JP3400518B2 - Water quality control method for boiling water nuclear power plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to a boiling water nuclear power plant.
Control rod drive mechanism and water quality control method
(CRD) housing and furnace instrumentation tube (ICM) housing
Structural materials provided in the reactor bottom area, such as
Stress corrosion cracking (SCC) crack growth of (stainless steel)
Of carbon steel materials around the reactor such as
Boiling water type controlling hydrogen injection suitable for suppressing wall thinning
Nuclear power plantofIt relates to a water quality control method. [0002] 2. Description of the Related Art In general, furnaces of a boiling water nuclear power plant
Oxygen and hydrogen molecules are generated by radioactive decomposition of water
The oxygen concentration and hydrogen peroxide concentration at the bottom of the reactor
The defined effective oxygen concentration is about
It rises to 200 ppb. This effective oxygen concentration is high
And stress corrosion cracking (SCC) of stainless steel.
It is known to increase the sensitivity of others
As described in JP-B-63-19838,
Measure the corrosion potential of the secondary cooling water, dissolved oxygen and dissolved hydrogen,
By controlling the amount of hydrogen injection according to each measurement, water
Of radioactive decomposition of the reactor water to reduce the concentration of dissolved oxygen in the reactor water
It is thought that. In this case, as shown in the known example,
As described above, the primary cooling water measurement is performed in the reactor recirculation system and the water supply system.
It is common practice to provide a sampling line
You. [0003] Also, Japanese Patent Application Laid-Open No. 3-85495 describes
In a nuclear power plant,
Connect the sampling line to the bottom drain line
Then, the water at the bottom of the reactor is
Quality is measured directly using a corrosive environment monitor and the hydrogen injection
There is something to control. [0004] SUMMARY OF THE INVENTION
Conventional technologies have the following problems. JP-B-63-198
In the prior art described in Japanese Patent Publication No. 38-38, as described above,
Measurement of dissolved oxygen concentration measurement equipment provided with water in the reactor recirculation system
The amount of hydrogen injected into the water supply system is controlled based on the results.
However, the water quality at the bottom of the reactor
Controls dissolved oxygen concentration in reactor recirculation system, slightly different from quality
Does not accurately control the dissolved oxygen concentration at the bottom of the reactor.
No. For this reason, CRD housing and ICM housing
How SCC of Structural Materials Provided at the Bottom of the Reactor
Was not appropriate. In addition, stainless steel
SCTo delay the progress of C, lower the dissolved oxygen concentration in the reactor water.
Pipes connected to the bottom of the reactor or reactor
Carbon steel material is used for coolant purification system piping equipment
In the case of a plant, if the dissolved oxygen concentration is too low, carbon steel
Accelerates corrosion. Therefore, the dissolved oxygen concentration at the bottom of the reactor
If the concentration cannot be controlled accurately, the dissolved oxygen concentration will decrease.
There was also concern that corrosion of carbon steel materials would be accelerated. Further, Japanese Patent Application Laid-Open No. 3-85495 describes
In the conventional technology, the water quality of the pressure vessel bottom drain line
The amount of hydrogen injected into the water supply system is controlled while measuring. Only
A sampling line at the bottom drain of the furnace bottom.
To prevent clogging in pipes due to sedimentation cladding and dose rate
There are concerns about the rise of the monitor, etc.
Is expected to be difficult to maintain for long-term use
SuitableAbsent. As a long-term monitoring method,
Sampling line for recirculation system, water supply system, etc.
It is desirable to provide. An object of the present invention is to reduce the effective oxygen concentration at the bottom of the furnace.
To accurately control and maintain the effective oxygen concentration properly
To appropriately mitigate corrosive environments such as reactor bottom equipment
Water quality control for boiling water nuclear power plants
The lawTo provide. [0007] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
According to the present invention,Pipes and sources connected to the bottom of the reactor
Carbon steel material is used in the piping system of the reactor coolant purification system.
ToWater quality control method for boiling water nuclear power plant.
In the reactor recirculation system or reactor coolant purification system
Effective oxygen defined by the oxygen concentration and hydrogen peroxide concentration
Measuring concentration, reactor recirculation system determined in advance
Or the effective oxygen concentration of the reactor coolant purification system and the reactor bottom
Based on the correlation with the effective oxygen concentration of
Determining the effective oxygen concentration at the bottom of the reactor,Reactor found
The effective oxygen concentration at the bottom is not less than 15 ppb and not more than 50 ppb
To be within the rangeControls the amount of hydrogen injected into reactor water
To doFeatures of boiling water nuclear power plant water
A quality control method is provided. [0008] [0009] [0010] [0011] [0012] [0013] [0014] [Function] Analysis and evaluation of water quality in a nuclear reactor by the present inventors
As a result, the effectiveness of the reactor recirculation system or reactor coolant purification system
Oxygen concentration, effective oxygen concentration at the bottom of the reactor, and hydrogen concentration in the water supply system
It was found that the correlation between degree and degree could be grasped quantitatively.
The present invention is based on this finding.,Reactor recirculation system
Or the effective oxygen concentration of the reactor coolant purification system and the reactor bottom
The correlation with the effective oxygen concentration of
Reactor recirculation system for easy maintenance
Or in the reactor coolant purification system, based on the correlation
Oxygen concentration in the reactor recirculation system or reactor coolant purification system
The effective oxygen concentration at the bottom of the reactor is calculated from the measured
The effective oxygen concentration at the bottom of the furnace is within a predetermined range (that is,
Control the amount of hydrogen injected so that. As described above, the injection amount of hydrogen is controlled using the correlation.
Control to monitor the corrosive environment at the bottom of the reactor.
Control the amount of hydrogen injected, making replacement difficult
More accurate water quality control for equipment at the bottom of the reactor
And the injection amount is the minimum necessary (That is,
Positive injection volume)Will be controlled in the reactor bottom area
Of SCC crack growth in structural materials and reactor cooling
Suppress corrosion thinning of carbon steel materials around furnaces such as waste material purification systems
Can be Also, the installation position of the sampling line
Is limited to reactor recirculation or reactor coolant purification systems
Therefore, the maintenance of water quality measurement equipment is also required.
Reactor building outside reactor containment that can be accessed during normal operation
Measurement system for the connection line from the furnace bottom
It is much easier than. Also, maintain equipment reliability
Is also easy. According to experimental data, hydrogen injection
When the dissolved oxygen concentration is reduced to 50 ppb or less,
The crack growth rate drops to about 1/10 of the normal
When the elemental concentration is reduced to 15ppb or less, the corrosion rate of carbon steel becomes
Starting to rise, lowering the effective oxygen concentration to below 5 ppb
Then, the corrosion rate of carbon steel rises to several hundred mdm
I understood. [0017] Therefore, pipes and raw materials connected to the furnace bottom are
Carbon steel material is used in the piping system of the reactor coolant purification system.
PlantAgainst, The control range of the effective oxygen concentration is 5 ppb
５０50 ppb, more preferably 15 ppb ≦ [O₂]
_eff≤50 ppb to suppress corrosion and
Can be prevented. [0018] [0019] Embodiments of the present invention will be described below with reference to the drawings.
You. First, the boiling water nuclear power according to the first embodiment of the present invention
Power plantWater quality control methodAnd boiling water power plant
Will be described with reference to FIGS. In FIG. 1, the book
The boiling water nuclear power plant according to the embodiment includes a reactor 1,
The main steam pipe P1 and the steam generated from the reactor 1
A turbine 2 sent via P1 to drive the generator;
The condensate collected by the condenser 2a at the bottom of the
The water supply system 50 which circulates and returns to the
A reactor recirculation system 51 for returning filtered reactor water to the core bottom,
Branching from the reactor recirculation system 51, purifying the reactor water and supplying water 5
Reactor coolant purification system 52 to return to 0 and draining of reactor water
And a target reactor bottom drain system 53.
The water supply system 50 includes a condensate pump 23, a condensate purification device 3,
Feed water heaters 4A, 4B, feed pump 20, and
It is composed of connecting pipes P2 to P7. Reactor recirculation
The ring system 51 includes the recirculation pump 21 and the recirculation pump 21.
It is composed of pipes P8 and P9 connected to the reactor 1.
The reactor coolant purification system 52 includes a purification system pump 24 and purified water.
Heaters 5A and 5B, filter desalter 6 and connect these
It is composed of pipes P17 to P23. Reactor bottomed
The rain system 53 includes pipes P12 to P12 forming a drain line.
P14 and valves 31, 32. Dre
From the pipeline P12 of the pipeline, a pipe P with a valve 33
15 and P16 branch, and piping P16 cleans the reactor coolant.
Reactor cooling water is connected to the system 52
52 performs partial purification. In addition, the program of this embodiment
The runt controls the water quality at the bottom of the reactor in addition to the above configuration.
And a hydrogen injection system 54 for performing the operation. This hydrogen injection system
Reference numeral 54 denotes a branch from the reactor coolant purification system 52 and
Pipes P24, P25 and valve 35 constituting the grin
And O installed at the end of this sampling line_TwoMo
Nita 11 and O_TwoUsing the detection values of the monitor 11
Oxygen concentration in the furnace recirculation system [O_Two] And the concentration of hydrogen peroxide [H_TwoO
_TwoThe effective oxygen concentration [O_Two]_effThe value of the reactor
A control device 12 for converting into an effective oxygen concentration at the bottom, and a water supply system
And a hydrogen injection facility 55 installed at 50. water
The element injection equipment 55 includes the hydrogen supply source 13 and the hydrogen supply source 13.
Pipes P26 and P27 to connect to the water supply system 50, and valves
36, and a hydrogen injection line composed of Ba
The lube 36 responds to an electric signal output from the control device 12.
The opening degree is controlled by the controller 12, and the controller 12
According to the effective oxygen concentration at the bottom of the reactor
An electric signal for controlling the opening of the valve 36 is generated. O_TwoReactor water measured by monitor 11
Effective oxygen concentration determined by oxygen concentration and hydrogen peroxide concentration
Is the hydrogen peroxide concentration [H_TwoO_Two] Stoichiometric ratio
And is defined by the following equation: [O_Two]_eff= [O_Two] +1/2 [H_TwoO_Two] However, [O_Two]_eff: Effective oxygen concentration [O_Two]: Oxygen concentration [H_TwoO_Two]: Hydrogen peroxide concentration Usually, H_TwoO_TwoAre sampling lines P24 and P25
Because it is almost completely decomposed, O_TwoBy monitor 11
[O_Two] +1/2 [H_TwoO_TwoMeasure the dissolved oxygen concentration corresponding to
Can be specified. In this embodiment, the reactor coolant
The sampling line is branched from the purification system 52 and the effective oxygen
The concentration was measured.
From the sampling line to measure the effective oxygen concentration.
Alternatively, the configuration may be as follows. FIG. 2 shows details of the control function of the control device 12.
This will be described with reference to a flowchart. O_TwoMonitor 11
Measures the effective oxygen concentration in the reactor recirculation system.
When the electric signal is input to the control device 12 (step 10)
0), the measured value of the effective oxygen concentration was
Between the effective oxygen concentration in the circulation system and the effective oxygen concentration in the reactor bottom
Conversion based on the correlation to determine the effective oxygen concentration at the bottom of the reactor
(Step 101). Effective acid of this reactor recirculation system
Preliminary analysis of correlation between elemental concentration and effective oxygen concentration at reactor bottom
Or store what you have determined by experiment in memory
It is a thing. Effectiveness of reactor bottom obtained in this way
It is determined whether the oxygen concentration is 5 ppb or more (step 1).
02), if the effective oxygen concentration is determined to be less than 5 ppb,
Generates an electrical signal to reduce the opening of the
Reduce the amount of hydrogen injected into the water supply system from the input facility 55
(Step 103). On the other hand, it is determined that the effective oxygen concentration is 5 ppb or more.
If it is, it is determined whether the effective oxygen concentration is 50 ppb or more.
(Step 104), the effective oxygen concentration is 50 ppb or less.
If it is determined to be lower, an electric signal for maintaining the opening of the valve 36 is provided.
And the amount of hydrogen injected from the hydrogen injection equipment 55 is maintained.
(Step 105). The effective oxygen concentration at the bottom of the reactor is 50 p.
pb or more, the opening of the valve 36 is increased.
Generates an electrical signal from the hydrogen injection equipment 55 to the water supply system.
The injection amount of hydrogen is increased (step 106). The amount of hydrogen injected by controlling the opening of the valve 36
Control the correlation between the amount of hydrogen injected and the water quality (effective oxygen concentration)
This can be implemented by inputting the information to the control device 12 in advance.
You. Thus, in this embodiment, the effective oxygen at the bottom of the reactor is
The concentration is controlled to be in the range of 5 ppb to 50 ppb.
It is. Next, the plant in this embodimentWater quality control
MethodThe concept and the effect of the above will be described. Recent water radiation
According to the model calculation results from the decomposition analysis, the water inside the reactor
The quality distribution differs greatly in each region in the furnace as shown in Fig. 4.
Is characterized. Also, as shown in FIG.
In the example of evaluation of a plant with a water pump,
The water quality of the part and other areas are different. This Figure 5 is for water supply
In the reactor when 0.4 ppm of hydrogen is injected
This is an example of the results of a model analysis of water quality. model
Although the analysis includes some assumptions in the reaction constants, etc.
It is generally known that the results agree relatively well with the measured values.
I have. In addition, dissolved oxygen in the reactor recirculation system and reactor bottom
Concentrations can vary considerably in recent studies, as shown in Figure 6.
I knew it. This is the oxygen in the downcomer part,
Due to the recombination effect of hydrogen peroxide and hydrogen, especially
Down at plant with jet pump with high flow rate
Inferior recombination effect in flaking area
This increases the oxygen concentration. As can be seen from the above, hydrogen injection
The effect of reducing the water-soluble oxygen content in the furnace also depends on the location in the furnace.
Monitoring system that takes this point into account
is necessary. As shown in FIG. 4 and FIG.
Effective oxygen concentration and source of reactor recirculation system or reactor coolant purification system
Phase between the effective oxygen concentration in the reactor bottom and the hydrogen concentration in the water supply system
It was also found that Seki could be grasped quantitatively. On the other hand, sampling that can be installed in a plant
The line is for maintenance of monitor reliability and maintenance.
Since the installation position is limited considering easiness,
Hydrogen injection based on measurements at their limited location
It is desirable to control This example is based on the above knowledge.
Reactor recirculation system as shown in FIG. 3 in advance
Or the phase of the reactor coolant purification system and the effective oxygen concentration at the bottom of the reactor
Stakes are required, and reactor maintenance is easy.
Measure oxygen concentration in circulation or coolant purification system
By controlling the hydrogen injection rate as an indicator,
It is possible to accurately control the water quality at the bottom. Also,
The sampling line is installed at the reactor recirculation system or
Since it is limited to the reactor coolant purification system, a water quality measurement device
Maintenance can be approached during normal operation
Since it can be installed inside the reactor building outside the PCV, the reactor
Extremely easy compared to the measurement system of the connection line from the bottom
is there. Also, it is easy to maintain the reliability of the device. The correlation shown in FIG. 3 can be used for analysis or testing.
Therefore, it may be determined. Figure7Is similar to the analysis shown in FIG.
The effective oxygen concentration of the recirculation system and the reactor bottom
The correlation with the effective oxygen concentration of the part was calculated. In FIG.
If the correlation shown is determined by analysis,7Of the correlation shown in
It is determined by taking the average value. Effective oxygen concentration in reactor recirculation system and reactor bottom
If the correlation with the effective oxygen concentration of
Injection test shows how much hydrogen is injected
For example, it gradually changes from 0 ppm to about 2.4 ppm
It can be obtained by changing as follows. In this case, a short-term trial
The measurement system at the time of the test is as shown in JP-A-3-85495.
Pressure vessel bottom drain piping or sampler at furnace bottom
This can be dealt with by providing a temporary installation line. On the other hand, when controlling the water quality at the bottom of the reactor,
Reactor bottom SCPerspective of C control and carbon steel corrosion reduction
It is important to understand the control range of the effective oxygen concentration from
is there. FIG. 8 shows the dissolved oxygen concentration obtained from experimental data and the like.
4 shows the relationship between the crack growth rate of stainless steel by SCC. This
As shown in the figure, the dissolved oxygen concentration was reduced to 50 ppb by hydrogen injection.
Below, the crack growth rate of SCC is 1/1
It can be seen that it drops to about 0.On the other hand, FIG.
It is a figure which shows the corrosion rate of carbon steel with respect to oxygen concentration. this
From the experimental data shown in FIG. 9, the effective oxygen concentration was 15 ppb
When it is reduced below, the corrosion rate of carbon steel starts to increase and 5pp
b, the corrosion rate of carbon steel is several hundred mdm.
(mg / dm^Two・ Mo) (Pipe thickness is about 2mm)
You can see that. Pipes and reactors actually connected to the bottom of the reactor
Coolant purification piping systems use carbon steel materials.
Where hydrogen is injected and hydrogen is injected in such a plant.
In that case, it is necessary to consider that point. This embodiment is based on the above findings.
8 and 9 that the effective oxygen concentration at the reactor bottom is 5
Control the amount of hydrogen injected so as to be ppb to 50 ppb
You. I put this idea togetherButIt is FIG. You
In other words, two conditions that conflict with each other when introducing hydrogen
Take into account. The first condition is that the structural material in the reactor bottom region is
SCC crack propagation delay, improving SCC life
For this purpose, the effective oxygen concentration at the bottom of the furnace is set to 50 ppb or less. Also
Another condition is to prevent corrosion of the bottom drain piping.
To reduce the effective oxygen concentration at the bottom of the furnace
To 5 ppb or more. Therefore, the distribution connected to the furnace bottom
Use of carbon steel materials for pipes and piping equipment for reactor coolant purification system
5ppb ≦ [O_Two]_eff≤50
ppb by controlling the hydrogen injection amount.
Of the bottom material of the reactor pressure vessel with a minimal amount of hydrogen injection
CC crack growth delay and carbon steel material around the reactor
Corrosion thinning can be prevented. As described above, according to the present embodiment, the boiling water type
CRD housing and ICM in nuclear power plants
Source such as housingChildPrecise control of the effective oxygen concentration at the bottom of the furnace
You can controlWith the proper amount of hydrogen injected,
The effective oxygen concentration at the bottom of the reactor can be maintained in an appropriate range.
Wear. Therefore,SC of structural material in reactor bottom region
Corrosion of reactor bottom equipment such as delaying C crack growth
environmentRelaxReactor that is difficult to replace
The integrity of the equipment material at the bottom can be maintained. In addition, the piping and the atom connected to the bottom of the reactor
Carbon steel material is used for piping equipment of the furnace coolant purification system.
In the case of a plant, the control range of the effective oxygen concentration is 5 ppb
≤ [O_Two]_eff≤50ppb for carbon steel material
Corrosion can be reliably prevented or suppressed.
Become. In addition, it is installed in a reactor recirculation system or a water supply system.
Conventional sampling line is available
No new sampling line is required. Also furnace
In comparison with the sampling line connected to the bottom,
It is unlikely that the dose rate will increase due to accumulation of
Maintenance of instruments, instruments, etc.
It is easy to maintain reliability. In the above embodiment, the effective acid
The elemental concentration was controlled in the range of 5 ppb to 50 ppb.
In order to further suppress the corrosion of the steel material, the solution shown in FIG.
From the results of the analysis, control in the range of 15 ppb to 50 ppb
Is preferred. In addition, the thickness of carbon steel material is
mm ppb ≤ [O_Two]_eff≦ 1
Corrosion is expected to proceed when 5 ppb is used.
Operates the plant while performing appropriate corrosion monitoring on a regular basis.
Make sure that the corrosion allowance has sufficient margin during the service life.
A countermeasure can be considered as an alternative. Therefore
Effective oxygen concentration can be changed from 5ppb to 15ppb
Noh. A second embodiment of the present invention will be described with reference to FIGS.
Will be described. In FIG. 11, equivalent to the members shown in FIG.
Are given the same reference numerals. Plant of this implementation
Is a hydrogen injection system 54 for controlling the water quality at the bottom of the reactor.
A is provided. The hydrogen injection system 54A includes a water supply system 50A.
The pipe P26, which branches off and forms a sampling line,
P27 and valve36And the end of this sampling line
H installed at the end_TwoMonitor 14 and H_TwoOn the monitor 14
Of the hydrogen concentration in the water supply system 50
A control device 12A for converting to an oxygen concentration and a water supply system 50 are provided.
And a hydrogen injection facility 55 installed. Valve 36
Is the opening according to the electric signal output from the controller 12A.
Is controlled by the controller 12A.
Valve 3 according to the effective oxygen concentration at the bottom of the reactor
6 to generate an electric signal for controlling the opening degree. FIG. 12 shows the details of the control function of the control device 12A.
This will be described with reference to the flowchart shown in FIG. H_Twomonitor
14, the hydrogen concentration in the water supply system 50 is measured,
When the signal is input to the control device 12A (step 30)
0), the measured value of the hydrogen concentration is shown in FIG.
Based on correlation between elemental concentration and effective oxygen concentration at reactor bottom
To obtain the effective oxygen concentration at the bottom of the reactor (step
301). Hydrogen concentration in this water supply system and effective acid at the bottom of the reactor
Correlation with elemental concentration was determined in advance by analysis or test
The thing is stored in the memory. Subsequent operations
Is the same as in the first embodiment. That is, the calculated reactor bottom
It is determined whether the effective oxygen concentration of the part is 5 ppb or more (S
(Step 302), it is determined that the effective oxygen concentration is less than 5 ppb.
Generates an electrical signal to reduce the opening of the valve 36
And the amount of hydrogen injected from the hydrogen injection equipment 55 into the water supply system 50
Is reduced (step 303). Effective oxygen concentration is 5p
If it is determined that the effective oxygen concentration is 50 ppb or more,
It is judged whether or not it is above (step 304).
If it is determined to be 50 ppb or less, the opening of the valve 36 is maintained.
Generates an electrical signal to carry the hydrogen from the hydrogen injection equipment 55
Is maintained (step 305). At the bottom of the reactor
If the effective oxygen concentration is determined to be 50 ppb or more, the valve
Generates an electric signal to increase the opening of the
Increase the amount of hydrogen injected from the storage 55 into the water supply system (step
306). Thus, in this embodiment, the reactor bottom
Is within the range of 5 ppb to 50 ppb
Is controlled as follows. The correlation shown in FIG.
It may be determined according to the difference. Analyzing the correlation shown in Figure 13
In the case of, the water supply for the reactor bottom water shown in Fig. 6
Obtained by taking the average value of hydrogen concentration and dissolved oxygen in the furnace
Can be Also, if required by testing, short-term injection
According to the test, the amount of injected hydrogen was adjusted to, for example, 0p
Change from pm to about 2.4 ppm step by step
The effective oxygen concentration at the bottom of the reactor.
Can be In this embodiment, the same as in the first embodiment is used.
The effect can be obtained. In addition, according to the present embodiment,
Since the hydrogen concentration in water is directly controlled,
And stable injection operation can be expected. A third embodiment of the present invention will be described with reference to FIG.
I do. This embodiment is different from the first embodiment in that the carbon steel material
To monitor the corrosion of steel. That is, in FIG.
And O_TwoThe monitor 11 has a corrosion monitor 15 connected to the pipe P2.
8 are connected. This corrosion monitor 15 is charcoal
It measures the corrosion rate of raw steel materials and monitors the corrosion rate.
You. For example, an ultrasonic measurement meter is used as the corrosion monitor 15.
The detection signal is input to the control device 12 and the measurement result is
Notify. Infiltration of corrosion test piece as corrosion monitor
Then, the corrosion state may be monitored. The carbon steel
A more reliable operation with regard to corrosion prevention is possible. In this embodiment, the effective oxygen concentration is 5 p.
When it is reduced to below pb, the corrosion rate of carbon steel is several hundred mdm.
Is actually connected to the bottom of the furnace, taking into account
Pipes and reactor coolant purification system using carbon steel materials
It monitors corrosion near piping equipment. to this
Thus, as described in the first embodiment, the effective oxygen
Control so that the concentration is in the range of 5ppb to 15ppb
Plant operation with appropriate corrosion monitoring
Make sure that the corrosion allowance has sufficient margin during the service life.
We can respond. [0040] According to the present invention,Effective oxygen concentration at furnace bottom
Hydrogen can be controlled accurately, Furnace by injection volume
It is possible to properly maintain the effective oxygen concentration at the bottom.
You. Therefore,CRD housing and ICM housing
Corrosion environment such as reactor bottom equipmentProperlyease
It becomes possible. This makes atoms difficult to replace
Maintain the integrity of equipment materials at the bottom of the furnace. Further, it is installed in a reactor recirculation system or a water supply system.
Conventional sampling line is available
No new sampling line is required. Also,
The sedimentation rate is lower than the sampling line connected to the bottom of the furnace.
It is unlikely that rad will accumulate and raise the dose rate.
System, instruments, etc. are easy to maintain, and
Monitor reliability can be maintained. Further, piping and a reactor connected to the bottom of the reactor
Plumbing equipment that uses carbon steel material for coolant purification system piping equipment
The effective oxygen concentration control range for the runt is 15 ppb or less.
Upper 50ppb or lessRukoWith the reactor bottom SCC
In addition to the reduction of
Can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a boiling water nuclear power plant according to a first embodiment of the present invention. FIG. 2 is an operation flowchart of the first embodiment of the present invention. FIG. 3 is a diagram showing a correlation between the effective oxygen concentration in the reactor recirculation system of the first embodiment and the effective oxygen concentration in the reactor bottom. FIG. 4 is a diagram showing a distribution of an effective oxygen concentration in a nuclear reactor. FIG. 5 is a diagram showing a change in the effective oxygen concentration with respect to the concentration of feedwater hydrogen at a representative point inside the reactor. FIG. 6 is a diagram showing a correlation between the hydrogen concentration in the water supply system and the effective oxygen concentration at the bottom of the reactor obtained from the analysis. FIG. 7 is a diagram showing a correlation between the effective oxygen concentration in the reactor recirculation system and the effective oxygen concentration in the reactor bottom obtained from the analysis. FIG. 8 is a view showing a relative ratio of an SCC delay speed to an effective oxygen concentration. FIG. 9 is a diagram showing the corrosion rate of carbon steel with respect to the effective oxygen concentration. FIG. 10 is a diagram showing a concept of a hydrogen injection amount control range. FIG. 11 is an overall schematic diagram of a second embodiment of the present invention. FIG. 12 is an operation flowchart of the second embodiment of the present invention. FIG. 13 is a diagram showing a correlation between the hydrogen concentration in the water supply system and the effective oxygen concentration at the reactor bottom according to the second embodiment. FIG. 14 is an overall schematic diagram of a third embodiment of the present invention. [EXPLANATION OF SYMBOLS] 1 reactor 2 turbine 3 condensate purifier 4A, 4B feedwater heaters 5A, 5B purifier system heater 6 filtration demineralizer 11 O ₂ monitor 12 controller 13 hydrogen source 14 H ₂ monitor 15 Corrosion Monitor 50 Water supply system 51 Reactor recirculation system 52 Reactor cooling system 53 Reactor bottom drain system 54 Hydrogen injection system 55 Hydrogen injection equipment

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsumi Ohkado 3-1-1 Sachimachi, Hitachi-City, Ibaraki Pref. Hitachi, Ltd. Inside Hitachi Plant (72) Inventor Shigeo Hattori 3-1-1 Sachimachi, Hitachi-City, Ibaraki No. 1 Hitachi, Ltd. Hitachi factory (72) Inventor Masami Ando 3-1-1, Sakaimachi, Hitachi, Ibaraki Pref. Hitachi, Ltd. Hitachi factory (56) References JP-A-5-100087 (JP, A) JP-A-64-84192 (JP, A) JP-A-59-220687 (JP, A) JP-A-6-3484 (JP, A) JP-B-63-19838 (JP, B1) (58) Survey Fields (Int.Cl. ⁷ , DB name) G21D 3/08 G21D 1/00 G21D 19/30

Claims (1)

(57) [Claims] [Claim 1] Water quality control of a boiling water nuclear power plant using carbon steel material for piping connected to the reactor bottom and piping equipment for a reactor coolant purification system In the method, in a reactor recirculation system or a reactor coolant purification system, measuring an effective oxygen concentration defined by an oxygen concentration and a hydrogen peroxide concentration, a reactor recirculation system or a reactor determined in advance. Calculating the effective oxygen concentration at the reactor bottom from the measured values based on the correlation between the effective oxygen concentration of the coolant purification system and the effective oxygen concentration at the reactor bottom; More than 5
A method for controlling water quality of a boiling water nuclear power plant, comprising controlling an injection amount of hydrogen into reactor water so as to be within a range of 0 ppb or less .