but in the experiment, up to four high-pressure pump units are connected in parallel using a merge header. Have a proven track record.

  Further, in the cleaning and decontamination apparatus for the reactor pressure vessel nozzle portion according to the present embodiment, the portion ahead from the foot valve 26 is immersed in the reactor water containing radioactivity, so that high pressure water is not injected. In some cases, the reactor water may flow back to the high-pressure pump units 21 and 21 that are non-polluting devices due to the siphon effect. The foot valve 26 is also useful as a countermeasure against this backflow, and functions as a boundary valve. Furthermore, by providing the stop valve 25, it is possible to reliably prevent the rise of the reactor water when the high-pressure washing water is not injected. A check valve can be adopted as an alternative device.

  According to the cleaning decontamination apparatus for the reactor pressure vessel nozzle portion according to the first embodiment shown in FIG. 3, the conventional high-pressure water jet nozzle (cleaning head) is seated on the inspection target nozzle, and the narrow portion of the thermal sleeve Even when compared with a decontamination apparatus that injects high-pressure water toward the target, the capacity and quantity of equipment to be clearly prepared can be greatly reduced or reduced.

  That is, according to the above conventional example, a high-flow pump car with a large flow rate is used as a supply source of high-pressure water. However, it is impossible to install and use a high-pressure pump car inside a reactor building, so it will be installed in a yard outside the building. In the yard work, the work of securing the cleaning water supply and the work of pulling the high-pressure water transfer line into the reactor building occur. When the high-pressure hose is drawn into the building, a building through-hole (spare sleeve) is required, and when the spare sleeve is present at a high place, it is essential to prepare a temporary scaffold, and the preparation work becomes complicated.

  Furthermore, when the high-pressure water transfer line is inserted into the building through-hole, a penetrating treatment for maintaining negative pressure in the reactor building is required. Even if the high-pressure water transfer line (high-pressure hose) is drawn into the building, it is necessary to construct a high-pressure water transfer line from the first floor to the top floor of the reactor building. The laying distance of the high-pressure hose is a complicated operation that easily exceeds 60 m from the high-pressure pump car installed in the yard to the top floor. Moreover, the pressure drop and the flow rate drop due to the flow path length are considerable values, and the cleaning power (impact power) inevitably decreases.

  However, according to the reactor pressure vessel nozzle cleaning and decontamination apparatus according to the present embodiment, a high-pressure pump vehicle with a large flow rate is not used as a supply source of high-pressure water, and the discharge pressure and the discharge flow rate are the same. Because the required flow rate is secured by arranging several small portable high-pressure pump units in the reactor building and operating them in parallel, the laying distance of the high-pressure hose is short, and the pressure drop and flow rate due to the channel length Since the decrease hardly occurs, the cleaning power (impact force) by the spray nozzle does not decrease. Therefore, efficient cleaning and decontamination work can be performed.

  In addition, the foot valve 26 provided with the cleaning / decontamination apparatus can also be used to prevent the backflow of the reactor water and to be turned on / off (open / close) during the cleaning operation. By this ON-OFF (opening / closing), high-pressure water can be intermittently jetted, and an improvement in cleaning efficiency due to the clad peeling effect due to the wave impact of this high-pressure water can also be expected.

(Example 2)
(Constitution)
A second embodiment of the present invention will be described with reference to FIGS.

  In addition, the cleaning decontamination apparatus for the reactor pressure vessel nozzle portion according to the second embodiment has a plurality of injection nozzles 32 in addition to the configuration of the cleaning decontamination apparatus according to the first embodiment having the high-pressure water supply system shown in FIG. 4 is smaller than the gap width W1 between the clamp joints 10 and 11 fixed to the thermal sleeve 6 and the inner wall surface 2a of the reactor pressure vessel 2, as shown in FIG. The tip of the high-pressure hose 22 and the high-pressure water header 31 are connected via a swivel joint 27 so that the high-pressure water header 31 can rotate with respect to the high-pressure hose 22, for example, in the horizontal direction of the shaft (pipe longitudinal axis (Only in the horizontal direction with respect to the horizontal direction).

  FIG. 4 is a diagram showing an external structure of the apparatus main body 30 of the cleaning / decontamination apparatus dedicated to the thermal sleeve of the low-pressure water injection nozzle 1. The high-pressure water for cleaning is supplied to the high-pressure water header 31 assembled to the apparatus main body 30 through the high-pressure hose 22 from the high-pressure water supply system shown in FIG. A plurality of injection nozzles 32 that are branched from the high-pressure water header 31 and inject high-pressure water toward the narrow portion 7 are connected to each other via high-pressure jet nozzle bodies 40. The plurality of injection nozzles 32 are moved up and down by using an operation pole 33 suspended from the fuel changer platform. As a measure for preventing the apparatus main body 30 from falling, a stainless steel suspension wire 38 is attached to the reinforcing rib 37 of the apparatus main body 30.

  The apparatus body 30 is formed by integrally joining a guide plate 34 on which a positioning cylinder 35 (air cylinder) described later is mounted, a guide rib 36 that holds the high-pressure water header 31, and a reinforcing rib 37 that reinforces the apparatus body 30. Is formed. The upper end of the reinforcing rib 37 is connected to the lower end of the operation pole 33 that suspends the apparatus main body 30.

  That is, the apparatus main body 30 is suspended at the lower end of the operation pole 33, while the upper end of the operation pole 33 is engaged with, for example, an auxiliary hoist of the fuel changer, so that a plurality of devices disposed in the apparatus main body 30 are provided. The spray nozzle 32 is configured to move up and down and right and left so as to face the gap position of the thermal sleeve to be cleaned.

  Further, the tip of the high-pressure hose 22 and the high-pressure water header 31 are connected via a swivel joint 27, and the high-pressure water header 31 is configured to be rotatable with respect to the high-pressure hose 22.

  The apparatus main body 30 is equipped with air cylinders 35 as two positioning cylinders for fixing the injection nozzle 32 for injecting high-pressure water at a predetermined position in the furnace. A pair of guide rods 39 for guiding the seating position on the upper portion of the thermal sleeve is provided at both ends of the high-pressure water header 31, and the outer peripheral portion of the thermal sleeve to be cleaned is sandwiched between the guide rods 39.

  A cushion 43 is attached to the tip of the drive shaft of the positioning cylinder (air cylinder) 35. When the apparatus main body 30 is placed at a predetermined position, the drive shaft of the positioning cylinder 35 extends and the cushion 43 is moved to the furnace. The main body 30 is pressed against and fixed to the inner wall of the reactor pressure vessel as a reaction of the abutting force against the outer peripheral wall of the upper ring 9 of the inner shroud.

  The lower end of the air tube 41 that supplies / discharges the driving fluid (air) that drives the positioning cylinder 35 is connected to the positioning cylinder 35 on the apparatus main body, while the upper end of the air tube 41 is on the fuel exchanger. It is connected to a cylinder operation unit 42 that is arranged and performs a supply / discharge operation of driving fluid (air), and is configured so that positioning and fixing of the injection nozzle provided in the apparatus main body can be performed by remote control.

  Further, a drain hole 44 is provided at the bottom of the guide plate 34 of the apparatus main body 30, and the weight of the apparatus main body 30 is reduced by extracting the cleaning water and the furnace water staying in the apparatus main body 30 from the drain hole 44. The operation pole 33 is configured to improve the operability of the apparatus main body 30 and to prevent the apparatus main body 30 from being contaminated with cleaning water.

  The apparatus main body 30 is provided with a high-pressure water header 31 that evenly distributes high-pressure water. The high-pressure water header 31 follows a characteristic of a conventional cleaning nozzle (head) and has a horseshoe shape, and a plurality of high-pressure jet nozzle bodies 40 are attached at equal intervals therefrom. Further, an injection nozzle (high-pressure jet nozzle) 32 that injects high-pressure water is attached to the tip of the high-pressure jet nozzle body 40. The injection nozzle 32 and the high-pressure jet nozzle body 40 are formed with a dimension width (φ30 mm or less) that can be inserted without difficulty into the gap (about 43 mm) between the inner wall of the reactor and the clamp joint (half clamp) of the low-pressure water injection nozzle. Has been. That is, the width of the plurality of injection nozzles including the high-pressure jet nozzle body 40 is formed to be smaller than the gap width between the clamp joint fixed to the thermal sleeve and the inner wall surface of the reactor pressure vessel.

  Next, mechanisms such as access to the low-pressure water injection nozzle 1 to be cleaned and cleaning position fixing will be described. By attaching a guide rod 39 formed in accordance with the external dimensions of the thermal sleeve of the low-pressure water injection nozzle 1, the injection nozzle 32 part can be comfortably placed in the narrow part between the inner wall of the reactor and the half clamp of the low-pressure water injection nozzle 1. It can be inserted and the pipe (thermal sleeve) center can be aligned. A positioning cylinder (air cylinder) 35 is mounted on a guide plate 34 that protrudes in a direction orthogonal to the guide rib 36, and is connected to a positioning cylinder operation unit 42 via an air tube 41. The positioning cylinder operating unit 42 disposed on the refueling machine platform is operated to control the expansion and contraction of the drive shaft piston of the positioning cylinder 35. The guide plate 34 is provided with a drain hole 44 for discharging the reactor water and cleaning water staying in the apparatus main body 30 in consideration of the operability of the vertical movement of the apparatus main body 30.

  In addition, the gap (narrow part) between the low pressure injection nozzle body and the thermal sleeve may be eccentric in the center and the gap opening may be uneven. In this case, even if the cleaning nozzle body is seated in a certain direction and high-pressure water is sprayed, there is a possibility that the spray water cannot be injected deeply into the thermal sleeve narrow part and high-speed flow may not be generated in this part. May decrease.

  In order to avoid this problem, the joint connecting the high-pressure hose 22 and the high-pressure jet nozzle body 40 (cleaning nozzle body) is a swivel joint 27, and the high-pressure water header 31 can be easily moved to the left and right by about 45 ° while checking the cleaning effect. The tilt can be changed and adjusted.

  In order to efficiently inject high-pressure water into the gap between the thermal sleeves, the angle of the high-pressure jet nozzle body 40 and the tip injection nozzle (high-pressure jet nozzle) 32 that injects high-pressure water are also mutually adjusted. A mechanism capable of performing the above is similarly provided. This angle adjustment mechanism makes it possible to finely adjust the injection angle of high-pressure water on site.

  A state (action) of performing the cleaning operation of the low-pressure water injection nozzle using the cleaning / decontamination apparatus for the reactor pressure vessel nozzle portion according to the second embodiment will be described with reference to FIG.

  First, parts constituting the cleaning and decontamination apparatus are carried onto the operation floor of the reactor building, and a high-pressure water supply unit and an apparatus main body including an injection nozzle are assembled as shown in FIGS. It is important to adjust the mounting angle between the high-pressure jet nozzle body 40 and the injection nozzle 32 provided in the high-pressure water header 31 shown in FIG. 4 in advance. Next, the apparatus main body 30 including the injection nozzle 32 is suspended using an auxiliary hoist attached to the fuel changer. The apparatus main body 30 is separately hung by a stainless steel hanging wire 38 to prevent the apparatus main body 30 from falling.

  The operation of the apparatus main body 30 including the injection nozzle 32 is performed using the operation pole 33 from the fuel exchanger platform. Next, as shown in FIG. 5, the apparatus main body 30 is brought close to the low-pressure water injection nozzle 1 to be cleaned and is seated on the nozzle thermal sleeve 6. The apparatus main body 30 including the high-pressure water header 31, the high-pressure jet nozzle body 40, and the injection nozzle 32 is formed to have a dimension that allows passage between the head bolt bracket 19 of the core shroud 9 and the inner wall surface 2a. ing. Therefore, interference with the in-furnace equipment during the movement of the apparatus main body 30 is avoided, and the soundness of the in-furnace structure is ensured.

  When performing the cleaning operation in the furnace, the operation of each part of the cleaning and decontamination apparatus is performed while observing the monitor of the in-furnace underwater camera, and the injection nozzle 32 is seated on the thermal sleeve 6 to be cleaned without any problem. Make sure.

  Thereafter, the positioning cylinder operating unit 42 is operated to push (extend) the drive shaft piston of the positioning cylinder 35 toward the wall surface of the shroud upper ring 9, thereby bringing the apparatus main body 30 including the injection nozzle 32 into the furnace inner wall surface 2 a. Crimp to the side and fix.

  After the fixing of the apparatus main body 30 including the injection nozzle 32 is completed, the high pressure pump units 21 and 21 (FIG. 3) connected in parallel are started together, and the high pressure water reaches the stop valve 25 with the pressure gauge 24. Check that it is supplied.

In the shutoff operation of the high-pressure pump, the safety mechanism in the high-pressure pump units 21 and 21 is operated, and the auto valve in the unit is operated to enter an operation mode in which high-pressure water circulates in the unit. Nozzle side pressure is suppressed. Therefore, although numerical pressure gauge 24 after a few seconds down from 190 kg / cm ² to about 50 kg / cm ^2, aware that it is not a bug.

  Next, the stop valve 25 is opened, and the foot valve 26 is stepped on to inject high-pressure water toward the gap of the narrow portion 7 of the thermal sleeve. In the containment vessel dry well (D / W (outside the furnace)), the dose equivalent rate of the outer surface of the low-pressure water injection nozzle 1 to be cleaned is measured, and the cleaning decontamination is performed when the dose equivalent rate decreases and reaches a certain value. End of work.

  When the dose equivalent rate on the outer surface of the low-pressure water injection nozzle 1 to be cleaned varies in the circumferential direction, the positioning cylinder operating unit 21 is operated to retract (contract) the drive shaft piston of the positioning cylinder 35 The main body 30 is arbitrarily rotated by the operation pole 33 (inclination can be changed up to 45 ° left and right), and the starting operation of the high-pressure pump units 21 and 21 from the fixing operation of the main body 30 in the same procedure. Then, through the foot valve operation and the high-pressure water injection operation, check the reduction of the nozzle outer surface dose again.

  According to the cleaning / decontamination apparatus for the reactor pressure vessel nozzle portion according to the second embodiment, the conventional high-pressure water jet nozzle (cleaning head) is seated on the inspection target nozzle and directed toward the narrow portion of the thermal sleeve. Even when compared with a decontamination apparatus that injects high-pressure water, the capacity and quantity of equipment that is clearly prepared can be greatly reduced or reduced.

  That is, in the conventional decontamination apparatus, the laying length of the high-pressure hose for supplying and transferring high-pressure water exceeded 100 m from the high-pressure pump to the site to be cleaned. Met. In the high-pressure hose to be used, it is preferable that the upper limit of the flow rate of the high-pressure water is usually about 10 m / sec in consideration of hose wear. Although depending on the diameter of the high-pressure hose used, the pressure loss increases in proportion to the hose length. Therefore, according to this embodiment, the cleaning force (impact force) is less reduced than the conventional example, and the efficiency is low. Cleaning decontamination can be carried out.

In addition, regarding the injection flow rate of high-pressure water, the above-described conventional example requires reverse injection (reaction power) of the same force as the cleaning power to stabilize the cleaning head at the front end. The discharge amount used for the cleaning is 1/2, which is 95 L / min. On the other hand, the apparatus of this embodiment does not require the injection of high-pressure water to generate reverse injection (reaction power), and operates two general-purpose high-pressure pump units 21 with a maximum of 50 L / min in parallel. Therefore, the discharge capacity specification is about 100 L / min in total, and the cleaning ability equivalent to or higher than the specification of the conventional high-pressure pump vehicle can be exhibited with a simple configuration.
In addition, the reaction power (cleaning power) F by the nozzle injection (one-side injection) in the present embodiment can be expressed by the following equation (2).
F = γQ / g · ν [kgf] ν = √ (20 · g · P) (2)
Here, Q is the injection flow rate m ³ / s, γ is the liquid specific weight kg / m ³ , g is the acceleration m / s ² , and P is the pressure kgf / cm ² .

Based on the above formula, when the reaction power is obtained from the equipment specification conditions of the apparatus of this embodiment, it is about 33 kgf. The pressing force of the positioning cylinder 35 against this reaction force is about 68 kgf if the cylinder diameter is φ25 mm × 2 units and the drive air pressure is 7 kgf / cm ² . There is sufficient ability to press the injection nozzle 32 against the furnace inner wall surface 2a, and the injection position does not fluctuate due to the reaction force of the high-pressure injection water, and a stable cleaning effect and a safe working state can be ensured.

  DESCRIPTION OF SYMBOLS 1 ... Low pressure injection system nozzle, 2 ... Reactor pressure vessel, 2a ... Reactor inner wall surface, 3 ... Nozzle body, 4 ... Safe end, 5 ... Injection pipe, 6 ... Thermal sleeve, 7 ... Narrow part, 8 ... Bellows, 9 ... shroud upper ring (upper furnace shroud), 10 ... upper half clamp (clamp joint), 11 ... lower half clamp (clamp joint), 21 ... (portable) high pressure pump unit, 22 ... high pressure hose, 23 ... high pressure water Operation unit, 24 ... Pressure gauge, 25 ... Stop valve, 26 ... Foot valve (foot valve), 27 ... Swivel joint, 30 ... Main unit, 31 ... High pressure water header (header pipe), 32 ... Injection nozzle (high pressure water direct injection) Nozzle, high-pressure jet nozzle), 33 ... operation pole, 34 ... guide plate, 35 ... positioning cylinder (air cylinder), 36 ... guide rib, 37 ... Strong ribs, 38 ... stainless steel hanging wire 39 ... guide rod, 40 ... pressure jet nozzle body, 41 ... air tube, 42 ... positioning cylinder operating unit, 43 ... cushion, 44 ... drain hole, 45 ... head bolt bracket.

Claims (8)

In the reactor decontamination device for the reactor pressure vessel nozzle that performs water jet cleaning of the narrow part between the nozzle body provided in the reactor pressure vessel and the thermal sleeve provided concentrically, the reactor pressure vessel is moved up and down. a suspension is the apparatus body freely, and high-pressure water header provided at a lower portion of the apparatus main body, a plurality of injection nozzles for injecting high pressure water toward the narrow portion is branched from the high-pressure water header, the high-pressure water header A plurality of high-pressure pump units for supplying high-pressure water to the high-pressure hose for supplying high-pressure water from the high-pressure pump unit to the high-pressure water header, and the narrow portion depth direction of the injection nozzle attached to the high-pressure water header and a angle adjusting mechanism for the mounting angle to allow adjustment of the reactor pressure vessel nozzle high-pressure pump unit, characterized in that it is parallel operation of the plurality groups Cleaning decontamination apparatus. 2. The reactor pressure vessel nozzle part according to claim 1, wherein a width of each of the plurality of injection nozzles is smaller than a gap width between a clamp joint fixed to the thermal sleeve and an inner wall surface of the reactor pressure vessel. Cleaning decontamination equipment. The reactor pressure according to claim 1 or 2, wherein a foot valve is disposed on a discharge side of the plurality of high-pressure pump units, and high-pressure water is intermittently injected by opening and closing the foot valve. Cleaning and decontamination equipment for container nozzle. The tip of the high-pressure hose and a high-pressure water header are connected via a swivel joint, and the high-pressure water header is configured to be rotatable with respect to the high-pressure hose. The apparatus for cleaning and decontaminating a reactor pressure vessel nozzle part according to any one of the preceding claims. While the apparatus main body is suspended at the lower end of the operation pole, the upper end of the operation pole is locked to the auxiliary hoist of the fuel exchanger, so that a plurality of injection nozzles arranged in the apparatus main body are to be cleaned. The apparatus for cleaning and decontaminating a reactor pressure vessel nozzle part according to any one of claims 1 to 4, wherein the apparatus is configured to move up and down and left and right so as to face the gap position. The apparatus main body is equipped with a positioning cylinder for fixing the injection nozzle for injecting high-pressure water at a predetermined position, and a pair of guide rods for guiding the apparatus main body to the seating position on the upper portion of the thermal sleeve to be cleaned is high-pressure. The apparatus for cleaning and decontaminating a reactor pressure vessel nozzle according to any one of claims 1 to 5, wherein the apparatus is provided at both ends of the water header. The operation unit for supplying / discharging the driving fluid for driving the positioning cylinder is arranged on the fuel changer so that the injection nozzle arranged in the apparatus main body can be positioned and fixed remotely. The apparatus for cleaning and decontaminating a reactor pressure vessel nozzle according to claim 6. A drain hole is provided at the bottom of the apparatus body, and the washing water and the reactor water staying in the apparatus body are extracted from the drain hole, thereby reducing the weight of the apparatus body and improving the operability of the apparatus body by the operation pole. In addition, the apparatus for cleaning and decontaminating a reactor pressure vessel nozzle unit according to any one of claims 1 to 7, wherein the apparatus main body is configured to prevent contamination with cleaning water.

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