WO1996022605A1 - Centrale electrique nucleaire et procede de fonctionnement - Google Patents

Centrale electrique nucleaire et procede de fonctionnement Download PDF

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Publication number
WO1996022605A1
WO1996022605A1 PCT/JP1995/000040 JP9500040W WO9622605A1 WO 1996022605 A1 WO1996022605 A1 WO 1996022605A1 JP 9500040 W JP9500040 W JP 9500040W WO 9622605 A1 WO9622605 A1 WO 9622605A1
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WO
WIPO (PCT)
Prior art keywords
metal
concentration
nuclear power
power plant
coolant
Prior art date
Application number
PCT/JP1995/000040
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English (en)
Japanese (ja)
Inventor
Naoto Uetake
Hideyuki Hosokawa
Makoto Nagase
Original Assignee
Hitachi, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi, Ltd. filed Critical Hitachi, Ltd.
Priority to JP52215396A priority Critical patent/JP3179500B2/ja
Priority to PCT/JP1995/000040 priority patent/WO1996022605A1/fr
Publication of WO1996022605A1 publication Critical patent/WO1996022605A1/fr

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C19/00—Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
    • G21C19/28—Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core
    • G21C19/30—Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core with continuous purification of circulating fluent material, e.g. by extraction of fission products deterioration or corrosion products, impurities, e.g. by cold traps
    • G21C19/307—Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core with continuous purification of circulating fluent material, e.g. by extraction of fission products deterioration or corrosion products, impurities, e.g. by cold traps specially adapted for liquids
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to a plant operating method, and more particularly to a plant operating method suitable for a nuclear plant using light water or heavy water as a coolant, and a nuclear plant implementing the plant.
  • radionuclides generated by neutron irradiation in a nuclear reactor adhere to the primary cooling system piping, etc., and cause workers to be exposed to radiation during regular inspections. For this reason, various methods are being studied to prevent the attachment of radionuclides to pipes.
  • Japanese Patent Application Laid-Open No. 62-24195 discloses a technique in which a stable preliminary oxide film is formed on the inner surface of a pipe in advance under a certain condition.
  • this method has a disadvantage that the effect of pre-oxidation decreases with time because the oxide film grows even during the operation of the reactor. Further, the pre-oxidation treatment has a disadvantage that it takes time.
  • JP-A-63-172999 discloses a method of using zinc in which Zn-64, which is a parent nuclide of Zn-65, is reduced by isotope separation.
  • this method has high cost of isotopic separation and is economically problematic.
  • An object of the present invention is to reliably reduce the dose of piping at a low cost and to achieve an effect.
  • the above object is achieved by continuously injecting a metal whose oxide has a corundum structure into primary cooling water during reactor operation.
  • Fig. 3 schematically shows this adhesion mechanism.
  • the problem at the time of routine inspection is the radioisotopes of Co-58 and C0-60 cobalt, which have relatively long elimination periods.
  • Most of these radionuclides exist as cobalt divalent ions in reactor water.
  • iron divalent ion is oxidized by dissolved oxygen in water to form iron trivalent ions.
  • ',' Because the solubility of iron trivalent ion is extremely low, it becomes oxide solid again and becomes a pipe surface. To be deposited.
  • Ferrites are mainly composed of nickel ferrite formed by the reaction with nickel ions, which are the divalent metal ions that are the most abundant in the reactor water. Causes nuclides to adhere to pipes. Since zinc ions are also divalent ions, the ability to form ferrite is relatively low, and their stability is relatively low, so they dissolve immediately upon precipitation, and as a result, the amount of adhesion as a fluoride decreases. I do.
  • Metal ions forming such corundum-type oxides include aluminum trivalent ion, gallium trivalent ion, chromium trivalent ion, titanium trivalent ion, vanadium trivalent ion, iron trivalent ion, and rhodium trivalent ion. Etc. Of these, iron trivalent ions are a source of the ferrite described above, and are therefore not preferred as the implanted metal of the present invention. In addition, titanium trivalent ion, vanadium trivalent ion and rhodium trivalent ion do not have very good stability of corundum-type oxides.
  • chromium trivalent ions do not have good stability in the reactor water and immediately change to chromate ions (corresponding to chromium hexavalent ions). It must be shared with a reducing agent that reduces chromium trivalent ions or used in a reducing atmosphere.
  • metal ions added to the reactor water are activated in the reactor core, they will remain in the hematite, which is a random-type oxide, and adhere to the pipes, causing an increase in pipe dose. Therefore, it is necessary to select metal ions to be added that do not have such a problem of secondary radionuclide generation.
  • Fig. 8 shows the nuclear properties of metals that easily become corundum-type oxides in comparison with zinc. As shown in Fig. 8, chromium has a relatively long half-life of the generated nuclide produced by activation (27.8 days). (2.24 minutes, G a is 14.1 hours)
  • nuclides with a long half-life will not be produced by neutron activation.
  • the cost is very low because isotope separation is not required and the abundance as a resource is large.
  • aluminum has a short half-life of product nuclides, and high-purity aluminum can be obtained at low cost.
  • injection does not cause any new problems.
  • chromium can be adequately applied to brands where a half-life of less than one month is acceptable.
  • titanium, vanadium, and rhodium have sufficiently short half-lives of 5.76 minutes, 3.75 minutes, and 42.3 seconds, respectively. If acceptable, enough Applicable to
  • the injection amount may be controlled so that the ratio with respect to the concentration of divalent metal ions contributing to the precipitation of ferrite is a certain value or more (at least 1 or more).
  • the main component of divalent metal ions in the reactor water is The ratio of nickel ions to metal ions to be implanted may be used as an index. If the injection amount is too large, the service life of the primary cooling water purification device containing ion-exchange resin etc. will be shortened, so the injection amount must be as small as possible within the effective range. It is also possible to directly measure the dose of piping that causes exposure, and control the amount of injection based on the rate of increase. BRIEF DESCRIPTION OF THE FIGURES
  • FIG. 1 is a diagram showing a first embodiment in which the present invention is applied to a boiling water nuclear power plant.
  • FIG. 2 is a diagram showing an aluminum electrolytic device of the first embodiment.
  • Fig. 3 is a diagram illustrating the mechanism of attachment of radionuclides to piping in a nuclear plant.
  • FIG. 4 is a diagram for explaining the mechanism of precipitation of corundum-type oxide on the piping of a nuclear power plant.
  • FIG. 5 is a diagram showing a change over time in the amount of radioactivity adhering to a pipe.
  • FIG. 6 is a diagram showing a second embodiment in which the present invention is applied to a boiling water nuclear power plant.
  • FIG. 7 is a diagram showing a third embodiment in which the present invention is applied to a pressurized water nuclear power plant.
  • FIG. 8 is a diagram showing nuclear properties of a metal that easily becomes a corundum oxide.
  • Fig. 1 shows a first embodiment of the present invention applied to a boiling water nuclear power plant: Nuclear fuel 25, turbine 21, condenser ⁇ , condensate purifier 23 , Feed water heater 24, recirculation system 26, reactor water purification device 27, aluminum injection device, etc.
  • the steam exiting the turbine 21 is returned to liquid by the condenser 22, and the condensate exiting the condenser 22 is removed by the condensate purification device 23.
  • the condensate purified by the condensate purifier 23 is ripened by the feed water ripener 24. ',' At that time, metal corrosion products are generated due to the corrosion of the piping of the feed water ripener 24. This is brought into the furnace together with the water supply.
  • the metal corrosion product brought into the reactor adheres to the surface of the boiling part of the fuel rod of nuclear fuel 2 ⁇ , where it is activated by irradiation with neutrons generated by the fission of nuclear fuel 25, resulting in radionuclide Become.
  • Some of the radionuclides generated on the surface of the nuclear fuel 25 are eluted again into the reactor water.
  • the reactor water purifier 27 removes the remainder of the radionuclides eluted in the reactor water, while the remainder is oxidized as the oxidation of the pipe surface progresses while circulating through the recirculation system 26. It is taken in and causes an increase in the pipe dose rate.
  • an aluminum solution tank 29 and an aluminum injection pump 28 were provided as an aluminum injection device, and a condensate purification device 23 and a feedwater heater 24 were provided.
  • aluminum is injected continuously or intermittently during operation of the reactor.
  • the continuous presence of aluminum ions that easily form a corundum structure in the reactor water allows the divalent cobalt ions, cobalt-60 and cobalt-158, which are the main nuclides to be exposed, to be exposed. Since it is possible to prevent the formation of the cobalt-containing light and adhere to the inner surface of the pipe, it is possible to surely reduce the dose of the pipe.
  • the aluminum to be injected is supplied to the aluminum solution tank 29 in the form of a suspension of aluminum hydroxide, and is injected at a rate such that the aluminum concentration in the reactor water becomes about 50 ppb.
  • an aluminum electrolytic device 33 As another form of aluminum to be injected, there is a method using an aluminum electrolytic device 33 as shown in Fig. 3: In this device, a metal aluminum electrode 31 is placed on the anode side of a DC power supply, and platinum is placed on the cathode side. The electrode 32 is connected to generate a solution containing aluminum ions to be implanted by electrolysis. This aluminum electrolytic device 33 can be used in place of the aluminum solution tank 29.
  • Cobalt-58 a radionuclide
  • a loop device that circulates high-temperature water simulating reactor water conditions, and zinc ions were continuously injected so that the zinc ion concentration in the reactor water simulator became 5 O ppb.
  • the aluminum ion concentration in the reactor water simulator was kept at 5 O ppb, aluminum ions were continuously injected, and when the reactor water simulator was not implanted, the cobalt ion was transferred to stainless steel piping.
  • Fig. 4 shows an example of measuring the amount of adhesion of No. 8. From FIG. 4, it can be seen that the presence of aluminum ions in the simulated reactor water reduces the amount of cobalt-158 adhering to the pipe surface to the same extent as the presence of zinc ions.
  • Aluminum to be injected include aqueous solutions, solutions with organic solvents, and suspensions with water using aluminum organometallic compounds such as aluminum ethoxide, aluminum isopropoxide, and aluminum lactate. Or in the form of a suspension with an organic solvent.
  • aluminum organometallic compounds such as aluminum ethoxide, aluminum isopropoxide, and aluminum lactate.
  • aluminum organometallic compounds such as aluminum ethoxide, aluminum isopropoxide, and aluminum lactate.
  • aluminum organometallic compounds such as aluminum ethoxide, aluminum isopropoxide, and aluminum lactate.
  • the concentration of divalent metal ions in the reactor water should be higher than the standard.
  • Nickel ions can be considered as the main component of the divalent metal ion in the reactor water. Therefore, if the aluminum concentration is controlled to be equal to or higher than the nickel concentration, the pipe dose can be reduced.
  • the nickel concentration in the reactor water is about 2 to 3 ppb during the start-up operation of the reactor, and about 0.2 to 0.3 ppb during the commercial operation of the reactor (during normal operation). Therefore, it is sufficient to control the aluminum concentration in the reactor water according to such an operation state.
  • FIG. 1 differs from the first embodiment shown in FIG. 1 in that an element analyzer 51 for analyzing the aluminum concentration in the reactor water and an aluminum injection pump 2 based on the analysis results of the element analyzer 51 are provided. That is, a control device 53 that controls the motor 8 is provided.
  • a sampling line 50 is provided upstream of the reactor water purification device 27.
  • the aluminum concentration is analyzed by an elemental analyzer 51 such as an ion chromatograph or ICP-MS, and a signal corresponding to the aluminum concentration is transmitted to the controller 3.
  • the control device 53 controls the aluminum injection pump 28 based on the signal corresponding to the aluminum concentration and the amount of change thereof, so that the aluminum solution tank 29 is controlled so that the aluminum concentration in the reactor water falls within a predetermined range. Control the aluminum injection speed.
  • FIG. 1 The elemental analyzer 51 analyzes both the aluminum concentration and the nickel concentration in the reactor water and sends signals corresponding to the aluminum concentration and the nickel concentration to the controller 53.
  • the controller 53 The concentration ratio between aluminum and nickel in the water is determined, and based on this concentration ratio, the aluminum injection pump 28 is controlled, and the aluminum injection speed from the aluminum solution tank 29 is controlled so that the concentration ratio falls within a predetermined range. Control.
  • the concentration ratio of aluminum and nickel in the reactor water can be adjusted within a predetermined range, effectively preventing cobalt from adhering to the piping, and minimizing the injection amount of aluminum. it can.
  • the surface dose rate of the recirculation system 26 is measured by the radiation measuring device 55 shown in FIG. 6, and the control device 53 is adapted to this surface dose rate.
  • the corresponding signal is input from the radiation measurement device 55, and the rate of change of the surface dose rate is determined based on this signal. If the rate of change becomes too large beyond the predetermined allowable range, the controller 53 controls the aluminum injection pump 28 to increase the amount of aluminum injected from the aluminum solution tank 29. .
  • the location where the surface dose rate is measured may be other than the recirculation system 26, for example, the upstream side of the reactor water purification device 27.
  • This plant consists of a pressure vessel 60, a pressurizer 62, a nuclear fuel 63, a steam generator 64, a purifier 65, a boric acid water injection system 66, a dilute water injection system 67, and an aluminum injection system 68 Etc.
  • the primary cooling water 61 is pressurized by the pressurizer 62 so as not to boil.
  • This primary cooling water 6 1 is used for nuclear fuel 6 3 in pressure vessel 60.
  • the water that has been ripened and heated by heat is subjected to heat exchange in the steam generator 64, and the heat is passed to the secondary cooling water 69 and returned to the pressure vessel # 0 again.
  • a part of the primary system cooling water 61 is guided to the reactor water purification system, and impurities are removed by the purification device G5.
  • the steam generated by the steam generator 64 is used for power generation in the turbine 21, and is returned to water by the condenser 22.
  • the reaction of the nuclear fuel 63 is controlled using both the flow rate of the primary cooling water 61 and the concentration of boric acid in the primary cooling water 61.
  • a borate water injection system 6 G and a dilution water injection system G 7 are connected.
  • an aluminum injection system 68 is provided, and the injection position for the primary cooling water 61 is provided between the purification device 65 and the pressure vessel 60. Inject aluminum continuously or intermittently during reactor operation.
  • the continuous presence of aluminum ions that easily form a corundum structure in the reactor water makes it possible to obtain the divalent cations of cobalt 160 and cobalt 588, which are the main nuclides for exposure. Since the cobalt ions can form a ferrite containing the cobalt and prevent the cobalt ions from adhering to the inner surface of the pipe, the pipe dose can be reliably reduced:
  • a suspension of aluminum hydroxide, an aluminum organometallic compound, or the like can be used as a form of the aluminum to be injected.
  • the primary system cooling water was sampled from a position other than between the purifier 65 and the aluminum injection position to measure the concentration of elements such as aluminum nickel, and the amount of aluminum injection was determined based on the measurement results.
  • the amount of aluminum injected is kept to a minimum and the dose rate of piping is reduced by configuring a control system that controls can do.
  • a method of operating a nuclear power plant and a nuclear power plant can be provided.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)

Abstract

Cette invention concerne un ion métallique à l'aide duquel il est possible de fabriquer une structure de corindon, laquelle reste continuellement dans le circuit primaire de refroidissement d'eau durant le fonctionnement d'une centrale nucléaire. Ce système permet d'éviter la déposition, sur les parois internes du circuit primaire de refroidissement d'eau, d'ion de cobalt bivalent de cobalt-60 ou de cobalt-58, lequel est l'un des principaux composants d'un nucléide radioactif qui se dépose sur la tuyauterie pour former un ferrite contenant du cobalt. Ce système permet de réduire en toute sécurité la dose d'irradiation reçue par la tuyauterie.
PCT/JP1995/000040 1995-01-18 1995-01-18 Centrale electrique nucleaire et procede de fonctionnement WO1996022605A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP52215396A JP3179500B2 (ja) 1995-01-18 1995-01-18 原子力プラント及びその運転方法
PCT/JP1995/000040 WO1996022605A1 (fr) 1995-01-18 1995-01-18 Centrale electrique nucleaire et procede de fonctionnement

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP1995/000040 WO1996022605A1 (fr) 1995-01-18 1995-01-18 Centrale electrique nucleaire et procede de fonctionnement

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WO1996022605A1 true WO1996022605A1 (fr) 1996-07-25

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7844024B2 (en) 2004-07-22 2010-11-30 Hitachi-Ge Nuclear Energy, Ltd. Suppression method of radionuclide deposition on reactor component of nuclear power plant and ferrite film formation apparatus

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5337484A (en) * 1976-09-20 1978-04-06 Hitachi Ltd Monitor for radiant rays
JPS6179194A (ja) * 1984-09-27 1986-04-22 株式会社東芝 炉水給水装置
JPS61170697A (ja) * 1985-01-25 1986-08-01 株式会社日立製作所 原子炉

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5337484A (en) * 1976-09-20 1978-04-06 Hitachi Ltd Monitor for radiant rays
JPS6179194A (ja) * 1984-09-27 1986-04-22 株式会社東芝 炉水給水装置
JPS61170697A (ja) * 1985-01-25 1986-08-01 株式会社日立製作所 原子炉

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7844024B2 (en) 2004-07-22 2010-11-30 Hitachi-Ge Nuclear Energy, Ltd. Suppression method of radionuclide deposition on reactor component of nuclear power plant and ferrite film formation apparatus
US7889828B2 (en) 2004-07-22 2011-02-15 Hitachi-Ge Nuclear Energy, Ltd. Suppression method of radionuclide deposition on reactor component of nuclear power plant and ferrite film formation apparatus
US8457270B2 (en) 2004-07-22 2013-06-04 Hitachi-Ge Nuclear Energy, Ltd. Suppression method of radionuclide deposition on reactor component of nuclear power plant

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Publication number Publication date
JP3179500B2 (ja) 2001-06-25

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