U.S. patent application number 14/084157 was filed with the patent office on 2014-05-22 for platinum oxide colloidal solution, manufacturing method therefor, manufacture apparatus thereof, and method of injection noble metal of boiling water nuclear power plant.
This patent application is currently assigned to Hitachi-GE Nuclear Energy Ltd.. The applicant listed for this patent is Hitachi-GE Nuclear Energy Ltd.. Invention is credited to Kazushige ISHIDA, Nobuyuki OTA, Masahiko TACHIBANA, Yoichi WADA.
Application Number | 20140140465 14/084157 |
Document ID | / |
Family ID | 50727933 |
Filed Date | 2014-05-22 |
United States Patent
Application |
20140140465 |
Kind Code |
A1 |
ISHIDA; Kazushige ; et
al. |
May 22, 2014 |
Platinum Oxide Colloidal Solution, Manufacturing Method Therefor,
Manufacture Apparatus Thereof, and Method of Injection Noble Metal
of Boiling Water Nuclear Power Plant
Abstract
An aqueous solution of alkali hexahydroxo platinate is produced.
As a alkali hexahydroxo platinate, sodium hexahydroxoplatinate or
potassium hexahydroxoplatinate is used. The aqueous solution of
alkali hexahydroxo platinate is passed through a hydrogen form
cation exchange resin layer in a cation exchange resin tower. The
aqueous solution of alkali hexahydroxo platinate makes contact with
the hydrogen form cation exchange resin of the hydrogen form cation
exchange resin layer, thus a suspension of hexahydroxo platinic is
generated. If gamma rays are irradiated to the suspension, a
platinum oxide colloidal solution in which colloidal particles
including a platinum dioxide, a platinum monoxide, and a platinum
hydroxide exist is generated. In a platinum oxide colloidal
solution, the content of impurities is little and a noble metal
compound is dispersed stably in water.
Inventors: |
ISHIDA; Kazushige; (Tokyo,
JP) ; TACHIBANA; Masahiko; (Tokyo, JP) ; WADA;
Yoichi; (Tokyo, JP) ; OTA; Nobuyuki; (Hitachi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi-GE Nuclear Energy Ltd. |
Hitachi-shi |
|
JP |
|
|
Assignee: |
Hitachi-GE Nuclear Energy
Ltd.
Hitachi-shi
JP
|
Family ID: |
50727933 |
Appl. No.: |
14/084157 |
Filed: |
November 19, 2013 |
Current U.S.
Class: |
376/306 ;
422/186; 502/172; 502/339; 502/5 |
Current CPC
Class: |
B01J 39/18 20130101;
B01J 2219/12 20130101; B01J 19/082 20130101; G21C 15/28 20130101;
B01J 13/0047 20130101; B01D 15/362 20130101; G21C 17/0225 20130101;
C02F 1/42 20130101; B01J 39/04 20130101; B01J 37/344 20130101; B01J
2219/0877 20130101; B01J 23/42 20130101 |
Class at
Publication: |
376/306 ;
502/339; 502/172; 502/5; 422/186 |
International
Class: |
G21C 15/28 20060101
G21C015/28; B01J 37/34 20060101 B01J037/34; B01J 31/28 20060101
B01J031/28; C02F 1/42 20060101 C02F001/42; B01J 23/42 20060101
B01J023/42 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2012 |
JP |
2012-253078 |
Feb 26, 2013 |
JP |
2013-035424 |
Claims
1. A method of manufacturing a platinum oxide colloidal solution
comprising an ion exchange process of substituting hydrogen ions
for cations included in an aqueous solution of hexahydroxoplatinate
salt and generating a suspension; and a colloid generation process
of irradiating gamma rays to said suspension.
2. The method of manufacturing a platinum oxide colloidal solution
according to claim 1, wherein said aqueous solution comes into
contact with a hydrogen form cation exchange resin in said ion
exchange process.
3. The method of manufacturing a platinum oxide colloidal solution
according to claim 1, wherein said hexahydroxoplatinate salt is
sodium hexahydroxoplatinate or potassium hexahydroxoplatinate.
4. The method of manufacturing a platinum oxide colloidal solution
according to claim 1, wherein said aqueous solution includes
alcohol.
5. The method of manufacturing a platinum oxide colloidal solution
according to claim 4, wherein when the number of carbons
configuring a molecule of said alcohol is n, a concentration of
said alcohol is lower than 0.17/n (mM).
6. The method of manufacturing a platinum oxide colloidal solution
according to claim 4, wherein when the number of carbons
configuring a molecule of said alcohol is n, a concentration of
said alcohol is 0.03/n (mM) or lower.
7. The method of manufacturing a platinum oxide colloidal solution
according to claim 1, wherein an irradiation quantity of said gamma
rays is 7 kGy or larger.
8. A platinum oxide colloidal solution manufacturing apparatus
comprising: a cation exchange resin filling unit for substituting
hydrogen ions for cations included in an aqueous solution of
hexahydroxoplatinate salt and generating a suspension; a reaction
vessel connected to said cation exchange resin filling unit and
supplying said suspension from said cation exchange resin filling
unit; and a gamma ray generation apparatus facing to said reaction
vessel and irradiating gamma rays to said suspension in said
reaction vessel.
9. The platinum oxide colloidal solution manufacturing apparatus
according to claim 8, comprising: a pump for supplying a liquid to
said cation exchange resin filling unit.
10. A platinum oxide colloidal solution, wherein said solution is
an aqueous solution including platinum oxide colloidal
particles.
11. The platinum oxide colloidal solution according to claim 10,
wherein said colloidal particles include a platinum oxide and a
platinum hydroxide having a platinum valence of 2 to 4.
12. The platinum oxide colloidal solution according to claim 10,
wherein said colloidal particles include a platinum dioxide of 90
atomic % or higher.
13. The platinum oxide colloidal solution according to claim 10,
wherein said aqueous solution includes alcohol, and Wherein when
the number of carbons configuring a molecule of said alcohol is n,
a concentration of said alcohol is lower than 0.17/n (mM).
14. The platinum oxide colloidal solution according to claim 10,
wherein said colloidal particles do not practically include an
alkaline metal and an alkaline earth metal.
15. The platinum oxide colloidal solution according to claim 10,
wherein said colloidal particles are practically made up of only
platinum, oxygen, and hydrogen.
16. A method of injecting a noble metal of a boiling water nuclear
power plant, comprising of steps: injecting a noble metal compound
colloidal solution including colloidal particles including a noble
metal oxide and a noble metal hydroxide, each surface of said
colloidal particles being charged negatively at pH of 5.6 or
higher, into a pipe connected to a reactor pressure vessel through
an injection pipe connected to said pipe of said reactor pressure
vessel; and injecting said noble metal compound colloidal solution
into cooling water in said reactor pressure vessel through said
pipe connected to said reactor pressure vessel.
17. The method of injecting a noble metal of a boiling water
nuclear power plant according to claim 16, wherein colloidal
particles including a platinum oxide and a platinum hydroxide are
used as said colloidal particles.
18. The method of injecting a noble metal of a boiling water
nuclear power plant according to claim 17, wherein gamma rays are
irradiated to a hexahydroxo platinate suspension generated by
substituting hydrogen ions for cations included in a hexahydroxo
platinate solution; and Wherein a platinum oxide colloidal solution
generated by said irradiation of said gamma rays and including said
colloidal particles including said platinum oxide and said platinum
hydroxide is used as said noble metal compound colloidal
solution.
19. The method of injecting a noble metal of a boiling water
nuclear power plant according to claim 16, wherein a particle
diameter of said colloidal particles is within a range from 1 nm to
4.5 nm.
20. The method of injecting a noble metal of a boiling water
nuclear power plant according to claim 16, wherein said noble metal
compound colloidal solution including said colloidal particles is
mixed with a solution including zinc; and wherein said noble metal
compound colloidal solution including said colloidal particles and
zinc is injected into said pipe connected to said reactor pressure
vessel.
Description
CLAIM OF PRIORITY
[0001] The present application claims priority from Japanese Patent
application serial no. 2012-253078, filed on Nov. 19, 2012 and
Japanese Patent application serial no. 2013-035424, filed on Feb.
26, 2013, the content of which is hereby incorporated by reference
into these application.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates to a platinum oxide colloidal
solution, a manufacturing method therefor, a manufacture apparatus
thereof, and a method of injecting a noble metal of a boiling water
nuclear power plant.
[0004] 2. Background Art
[0005] In a boiling water nuclear power plant, it is important from
the viewpoint of improving operation rate of the boiling water
nuclear power plant to suppress stress corrosion cracking of
reactor internals installed in a reactor pressure vessel and pipes
(for example, recirculation pipes) connected to the reactor
pressure vessel.
[0006] Regarding the stress corrosion cracking, the following is
known and measures for the stress corrosion cracking are taken.
High-temperature and high-pressure cooling water (hereinafter,
referred to as reactor water) in contact with the reactor
internals, and the pipes connected to the reactor pressure vessel
contains oxygen and hydrogen peroxide generated by radiolysis of
the reactor water in a core in the reactor pressure vessel.
Therefore, the stress corrosion cracking progresses remarkably as
the oxygen concentration and hydrogen peroxide concentration in the
reactor water increase. The progress of each stress corrosion
cracking in the reactor internal and pipes in contact with the
reactor water can be suppressed by reducing the oxygen
concentration and hydrogen peroxide concentration in the reactor
water.
[0007] There is noble metal injection as a typical method for
suppressing the stress corrosion cracking. The noble metal
injection is a technology of injecting a compound of a noble metal
(platinum, rhodium, or palladium) into the reactor water,
depositing the noble metal on surfaces of the reactor internals and
an inner surface of each pipe connected to the reactor pressure
vessel, and injecting hydrogen into the reactor water (for example,
refer to Japanese Patent Laid-open No. 7 (1995)-311296). The noble
metal promotes the respective reactions of hydrogen with each of
oxygen and hydrogen peroxide and reduces the oxygen concentration
and hydrogen peroxide concentration in the reactor water in contact
with the surfaces of the reactor internals and the inner surface of
each pipe connected to the reactor pressure vessel. Japanese Patent
Laid-open No. 7 (1995)-311296 describes an acetylacetonate compound
of a noble metal and a nitric compound of a noble metal as a noble
metal compound to be injected into the reactor water. In Japanese
Patent Laid-open No. 7 (1995)-311296, a solution with the nitric
compound of the noble metal dissolved in water or a solution with
the acetylacetonate compound of the noble metal dissolved in
alcohol such as ethanol is injected into the reactor water.
[0008] On the other hand, although not for the reactor water, in
Japanese Patent Laid-open No. 2002-245854, a metal colloidal liquid
containing a compound having respectively at least one of an amino
group and a carboxyl group is disclosed. Here, gold, silver,
copper, platinum, palladium, rhodium, ruthenium, iridium, osmium
and others as a metallic component are cited. Further, it is
described that light such as UV, an electron beam, and thermal
energy may be used for reduction of metallic salt. Furthermore, as
a method for washing a solution including metallic colloidal
particles, a method of demineralizing by an ultra-filter or an ion
exchanger is described.
[0009] It is described in Japanese Patent Laid-open No. 2003-215289
that nano particles including a noble metal are injected into the
reactor water. In Japanese Patent Laid-open No. 2003-215289, ZnO,
Al.sub.2O.sub.3, or ZrO.sub.2 as a neutral active material is used
and noble metal nano particles with a noble metal (platinum,
palladium, ruthenium, rhodium, osmium, or iridium) adhered on the
surface of the neutral active material are injected into the
reactor water flowing through the recirculation system connected to
the reactor pressure vessel. Hydrogen is injected into the reactor
water and the hydrogen and the oxygen contained in the reactor
water are reacted to water by the catalytic activity of the noble
metal. As a result, the dissolved oxygen concentration in the
reactor water is reduced.
[0010] Further, Japanese Patent Laid-open No. 2005-10160 describes
a method of preventing stress corrosion cracking of structural
material. In the method of preventing the stress corrosion
cracking, an enriched suspension of catalyst nano particles of a
noble metal (for example, platinum) is injected into the reactor
water in the reactor pressure vessel through the pipe (for example,
a residual heat removal pipe, a recirculation pipe, and a water
feed pipe, etc.) connected to the reactor pressure vessel.
[0011] The pipes connected to the reactor pressure vessel are made
up of stainless steel or carbon steel, so that if any pipe is
exposed to high-temperature water, the inner surface (liquid
contact surface) of the pipe is covered with an oxide film
containing a main component of .alpha.-Fe.sub.2O.sub.3. It is
reported that a point of zero charge (pH when the surface potential
becomes 0) of .alpha.-Fe.sub.2O.sub.3 is 3.7 to 5.2 at 23.degree.
C. and 3.4 at 235.degree. C. (P. Jayaweera et al., Colloids and
Surfaces A: Physicochemical and Engineering Aspects, 85, pp. 19-27
(1994)).
CITATION LIST
Patent Literature
[0012] [Patent Literature 1] Japanese Patent Laid-open No. 7
(1995)-311296 [0013] [Patent Literature 2] Japanese Patent
Laid-open No. 2002-245854 [0014] [Patent Literature 3] Japanese
Patent Laid-open No. 2003-215289 [0015] [Patent Literature 4]
Japanese Patent Laid-open No. 2005-10160
Non Patent Literature
[0015] [0016] [Non Patent Literature] P. Jayaweera et al., Colloids
and Surfaces A: Physicochemical and Engineering Aspects, 85, pp.
19-27 (1994)
SUMMARY OF THE INVENTION
Technical Problem
[0017] A solution that nitric acid compound of the noble metal is
dissolved in water or a solution that acetylacetonate compound of
the noble metal is dissolved in alcohol such as ethanol which are
described in Japanese Patent Laid-open No. 7 (1995)-311296 brings
not only the noble metal but also nitric acid, acetylacetone, or
alcohol into the reactor water. The nitric acid compound discharges
nitric acid ions into the reactor water, so that there is a
possibility of increasing electric conductivity of the reactor
water. The acetylacetonate compound and alcohol discharge organic
acid ions and carbon ions into the reactor water, so that there is
a possibility of increasing the electric conductivity of the
reactor water. The increase in the electric conductivity of the
reactor water is not preferable from the viewpoint of corrosion
suppression of the structural member of the nuclear power
plant.
[0018] It is desirable to reduce the electric conductivity of the
reactor water from the viewpoint of corrosion suppression of the
structural member of the nuclear power plant. Furthermore,
impurities may be activated by neutron irradiation in the core and
become an exposure source. Therefore, it is preferable to reduce
the impurity content in the reactor from the viewpoint of exposure
reduction.
[0019] On the other hand, to inject a noble metal compound into the
reactor water, it is necessary that the noble metal compound is
stably dispersed in the solution that the compound is injected. If
the noble metal compound is not dispersed stably in the concerned
solution and is in a depositable form, the noble metal compound is
deposited in the pipe through which it is injected into the reactor
water and the pipe is blocked, so that there is a fear that the
noble metal compound may not be injected into the reactor
water.
[0020] The colloidal particles included in the metallic colloidal
liquid described in Japanese Patent Laid-open No. 2002-245854
contain a main component of a metal but do not contain a main
component of a metallic oxide. Further, the deminaralization by the
ion exchanger described in Japanese Patent Laid-open No.
2002-245854 is executed after generation of the metallic colloidal
particles and it is considered difficult to sufficiently remove
ions adsorbed to the colloidal particles.
[0021] Regarding the injection of the noble metal nano particles
with the noble metal adhered on the surface of the neutral active
material which is described in Japanese Patent Laid-open No.
2003-215289 and the injection of the noble metal catalyst nano
particles which is described in Japanese Patent Laid-open No.
2005-10160, since nitric acid, acetylacetone, and alcohol are not
injected into the reactor water, the increase in the electric
conductivity of the reactor water can be avoided and the corrosion
of the plant structural member can be suppressed. However, as a
result of the examination on the noble metal injection methods
described in Japanese Patent Laid-open No. 2003-215289 and Japanese
Patent Laid-open No. 2005-10160, the inventors found that the
problem explained below arises.
[0022] The point of zero charge (pH when the surface potential
becomes 0) of ZnO, Al.sub.2O.sub.3, and ZrO.sub.2 which are neutral
active materials described in Japanese Patent Laid-open No.
2003-215289 is 9 to 11 and the neutral active material is
positively charged in neutral pure water (pH 7) (in the case of
alkaline from the point of zero charge, charged negatively and in
the case of acidity, charged positively). On the other hand, an
inner surface of an injection pipe of the noble metal nano particle
injecting apparatus connected to the pipe connected to the reactor
pressure vessel is covered with an iron oxide film and the point of
zero charge of the iron oxide is 3.7 to 5.2, so that the inner
surface of the injection pipe is charged negatively when this inner
surface comes into contact with the neutral pure water (pH 7).
Therefore, there is a risk that the neutral active material is
adsorbed electrostatically to the oxide on the inner surface of the
injection pipe. If the neutral active material with the noble metal
adhered on its surface is deposited on the inner surface of the
injection pipe, the quantity of the noble metal (for example,
platinum) brought into the reactor pressure vessel is reduced and
in correspondence to it, the neutral active material with the noble
metal adhered on its surface must be injected excessively.
[0023] In Japanese Patent Laid-open No. 2005-10160, when injecting
the enriched suspension of the catalyst nano particles of the noble
metal into the reactor water in the reactor pressure vessel through
the injection pipe of the noble metal nano particle injector
connected to the pipe connected to the reactor pressure vessel,
there is a risk that a part of the nano particles included in the
enriched suspension precipitates in the injection pipe with no
stirrer installed. Therefore, the noble metal quantity injected
into the reactor water in the reactor pressure vessel is reduced,
so that the catalyst nano particles of the noble metal must be
injected excessively.
[0024] A first object of the present invention is to provide a
platinum oxide colloidal solution which has little impurity content
and in which the noble metal compound is stably dispersed in
water.
[0025] A second object of the present invention is to provide a
method of injecting a noble metal of the boiling water nuclear
power plant capable of suppressing deposition of the noble metal on
an inner surface of a injection pipe and increasing quantity of the
noble metal injected into cooling water in a reactor pressure
vessel.
Solution to Problem
[0026] A feature of the first invention for attaining the above
first object is that a suspension is generated by substituting
hydrogen ions for cations included in an aqueous solution of
hexahydroxoplatinate salt, and a platinum oxide colloidal solution
is manufactured by irradiating the obtained suspension with gamma
rays.
[0027] A feature of the second invention for attaining the above
second object is that a noble metal compound colloidal solution
including colloidal particles including a noble metal oxide and a
noble metal hydroxide, a surface of each of the colloidal particles
being charged negatively at pH of 5.6 or higher, is injected into a
pipe connected to a reactor pressure vessel through an injection
pipe connected to the pipe connected to the reactor pressure
vessel; and the noble metal compound colloidal solution is injected
into cooling water in the reactor pressure vessel through the pipe
connected to the reactor pressure vessel.
[0028] When the noble metal compound colloidal solution including
the colloidal particles is injected into the cooling water in the
reactor pressure vessel through the injection pipe connected to the
pipe connected to the reactor pressure vessel and the pipe
connected to the reactor pressure vessel, the colloidal particles
included in the noble metal compound colloidal solution are not
adsorbed to each inner surface of the injection pipe and the pipe
connected to the reactor pressure vessel because the surface of
each of the colloidal particles is charged negatively at pH of 5.6
or higher. Therefore, the quantity of the colloidal particles
injected into the cooling water in the reactor pressure vessel can
be increased and the quantity of the noble metal injected into the
cooling water can be increased.
Advantageous Effect of the Invention
[0029] According to the first invention, a platinum oxide colloidal
solution that the content of impurities (a compound including an
element except platinum, oxygen, and hydrogen) is little and
platinum oxide colloidal particles are stably dispersed in water
can be obtained. When injecting the platinum oxide colloidal
solution into the reactor water, the pipe used for injection can be
prevented from clogging. And, when injecting the platinum oxide
colloidal solution into the reactor water, the impurities can be
prevented from mixing with the reactor water. As a result, the
increase in the electric conductivity of the reactor water can be
suppressed.
[0030] According to the second invention, deposition of the noble
metal to each inner surface of the injection pipe and the pipes
connected to the reactor pressure vessel to which the injection
pipe is connected is suppressed and the quantity of the noble metal
injected into the cooling water in the reactor pressure vessel can
be increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a flow chart showing a method of manufacturing
platinum oxide colloidal solution according to embodiment 1 which
is a preferable embodiment of the present invention.
[0032] FIG. 2 is a schematic diagram showing an apparatus of
substituting metallic ions included in solution of
hexahydroxoplatinate salt for hydrogen ions, the apparatus being
used for a method of manufacturing platinum oxide colloidal
solution of embodiment 1.
[0033] FIG. 3 is a structural diagram showing the apparatus of
irradiating gamma rays to suspension of hexahydroxo platinic.
[0034] FIG. 4 is a characteristic diagram showing a relation
between absorption dose of gamma rays and concentration of
generated platinum oxide colloidal solution.
[0035] FIG. 5 is an explanatory drawing showing results of
investigation of influence of methanol on reduction of hexahydroxo
platinic.
[0036] FIG. 6 is a transmission electron microscopic photograph
showing platinum oxide colloidal particles included in platinum
oxide colloidal solution manufactured in embodiment 1.
[0037] FIG. 7 is a graph showing X-ray photoelectron spectroscopy
(XPS) analytical results of platinum oxide colloidal particles
included in platinum oxide colloidal solution manufactured in
embodiment 1.
[0038] FIG. 8 is a structural diagram showing a manufacturing
apparatus of platinum oxide colloidal solution used for a method of
manufacturing platinum oxide colloidal solution according to
embodiment 2 which is another preferable embodiment of the present
invention.
[0039] FIG. 9 is an explanatory drawing showing electrophoresis of
platinum oxide colloidal particles.
[0040] FIG. 10 is a characteristic diagram showing hydrochloric
acid titration measurement results of platinum oxide colloids.
[0041] FIG. 11 is an explanatory drawing showing a particle
diameter distribution of platinum oxide colloidal particles
included in platinum oxide colloidal solution.
[0042] FIG. 12 is a structural diagram showing a boiling water
nuclear power plant to which a method of injecting noble metal of a
nuclear power plant according to embodiment 3 which is another
preferable embodiment of the present invention is applied.
[0043] FIG. 13 is a detailed structural diagram showing a noble
metal compound injecting apparatus shown in FIG. 12.
[0044] FIG. 14 is an explanatory drawing showing a change of
stainless steel corrosion potential due to injection of platinum
oxide colloidal solution into high-temperature water at 280.degree.
C.
[0045] FIG. 15 is a characteristic diagram showing the influence of
oxygen and hydrogen peroxide concentrations on stainless steel
corrosion potential in high-temperature water at 280.degree. C.
[0046] FIG. 16 is a structural diagram showing a noble metal
compound injecting apparatus applied to a method of injecting noble
metal of a nuclear power plant according to embodiment 4 which is
another preferable embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] The inventors examined manufacturing of platinum oxide
colloidal solution (platinum oxide sol) of which impurity content
is little and noble metal compound is dispersed stably in
water.
[0048] As a result, the inventors found that gamma rays are
irradiated to a suspension of hexahydroxo platinic generated by
substituting alkaline ions (Na.sup.+, K.sup.+) in an aqueous
solution of hexahydroxoplatinate salt (sodium hexahydroxoplatinate
(Na.sub.2Pt(OH).sub.6) or potassium hexahydroxoplatinate
(K.sub.2Pt(OH).sub.6)), that is, alkali hexahydroxo platinate for
the hydrogen ions (H.sup.+), thus the above platinum oxide
colloidal solution can be generated.
[0049] To substitute the hydrogen ions for the alkaline ions
(cations) in the aqueous solution of the alkali hexahydroxo
platinate, it is desirable to permit the aqueous solution of the
alkali hexahydroxo platinate to pass through an adsorption layer
filled with hydrogen form cation exchange resin (cation exchange
resin with hydrogen ions adsorbed to cation exchange group), thus
substituting the alkaline ions for hydrogen ions included in
hydrogen form cation exchange resin. If the hydrogen ions are
substituted for the alkaline ions, the suspension of hexahydroxo
platinic (the suspension of hexahydroxo platinic acid) is
generated.
[0050] Then, if gamma rays are irradiated to the suspension of
hexahydroxo platinic, a brown and transparent platinum oxide
colloidal solution is generated. The generation of the platinum
oxide colloidal solution depends on the absorption dose which is a
product of the absorption dose rate of the irradiated gamma rays
and the irradiation time. If the absorption dose is small,
hexahydroxoplatinic particles remain. The hexahydroxoplatinic
particles in the suspension of hexahydroxo platinic generated by
substituting the alkaline ions for the hydrogen ions float in water
for one to two days, though after a longer period of time than it,
those particles are deposited. Therefore, it is desirable to
irradiate gamma rays until platinum oxide colloid is generated. If
gamma rays are irradiated 7 kGy or more as an absorption dose, the
hexahydroxo platinic can be made to platinum oxide colloid.
[0051] The methanol concentration included in the aqueous solution
of the alkali hexahydroxo platinate or the suspension of the
hexahydroxo platinic must be set to 0.03 mM (M is mol/L) or lower.
The reason is that if the methanol concentration becomes higher
than this, the hexahydroxo platinic is reduced to a platinum metal
and is deposited. In the case of ethanol and propanol, they must be
respectively set to 0.015 mM and 0.01 mM or lower.
[0052] Hereinafter, the preferable embodiments of the present
invention will be explained in detail by referring to the
drawings.
Embodiment 1
[0053] A method of manufacturing platinum oxide colloidal solution
according to embodiment 1 which is a preferable embodiment of the
present invention will be explained by referring to FIGS. 1, 2, and
3.
[0054] FIG. 1 shows manufacturing processes of the platinum oxide
colloidal solution.
[0055] The manufacturing processes of the platinum oxide colloidal
solution include three processes.
[0056] An aqueous solution of a alkali hexahydroxo platinate
(hexahydroxoplatinate salt) at a predetermined concentration is
produced (step S101). The metallic ions (cations such as sodium
ions and potassium ions are removed from the aqueous solution (step
S102) (an ion exchange process). Gamma rays are irradiated to the
suspension generated due to removal of the metallic ions (step
S103) (a colloidal generation process).
[0057] In step S101, the aqueous solution of the alkali hexahydroxo
platinate is produced. When the alkali hexahydroxo platinate is
obtained as a solid, the solid is dissolved in pure water and the
aqueous solution of the alkali hexahydroxo platinate at a
predetermined concentration is produced. When the alkali
hexahydroxo platinate is obtained as a aqueous solution, it is
diluted by pure water to the predetermined concentration.
[0058] In step S102, hydrogen ions are substituted for the metallic
ions included in the aqueous solution of the alkali hexahydroxo
platinate. The preferable method is a method using the hydrogen
form cation exchange resin. When the aqueous solution of the alkali
hexahydroxo platinate is supplied to an adsorption layer filled
with the hydrogen form cation exchange resin and is come into
contact with the hydrogen form cation exchange resin, the cations
(Na.sup.+ or K.sup.+) included in the solution are adsorbed to the
hydrogen form cation exchange resin and the hydrogen ions are
discharged into the aqueous solution. By doing this, the cations
such as sodium ions and potassium ions are removed from the aqueous
solution of the alkali hexahydroxo platinate.
[0059] FIG. 2 is a schematic diagram showing an apparatus for
substituting the metallic ions in the aqueous solution of the
alkali hexahydroxo platinate for the hydrogen ions.
[0060] As shown in FIG. 2, the aqueous solution of the alkali
hexahydroxo platinate stored in a vessel 21 is supplied to a
hydrogen form cation exchange resin tower 22 having the adsorption
layer filled with the hydrogen form cation exchange resin. The
aqueous solution flowing out from the adsorption layer filled with
the hydrogen form cation exchange resin in the hydrogen form cation
exchange resin tower 22 is collected by a vessel 23. When the
aqueous solution of the alkali hexahydroxo platinate comes into
contact with the hydrogen form cation exchange resin in the
hydrogen form cation exchange resin tower 22, the hydrogen ions
included in the hydrogen form cation exchange resin in the
adsorption layer are substituted for the metallic ions included in
the aqueous solution of the alkali hexahydroxo platinate and the
aqueous solution becomes cloudy. The reason is that immediately
after the substitution of the metallic ions for the hydrogen ions,
the hardly soluble hexahydroxo platinic included in the solution is
precipitated in the solution. Here, the solution got cloudy by the
hexahydroxo platinic is called a suspension of hexahydroxo
platinic. If the suspension of hexahydroxo platinic is produced by
such a method, the hexahydroxo platinic particles float in water
for about one to two days. However, the hexahydroxo platinic
particles are deposited after a longer period of time than
this.
[0061] In step S103, gamma rays are irradiated to the suspension of
hexahydroxo platinic. The irradiation of gamma rays to the
suspension of hexahydroxo platinic is executed while the
hexahydroxo platinic particles float in water.
[0062] FIG. 3 shows a structure of an apparatus for irradiating
gamma rays.
[0063] A vessel 35 filled with the suspension 32 of the hexahydroxo
platinic is installed in the vicinity of a gamma rays generation
source 31 (gamma rays generation apparatus) as shown in FIG. 3. The
irradiation rate of gamma rays 33 from the gamma rays generation
source 31 to the suspension 32 of the hexahydroxo platinic in the
vessel 35 is decided so as to set the absorption dose to 7 kGy or
higher. The operations of injection of gas and stirring of the
liquid are not necessary.
[0064] The appropriate irradiation rate of the gamma rays 33 is set
based on experimentation.
[0065] FIG. 4 shows a relation between absorption dose of gamma
rays and concentration of generated platinum oxide colloid. Here,
as an example of the alkali hexahydroxo platinate, sodium
hexahydroxoplatinate is used. The platinum concentration used for
the experimentation is about 2.6 mM. A horizontal axis indicates an
absorption dose of gamma rays and a vertical axis indicates a mol
concentration (based on the colloidal solution volume) of the
platinum included in the platinum oxide colloidal particles.
[0066] FIG. 4 shows that when the platinum oxide colloidal
concentration increases in correspondence to the increase in the
absorption dose and the absorption dose reaches 7 kGy or higher,
all the amount of platinum in the liquid becomes platinum oxide
colloid within the range of measurement variations. It is confirmed
that when the absorption dose rate is within the range from 0.22 to
2.37 kG/h, the same results are obtained.
[0067] According to the aforementioned manufacturing processes, the
colloidal solution is generated after the cations such as sodium
ions and potassium ions are removed from the aqueous solution of
the hexahydroxoplatinate, so that the concerned cations can be
prevented from adsorbing to the colloidal particles.
[0068] When dissolving the alkali hexahydroxo platinate in water,
there is a case that it is dispersed in alcohol such as methanol
and then is added into water. Even when the alkali hexahydroxo
platinate is hardly soluble in water, it is known that if it is
dispersed in alcohol, it may be dissolved in water. By such an
operation, there is a possibility that alcohol may be included in
the aqueous solution of the alkali hexahydroxo platinate.
[0069] To examine the influence of alcohol, a relation between
methanol addition concentration and the absorption dose when
methanol is added as alcohol and existence of generation of a
platinum oxide colloidal solution are examined.
[0070] FIG. 5 shows the results. A horizontal axis indicates a
methanol concentration and a vertical axis indicates the absorption
dose. Further, in FIG. 5, a mark of .largecircle. (white circle)
indicates generation of a brown and transparent solution and a mark
of (black circle) indicates generation of a black deposit.
[0071] When the methanol addition concentration is 0.03 mM or
lower, a brown and transparent solution is generated and no black
deposit is generated. On the other hand, when the methanol addition
concentration is 0.17 mM or higher, a black deposit is generated.
Therefore, the methanol concentration must be suppressed preferably
to lower than 0.17 mM and more preferably to 0.03 mM or lower.
[0072] When another alcohol (C.sub.nH.sub.2n+1OH, n=1, 2, - - - )
is contained, generally, the methanol concentration may be
suppressed preferably to lower than 0.17/n (mM) and more preferably
to 0.03/n (mM) or lower. For example, n=2 indicates ethanol, though
in the case of methanol, the methanol concentration may be
suppressed preferably to 0.085 mM or lower and more preferably to
0.015 mM or lower. Further, n=3 indicates propanol, though in the
case of propanol, the propanol concentration may be suppressed
preferably to 0.056 mM or lower and more preferably to 0.01 mM or
lower.
[0073] As aforementioned, the apparatuses shown in FIGS. 2 and 3
are of a batch type.
[0074] The characteristics of the platinum oxide colloidal solution
manufactured by the manufacturing method of the platinum oxide
colloidal solution of the present embodiment will be explained
hereunder.
[0075] The platinum oxide colloidal solution is an aqueous solution
containing platinum oxide colloidal particles.
[0076] The colloidal particles include platinum oxide and platinum
hydroxide having a platinum valence of 2 to 4.
[0077] The colloidal particles desirably include platinum dioxide
of 90 atomic % of higher.
[0078] An aqueous solution including colloidal particles of
platinum oxide may include alcohol. As for alcohol, when the number
of carbons configuring the molecule thereof is n, the alcohol
concentration is desirably lower than 0.17/n (mM).
[0079] FIG. 6 is a transmission electron microscopic photograph
showing the platinum oxide colloidal particles included in the
platinum oxide colloidal solution manufactured in the present
embodiment.
[0080] In FIG. 6, the mean particle diameter of a colloidal
particle 71 is 2.30.+-.0.52 nm. Here, the mean particle diameter is
a value obtained by measuring the diameters of the particles
displayed on the transmission electron microscopic photograph in a
fixed direction and calculating a mean value.
[0081] FIG. 7 is a graph showing the X-ray photoelectron
spectroscopy analytical results of the platinum oxide colloidal
particles of the embodiment included in the platinum oxide
colloidal solution manufactured in the present embodiment. The
horizontal axis indicates binding energy and a vertical axis
indicates intensity of phtoelectrons.
[0082] FIG. 7 shows that the colloidal particles have a main
component of PtO.sub.2 and contain PtO and Pt(OH).sub.2. Further,
impurities other than Pt, 0, and H are not detected and it is found
that the colloidal particles are substantially made up of only
these 3 elements.
[0083] The colloidal particles do not substantially include an
alkali metal and an alkaline earth metal.
[0084] Table 1 shows the calculated results of the rates of these
components.
TABLE-US-00001 TABLE 1 Compound Pt(OH).sub.2 PtO PtO.sub.2 at % 3 6
91 PtO.sub.2 is 91 atomic %, and 6 atomic % of PtO and 3 atomic %
of Pt(OH).sub.2 are included.
[0085] Further, it is found that the platinum oxide colloidal
particles are charged negatively by the electrophoresis
measurement.
[0086] According to the present embodiment, the platinum oxide
colloidal solution that the content of impurities (compounds
including elements except platinum, oxygen, and hydrogen) is little
and the platinum oxide colloidal particles are dispersed stably in
water can be obtained. When injecting the platinum oxide colloidal
solution into the reactor water, the pipe used for injection can be
prevented from clogging. And, when injecting the platinum oxide
colloidal solution into the reactor water, the impurities can be
prevented from mixing with the reactor water. As a result, the
increase in the electricity conductivity of the reactor water can
be suppressed.
Embodiment 2
[0087] The manufacturing method of the platinum oxide colloidal
solution according to 2 which is another preferable embodiment of
the present invention will be explained by referring to FIG. 8. In
the manufacturing method of the present embodiment, the platinum
oxide colloidal solution can be manufactured continuously.
[0088] FIG. 8 shows a structure of a manufacturing apparatus of the
platinum oxide colloidal solution used for the manufacturing method
of the platinum oxide colloidal solution of the present embodiment
and the manufacturing apparatus can manufacture continuously the
platinum oxide colloidal solution.
[0089] A platinum oxide colloidal solution manufacturing apparatus
60 for manufacturing the platinum oxide colloidal solution is
provided with a vessel 61 for storing the aqueous solution of the
alkali hexahydroxo platinate, a hydrogen form cation exchange resin
tower (cation exchange resin tower) 63 filled with the hydrogen
form cation exchange resin, a reaction vessel 64, a vessel 66 for
storing the platinum oxide colloidal solution, and a gamma rays
generation apparatus 67. The vessel 61 and the reaction vessel 64
are connected with a pipe 68, and the hydrogen form cation exchange
resin tower 63 is installed on the pipe 68. A pump 62 is installed
on the pipe 68 between the vessel 61 and the hydrogen form cation
exchange resin tower 63. The pump 62 pressurizes the aqueous
solution of the alkali hexahydroxo platinate which is a raw
material. Further, the reaction vessel 64 and the vessel 66 are
connected with a pipe 65. The gamma rays generation apparatus 67
faces to the reaction vessel 64. Gamma rays 33 from the gamma rays
generation apparatus 67 are irradiated to a liquid passing through
the reaction vessel 64 from the gamma rays generation apparatus
67.
[0090] In the platinum oxide colloidal solution manufacturing
apparatus 60, the aqueous solution of the alkali hexahydroxo
platinate adjusted to a predetermined concentration is stored in
the vessel 61 and the aqueous solution is supplied to the hydrogen
form cation exchange resin tower 63 by the pump 62.
[0091] When the aqueous solution of the alkali hexahydroxo
platinate passes through the hydrogen form cation exchange resin
tower 63, hydrogen ions are substituted for the metallic ions
included in the aqueous solution of the alkali hexahydroxo
platinate and a suspension of hexahydroxo platinic is generated.
The suspension is introduced into the reaction vessel 64 through
the pipe 68 and the gamma rays 33 are irradiated to the suspension
in the reaction vessel 64.
[0092] Irradiation of the gamma rays 33 of 7 kGy is necessary to
change the suspension of hexahydroxo platinic in the whole quantity
to a platinum oxide colloidal solution. For example, when the dose
rate is 2 kGy/h, so that the suspension of hexahydroxo platinic
stays in the reaction vessel 64 for more than 3.5 hours, the flow
rate of the suspension of hexahydroxo platinic discharged from the
pump 62 is adjusted. The platinum oxide colloidal solution
generated in the reaction vessel 64 is introduced to the vessel 66
through the pipe 65 and is stored in the vessel 66.
[0093] The platinum oxide colloidal solution manufactured by the
manufacturing method of the platinum oxide colloidal solution of
the present embodiment has the aforementioned characteristics
possessed by the platinum oxide colloidal solution manufactured by
the manufacturing method of the platinum oxide colloidal solution
of embodiment 1.
[0094] The present embodiment can obtain each effect produced in
embodiment 1.
Embodiment 3
[0095] The inventors examined noble metal adsorption phenomenon to
suppress the adsorption of the noble metal on the inner surface of
the injection pipe. As a result, the following is found. An inner
surface of an injection pipe of a noble metal injection apparatus
connected to a pipe (for example, a water feed pipe, and a reactor
purification system pipe, etc.) connected to a reactor pressure
vessel is covered with an iron oxide while solution including noble
metal is injected into the pipe connected to the reactor pressure
vessel through the injection pipe. As a result, the inner surface
of the injection pipe is charged negatively when it makes contact
with neutral pure water (pH 7). When a neutral aqueous solution
with a noble metal dissolved flows through the injection pipe,
cations (for example, Pt.sup.4+) of the noble metal in the aqueous
solution are electrostatically adsorbed to the negatively charged
inner surface of the injection pipe.
[0096] Material is charged positively when it is acid than the
point of zero charge and is charged negatively when it is alkaline.
The pH of water flowing through the pipe connected to the reactor
pressure vessel is within a range from 5.6 to 8.6, so that it is
considered that the inner surface of the pipe connected to the
reactor pressure vessel is charged negatively. Therefore, the
inventors reached the conclusion that if a material including a
noble metal a surface of which is charged negatively when pH is 5.6
or higher, is used in order to prevent the noble metal from
depositing to the respective negatively charged inner surfaces of
the pipe connected to the reactor pressure vessel and the injection
pipe connected to the aforementioned pipe, the adsorption of the
material including the noble metal on each inner surface of the
pipe connected to the reactor pressure vessel and the injection
pipe can be suppressed due to the electrostatic force of repulsion
and the material including the noble metal can be injected
effectively into the reactor water in the reactor pressure
vessel.
[0097] On the basis of this conclusion, the inventors examined the
manufacture of material including a noble metal with the surface
charged negatively. As a result, colloidal particles (platinum
oxide colloidal particles) the surface of which are charged
negatively, which include platinum oxide and platinum hydroxide,
and has platinum oxide as a main component, can be
manufactured.
[0098] The platinum oxide colloidal solution including the platinum
oxide colloidal particles can be manufactured by the manufacturing
method of the platinum oxide colloidal solution of embodiment 2
using the platinum oxide colloidal solution manufacturing apparatus
60. Further, the platinum oxide colloidal solution including the
platinum oxide colloidal particles can be manufactured even by the
manufacturing method of the platinum oxide colloidal solution of
embodiment 1.
[0099] When manufacturing the platinum oxide colloidal solution
including the platinum oxide colloidal particles using the platinum
oxide colloidal solution manufacturing apparatus 60, firstly, the
aqueous solution of alkali hexahydroxo platinate to be filled in
the vessel 61 is produced as mentioned above (step S101). The
aqueous solution of alkali hexahydroxo platinate to be produced is
a solution of sodium hexahydroxoplatinate (Na.sub.2Pt(OH).sub.6) or
a solution of potassium hexahydroxoplatinate (K.sub.2Pt(OH).sub.6).
The aqueous solution of alkali hexahydroxo platinate in the vessel
61 passes through a hydrogen form cation exchange resin layer in
the hydrogen form cation exchange resin tower (the cation exchange
resin tower) 63 (step S102). The aqueous solution of alkali
hexahydroxo platinate makes contact with the hydrogen form cation
exchange resin in the hydrogen form cation exchange resin layer,
thus, a suspension of hexahydroxo platinic is generated in the
hydrogen form cation exchange resin tower 63. The gamma rays 33 are
irradiated to the suspension of hexahydroxo platinic in the
reaction vessel 64 (step S103). If the gamma rays 33 are irradiated
to the suspension of hexahydroxo platinic at an absorption dose of
7 kGy or higher, a platinum oxide colloidal solution, in which
there exist colloidal particles (platinum oxide colloidal
particles) including platinum dioxide (PtO.sub.2), platinum
monoxide (PtO), and platinum hydroxide (Pt(OH).sub.2) can be
produced. As a result of an analysis of the platinum oxide
colloidal particles by the X-ray photoelectron spectroscopy (XPS),
the platinum oxide colloidal particles include PtO.sub.2 of 91
atomic %, PtO of 6 atomic %, and Pt(OH).sub.2 of 3 atomic % (refer
to Table 1). As mentioned above, the platinum oxide colloidal
particles are mostly platinum oxide. The platinum dioxide
(PtO.sub.2) and platinum monoxide (PtO) are a platinum oxide and
the platinum hydroxide (Pt(OH).sub.2) is a platinum hydroxide. The
platinum oxide colloidal solution is a noble metal compound
colloidal solution including colloidal particles including a
platinum oxide and a platinum hydroxide.
[0100] The inventors made an experiment for investigation of the
electrophoresis of the platinum oxide colloidal solution generated.
As shown in FIG. 9, a petri dish 40 is filled with agar 45 with
potassium chloride added and a positive electrode 41 connected to a
conductive line 42 and a negative electrode 43 connected to a
conductive line 44 are installed separately on both opposite side
walls of the petri dish 40. The positive electrode 41 and the
negative electrode 43 are in contact with the agar 45 in the petri
dish 40. A brown and transparent platinum oxide colloidal solution
46 is dripped on the agar 45 in the petri dish 40. In this status,
a voltage is applied between the positive electrode 41 and the
negative electrode 43 and the platinum oxide colloidal solution 46
is subjected to the electrophoresis. As a result, as shown in FIG.
9, it is found that colloidal particles 47 including brown and
transparent platinum oxide and platinum hydroxide existing in the
platinum oxide colloidal solution 46 gather on the side of the
positive electrode 41 and the colloidal particles 47 are charged
negatively.
[0101] Furthermore, the inventors titrated hydrochloric acid in the
platinum oxide colloidal solution 46, changed the pH of the
platinum oxide colloidal solution 46, measured the pH of the
platinum oxide colloidal solution 46, and observed precipitation of
the platinum oxide colloidal particles 47. The pH measured values
of the platinum oxide colloidal solution 46 are shown in FIG. 10
together with the pH calculated values of the platinum oxide
colloidal solution 46. FIG. 10 shows that the pH calculated values
calculated from the injection of the hydrochloric acid and the pH
measured values coincide with each other in the vicinity of pH 3.0
and the surface potential of the platinum oxide colloidal particles
becomes 0. At the time of titration of the hydrochloric acid, when
the pH of the platinum oxide colloidal solution 46 is in the
vicinity of 3.5, platinum oxide colloidal particles are
precipitated. Therefore, it is found that the generated platinum
oxide colloidal solution is charged negatively at pH of 5.6 or
higher.
[0102] A transmission electron microscopic photograph of the
generated platinum oxide colloidal particles is shown in FIG. 6.
Further, the particle diameter distribution of the platinum oxide
colloidal particles (refer to FIG. 6) observed by the transmission
electron microscope is shown in FIG. 11. As a result of observation
by the transmission electron microscope, it is found that the
particle diameter of the platinum oxide colloidal particles is
within a range from 1.0 nm to 4.5 nm and the platinum oxide
colloidal particles are nano particles. The platinum oxide
colloidal solution manufactured by the aforementioned method is
kept in a stably dispersed state for more than 6 months in the room
temperature rest state.
[0103] A method of injecting a noble metal of the nuclear power
plant according to embodiment 3 which is other preferable
embodiment of the present invention to which the aforementioned
investigation results of the inventors are reflected will be
explained by referring to FIGS. 12 and 13.
[0104] Firstly, a structure of a boiling water nuclear power plant
25 to which the method of injecting a noble metal of the nuclear
power plant of the present embodiment is applied will be explained
by referring to FIG. 12. The boiling water nuclear power plant 25
is provided with a reactor pressure vessel 1, a turbine 4, a
condenser 5, a reactor purification system, and a water feed system
and the like. In the reactor pressure vessel 1, a core 2 loading a
plurality of fuel assemblies is disposed internally. Each fuel
assembly includes a plurality of fuel rods filled with a plurality
of fuel pellets manufactured by a nuclear fuel material. A
plurality of internal pumps (not drawn) are installed at the bottom
of the reactor pressure vessel 1. A main steam pipe 3 connected to
the reactor pressure vessel 1 is connected to the turbine 4.
[0105] The water feed system is structured so as to install a
condensate filter demineralizer 7, a water feed pump 8, and a feed
water heater 9 on a water feed pipe 6 which is connected the
condenser 5 and the reactor pressure vessel 1, from the condenser 5
toward the reactor pressure vessel 1 in this order. The turbine 4
is installed on the condenser 5 and the condenser 5 is communicated
with the turbine 4. A bypass pipe 10 connected to the main steam
pipe 3 is connected to the condenser 5 through the feed water
heater 9.
[0106] The reactor purification system has a structure in which a
purification system pump 12, a regeneration heat exchanger 13, a
non-regeneration heat exchanger (not drawn), and a reactor water
purification apparatus 14 are installed on a purification system
pipe 11 for connecting the reactor pressure vessel 1 and the water
feed pipe 10 in this order. The purification system pipe 11 is
connected to the water feed pipe 6 on the downstream side of the
feed water heater 9. The reactor pressure vessel 1 is installed in
the reactor primary containment vessel disposed in the reactor
building (not drawn).
[0107] Cooling water in the reactor pressure vessel 1 (hereinafter,
referred to as reactor water) is pressurized by the internal pump
and is supplied to the core 2. The reactor water supplied to the
core 2 is heated by heat generated by nuclear fission of the
nuclear fuel material in each fuel rod and a part of the heated
reactor water is vaporized. The steam is removed moisture by the
steam separator (not drawn) and steam drier (not drawn) installed
in the reactor pressure vessel 1, then is introduced from the
reactor pressure vessel 1 to the turbine 4 through the main steam
pipe 3, and rotates the turbine 4. The generator (not drawn)
connected to the turbine 4 rotates and power is generated.
[0108] The steam discharged from the turbine 4 is condensed to
water by the condenser 5. The water, as feed water, is supplied
into the reactor pressure vessel 1 through the water feed pipe 6.
The feed water flowing through the water feed pipe 6 is removed
impurities by the condensate filter demineralizer 7 and is
pressurized by the water feed pump 8. The feed water is heated in
the feed water heater 9 by extraction steam extracted from the main
steam pipe 3 by the bypass pipe 10 and is introduced into the
reactor pressure vessel 1 through the water feed pipe 6.
[0109] A part of the reactor water in the reactor pressure vessel 1
flows into the purification system pipe 11 of the reactor
purification system by driving of the purification system pump 12,
is cooled by the regeneration heat exchanger 13 and the
non-regeneration heat exchanger, and then is purified by the
reactor water purification apparatus 14. The purified reactor water
is heated by the regeneration heat exchanger 13 and is returned
into the reactor pressure vessel 1 through the purification system
pipe 11 and the water feed pipe 6.
[0110] A hydrogen injection apparatus 15 and a platinum oxide
colloid injection apparatus 16 are connected to the water feed pipe
6 on the downstream side of the condensate filter demineralizer 7.
The platinum oxide colloidal injection apparatus 16 includes a
colloidal solution tank 17, an injection pipe 18, and an injection
pump 19 as shown in FIG. 13. The injection pipe 18 connected to the
colloidal solution tank 17 is connected to the water feed pipe 6.
An open/close valve 20, a flow rate meter 26, the injection pump
19, and an open/close valve 24 are installed on the injection pipe
18 from the colloidal solution tank 17 toward the water feed pipe 6
in this order. Using the platinum oxide colloidal solution
manufacturing apparatus 60 shown in FIG. 8, the platinum oxide
colloidal solution produced by the method of manufacturing platinum
oxide colloidal solution shown in FIG. 1, that is, the platinum
oxide colloidal solution having the pH of 7 to 8.5 and including
the platinum oxide colloidal particles each surface of which is
charged negatively is filled in the colloidal solution tank 17. The
platinum oxide colloidal solution includes platinum oxide colloidal
particles with a diameter within a range from 1.0 nm to 4.5 nm and
including platinum dioxide (PtO.sub.2), platinum monoxide (PtO),
and platinum hydroxide (Pt(OH).sub.2), that is, platinum oxide
colloidal particles including platinum oxide and platinum
hydroxide. The platinum oxide colloidal particles are charged
negatively at the pH of 5.6 or higher.
[0111] When the boiling water nuclear power plant 25 is in
operation, hydrogen is injected from the hydrogen injection
apparatus 15 into the water feed pipe 6 and the platinum oxide
colloidal solution is injected from the platinum oxide colloidal
injection apparatus 16 into the water feed pipe 6. The hydrogen and
the platinum oxide colloidal solution injected into the feed water
flowing through the water feed pipe 6 are injected into the reactor
water in the reactor pressure vessel 1 through the water feed pipe
6.
[0112] The injection of the platinum oxide colloidal solution will
be explained concretely. If the open/close valves 20 and 24 are
opened and the pump 19 is driven, the platinum oxide colloidal
solution including the platinum oxide colloidal particles in the
colloidal solution tank 17 is injected into the feed water flowing
through the water feed pipe 6 and the injection pipe 18. The
platinum oxide colloidal solution in the colloidal solution tank
17, the feed water flowing through the water feed pipe 6, and the
reactor water in the reactor pressure vessel have the pH of 5.6.
The platinum oxide colloidal solution having the pH of 7 to 8.5 and
including the platinum oxide colloidal particles charged negatively
flows through the injection pipe 18 with the inner surface charged
negatively, so that the platinum oxide colloidal particles charged
negatively and the inner surface of the injection pipe 18 repel
each other, thus the platinum oxide colloidal particles included in
the platinum oxide colloidal solution are not adsorbed to the inner
surface of the injection pipe 18 and the platinum oxide colloidal
solution is injected into the water feed pipe 6. In correspondence
to the platinum oxide colloidal particles not adsorbed to the inner
surface of the injection pipe 18, the platinum oxide colloidal
particles injected into the water feed pipe 6 are increased in
quantity and the quantity of platinum oxide injected into the water
feed pipe 6 is increased. The inner surface of the water feed pipe
6 is also charged negatively, so that the platinum oxide colloidal
particles charged negatively which are injected into the feed water
with the pH of 5.6 are not adsorbed even to the inner surface of
the water feed pipe 6 and the platinum oxide colloidal particles
injected into the reactor water in the reactor pressure vessel 1
are increased. In the reactor pressure vessel 1, gamma rays
generated due to the nuclear fission of the nuclear fuel material
included in the fuel rods of each fuel assembly loaded in the core
2 are irradiated to the reactor water, so that hydrogen ions
(H.sup.+) are generated due to radiolysis of the reactor water and
radiolysis of hydrogen peroxide included in the reactor water. The
hydrogen ions combine with the oxygen of the platinum oxide
included in the platinum oxide colloidal particles injected into
the reactor water or OH of the platinum hydroxide to generate
water, so that the platinum of the platinum oxide and platinum
hydroxide becomes platinum ions (Pt.sup.4+). The platinum ions are
adsorbed to the surface (the surface in contact with the reactor
water) of the reactor internal in the reactor pressure vessel 1 and
the inner surface of the pipe connected to the reactor pressure
vessel 1 through which the reactor water flows.
[0113] As mentioned above, hydrogen is injected into the reactor
water, so that the reaction of the dissolved oxygen and hydrogen
peroxide included in the reactor water with hydrogen is promoted by
the action of the platinum adsorbed to the surface of the reactor
internal and the inner surface of the pipe. Therefore, the oxygen
concentration and hydrogen peroxide concentration in the reactor
water are reduced and the stress corrosion cracking of the reactor
internal and pipe in contact with the reactor water is suppressed.
The platinum oxide colloidal solution produced by the manufacturing
processes shown in FIG. 1 in which the platinum oxide colloidal
particles including platinum dioxide (PtO.sub.2), platinum monoxide
(PtO), and platinum hydroxide (Pt(OH).sub.2) exist, is injected
into a stainless steel pipe through which high-temperature water at
280.degree. C. following the reactor water flows, and the response
of the inner surface of the stainless steel pipe is investigated,
and the results are shown in FIG. 14. The high-temperature water at
280.degree. C. including hydrogen peroxide of 400 ppb and hydrogen
of 130 ppb flows through the stainless steel pipe and the platinum
oxide colloidal solution in which the aforementioned platinum oxide
colloidal particles exist is injected from the upstream side. As a
result, if the platinum oxide colloidal solution is injected,
immediately, the corrosion potential of the stainless steel pipe is
reduced from 0.0 VvsSHE to -0.5 VvsSHE. Even if the injection of
the platinum oxide colloidal solution is stopped, the corrosion
potential of the stainless steel pipe is maintained just at -0.5
VvsSHE.
[0114] The relation between the oxygen concentration and hydrogen
peroxide concentration in the high-temperature water and the
corrosion potential of the stainless steel pipe is shown in FIG.
15. If the oxygen concentration in the high-temperature water
becomes 10 ppb or lower or the hydrogen peroxide concentration in
the high-temperature water becomes 1 ppb or lower, the corrosion
potential of the stainless steel pipe is reduced to -0.5 VvsSHE.
Namely, by this experiment, it is confirmed that the platinum oxide
colloidal particles are deposited on the inner surface of the
stainless steel pipe and the oxygen on the inner surface of the
stainless steel pipe is reduced to 10 ppb and the hydrogen peroxide
concentration is reduced to 1 ppb or lower.
[0115] According to the present embodiment, the platinum oxide
colloidal solution including the platinum oxide colloidal particles
including platinum oxide and platinum hydroxide, the platinum oxide
colloidal particles being charged negatively within the range of pH
of 5.6 or higher, is injected into the water feed pipe 6 through
the injection pipe 18 and furthermore is injected into the reactor
water in the reactor pressure vessel 1, so that the platinum oxide
colloidal particles are not adsorbed to the inner surface of the
injection pipe 18 and the quantity of the platinum oxide colloidal
particles injected into the reactor water in the reactor pressure
vessel 1 is increased. Therefore, as usual, in consideration of
deposition of platinum on the respective inner surfaces of the
injection pipe 18 and the water feed pipe 6, excessive injection of
platinum can be avoided. In the present embodiment, when the
quantity of platinum injected into the reactor water exceeds a
necessary predetermined quantity due to an increase in the
injection quantity of the platinum oxide colloidal particles into
the reactor water, the platinum oxide colloidal solution injected
from the colloidal solution tank 17 into the water feed pipe 6 can
be reduced.
[0116] The platinum oxide colloidal particles injected into the
reactor water are nano particles having a particle diameter within
a range from 1.0 nm to 4.5 nm, so that even if a dispersant such as
alcohol is not used, the particles are dispersed stably in the
reactor water. Therefore, platinum can be deposited effectively on
the surface of the reactor internal in the reactor pressure vessel
1 and the inner surface of the pipe connected to the reactor
pressure vessel 1 through which the reactor water flows.
[0117] In the present embodiment, the platinum oxide colloidal
solution including the platinum oxide colloidal particles and
injected into the reactor water is generated in the processes shown
in FIG. 1 by generating the suspension of hexahydroxo platinic by
substituting hydrogen ions for the cations included in the
hexahydroxo platinate solution, and irradiating gamma rays to the
suspension of hexahydroxo platinic, so that the content of
impurities is little and the platinum oxide colloidal particles
become nano particles. Therefore, due to injection of the platinum
oxide colloidal solution into the reactor water, the impurities
injected in the reactor water become very little. The platinum
oxide colloidal particles are nano particles with the particle
diameter aforementioned, so that as mentioned above, the
dispersibility to the reactor water is improved.
[0118] The injection pipe 18 of the platinum oxide colloid
injection apparatus 16 may be connected to another pipe connected
to the reactor pressure vessel 1, for example, the purification
system pipe 11 or the pipe of the residual heat removal system
instead of the water feed pipe 6. When connecting the injection
pipe 18 to the purification system pipe 11, the injection pipe 18
may be connected to the purification system pipe 11 on the
downstream side of the reactor water purification apparatus 14.
Embodiment 4
[0119] A method of injecting a noble metal of the nuclear power
plant according to embodiment 4 which is other preferable
embodiment of the present invention will be explained by referring
to FIG. 16.
[0120] A platinum oxide colloid injection apparatus 16A used for
the method of injecting a noble metal of the present embodiment,
similarly to the platinum oxide colloid injection apparatus 16,
includes the colloidal solution tank 17, the injection pipe 18, and
the injection pump 19 as shown in FIG. 16. The open/close valve 20,
the flow rate meter 26, and the injection pump 19 are installed on
the injection pipe 18 connected to the colloidal solution tank 17
in this order from the colloidal solution tank 17 toward the
downstream side. The injection pipe 18 is connected to an injection
pipe 27 of a zinc injection apparatus (not drawn) connected to the
water feed pipe 6. An open/close valve 28 is installed on the
injection pipe 27 and a connection point of the injection pipe 18
to the injection pipe 27 is positioned on the upstream side of the
open/close valve 28. The colloidal solution tank 17 is filled with
the platinum oxide colloidal solution including the platinum oxide
colloidal particles which has the pH of 7 to 8.5 and is charged
negatively.
[0121] The nuclear power plant to which the method of injecting a
noble metal of the present embodiment is applied has a structure
that the platinum oxide colloid injection apparatus 16 is replaced
with the platinum oxide colloid injection apparatus 16A in the
boiling water nuclear power plant 25 shown in FIG. 12. The
injection pipe 27 is connected to the water feed pipe 6. Similarly
to embodiment 3, the injection pipe 27 may be connected to the
purification system pipe 11 on the downstream side of the reactor
water purifier 14.
[0122] When the boiling water nuclear power plant is in operation,
the open/close valves 20 and 28 are opened and the injection pump
19 is driven, thus the platinum oxide colloidal solution having the
pH of 7 to 8.5 and including the platinum oxide colloidal particles
which is charged negatively is injected into the feed water in the
water feed pipe 6 from the colloidal solution tank 17 through the
injection pipes 18 and 27. The feed water of pH 6 including the
platinum oxide colloidal particles is injected into the reactor
water of pH 5.6 in the reactor pressure vessel 1 through the water
feed pipe 6. The platinum included in the platinum oxide colloidal
particles in the reactor water, similarly to embodiment 1, is
adsorbed to the surface of the reactor internal in contact with the
reactor water and the inner surface of the pipe connected to the
reactor pressure vessel 1. The dissolved oxygen concentration and
the hydrogen peroxide concentration in the reactor water are
reduced by the action of the platinum and the generation of stress
corrosion cracking in the reactor internal and pipe is
suppressed.
[0123] A solution including zinc is injected into the water feed
pipe 6 from the injection pipe 27 of the zinc injection apparatus.
As a result, the solution including zinc and the platinum oxide
colloidal solution are mixed in the injection pipe 27 and the mixed
solution is supplied to the water feed pipe 6. The pH of the
solution including zinc is 4 to 6, so that the platinum colloidal
particles charged negatively which are included in the platinum
oxide colloidal solution are not adsorbed to the respective inner
surfaces of the injection pipes 18 and 23.
[0124] The present embodiment can obtain each effect generated in
embodiment 3. Further, the present embodiment shares a part of the
injection pipe 27 for injecting the solution including zinc as a
pipe for injecting the platinum oxide colloidal solution, so that
the platinum oxide colloid injection apparatus 16A can be made
compacter than the platinum oxide colloid injector 16.
REFERENCE SIGNS LIST
[0125] 1: Reactor pressure vessel, 2: Core, 4: Turbine, 5:
Condenser, 6: Water feed pipe, 8: Water feed pump, 11: Purification
system pipe, 14: Reactor water purification apparatus, 15: Hydrogen
injection apparatus, 16, 16A: Platinum oxide colloid injection
apparatus, 17: Colloidal solution tank, 18, 27: Injection pipe, 21,
23, 35, 61, 66: Vessel, 22, 63: Hydrogen form cation exchange resin
tower, 31: Gamma rays generation source, 32: Suspension of
hexahydroxo platinic, 33: Gamma rays, 60: Platinum oxide colloidal
solution manufacturing apparatus, 62: Pump, 64: Reaction vessel,
65, 68: Pipe, 67: Gamma rays generation apparatus, 71: Colloidal
particles
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