WO2007091559A1 - 化学除染装置およびその除染方法 - Google Patents
化学除染装置およびその除染方法 Download PDFInfo
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- WO2007091559A1 WO2007091559A1 PCT/JP2007/052028 JP2007052028W WO2007091559A1 WO 2007091559 A1 WO2007091559 A1 WO 2007091559A1 JP 2007052028 W JP2007052028 W JP 2007052028W WO 2007091559 A1 WO2007091559 A1 WO 2007091559A1
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- ozone
- reactor
- water
- decontamination
- pressure vessel
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Classifications
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/28—Treating solids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
- B08B3/04—Cleaning involving contact with liquid
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
- G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
- G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
- G21F9/004—Decontamination of the surface of objects with chemical or electrochemical processes of metallic surfaces
Definitions
- the present invention relates to chemical decontamination technology using ozone, and in particular, for example, on the surface of a decontamination object such as a reactor constituent material in a primary reactor system such as nuclear reactor equipment or piping.
- the present invention relates to a chemical decontamination apparatus for chemically dissolving and decontaminating an attached or generated oxide film and a decontamination method thereof.
- Patent Document 1 Japanese Patent Application Laid-Open No. 2000-814908 discloses a technique for chemical decontamination by controlling the pH of ozone water to 5 or lower and increasing the dissolved ozone concentration.
- Kokai 2002-250794 added at least one oxidation aid selected from carbonic acid, carbonate, boric acid, borate, sulfuric acid, sulfate, phosphoric acid and phosphate to ozone water, A chemical decontamination technique that suppresses corrosion of the material is disclosed.
- Patent Document 3 Japanese Patent Laid-Open No. 2002-228796 discloses a chemical decontamination technique using ozone that supplies ozone gas by a multi-tube hollow fiber membrane mixer and efficiently dissolves ozone gas in water. It is written.
- Patent Document 1 adds nitric acid to water to generate ozone water having a pH of 5 or lower, and performs an oxidation treatment in this aqueous pH solution to dissolve the oxide film. Chemical decontamination is performed.
- the acid additive added to water is nitric acid, there is a problem that the corrosion of the reactor components by ozone water, which is weak in the acidity of the aqueous ozone solution, cannot be suppressed.
- Patent Document 2 describes a technique in which phosphoric acid is added as an oxidation aid in order to suppress corrosion of the reactor constituent material.
- phosphoric acid is close to a weak acid, even if phosphoric acid is added as an oxidation aid, corrosion of reactor components having weak oxidizing power cannot be effectively and effectively suppressed. It is necessary to add a large amount of phosphoric acid in order to have a large oxidizing power. As a result, secondary waste after decontamination As a result, a large amount of wastewater is generated, and a new problem arises that requires a large amount of labor and cost for the treatment of this secondary waste.
- nuclear reactor equipment and various pipes are made of steel materials such as stainless steel and carbon steel.
- Reactor equipment and the inner surface of piping are corroded by contact with high-temperature water, and an oxide film is formed. Radioactivity in the reactor water is taken into the reactor film exposed to the high-temperature water and the oxide film formed on the wetted part of the inner surface of the pipe, which becomes the radiation source.
- the oxide film formed on the wetted parts on the inner surface of the nuclear reactor equipment and various pipes is chemically dissolved and removed by a chemical decontamination technique.
- This chemical decontamination method is a radioactivity removal technology that chemically dissolves the oxide film. If the shape of the object to be decontaminated is complex, it is difficult to remove and chemical decontamination of parts that are used again after decontamination In recent years, a number of technologies that apply chemical decontamination have been reported.
- the decontamination effect is enhanced by combining a decontamination agent that dissolves ferric oxide and an oxidizing agent that dissolves chromate.
- a decontamination agent that dissolves ferric oxide
- an oxidizing agent that dissolves chromate.
- the oxidizing agent permanganic acid, potassium permanganate solution, ozone water or the like is used. In the case of ozone water, the self-degradability of ozone is so strong that it must be supplied constantly.
- Patent Document 7 Japanese Patent Application Laid-Open No. 2001-91692 discloses a technique that uses an ion exchange resin for a chemical cleaning apparatus for a nuclear reactor structure that removes radioactive contamination of the nuclear reactor structure. ing.
- decontamination water In nuclear power plants, water circulating through decontamination objects such as reactor equipment and various pipes is high-temperature water, and the decontamination temperature is usually 70 ° C or higher. Since decontamination water is a gas-liquid mixture of water and ozone, ozone injection into the upstream side of the reactor recirculation pump pump is pumped by the injected ozone into the pump part of the recirculation pump. There is a risk of pump damage.
- the upper flange force is more than a few meters, for example, about 6m, down to the elastic part (down force part) of the gap between the shroud where the reactor downflow occurs and the reactor pressure vessel.
- An ozone injection jig that can withstand 1600m 3 Zh furnace flow and gas injection is required.
- the inventors of the present invention have been able to obtain sufficient decontamination performance when the pH of ozone water is 3 or less in the chemical decontamination technology using ozone, while decontamination performance is obtained when the pH exceeds 3. From the repeated tests of chemical decontamination technology, it was newly found that the remarkably decreased.
- An object of the present invention is to provide a chemical decontamination apparatus and its decontamination method using ozone which has improved decontamination performance and improved performance while maintaining the soundness of the object.
- Another object of the present invention is to reduce the corrosion of the decontamination target by optimizing the corrosion control additive of the decontamination target such as the reactor constituent material, etc., with ozone water satisfying the condition of pH 3 or less. It is an object of the present invention to provide a chemical decontamination apparatus and a decontamination method that can efficiently and efficiently improve the effect of decontamination cleaning.
- Still another object of the present invention is to provide an ozone diffuser tube that can stably supply ozone gas to obtain ozone water having an appropriate ozone concentration, increase decontamination efficiency, and withstand flow in the furnace.
- In-furnace chemical decontamination equipment that has been installed stably above, obtained an appropriate ozone concentration by ozone gas that is continuously and stably injected, and improved decontamination efficiency by the location of the ozone diffuser and its To provide a decontamination method.
- the chemical decontamination apparatus according to the present invention provided to solve the above-described problems is obtained by using ozone water to form an acid film containing a radioactive substance generated or attached to the surface of an object to be decontaminated.
- a chemical decontamination device that chemically dissolves and decontaminates,
- Ozone generating means for generating ozone gas
- An ozone supply means for supplying the generated ozone gas to the ozone supply section in water, and a sintered metal element that is installed in the ozone supply section and receives the supply of ozone gas.
- Ozone supply means force Ozone gas supplied to the inside of the sintered metal element is made to flow outside the element and supplied into water to generate ozone water.
- a chemical decontamination apparatus provided to solve the above-described problem is provided with a core shroud in a reactor pressure vessel, and formed between the core shroud and the reactor pressure vessel.
- a jet pump is provided in the down force portion to be provided, a reactor recirculation system for recirculating the water in the reactor pressure vessel is provided, and the reactor pressure vessel is driven by driving a recirculation pump of the reactor recirculation system.
- a chemical decontamination device that applies flow to the water in the reactor to decontaminate the reactor pressure vessel or the reactor primary system.
- Ozone generating means for generating ozone gas
- Ozone supply means for supplying the generated ozone gas to the ozone supply section in the vicinity of the jet pump inlet or in the recirculation pipe of the reactor recirculation system;
- the ozone gas supplied into the sintered metal element by the ozone supply means flows outside the element and is supplied into water to generate ozone water.
- the chemical decontamination method according to the present invention provided to solve the above-described problem is a method in which an acid film containing a radioactive substance generated or attached to the surface of an object to be decontaminated is treated with ozone water.
- the ozone water as a decontamination solution when chemically dissolving and decontaminating, the ozone water film of the decontamination target is chemically dissolved and decontaminated using this ozone water.
- ozone water is dissolved in water to generate ozone water.
- a chemical decontamination method according to the present invention provided to solve the above-described problem is provided in a down force portion between a reactor pressure vessel and a core shroud installed therein.
- a jet pump that forcibly circulates water is provided. Reactor water from the jet pump is recirculated by driving the recirculation pump of the reactor recirculation system to impart flow to the ozone water, so that A chemical decontamination method for chemically decontaminating a furnace primary system with ozone,
- Ozone water is generated by supplying the ozone gas to water to which the acid support agent and pH adjuster are added.
- a chemical decontamination apparatus provided to solve the above-described problem is a reactor primary system decontamination object, an organic acid as a reducing agent, and ozone water as an oxidizing agent.
- a decontamination liquid supply means for supplying a decontamination liquid into the nuclear reactor of the primary reactor, Ozone supply means for injecting ozone gas into the reactor of the primary reactor, ozone water generating means for generating ozone water with the injected ozone gas,
- Ozone water circulation means for circulating the generated ozone water into the primary system of the reactor, wherein the ozone supply means is provided with an ozone diffuser pipe for aeration of ozone gas on the suction side of the ozone water generation means.
- the chemical decontamination method according to the present invention provided to solve the above-described problems uses a primary reactor decontamination object using a reducing agent using organic acid and ozone water.
- the reactor recirculation system is pumped to generate a flow of circulating water in the reactor recirculation system and reactor,
- Ozone diffuser installed in the upper part of the reactor internals, injecting ozone gas, supplying the injected ozone gas to the circulating water to generate ozone water of dissolved ozone, and using decontamination liquid supply means A decontamination solution supplied in the reactor and ozone water of dissolved ozone are combined to chemically decontaminate the decontamination target of the reactor primary system.
- the decontamination performance is achieved by dissolving the acid film while maintaining the soundness of the object to be decontaminated. Can be improved.
- the chemical decontamination apparatus and the decontamination method thereof according to the present invention in another preferred embodiment of the present invention described above satisfy the condition that ozone water has a pH of 3 or less, and It is possible to optimize the corrosion inhibitor additive, efficiently and efficiently suppress the corrosion of the object to be decontaminated, and increase the effect of decontamination cleaning.
- ozone gas is stably and continuously supplied into the nuclear reactor. Then, ozone water with a predetermined concentration is efficiently generated by the supplied ozone gas, and this ozone water is circulated in the reactor pressure vessel and the reactor primary system to efficiently contaminate the reactor primary system contamination target. Chemical decontamination can be performed stably and the decontamination efficiency can be improved.
- FIG. 1 An oxide film of the chemical decontamination method using ozone according to the first embodiment of the present invention. The figure which shows the relationship between the amount of dissolution and pH.
- FIG. 2 is a diagram showing the amount of secondary waste generated by the chemical decontamination method using ozone according to the first embodiment of the present invention.
- FIG. 3 is a system diagram showing a chemical decontamination apparatus as a second embodiment according to the present invention.
- FIG. 4 is a schematic view of an ozone dissolution mixer applied to the chemical decontamination apparatus of FIG.
- FIG. 5 is a distribution diagram of dissolved ozone concentration of the chemical decontamination method using ozone applied to the chemical decontamination apparatus according to the present invention.
- FIG. 6 is a graph showing the relationship between pH and dissolved ozone self-decomposition constant in the chemical decontamination method using ozone applied to the chemical decontamination apparatus according to the present invention.
- FIG. 7 shows a chemical decontamination apparatus as a third embodiment according to the present invention, and is a schematic view for decontamination inside a reactor pressure vessel of a BWR.
- FIG. 8 is a configuration diagram showing a fourth embodiment of an in-furnace chemical decontamination apparatus according to the present invention.
- FIG. 9 is a configuration diagram showing a fifth embodiment of the in-furnace chemical decontamination apparatus according to the present invention.
- FIG. 10 Graph of dissolved ozone concentration measured at various locations in the reactor.
- FIGS. 11A and 11B are diagrams each simply showing the measurement locations in the reactor where ozone concentration is measured.
- FIG. 12 is a configuration diagram showing a sixth embodiment of the in-furnace chemical decontamination apparatus according to the present invention.
- FIG. 13 is a block diagram showing a seventh embodiment of the in-furnace chemical decontamination apparatus according to the present invention.
- FIG. 14 is a configuration diagram showing an eighth embodiment of an in-furnace chemical decontamination device according to the present invention.
- FIG. 15 is a configuration diagram showing a ninth embodiment of an in-furnace chemical decontamination device according to the present invention.
- b Nozzle suction ozone concentration
- c Nozzle suction ozone concentration
- d Nozzle suction ozone concentration
- e Nozzle suction ozone concentration
- f Nozure suction ozone concentration
- g Reactor recirculation system outlet Nozzle part ozone concentration
- h pump discharge ozone concentration
- i pump discharge ozone concentration
- j pump discharge ozone concentration
- k pump discharge ozone concentration
- 1 pump discharge ozone concentration.
- the chemical decontamination apparatus of the present invention uses an ozone water having a pH of 3 or lower to decontaminate an object such as a raw material. Efficiently decomposes and chemically decontaminates the oxide film containing radioactive substances attached to the surface of the reactor core material, improving the decontamination performance while maintaining the soundness of the reactor core material .
- the chemical decontamination method according to the first embodiment of the present invention is suitable, for example, for decontamination of reactor constituent materials and corrosion inhibition.
- a nickel-based alloy such as Inconel
- Inconel a nickel-based alloy
- the size of Inconel 182 test piece is 30 X 10 X 2mm 3
- the immersion condition of this test piece is the dissolved ozone concentration of ozone water 3ppm, temperature 80 ° C, soaking time 1 Oh.
- Test parameters are:
- the Inconel test piece was observed on the surface of the test piece before and after immersion in ozone water, and visually and using an optical microscope.
- Table 1 shows the ozone water immersion test results of Inconel 182 specimens.
- ozone water to which phosphoric acid, for example, is added as an oxidizing aid and nitric acid, for example, is added as a pH adjusting agent can suppress corrosion of the nickel-based alloy due to the corrosion preventing effect of phosphoric acid.
- the corrosion-inhibiting effect of the nickel-based alloy can ensure and maintain the soundness of reactor components, for example, the material in the reactor pressure vessel of nuclear power plants and after decontamination of the primary reactor system.
- the acid-reduction potential as an index of the acidity of ozone water is large in acidity and small in alkalinity.
- the oxide film was made from SUS304 specimens in boiling water reactor (BWR) —water under high temperature and high pressure (288 ° C, 8.3 MPa, oxygen concentration 200 ppb) simulating the water quality conditions of the secondary cooling system for 3000 hours. It was produced by soaking.
- the dissolution test procedure for the acid film is to immerse a stainless steel with an oxide film, such as SUS304, in ozone water at 80 ° C for 2 hours, and then add it to 95 ° C, 20 OOppm oxalic acid aqueous solution. It was immersed for 2 hours and the weight reduction of the SUS specimen was measured.
- the treatment conditions of the ozone water were carried out in the range of pH 3 to pH 5 (adjusted by the addition amount of phosphoric acid and nitric acid) with the dissolved ozone concentration fixed at 3 ppm.
- Fig. 1 shows the results of the dissolution test of the oxide film of the SUS304 test piece.
- the dissolved amount of the oxide film increased as the pH of the ozone water decreased.
- the pH of the ozone water was 3 or less, a tendency to become almost constant was observed.
- the dissolved amount of the oxide film of ozone water pH3 was approximately 5 times the dissolved amount of ozone water pH5.
- the ozone water has an acidity of pH 3 or less.
- the condition that the ozone water has a pH of 3 is phosphoric acid 2 as an oxidizing aid.
- phosphoric acid is an acid close to a weak acid, so about 50 times the basic concentration (20ppm), for example, about lOOOppm is added. There is a need to.
- Phosphoric acid and nitric acid in water indicate the amount of anion-exchanged resin produced in comparison with Example A. As can be seen from FIG. 2, in this embodiment, the amount of anion-exchanged resin generated can be reduced to 1Z25 of Conventional Example B.
- FIG. 3 is a schematic view showing a chemical decontamination apparatus as a second embodiment according to the present invention.
- FIG. 3 shows a dissolved ozone concentration confirmation test apparatus simulating a BWR to which the chemical decontamination apparatus according to the present invention is applied.
- This dissolved ozone concentration confirmation test apparatus 10 has a cylindrical tank 11 simulating a reactor pressure vessel.
- the tank 11 has a substantially cylindrical shape for controlling the flow of water in the tank.
- This internal structure 12 simulates a core shroud.
- the tank capacity of the cylindrical tank 11 is, for example, 3.5 m 3 . In this case, the cylindrical tank 11 and the internal structure 12 correspond to the decontamination target.
- sampling nozzles 13a to 13f are attached to the inner peripheral wall surface of the cylindrical tank 11 at a plurality of positions, for example, six positions in order to measure the concentration of dissolved ozone water in the tank 11.
- the water in the cylindrical tank 11 is circulated through the A and B circulation systems 15A and 15B.
- the system B circulation system 15B is configured in the same manner as the system A circulation system 15A, and the water flowing through the system B circulation system 15B is supplied by the system B circulation pump 21 to the system B lower suction pipe 22 and the system B upper suction pipe. 23 is sucked in and discharged from the B system discharge pipe 24 into the cylindrical tank 11.
- a porous sintered metal element 27 is installed at the bottom of the cylindrical tank 11, and ozone gas (O 2) generated from the ozone generator 28 is eleme- rated into the sintered metal element 27.
- a gas supply pipe 29 is connected to the interior of the cylinder.
- an A system ozone dissolution mixer 31 and a B system ozone bed mixer 32 are installed in the A system discharge pipe 19 and the B system discharge pipe 24 of the A system and B system circulation systems 15A and 15B.
- the A system ozone dissolution mixer 31 has an A system gas supply pipe 33 for supplying ozone gas generated from the ozone generator 28, and the B system ozone dissolution mixer 32 has a B system gas supply pipe 3 4 in the same manner. , Each connected.
- the ozone melting mixers 31, 32 have the same configuration and function in the A system and the B system, the A system ozone melting mixer 31 will be described as an example.
- FIG. 4 shows the configuration of the A-system ozone melting mixer 31.
- the A-system ozone melting mixer 31 includes a substantially T-shaped tubular holder 36 installed in a part of the A-system discharge pipe 19 and a porous sintered metal element 37 accommodated in the holder 36.
- the holder 36 is connected to the A system discharge pipe 19 by outer peripheral flanges 38a and 38b which are pipe connecting flanges.
- the sintered metal element 27 and the sintered metal element 37 of the A-system ozone melting mixer 31 that are grounded to the bottom of the cylindrical tank 11 are sealed, and the other is sealed with the gas supply pipe 29 and the A-system.
- ozone gas is supplied into the element.
- the sintered metal element of the B system ozone melting mixer 32 is the same as the sintered metal element 37 of the A system.
- the central opening of the T-shaped tubular holder 36 is covered with a lid-shaped flange cover 39.
- the A-system gas supply pipe 33 is fixed by a lid-shaped flange cover 39 at the top of the holder 36.
- the sintered metal elements 27 and 37 are known to be made of stainless steel or bronze. In the embodiment shown in FIG. 4, stainless steel, for example, SUS316L is used in consideration of chemical resistance.
- the pore diameter formed in the sintered metal elements 27 and 37 is a minimum ⁇ ⁇ force, for example 63 m, and the maximum ⁇ max is, for example, 850 m.
- a test for dissolving ozone gas in water in the cylindrical tank 11 was performed using the dissolved ozone concentration confirmation test apparatus 10 shown in FIG. 3 and FIG.
- the conditions of the water in the cylindrical tank 11 are as follows: the liquid volume is 3.5 m 3 , the temperature is 80 ° C, for example, 20 ppm phosphoric acid as an oxidizing aid and 40 ppm nitric acid as a pH adjuster, The pH of the ozone water was adjusted to 3.
- the water flow conditions for the A and B lines are, for example, 80 m 3 Zh for a total of 160 m.
- the supply condition of ozone gas is that gas phase ozone concentration is, for example, 120 gZm 3 , ozone gas supply
- the amount of A line and B line is 45gZh, for example, for a total of 90gZh.
- FIG. 5 shows the measurement results of the dissolved ozone concentration when the water conditions, flow conditions, and ozone gas supply conditions in the cylindrical tank 11 are set as described above.
- the horizontal axis shown in FIG. 5 represents the sampling device (sampling nozzles 13a to 13a shown in FIG.
- the vertical axis indicates the dissolved ozone concentration in water.
- ⁇ indicates that ozone gas is supplied from the A system and B system ozone melting mixers 31, 32, and ⁇ indicates that ozone gas is supplied from the sintered metal element 27 installed at the bottom of the cylindrical tank 11.
- the dissolved ozone concentration when (O) is supplied is shown.
- the dissolved ozone concentration changed in the range of 0.6 to 0.8 ppm, as indicated by the ⁇ mark.
- ozone gas is supplied to the water flowing in a narrow space like the A system and B system discharge pipes 19, 24, so that the water and ozone gas are almost completely mixed. It turns out to be effective.
- a porous sintered metal element 37 having a high mechanical strength and a high pressure resistance is applied to the A-system and B-system ozone melting mixers 31 and 32.
- the sintered metal element 37 one having a small pore diameter is preferably used.
- Sintered metal element 37 is a force commonly used for water filtration, liquid foaming and agitation, as shown in FIG. As shown in the solution test results, it can be used as a mixer that dissolves ozone gas in water efficiently and efficiently.
- dissolved ozone in water is relatively stable in acidic solutions.
- dissolved ozone decomposes rapidly as the acidity in water decreases, and as the pH and temperature increase.
- the degree of ozone self-decomposition is reported to be in the range of 1.0 to 2.0 (dimensionless).
- the temperature condition of the acquired data is almost 60 ° C or less.
- the dissolved ozone concentration confirmation test apparatus shown in Figs. 3 and 4 was used to measure the self-decomposition rate order of dissolved ozone at 80 ° C, which is the decontamination condition of ozone water. did.
- Fig. 6 shows the measurement results of the self-decomposition rate constant of dissolved ozone.
- Figure 6 shows that the self-decomposition reaction of ozone follows the linear equation, and shows the pH dependence of the self-decomposition rate constant.
- the self-decomposition rate constant of dissolved ozone tends to increase linearly with increasing pH (recognized).
- the decomposition rate constant of pH 3 ozone water adjusted with phosphoric acid and nitric acid was found to be about 1 ⁇ 2 of ⁇ 3.5 ozone water adjusted with phosphoric acid alone, and about 1Z 10 of ⁇ 4 adjusted with phosphoric acid alone.
- phosphoric acid or phosphate for example, is added to ozone water as an oxidizing aid, and nitric acid, for example, is added as a pH adjuster, and sintered metal installed in the vertical and vertical discharge pipes 19, 24.
- Ozone gas is supplied from the genus element 37 into the water flowing through the pipe, and this ozone gas supply can suppress the efficient dissolution of ozone and the self-decomposition of dissolved ozone. A large chemical decontamination effect can be obtained.
- FIG. 7 is a schematic view showing a chemical decontamination apparatus as a third embodiment according to the present invention.
- This embodiment shows a chemical decontamination apparatus 51 that decontaminates a reactor pressure vessel 50 of a boiling water reactor (BWR) with ozone.
- BWR boiling water reactor
- a reactor core 53 is formed in the reactor pressure vessel 50, and a large number of fuel assemblies are supported by the core support plate 54 and the upper lattice plate 55 formed in the reactor core 53. Further, control rods (not shown) are put in and out of the reactor core 53 by the control rod drive mechanism 56.
- Fig. 7 shows the state where the fuel assemblies and control rods, steam separators, steam dryers and other in-furnace equipment are removed.
- the reactor core 53 is surrounded by a core shroud 57, and a jet pump 59 is provided in a down force portion 58 that is an annular space between the core shroud 57 and the reactor pressure vessel 50.
- a plurality of jet pumps 59 are provided at intervals in the circumferential direction of the down force force portion 58.
- two reactor recirculation systems 60 are provided below the reactor pressure vessel 50, and a recirculation pump 62 is provided in each of the recirculation system pipes 61 of the reactor recirculation system 60. It is provided.
- the reactor water in the reactor pressure vessel 50 is returned to the reactor pressure vessel 50 through the recirculation system piping 61, and the jet pump 59
- the reactor water is drawn down and guided to the lower plenum 64 of the core.
- a control rod drive mechanism housing 65 is provided through the bottom.
- a porous sintered metal element 66 is installed in the vicinity of the upper portion of the jet pump 59 installed in the down force portion 58.
- a plurality of sintered metal elements 66 are provided along the inner peripheral wall of the reactor pressure vessel 50 in the vicinity of the upper portion of the jet pump 59.
- Each sintered metal element 66 is connected to an ozone generator 67 through an ozone gas supply pipe 68.
- Ozone gas (O) generated in the ozone generator 67 is sintered through the ozone gas supply pipe 68.
- Ozone gas is supplied to the inside of the element 66 and from each element 66 to the outside of the element, specifically, toward the down force portion 58 in the reactor pressure vessel 50.
- the supplied ozone gas is sucked into the jet pump 59 together with the surrounding reactor water and led to the lower plenum 64 of the core.
- the reactor pressure vessel 50 is filled with water (hereinafter referred to as ozone water), and the recirculation pump 62 of the reactor recirculation system 60 is operated at a rotational speed of, for example, 20% during the rated operation.
- ozone water water
- the recirculation pump 62 of the reactor recirculation system 60 is operated at a rotational speed of, for example, 20% during the rated operation.
- ozone water for example, 20 ppm of phosphoric acid as an acid support agent and, for example, nitric acid as a pH adjuster are added, and the pH of the ozone water is adjusted to 3 or less, for example, 3. Then, water (ozone water) in the reactor pressure vessel 50 is heated to about 80 ° C.
- ozone gas is generated from the ozone generator 67 of the chemical decontamination apparatus 51, and the generated ozone gas is supplied to the sintered metal element 66 installed near the upper portion of the jet pump 59 through the ozone gas supply pipe 68.
- Ozone gas is supplied to the inside of the sintered metal element 66, and the supplied ozone gas is also supplied to the ozone water outside the element, and the fine bubbles in the ozone water are supplied to the ozone water outside the element. It becomes. Ozone gas becomes fine bubbles in ozone water, sucked into the jet pump 59, mixed with the reactor water, melted into some reactor water, discharged to the lower plenum 64 at the bottom of the reactor, and reversed by this lower plenum 64 And moved to 53 parts of the reactor core.
- the flow state of the ozone gas bubbles in the reactor pressure vessel 50 is substantially the same as the example shown in FIG. 3, the ozone gas is efficiently dissolved in water by the jet pump 59.
- the amount of water held in the reactor pressure vessel 50 is 800 to: 300 to 400 m 3 in the LlOOMWe class.
- the dissolved ozone concentration in the cylindrical tank 11 is 2 by adding 90 gZh of ozone gas to 3.5 m 3 of water. Can be kept in the range of 0 to 2.5 p pm.
- the actual BWR has approximately 100 times the amount of water held in the reactor pressure vessel 50. Therefore, the dissolved ozone concentration in the reactor pressure vessel 50 of the actual machine is less than 9000gZh and the ozone water flow It can be 2 ppm or more.
- phosphoric acid or phosphate for example, is added to ozone water as an acid-assisting aid, and for example, nitric acid is added as a pH adjuster. Therefore, the integrity of the nuclear reactor materials can be maintained even when the target is chemical decontamination.
- the ozone water that is the decontamination solution satisfies the condition of pH 3 or less, and the corrosion of the components constituting the chemical decontamination object, for example, reactors, is efficient.
- the additive that suppresses corrosion can be optimized, the soundness of the nuclear reactor constituent material can be maintained, and the decontamination performance can be improved.
- FIG. 8 is a configuration diagram showing a fourth embodiment of the in-furnace chemical decontamination apparatus according to the present invention.
- This in-reactor chemical decontamination apparatus 110 is for decontamination of decontamination objects such as reactor equipment and various pipes in a nuclear power plant, and boiling water nuclear power generation is used as the decontamination object.
- decontamination objects for the primary reactor such as the reactor pressure vessel 111, the piping 113 of the reactor recirculation system 112, and the recirculation pump 114.
- Decontamination objects include boiling water reactors (BWR, ABWR) as well as pressurized water reactor reactor vessels and reactor primary systems.
- Reactor recirculation system 112 is normally provided in two systems, and is provided in reactor pressure vessel 111.
- the core shroud 116 is housed in the reactor pressure vessel 111, and the core 117 is formed in the core shroud 116.
- the core 117 is supported by the core support plate 118 and the upper support plate 119.
- a lower core plenum 121 is formed below the core 117, and an upper core plenum 122 is formed thereabove.
- a gap between the reactor pressure vessel 111 and the core shroud 116 is formed as a sleeve-like or annular spiral portion 123.
- a plurality of jet pumps 124 of 6 to 12 units to 10 to 20 units are provided in the circumferential portion 123 along the circumferential direction.
- the jet pump 124 reverses the jet pump riser pipe 126 connected to the header pipe 125 branched from the recirculation pipe 113 via the inlet nozzle 115b and the upward flow rising up the jet pump riser pipe 126.
- the jet pump nozzle 127 is divided into two parts; the jet pump 124 formed around the pump nozzle 127; the throat section (mixing chamber) 128 that sucks and mixes the system water (reactor water) from the suction port; And a diffuser 129 for guiding the generated water to the lower core plenum 121.
- the in-core chemical decontamination apparatus 110 includes a temporary decontamination loop 130 attached to the lower outside of the reactor pressure vessel 111.
- the temporary decontamination loop 130 includes a temporary circulation line 132 connected to a control rod housing 131 of a control rod drive mechanism (CRD) provided at the bottom of the reactor pressure vessel 111, and a circulation pump provided in the temporary circulation line 132.
- CCD control rod drive mechanism
- 133 and a chemical decontamination equipment 134, and the downstream side of the chemical decontamination equipment 134 is connected to a temporary spraying 135 to constitute a decontamination supply means!
- the temporary spraying 135 is attached to the upper part of the reactor pressure vessel 111, and a decontamination solution such as oxalic acid is sprayed from the spraying 135 into the reactor pressure vessel 111 during chemical decontamination work.
- the temporary circulation loop 130 extracts the decontamination liquid from the lower part of the reactor pressure vessel 111 through the temporary circulation line 132 by the circulation pump 133 and sends it to the chemical decontamination equipment 134.
- the chemical decontamination equipment 134 is a device that performs chemical decontamination, for example, a heater, an ion-exchange resin tower that collects radioactivity, a decontamination solution that decomposes the decontamination agent after decontamination is completed. It consists of a device and a chemical injection pump that injects decontaminating agents (liquid) such as oxalic acid.
- the decontamination liquid from the chemical decontamination equipment 134 is sprayed into the reactor pressure vessel 111 by the spraying 135 from the upper side.
- the temporary circulation loop 130 includes a chemical decontamination equipment 134 and constitutes a decontamination liquid supply means!
- the in-core chemical decontamination apparatus 110 includes in-reactor equipment such as the reactor pressure vessel 111, the core shroud 116, the core support plate 118, the upper lattice plate 119, the jet pump 124, and the like. And chemicals for decontamination of the decontamination target in the reactor primary system of the reactor recirculation system 112. In order to increase the decontamination efficiency, the atoms necessary for the in-reactor flow in the reactor pressure vessel 111 are used. The furnace recirculation pump 114 is operated.
- the jet pump 124 constitutes ozone water generating means for generating ozone water by mixing the ozone gas supplied from the ozone supply means 140, and the reactor recirculation system 112 supplies the generated ozone water to the primary system of the reactor. Construct ozone water circulation means to circulate inside!
- the reactor recirculation pump 114 By operating the reactor recirculation pump 114, the ozone water or the decontamination liquid in the reactor pressure vessel 111 passes through the reactor recirculation system 112, and from the recirculation system piping 113, the jet pump riser 126 passes through. Ascending, surrounding water is taken in from the pump nozzle 127 of the jet pump 124 and discharged to the lower plenum 121 of the core. The decontamination liquid discharged to the core lower plenum 121 is reversed here, moves up in the core shroud 116, and is guided to the alaser part 123 again. The decontamination liquid guided to the circulator 123 is lowered and guided again to the reactor recirculation system 112 provided at the lower portion of the circulator 123. In-reactor structure in the reactor pressure vessel 111 The in-reactor equipment and the reactor recirculation system 112 constitute a reactor primary system.
- An organic acid such as oxalic acid is usually used as a decontamination solution used for chemical decontamination, and this organic acid decontamination solution (decontamination agent) is used in the reduction decontamination step.
- this organic acid decontamination solution decontamination agent
- the radiation ability of iron oxide and Co-60, Co-58 and the like incorporated in the oxide is eluted (dissolved) in the decontamination solution.
- ozone supply means 140 for supplying ozone gas into the reactor pressure vessel 111 is provided above the reactor pressure vessel 111.
- the ozone supply means 140 is supplied with the ozonizer 141 constituting the ozone generator and the ozone (O) gas generated by the ozonizer 141.
- the ozone diffuser 143 is also provided above the reactor pressure vessel 111, for example, an operation floor (not shown) force, and its tip is guided to the circular portion 123, so that the jet pump nozzle 127 of the jet pump 124 It is installed upright near the top.
- the ozone gas generated by the ozonizer 141 is blown out from an ozone diffuser 143 that opens near the suction port (throat) of the jet pump nozzle 127.
- Ozone diffuser 143 is reactor pressure A plurality of, for example, six to twelve, for example, are arranged in the circumferential direction so that the tip thereof faces the alasus portion 123 in the container 111.
- the internal structure of the reactor which is the object to be decontaminated by the decontamination liquid contained in the reactor pressure vessel 111, adhered to the metal surface of the reactor primary system of the reactor recirculation system 112.
- Oxidation treatment that dissolves metal oxides such as iron with decontaminating agents such as oxalic acid, dissolves and purifies them, while operating ozone supply means 140 to dissolve the oxide film. The process proceeds to the oxidation process.
- the oxidation treatment in chemical decontamination is to dissolve the radioactivity incorporated into the chromium oxide in the inner layer of the metal surface of the decontamination object.
- ozone water having a predetermined ozone concentration of 1 ppm or more is used as the oxidizing agent.
- ozone is a self-decomposing gas and has a short life, it is necessary to continuously inject ozone gas from the ozone supply means 140 into the water in the reactor pressure vessel 111. Ozone gas is generated by the ozonizer 141, diffused through the ozone diffuser 143, and injected into the furnace
- the injection point of the ozone gas is forcibly sucked into the jet pump 124 on the flow of the in-reactor of the reactor recirculation pump 114 on the upper portion of the alaser portion 123.
- the position where the ozone diffuser 143 is installed is preferably close to the suction port (throat) of the jet pump 124, but in order to overcome the water depth of the ozone gas pressure and stably inject it, a booster such as a pressure pump is used. If there is no, the upper end force of the core shroud 116 is also provided within a required distance, for example, in the range of about lm.
- a plurality of, for example, several to ten, ozone diffusers 143 are provided in the circumferential direction near the upper portion of the jet pump 124 and above the circular portion 123.
- the purpose of the oxidation treatment with ozone water is to dissolve the acid-rich film with high chromium content in the inner layer of the decontamination object.
- the acidifying process for performing the treatment is completed. Even after the acidification process is completed, it is necessary to rely on the self-decomposition of ozone, which does not require any particular decomposition of ozone, and then injecting oxalic acid in the subsequent reduction process.
- reference numeral 145 is a water supply sparger connected to the reactor water supply system via a header pipe, and reference numeral 146 is a core spray pipe.
- In-reactor chemical decontamination equipment 110 is installed in the reactor pressure vessel 111 to decontaminate the reactor primary system such as the reactor pressure vessel 111, reactor structure, reactor equipment, reactor recirculation system 112, etc. Large-scale chemical decontamination of objects is carried out at regular periodic inspections or maintenance inspections when the reactor has been shut down.
- the recirculation pump 1 of the reactor recirculation system 112 that circulates the primary water of the reactor primary system is operated to generate a flow in the reactor pressure vessel 111 while supplying ozone.
- the ozone gas generated by the ozone generator 141 is efficiently injected into the suction port of the jet pump 124,
- the reactor pressure vessel 111 is circulated. That is, the generated ozone gas is sucked from the suction port of the jet pump 124 and stirred with pump water in the mixing chamber 128 and the diffuser 129 to generate ozone water, which is actively mixed.
- the generated ozone water is guided to the lower core plenum 121.
- the mixed flow (ozone water) guided to the lower core plenum 121 is reversed here and guided into the core shroud 116 and becomes an upward flow in the core shroud 116.
- the bubbles of ozone gas guided from the suction part of the jet pump 124 through the mixing chamber 128 to the diffuser 129 are agitated by mixing effect and become ozone water, which is discharged to the furnace bottom (core lower plenum). Then, the oxide film on the bottom of the furnace is oxidized and dissolved. After this oxidative dissolution, the ozone water sequentially contacts with the core support plate 118, the inner wall of the core shroud 116, and the upper lattice plate 119, which are internal structures, and sequentially dissolves the acid film formed on the surface. On the other hand, surplus ozone gas that could not be dissolved due to the mixing effect moves from the water surface in the center of the furnace to the gas phase and is exhausted to the outside.
- FIG. 9 is a configuration diagram showing a fifth embodiment of the in-furnace chemical decontamination apparatus according to the present invention.
- FIG. 9 shows a plan view of the inside of the reactor pressure vessel 111 provided in the boiling water nuclear power plant.
- the reactor pressure vessel 111, the core shroud 116, the jet pump 124, and the ozone diffuser tube are shown.
- FIG. FIG. 9 shows an example in which 10 to 20 jet pumps 124 are installed in the spiral portion 123 formed between the reactor pressure vessel 111 and the core shroud 116.
- the jet pumps 124 are installed at a predetermined interval in the circumferential direction of the radius portion 123.
- An ozone diffuser 143 constituting the ozone gas supply means 140 is provided in the vicinity of the upper part of the jet pump 124 making a pair.
- the configuration in the reactor pressure vessel 111 of the nuclear power plant, the reactor recirculation system, and the configuration of the temporary decontamination loop as a decontamination solution supply device are not different from those shown in the fourth embodiment, so the same reference numerals are used. In addition, the illustration and explanation of the configuration are omitted or simplified.
- Reference numeral 142 denotes a diffuser pipe conduit to the ozone diffuser pipe 143. (Ozone supply pipe), reference numeral 150 is an access hole cover.
- the system water flow in the reactor pressure vessel 111 is changed by the operation of the recirculation pump 114 of the reactor recirculation system 112.
- the riser pipe 126 of the jet pump 124 is raised from the circulation system 112 through the header pipe (ring header), branched into two branches by the jet pump nozzle 127, and guided to the one-to-two jet pumps 124.
- the ozone diffuser 143 of the ozone gas supply means 140 is provided near or directly above the upper part of the ten pairs of jet pump nozzles 127.
- the ozone diffuser 143 is divided into one pair corresponding to the jet pump pair.
- the reactor water led to the alaser part 123 flows downward and is led to the outlet of the reactor recirculation system 112 below the alasus, but is guided to the reactor recirculation system 112.
- the reactor water contains almost no ozone gas blown out from the ozone diffuser 143. Therefore, there is no need to worry about the occurrence of cavity in the recirculation pump 114 of the reactor recirculation system 112.
- the ozone water discharged from the recirculation pump 114 is guided to the jet pump 124, and when discharged from the pump nozzle 127 of the jet pump 124, surrounding furnace water (circulation water in the furnace) is entrained together with ozone gas. , Led to the mixing chamber 128 of the jet pump 124.
- the ozone gas guided to the mixing chamber 1 28 is dissolved into the water by the mixing effect, and is guided from the diffuser 129 to the lower plenum 121 of the core.
- Support plate 118, shroud inner wall, upper lattice plate 119 oxide skin Dissolve the membrane sequentially.
- the outlet nozzle of the reactor recirculation system 111 exists at the 0 ° and 180 ° positions of the reactor pressure vessel 111 of the reactor pressure vessel 111 where the ozone diffuser 143 is not installed. Since the downward flow of 123 proceeds as a deflected flow, it is not necessary to install an ozone diffuser at the 0 ° and 180 ° positions of the circular portion 123! /.
- the in-furnace chemical decontamination apparatus 110A shown in the second embodiment can also carry out large-scale in-furnace chemical decontamination work. Also in this chemical decontamination work, ozone water with a predetermined ozone concentration can be distributed to the entire reactor primary system of the reactor pressure vessel 111 and the reactor recirculation system 112.
- the broken line in Fig. 10 shows the relationship between the ozone concentration evaluation points (each place in the reactor of the reactor pressure vessel) a to l and the dissolved ozone concentration at the evaluation point position when 10 ozone diffuser tubes 143 are installed. It is a graph to show.
- the ozone concentration evaluation points a to l in FIG. 10 correspond to the respective locations a to l in the reactor pressure vessel shown in FIGS. 11A and 11B.
- the ozone gas discharged from the ozone diffuser 143 is, for example,
- Non-Patent Document 1 (Aoi et al., “Development of ozone decontamination technology (Part 2) —Evaluation of decontamination performance and its impact on materials” “The Japan Society of Atomic Energy Society“ 2001 Spring Annual Meeting ”, lecture number M38, Abstract III of the lecture (p. 691) reports that a sufficient removal effect can be obtained with a dissolved ozone concentration of lppm or more.
- FIG. 12 is a configuration diagram showing a sixth embodiment of the in-furnace chemical decontamination apparatus according to the present invention.
- FIG. 12 shows a cross section of the reactor pressure vessel 111 provided in the boiling water nuclear power plant.
- 10 to 20 jet pumps 124 are installed in an elastic part 123 formed between the reactor pressure vessel 111 and the core shroud 116.
- the jet pumps 124 are installed at a predetermined interval in the circumferential direction of the radius portion 123.
- An ozone diffuser 143 constituting the ozone gas supply device 140 is provided above the middle part between each pair of the jet pumps 124.
- the ozone diffusing pipe 143 is arranged in an upright state in the vicinity of the upper part of the intermediate portion between adjacent jet pump pairs.
- the ozone diffuser 143 is located between each pair of jet pumps 124 and adjacent jet pump pairs, except for the circumferential position of 0 °, 180 °, for example, where the outlet nozzle 115 of the reactor recirculation system 112 is located. Provided.
- the flow of the system water (circulated water) in the reactor circulating through the reactor recirculation system 112 is branched by the header piping (ring header) of the reactor recirculation system 112 and then jetted through the inlet nozzle 115b.
- the pump riser pipe 126 is lifted and branched into two branches by a jet pump nozzle 127 and enters a one-to-two jet pump 124.
- the ozone diffuser 143 of the ozone gas supply means 140 is installed between each pair of 10 to 20 jet pumps 124.
- the ozone diffuser 143 is Eight are installed.
- the number of ozone diffuser tubes 143 is not limited to 8, but select from 6 to 10 or more.
- ozone gas is injected from an ozone diffuser pipe 143 installed near the upper part of the jet pump nozzle 127, and this ozone gas is jetted between adjacent jet pump pairs. It is almost sucked into each suction port of pumps 124 and 124.
- the ozone gas sucked into the jet pump 124 is agitated and mixed in the throat part 128, while the ozone part guided down to the outlet nozzle 115a of the reactor recirculation system 112 by descending the alaser part 123 exists. do not do.
- Bubbles of ozone gas guided to the mixing chamber 128 of the jet pump 124 dissolve into the water by the mixing effect, descend in the diffuser 129, and are discharged to the lower plenum 121 of the core.
- the oxide film on the bottom of the furnace is dissolved by acid treatment with water discharged to the lower plenum 121 of the core.
- the acid film on the reactor internal structure (core support plate 118, shroud inner peripheral wall, upper grid plate 119) is dissolved in sequence.
- Excess ozone gas is transferred to the water surface gas phase section at the center of the reactor in the reactor pressure vessel 111 and exhausted to the outside.
- the ozone diffuser 143 is not installed at, for example, 0 ° and 180 ° circumferential positions. Ozone air diffuser 143 is not installed. a is provided, and the downward flow of the spiral portion 123 becomes a deflected flow toward the outlet nozzle 115a, so that the dissolution effect of the acid film is not reduced.
- the in-reactor chemical decontamination apparatus 110B large-scale in-reactor chemical decontamination work is effectively and efficiently performed in the reactor pressure vessel 111 and the entire reactor recirculation system 112. be able to.
- water with a predetermined ozone concentration ozone water
- this ozone water is operated in the entire reactor pressure vessel 111 or by the operation of the recirculation pump 114 of the reactor recirculation system 112. It is possible to carry out an acid treatment that circulates throughout the reactor recirculation system 112 and efficiently dissolves the internal structure and the acid film formed in the reactor recirculation system 112. it can.
- the solid line in FIG. 10 is a graph showing an example of ozone concentration measurement values at various locations (concentration evaluation points a to l) in the reactor pressure vessel 111 when the number of ozone diffuser tubes 143 is eight.
- ozone gas is supplied into the reactor pressure vessel 111 at a predetermined rate, for example, 11.5 kgZh.
- lppm or more was obtained even at the lowest ozone concentration in the reactor a to l (see Fig. 11A, Fig. 1 IB) in the reactor pressure vessel 111.
- a sufficient decontamination effect can be obtained by the above dissolved ozone concentration.
- the reactor pressure vessel 111 By combining the acid-soaking process using a dissolved ozone concentration of 1 ppm or more and the reductive decontamination process using a decontamination agent before and after this oxidation treatment, the reactor pressure vessel 111, the reactor internal structure In addition, the radioactivity of the reactor recirculation system 112 other than the activation of the primary reactor system can be removed, and a significant reduction in radiation dose can be achieved.
- a decontaminating agent such as oxalic acid is injected from the temporary spraying 135 into the reactor pressure vessel 111.
- FIG. 13 is a configuration diagram showing a seventh embodiment of the in-furnace chemical decontamination device according to the present invention.
- This embodiment is characterized by the mounting structure of the ozone diffuser 143 of the ozone gas supply device 140. Since the other configuration is not different from the in-furnace chemical decontamination apparatus 110B shown in FIG. 8, the same components are denoted by the same reference numerals, and description thereof will be omitted or simplified.
- the in-furnace chemical decontamination apparatus 110C shown in FIG. A plurality of ozone diffuser tubes 143 are stably installed in the reactor pressure vessel 111 in a standing state.
- the tip of the ozone diffuser 143 is suspended downward from an operation floor (not shown), and is disposed on the upper portion 123 of the reactor 123 between the reactor pressure vessel 111 and the core shroud 116.
- the ozone diffuser 143 is a long SUS pipe having a length of about several meters, for example, about 6 m, and the upper end of the diffuser is located above the reactor pressure vessel 111.
- the ozone diffuser tube 143 is disposed using a dead space near the peripheral wall of the reactor pressure vessel 111, and can effectively prevent interference with other in-reactor equipment.
- Fig. 13 is a longitudinal sectional view showing the lower left half of the reactor pressure vessel 111.
- a plurality of ozone diffuser tubes 143 installed in the reactor pressure vessel 111 in a standing state are shown in the reactor.
- the pressure vessel 111 is fixed at a plurality of upper and lower locations, for example, at least two locations at the top and bottom.
- the ozone diffuser 143 is fixed to the upper shroud ring 150 by the clamp device 151 near the lower end thereof, and to the water supply sparger 145 near the upper end thereof. Fixed at 152.
- a bolt bracket of a shroud head bolt standing on the upper shroud ring 150 can be used.
- a plurality of shroud head bolts are erected along the circumferential direction at the top of the upper shroud ring 150, and a bolt bracket is provided on the shroud head bolt.
- the in-furnace chemical decontamination apparatus 110C shown in the seventh embodiment has the ozone diffuser 143 of the ozone gas supply apparatus 140 attached to the reactor pressure vessel 111 at a plurality of locations at the top and bottom, and the ozone diffuser 143 By fixing the lower end side to the upper shroud ring 150, the injection point of ozone gas can be maintained stably and accurately.
- the upper part of the fuser part 123 is vigorously oscillated by the water flow of the reversing and descending flow of the upward flow rising in the core shroud 116 and the ozone gas jet flow that is also blown out at the tip of the ozone diffuser 143.
- the ozone diffuser 143 can be stably held and the ozone injection point can be accurately maintained.
- the in-core chemical decontamination apparatus 110C shown in the seventh embodiment it is possible to always supply ozone gas into the reactor pressure vessel 111 in a stable and safe state, with a predetermined ozone concentration.
- ozone water can be circulated and distributed throughout the reactor pressure vessel 111 and the entire recirculation piping 113 of the reactor recirculation system 112 outside the reactor core.
- the oxide film produced in the primary reactor system can be efficiently dissolved and oxidized.
- the ozone gas supply device 140 supplies ozone gas into the reactor pressure vessel 111 to dissolve the acid film, and the reductive decontamination process using the decontamination agent before and after the acid film.
- FIG. 14 is a configuration diagram showing an eighth embodiment of the in-furnace chemical decontamination apparatus according to the present invention.
- This embodiment relates to a structure for mounting the ozone diffuser 143 of the ozone gas supply means (device) 140 in the reactor pressure vessel 111. Since other configurations are not different from the in-furnace chemical decontamination apparatus 110 shown in the fourth embodiment, the same components are denoted by the same reference numerals, and description thereof is omitted or simplified.
- the in-core chemical decontamination apparatus 110D shown in Fig. 14 hangs down the ozone diffuser 143 of the ozone gas supply means 140 below the operation floor force (not shown), and the tips of the diffuser pipe are connected to the reactor pressure vessel 111 and the core shroud. 116 is arranged in an upright state so as to face the upper part of the spiral portion 123 formed between them.
- the ozone diffusing pipe 143 is a long SUS pipe having a length of about several meters, for example, about 6 m, and the upper end of the diffusing pipe is located in the upper part of the reactor pressure vessel 111.
- FIG. 14 is a longitudinal sectional view showing the lower left half of the reactor pressure vessel 111.
- the ozone diffuser 143 installed in the reactor pressure vessel 111 in a standing state is a reactor pressure vessel.
- the container 111 is fixed at a plurality of upper and lower positions, for example, at least two positions at the upper and lower positions.
- the ozone diffusing pipe 143 is fixed to the upper shroud ring 150 by the clamp device 151 near the lower end thereof, and the core spray pipe 146 near the upper end thereof. It is fixed by a clamping device 153.
- a downward flow is generated due to the reversal of the upward flow rising in the core shroud 116, and is intense due to the jet flow of ozone gas blown out from the tip nozzle portion of the ozone diffuser 143.
- the ozone diffuser 143 can be stably held by fixing the tip of the ozone diffuser 143 to the upper shroud ring 150, and the ozone injection point is accurately maintained. be able to.
- the ozone diffuser 143 and the diffuser pipe (ozone supply pipe) 142 do not cause excessive vibration of the long stainless steel pipe.
- the load on the coupling portion can be reduced.
- the ozone diffuser 143 is arranged using a dead space along the circumferential direction in the reactor pressure vessel 111.
- the in-core chemical decontamination apparatus 110D shown in Fig. 14 can also supply ozone gas into the reactor pressure vessel 111 in a stable and safe state at all times. Can be circulated throughout the reactor pressure vessel 111 and the entire reactor recirculation system 112 outside the reactor core, and the internal structure of the reactor pressure vessel 111 and the recirculation of the reactor recirculation system 112 can be recirculated. An oxidation treatment can be performed to efficiently dissolve the oxide film generated in the primary reactor system in the pipe 113.
- the reactor pressure vessel 111 can be treated as follows. Radioactivity other than activation of the reactor internals and the recirculation piping 113 of the reactor recirculation system 112 is eliminated, and a significant reduction in radiation dose can be achieved.
- FIG. 15 is a configuration diagram showing a ninth embodiment of the in-furnace chemical decontamination device according to the present invention.
- This embodiment relates to a structure for mounting the ozone diffuser 143 of the ozone gas supply means 140. Since the other configuration is not different from the in-furnace chemical decontamination apparatus 110 shown in FIG. 8, the same components are denoted by the same reference numerals, and description thereof will be omitted or simplified.
- FIG. 15 shows an embodiment relating to the attachment of the ozone diffuser 143 in the reactor pressure vessel 111.
- the ozone diffuser 143 of the ozone gas supply device 140 is fixed in the reactor pressure vessel 111 at a plurality of upper and lower positions, for example, at least two positions at the upper and lower positions.
- the ozone diffuser 143 is installed using the dead space in the reactor pressure vessel 111 while standing in the reactor pressure vessel 111.
- the ozone diffuser 143 is a long stainless steel pipe having a length of about several meters, for example, about 6 m, and is a jet disposed in the alaser part 123 between the reactor pressure vessel 111 and the core shroud 116.
- a plurality, for example, 8 to 10, are provided corresponding to the pump pairs.
- the front end (lower end) of the ozone diffuser 143 is located at the upper part of the spiral portion 123, and the upper end thereof is located at the upper part in the reactor pressure vessel 111.
- the ozone diffuser 143 is fixed to the upper shroud ring 150 near the lower end by the clamp device 151 and close to the upper end for in-furnace chemical decontamination. It is fixed to a temporary spraying 155 to be used by a clamping device 156.
- Temporary spraying 155 is installed at a position that does not submerge even at the highest water level WHL during chemical decontamination, and the ozone diffuser 143 is fixed at a higher position than in the fourth and fifth embodiments. Thus, it is stable against the flow in the furnace.
- the intermediate part may be fixed to at least one of the water supply sparger 145 and the core spray pipe 146 as required.
- a shroud head bolt bracket can be used.
- the ozone gas injection point can be accurately maintained and stabilized by fixing the lower end of the ozone diffuser 143 of the ozone gas supply apparatus 140 to the upper shroud ring 150. be able to.
- the in-core chemical decontamination apparatus 110E of the ninth embodiment can be applied to large-scale in-core chemical decontamination in the reactor pressure vessel and the reactor recirculation system.
- Ozone gas can always be supplied in a stable and safe state during work.
- Ozone gas is supplied from the ozone gas supply device 140 into the reactor pressure vessel 111, and the operation of the reactor recirculation system 112 circulates ozone water with a predetermined ozone concentration in the reactor pressure vessel 111 and the reactor recirculation system 112.
- the reactor internals of the reactor pressure vessel 111, the reactor internal structure, the reactor recirculation system 112 outside the core, and the recirculation pipe 113 of the reactor are formed into ozone water. It can be efficiently dissolved by the acid treatment.
- This in-reactor chemical decontamination apparatus 110E has a reactor pressure vessel 111 by combining it with an acid-soaking process (acid-soaking process) using ozone water before and after the reductive decontamination process using a decontamination agent. Radioactivity other than activation of the internal and reactor recirculation system 112 is eliminated, and a significant reduction in radiation dose can be achieved.
- the example in which the chemical decontamination apparatus using ozone is mainly applied to the reactor pressure vessel of the boiling water reactor and the primary reactor system is shown.
- the present invention can also be applied to the reactor vessel and primary reactor of a pressurized water reactor, and in addition, an oxide film containing radioactive material generated or attached to the surface of the decontamination target is chemically analyzed. It can also be applied to an apparatus that dissolves and decontaminates.
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Abstract
Description
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Priority Applications (5)
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US12/278,864 US8440876B2 (en) | 2006-02-09 | 2007-02-06 | Chemical decontamination apparatus and decontamination method therein |
KR1020087020497A KR101086600B1 (ko) | 2006-02-09 | 2007-02-06 | 화학 제염 장치 및 그 제염 방법 |
KR1020107021613A KR101063132B1 (ko) | 2006-02-09 | 2007-02-06 | 화학 제염 장치 및 그 제염 방법 |
CN2007800050723A CN101385093B (zh) | 2006-02-09 | 2007-02-06 | 化学除污装置以及化学除污方法 |
EP07713857.6A EP1983526B1 (en) | 2006-02-09 | 2007-02-06 | Chemical decontamination apparatus and decontamination method therein |
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JP2006032575A JP4204596B2 (ja) | 2006-02-09 | 2006-02-09 | 化学除染装置およびその除染方法 |
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JP2006-053698 | 2006-02-28 | ||
JP2006053698A JP4183714B2 (ja) | 2006-02-28 | 2006-02-28 | 炉内化学除染装置およびその除染方法 |
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KR (2) | KR101063132B1 (ja) |
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US20110259759A1 (en) * | 2008-10-13 | 2011-10-27 | Jean-Michel Fulconis | Method and device for decontaminating a metallic surface |
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Also Published As
Publication number | Publication date |
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EP1983526A1 (en) | 2008-10-22 |
KR101086600B1 (ko) | 2011-11-23 |
EP1983526B1 (en) | 2018-01-10 |
KR20100110399A (ko) | 2010-10-12 |
CN102262909A (zh) | 2011-11-30 |
EP1983526A4 (en) | 2014-03-19 |
TWI355003B (ja) | 2011-12-21 |
US8440876B2 (en) | 2013-05-14 |
CN102262909B (zh) | 2014-06-25 |
US20100168497A1 (en) | 2010-07-01 |
KR101063132B1 (ko) | 2011-09-07 |
KR20080087041A (ko) | 2008-09-29 |
TW200746176A (en) | 2007-12-16 |
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