JP3522842B2 - Measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
Of spent fuel assemblies in such high radiation environment
Used for measuring radiation, burnup, residual enrichment, etc.
It relates to a measuring device. [0002] 2. Description of the Related Art Generally, spent fuel is used in reprocessing facilities.
There is a storage and storage facility for nuclear power plants
Etc. of the reprocessing facility
From the radiation level emitted from the spent fuel assembly.
Derivation of burnup, residual enrichment, etc. of spent fuel assemblies
Fuel is received based on these burnups, residual enrichment, etc.
Availability, criticality management during fuel assembly storage, fuel assembly
It is very difficult to check the burnup during the shearing to melting process.
Becomes important. [0003] Therefore, radiation, burnup, etc. are required in reprocessing facilities.
Measurement equipment is required, especially for burnup and residual concentration.
Measuring devices such as shrinkage have not been put to practical use yet. But,
Measurement devices such as burnup including radiation measurement are considered from the aspect of configuration.
At least the spent fuel assembly and radiation
A loading mechanism for loading the unloader, etc., and loading on this loading mechanism
Radiation level from the detected signal from the radiation detector
A measuring unit to be obtained and a driving mechanism installed in the loading mechanism unit
Control unit that sends a control signal to the
Data processing unit that performs necessary data processing
It is thought that it is done. Further, in this measuring device, the spent fuel
The radiation measurement method for the aggregate and the radiation measurement method
Burnup, residual enrichment, etc. from radiation levels measured
It is considered to use a derivation method. [0005] Among them, the former method for measuring radiation is gross.
Sgamma ray measurement, emission neutron measurement, gamma ray spectrum
Measurement is used. This gross gamma ray measurement is used
Derived from the axial burnup distribution of the fuel assembly,
Emission neutron measurement and gamma ray spectrum measurement are used
From the burnup absolute value near the axial center of the spent fuel assembly.
Put out. On the other hand, the latter method of measuring burnup and the like and its solution
The analysis method derives burnup, residual enrichment, etc. from radiation levels.
But it still exists in concrete product form
do not do. [0007] However, the radiation measurement
At present, measuring devices such as burn-up and residual enrichment are products
Although not implemented, at least the following functions or articles
It is necessary to prepare for the matter. (1) Loading mechanism for loading spent fuel assemblies and
The radiation from the fuel assemblies loaded in the mechanism
Outgoing radiation detectors are exposed to high radiation environmental conditions.
Radiation resistance (about 10⁷ -10⁸ rad / year)
Must be composed of a material having (2) Should spent fuel assemblies be stored in water?
They must measure radiation in the water. That
In order to achieve this, each of the components including the loading mechanism is water-resistant,
Pressure resistance and corrosion resistance are required. (3) Spent fuel assemblies are roughly classified into PWR fuel assemblies.
And BWR fuels, and fuels differ in shape and size.
There are several types of fuel. The same for any of these fuels
It is necessary to measure radiation accurately under the above measurement conditions. (4) Gross gamma ray measurement is performed on the spent fuel
By measuring the relative burnup distribution in the axial direction, the radiation
Calibration of sensitivity between detectors is required. [0008] The present invention has been made in view of the above circumstances.
Various types of spent fuel assemblies with different shapes, dimensions, etc.
Body can be measured accurately under the same measurement conditions, and
It is an object of the present invention to provide a measuring device having excellent protection. Another object of the present invention is to provide a multi-wire system.
Using a radiation detector to reduce the number of cables and
To provide a measuring device that improves tenability
You. Another object of the present invention is to provide a one-line radiation detector.
Eliminates the effect of leakage current when using
It is an object of the present invention to provide a measuring device which aims at the above. In addition,
The other purpose of Akira is to use common radiation measurement equipment as well.
Measurement that eliminates the effects of leakage current and improves measurement accuracy
It is to provide a device. [0010] [MEANS FOR SOLVING THE PROBLEMS]
An invention corresponding to claim 1 is a spent fuel assembly.
In a measuring device that measures the radiation level of
Frame having an insertion part for inserting a fuel assembly into a part
And installed in the mechanism frame along the axial direction of the fuel assembly
Gamma ray detectors and the bottom of the mechanism frame
Each fuel assembly is driven up and down
Lifting and lowering drive means that enables sensitivity calibration of the X-ray detector,
It is installed at a position facing the fuel assembly in the mechanism frame.
A plurality of assembly holding means and each assembly holding hand
By driving the step, it is inserted into the mechanism frame
Fuel assemblyEach gamma ray detector is equidistantMeasurement position
PlaceIs the center positionMatchCentering mechanismAnd each
Assembly holding meansConnected to each other,
ButWhen approaching the fuel assembly,Of each assembly holding means
Force in the direction of pressing on the fuel assemblyAdjusted to reduce
Pressing force adjusting means for
The distance between the fuel assembly and the fuel assembly is adjustable.
Neutron detector to measure neutrons emitted from the
It is a measuring device characterized by the above. [0011] [0012] [0013] [0014] [0015] [0016] [0017] [0018] [0019] [0020] [0021] Accordingly, the invention corresponding to claim 1 is as described above.
Measures have been taken to ensure that
Insert the spent fuel assembly.
Watertight fixedly arranged according to the shape, size, etc. of the fuel assembly
Raises and lowers the spent fuel assembly with respect to the container's radiation detector
By controlling, almost uniform between each radiation detector
The detection sensitivity should be adjusted, and the radiation detector should be watertight.
In a container and select the material for the components.
Thus, the water resistance, pressure resistance, corrosion resistance, and the like can be improved. [0022] [0023] [0024] [0025] [0026] [0027] [0028] [0029] [0030] [0031] [0032] [0033] [0034] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Will be explained. FIG. 1 shows a first embodiment of the apparatus of the present invention.
It is a lineblock diagram showing a measuring device of a burnup including a ray. same
In the figure, reference numeral 1 denotes a mechanism frame serving as an apparatus main body,
A fuel assembly seat 2 is provided on the bottom plate side of the mechanism frame 1.
The lifting drive mechanism 3 having the is provided. This hoist
The fuel assembly seat 2 of the driving mechanism 3 includes a spent fuel assembly.
4 is seated in an upright position to extend in the vertical direction.
You. An example in which the mechanism frame 1 is one of the reprocessing facilities
For example, it is immersed in a large water tank. The drive system of the elevation drive mechanism 3 is shown in FIG.
It has an electric motor 21a installed on the air side
The drive source 21 transmits the rotational power of the electric motor 21a.
Rotating shaft 22a, bevel gear fixed to the tip of the rotating shaft
22b, bevel gear 22c meshing with this bevel gear 22b, etc.
And a gear having an appropriate gear ratio.
And transmitted from the air-side power transmission mechanism 22 side
A jack machine that forms part of the drive mechanism 3 with power
Composed of the underwater-side power transmission mechanism 5 transmitting to the structure 3a
Have been. Reference numeral 22d denotes a drive position detector, which is
The lifting position is determined from the rotation amount of the rotating shaft 22a.
You. Specifically, for example, the marking 22 is attached to the rotating shaft 22a.
e, and the drive position detector 22d on the left side of FIG.
When the marking 22e is detected, the first
The drive position detector 22d on the right side in the figure.
When the working 22e is detected, for example, the prescribed position when ascending
The fuel assembly is determined by the detection signal of these detectors 22d.
It controls the positioning of the body 4. The detector 22
d may be provided as two or more, and other position detecting means may be used.
Good. Further, the mechanism frame 1 or the frame
Is a type of radiation detector in a fixed frame that replaces the system 1
For example, many gloss guns with built-in gloss gamma detector
The detector watertight containers 6,... Are the same as the spent fuel assemblies 4.
Is fixed so as to maintain the separation distance of Further, a substantially central portion of the spent fuel assembly 4
One kind of radiation detector, such as emission
Emission neutron detector watertight container with built-in neutron detector 7,
7 keeps a certain distance from the spent fuel assembly 4
Are arranged as follows. The neutron detector watertight container 7 is provided in the air
The drive source 23 installed on the side and the underwater mechanism frame 1 side
Neutron detector watertight container drive mechanism 8
As described above, the fuel assembly 4 is separated from the spent fuel assembly 4 by a certain distance.
The drive is controlled so as to keep the separation distance. The driving mechanism 8 includes the driving mechanism 8 as shown in FIG.
8a supporting the watertight containers 7 on both sides of the fuel assembly 4
And a gas bridge erected between the supports 8a-8a.
Id shaft 8b, hydraulic cylinder 8c, and the hydraulic pressure
Guide pressure for introducing water to the required water pressure into the cylinder 8c
A structure including the watertight container 7 constituted by the pipe 8d
All or necessary components of 8a to 8d are in view of corrosion resistance and the like.
For example, those made of stainless steel are used. On the other hand, the drive source 23 is specifically shown in the figure.
Not obtained from the submersible pump and this submersible pump
Water to the pressure guiding pipe 8d
8c is configured by a water pressure control unit. these
The submersible pump and the water pressure control unit are installed on the air side. Further, for example, the ratio of the spent fuel assembly 4
In the relatively upper position, the gross gamma detectors 6,.
Make sure that the spent fuel assembly 4 is kept at a certain distance.
A driving source 24 and a driving source 24 for driving the spent fuel assembly 4
And a centering drive mechanism 9. This centering drive mechanism 9 is shown in FIG.
Centering arm 9a, hydraulic cylinder 9b
To the hydraulic cylinder 9b.
And a pressure guiding pipe 9c.
Stainless steel components are used from the viewpoint of corrosion resistance etc.
Is done. The drive source 24 is specifically shown in the figure.
Not obtained from the submersible pump and this submersible pump
Water to the pressure guiding pipe 8d
8c is configured by a water pressure control unit. these
The submersible pump and the water pressure control unit are installed in the air. Numeral 10 denotes spent fuel from the top of the mechanism frame.
This is a fuel assembly insertion section into which the assembly 4 is inserted. Cause
FIG. 5 is a diagram showing a schematic configuration example of a measuring device.
You. Next, the operation of the measuring device will be described.
First, the spent fuel collection from the fuel storage area by crane
The union 4 is lifted and the mechanism frame which is the underwater
The fuel assembly is inserted from the fuel assembly insertion portion 10 of the arm 1. Scold
Later, before the spent fuel assembly 4 sits on the seat 2,
Execute centering operation with centering drive mechanism 9
You. That is, the water sent from the drive source 24
The hydraulic cylinder 9a operates in response to the hydraulic pressure
Ring arm 9a sandwiches both sides of spent fuel assembly 4
And move the spent fuel assembly 4 left and right.
While moving to the center of the mechanism frame 1
And perform centering. This spent fuel assembly 4
During centering, drive source 24 to hydraulic cylinder 9b
Water is constantly sent and spent fuel assemblies 4 are kept at a constant pressure.
The user presses down and seats on the seating body 2 as it is. Next, the gross gamma detection of the gross gamma measurement is performed.
Elevator 6, ... Elevating drive mechanism to perform mutual sensitivity calibration
3 and the spent fuel assembly 4 is placed on the mechanism frame 1.
A large number of gloss gammas that operate up and down and extend up and down
Set to an appropriate position for the detectors 6,. Therefore,
The lifting drive mechanism 3 is provided at the position of the gloss gamma detectors 6,.
Up and down control of the spent fuel assembly 4 while considering the positional relationship
In addition to the function, the axial dimension of the spent fuel
If so, adjust the radiation reference position of the fuel assembly 4
It has a function of controlling the position of the seating body 2 to move up and down. The specific operation of the lifting drive mechanism 2 is as follows.
Driving from an electric motor 21a constituting a part of the power source 21
Power is transmitted to the jack mechanism 3a via the power transmission mechanisms 22 and 5.
The seat which transmits and is placed on the upper side of the jack mechanism 3a
The body 2 is moved up and down. The lifting drive distance is
Detected by the moving position detector 22d, and a detection signal
It is sent to the control unit that controls the dynamic motor 21a, and the drive position is controlled
Is what you do. As described above, the spent fuel assembly 4
Centering and gross gamma detector 6, ... mutual feeling
The fuel assembly 4 lifting and lowering operation is completed
For example, at the radiation measurement reference position of the fuel assembly 4,
Radiation from fuel assembly 4 is measured and released in gross gamma
Perform neutron measurement and gamma ray spectrum measurement. What
When performing gamma ray spectrum measurement,
From the spent fuel assembly 4
The radiation to be emitted is collimated, for example, on the wall of an aquarium.
The radiation coming through this collimator to another location
It will be measured by the measuring unit installed. The gloss gamma measurement is fixed to the mechanism frame 1.
Gloss Gamma Detector Gloss Gun in Watertight Container 6
It is measured by a detector. On the other hand, emission neutron measurement
From the viewpoint of improving the detection efficiency, the size of the spent fuel
Regardless of the method, the fuel assembly 4 and the emitted neutron detection
The separation distance from the emitted neutron detector in the watertight container 7 is
The watertight container 7 has been used by the drive mechanism 8
Only the fuel assembly 4 is driven. At this time, the drive system for measuring the emitted neutrons
Receives water pressure from the water sent from
The cylinder 8c operates and is released along the guide shaft 8b.
The neutron detector watertight container 7 is used for both the spent fuel assembly 4
Contact is made from the side, and positioning is performed. At this time,
Not controlled by water pressure control unit
Then, the watertight container 7 is configured to move quickly. water
While the closed container 7 is in contact with the spent fuel assembly 4,
Water is always sent to the hydraulic cylinder 8c and at a constant pressure
The spent fuel assembly 4 is kept pressed. Therefore, according to the configuration of the above embodiment,
For example, in this measurement device, for example, materials other than plastic and oil
The radiation resistance.
Wear. In addition, various radiation detectors are installed in watertight containers 6, 7, etc.
Stainless steel for storage and necessary components
Used to improve water resistance, pressure resistance and corrosion resistance
Can be. The shape and dimensions of the spent fuel assembly 4
Despite the difference, use the watertight container 7
Measurement by approaching or contacting the spent fuel assembly 4
The radiation measurement of the spent fuel assembly 4 is always the same.
It can be measured accurately under constant conditions. Further, radiation from the spent fuel assembly 4
During line measurement, the power of the drive mechanism is lost due to power loss etc.
However, as shown in FIG.
Provide a driving force opposite to the hydraulic driving force
If the elastic member 8e for the
A fail-safe that automatically separates the watertight container 7 from the assembly 4
Function can be secured. Next, a second embodiment of the apparatus of the present invention will be described.
This will be described with reference to FIG. Generally, this type of measuring device
In the gross gamma ray measurement, the spent fuel assembly 4
Because of the dose, the gross gamma detector
The built-in radiation detector gross gamma detector
An ion chamber is used. Also, spent fuel
Used to determine the relative combustion distribution in the axial direction of the assembly
Multiple gross gamma detections on both sides of the spent fuel assembly axial direction
And the radiation level from the spent fuel assembly 4
Is measured. As a result, the shape of the spent fuel assembly 4
Depends on length, for example 20 on one side, total 40
Gross gamma detector is installed. As described above, the gross gamma ray measurement uses
The number of channels is large, the operating environment conditions (under 10m in water,
High radiation) and severe maintenance
Because of the necessity, etc., the gross gamma detector and the signal
It is desirable that the number of connection cables between them is as small as possible. Therefore, in this apparatus, the gross gamma
Using a one-wire ion chamber as a detector,
Measure gross gamma rays emitted from spent fuel assembly 4
Measurement system consisting of a one-line gross gamma detector
This will be described with reference to FIG. That is, this measuring system is used for collecting spent fuel.
Detects high-level radiation emitted from coalescing 4 and ionizes
Radiation signal current I proportional to the radiation level by the action
_S Gross gamma detector that outputs
One-line gross gamma detector 31 and the detector 31
Radiation signal current I output from_S Cable 3 to derive
2 and one-line gross gamma detector 31 generates ionization action
A high-voltage power supply 33 for supplying power and a cable 32
Amplifier 34 amplifies the signal transmitted through
And the current signal input to the DC amplifier 34 is converted to a voltage signal.
And a feedback circuit 35 for converting the
Therefore, it is constituted. Therefore, the one-line gross gamma as described above
According to the configuration of the measurement system using the detector 31, the cable 3
2 to apply a high voltage to each one-line gross gamma detector 31
While the voltage is applied, it is detected by a one-line gross gamma detector 31,.
As we took out radiation level which we issued, two-wire system
The number of cables can be significantly reduced compared to cables,
This is effective when the number of channels is large. Also underwater
Long distance cable 32 from each gross gamma detector 31
There is a problem of workability because the
In the case of type cable 32, disconnection and other accidents can be quickly identified.
It can be grasped and has excellent workability and, consequently, excellent maintainability.
You. It also contributes to a significant reduction in product costs. Further, a third embodiment of the present invention will be described.
This will be described with reference to FIGS. This example
Is the field of the measurement system using the one-line gross gamma detector 31.
If a high voltage is applied to the detector 31,
Current is generated.
To realize the configuration. First, the influence of the leak current is examined.
I will try. Measurement using single-line gross gamma detector 31
System applies high voltage to the detector electrode and cable 32
The insulation resistance of the detector 31 and the cable 32
Leakage current I due to resistance_L Occurs. As a result, DC
The radiation signal current I from the detector 31 is_S When,
Leakage due to insulation resistance of detector 31 and cable 32
Current I_L And the radiation level from the detector 31
Will cause an error in the signal proportional to. Therefore, the degree of the error will be examined. now,
Supply voltage V to detector 31_S Is the shape and dimensions of the detector 31
Method, gas filling, gas pressure, etc.
500V. So, for example, in the case of 200V
Consider about Insulation resistance of detector 31 and cable 32
R_L Is about 1 × 10¹¹Ω. Also, the leakage current I_L
Is     I_L = V_S / R_L = 200/1 × 10¹¹= 2 × 10^-9A ... (1) Is represented by On the other hand, the radiation signal current I_S Is the detector 31
Approximately 1 × 10^-11 A / R
/ Hr. Also, radiation from the spent fuel assembly 4
Quantity E is 10 to 10^Four Degree, for example, 10^Three R /
Ask for hr. Therefore, the radiation signal current I_S
Is     I_S = S × E = 1 × 10^-11 × 10^Three = 10^-8A ... (2) Is represented by Therefore, the leakage current obtained by the equation (1)
Style I_L And radiation signal current I_S And the leakage current
I_L Is the radiation signal current I_S 20%. Up
In the above example, the radiation dose E from the spent fuel assembly 4 is 1
0^Three In this example, 10^Two R / hr
Current I_L Is the radiation signal current I_S Twice as large as
Error. Therefore, 10 to 10^Two R / hr radiation dose
In the case of, measurement becomes impossible. Therefore, the detector 31 and the cable 32
Eliminate the effect of leakage current caused by insulation resistance,
Radiation signal current I from spent fuel assembly 4_S The exact
From the viewpoint of measurement, the following configuration of the embodiment is used.
Measurement device. FIG. 8 shows the spent fuel assembly 4 installed in water.
Radiation emitted from the spent fuel assembly 4 in the state of being
FIG. 3 is a schematic configuration diagram when a level is measured. Sand
In other words, the entire configuration including the measurement system is
Such as sandwiching the fuel assembly 4 along the axial direction of the united 4
Gloss gamma detection, a radiation detector arranged in a state
, And the radiation measured by each of these detectors 31
Signal current I_S One-wire type MI cable for taking out
Built-in (inorganic insulated cable) 32a and connector for connection
Is mounted inside the mechanism frame 1 and
In addition, the relay board 36 is on land via the soft cable 32b.
The installation site panel 37 is connected and processed by this site panel 37.
The received signal is sent to the measuring instrument panel 38. It should be noted that each of the gloss gamma detectors 31
Built-in gross gamma detector watertight container 6 in the same manner as in the first embodiment.
Have been. For the outer sheath of the MI cable 32a, for example,
Stainless steel is used. In addition, on-site installation on land
37 includes a high-voltage power supply 33, a DC amplifier 34,
Built-in signal processing unit 40 (see FIG. 9) in addition to feedback circuit 35
Have been. The soft cable 32b is, for example, a
Stored in a flexible tube made of stainless steel
The relay board 36 is connected to a land-based field board 37.
This underwater relay board 36 is connected to the on-shore board 37
The reason for using the soft cable 32b as the
Lift the frame 1 out of the water for maintenance.
And to make it possible. The measuring instrument panel 38 has
Various signals are processed by receiving the signal from the floor panel 37.
Measuring instruments are stored. Therefore, N-channel gross gamma detection
The measurement system having instruments 31,... Has a configuration as shown in FIG.
ing. (1) First Embodiment for Removing Leakage Current
And FIG. 10 is a diagram showing an example of such an embodiment.
7 and the gross gamma detector 31 and the cable 3 as in FIG.
2 (32a, 32b), high voltage power supply 33, DC amplifier 34
And a feedback circuit 35, and a new signal processing
A section 40 has been added. This signal processing unit 40 is configured as shown in FIG.
A / D converter for A / D converting the signal from the DC amplifier 34
Conversion unit 41, a memory for storing the data after the A / D conversion
The circuit unit 42 performs predetermined arithmetic processing based on a program.
The processing unit 43 and the I / O circuit unit 44 perform the
It is configured. Next, the operation of the above embodiment will be described.
Will be described. The one-line gross gamma detector 31 is used
The radiation emitted from the spent fuel assembly 4 is detected,
Radiation radiation occurs due to ionization caused by high voltage
Radiation signal current I proportional to bell_S Is output. This release
Ray signal current I_S Increases the DC through the one-wire cable 32
Which is sent to the amplitude unit 34, where the DC small signal current I_S Increase
And a voltage is applied by the DC amplifier 34 and the feedback circuit 35.
After the conversion, it is sent to the signal processing unit 40. This signal processing
The unit 40 takes in the signal from the DC amplifier 34 and
Executes predetermined arithmetic processing based on the
Radiation signal current I without current_S Take out the measuring instrument panel
38. Incidentally, the radiation of the spent fuel assembly 4
When measuring the level, follow the following steps
(See FIG. 12). Procedure b ... When the operator is stored in the water of the fuel storage pool
Let's measure out of multiple spent fuel assemblies 4, ...
The storage area of the spent fuel assembly 4 to be used is selected. Procedure b. The operator operates the crane and
Lifting the spent fuel assembly 4 in the selected storage area
1st Embodiment
It is installed at a predetermined position of the mechanism frame 1 as described above. Procedure C: Spent fuel collection in mechanism frame 1
After the combination 4 is installed, the groves arranged on both sides of the fuel assembly 4
Spent fuel assembly 4 using sigma detectors 31,.
Measure the radiation dose emitted from. Procedure d. After completion of the radiation dose measurement,
The spent fuel assembly 4 from the mechanism frame 1
Take it out, bring it to the selected storage area and re-
Store. Therefore, the signal processing unit 40
Used in the mechanism frame 1
Measured current I after installing fuel assembly 4₁ And mechanism frame
Before installing the spent fuel assemblies 4 in the system 1
Current I_Two And radiation signal without leakage current
Signal current I_S Is what you get. That is, the signal processing unit 40 performs the procedure a. B
At this stage, the spent fuel assemblies 4 are still in the mechanism frame 1
Although it is not installed, at this time, as shown in FIG.
Signal current I from sigma detector 31_Two To DC amplifier 3
4 and a signal converted by the feedback circuit 35.
A / D converter 41 converts it to a digital signal
Then, it is stored in the memory circuit section 42. Signal current at this time
I_Two Means that the spent fuel assembly 4 is not installed
From the above, the gross gamma detector 31 expressed by the above equation (1)
Current I due to the insulation resistance of the cable 32_L Thought
Can be On the other hand, in the step C, the mechanism frame 1
Spent fuel assembly 4 is installed in
Signal current I from the gross gamma detector 31₁ Is also straightforward
A / D converter 4 via a current amplifier 34 and a feedback circuit 35
After being converted to a digital signal in step 1,
Be preserved. The signal current I at this time₁ Is given by the above equation (2)
Representation of gross gamma detector 31 and cable 32 insulation
Leakage current I due to resistance_L And spent fuel assembly 4
Radiation signal current I from_S And signal current including
be able to. The measurement of procedures 1 and 2 obtained as described above
Constant current I_Two And the measured current I in step 3₁And about gross
Leakage current I of gamma detector 31 and cable 32_L
And the radiation signal current I from the spent fuel assembly 4_S And to
When this is applied, the following equation (3) is obtained. [0081]   I_Two = I_L           I₁ = I_L + I_S                     … (3) Therefore, in the signal processing unit 40, the arithmetic processing unit 43
The respective signal currents I from the circuit section 42_Two , I₁ Read
Then, if the arithmetic processing of the following equation (4) is executed,
Signal current I from the fuel assembly 4_S Seeking
Can be. [0082]   I_S = I₁ -I_Two = (I_L + I_S ) -I_L                   … (4) Then, the radiation signal obtained by the signal processing unit 40
Current I_S Is sent to the outside via the I / O circuit section 44.
You. Therefore, it is necessary to perform a series of processing as described above.
And the gross gamma detector 31 and the cable 32
Leakage current I due to insulation resistance of_L In removing the effects of
To measure the true radiation level of the spent fuel assembly 4
Wear. (2) Second operation for removing leakage current
About the configuration example. FIG. 13 is a diagram showing an example of such an embodiment.
It is. This measurement system includes a gloss gamma detector 31 and a case.
Cable 32, high voltage power supply 33, DC amplifier 34, feedback circuit 3
5 and a configuration similar to that of FIG.
And a signal for outputting a control signal 51 based on the calculation result.
Signal processing unit 40a and a control signal 51 corresponding to the leak current.
The predetermined voltage V_R Output voltage generating circuit 52
And the cable 32 which is the input line of the DC amplifier 34
Bias current I_B And a bias element 53 such as a resistor for giving
Is provided. Next, the operation of the above embodiment will be described.
Will be described. Measurement of radiation dose of spent fuel assembly 4
The procedure is the same as in the first embodiment. That is,
The signal processing unit 40a stores the spent fuel still in the mechanism frame 1.
Procedure in which the aggregate 4 is not installed a. Gross in stage b
Signal current I from gamma detector 31_Two And take A
The digital signal is converted by the / D conversion unit 41 and the memory circuit unit
Save in 42. This signal current I_Two Is expressed by the above equation (1).
Gamma detector 31 and insulation resistance of cable 32
Leakage current I caused_L It is. Therefore, the signal processing unit 40 a
Current I_L Is measured and removed by the following two means.
You. One is a DC amplifier in the signal processing unit 40a.
34, and the output voltage becomes zero.
A control signal 51 is sent to a voltage generation circuit 52, and this voltage generation circuit
Voltage V generated from raw circuit 52_R Variable. The result
As a result, the voltage V_R Bias voltage according to
Style I_B Flows and is transmitted from the gross gamma detector 31
Coming signal current I_Two Acts to offset the DC amplifier
The output voltage at 34 decreases. Therefore, the signal processing unit 40a
Performs variable control until the output voltage of the DC amplifier 34 becomes zero.
The voltage generated by the voltage generation circuit 52 when it is zero
V_R Fixed to. The other is the leakage current I_L Measure and note
When stored in the re-circuit section 42, the leakage current I_L In response
The control signal 51 is sent to the voltage generation circuit 52. this
The voltage generation circuit 52 receives a control signal from the signal processing unit 40a.
51, the leakage current I_L
Bias current I of the same value as_B Voltage V at which_RTo
The generated leakage current can be canceled and removed. Each of the two leak current removing means is
It can be expressed by the following equation.     I_L -I_B = 0 (I_L = I_B …… (5) Then, the operator operates the crane and tries to measure.
Mechanism for lifting the spent fuel assembly 4 in the storage area
Carry it to the location of frame 1 and specify the mechanism frame 1
Gross which is installed at the position and arranged on both sides of the fuel assembly 4
Spent fuel assembly 4 using gamma detectors 31, ...
Measure the radiation dose emitted from At this time,
Style I_L And radiation signal current I_S And bias current I_B Directly
The current flows to the input terminal of the current amplifier 34,_L And I_B Equal
Control, the feedback circuit 35_S Only
To perform voltage conversion, the radiation signal current I_S Proportional to
Can be sent to the signal processing unit 40a.
You. Therefore, it is necessary to perform a series of processing as described above.
And the gross gamma detector 31 and the cable 32
Leakage current I due to insulation resistance of_L In removing the effects of
To measure the true radiation level of the spent fuel assembly 4
Wear. Therefore, according to the configuration of the third embodiment,
For example, since the two-wire system is a one-wire system, the connection cable 3
2 can be reduced to 1/2, and maintenance is improved,
Molding, cost reduction, and leakage
Eliminating the effect of current improves measurement accuracy
Reliability can be improved. The third embodiment is a one-wire type measuring system.
Is used to measure the radiation level of the spent fuel assembly 4
The example of removing the leakage current that occurs when
General measurement other than the measurement of the radiation dose of the spent fuel assembly 4
If leak current occurs in the measurement system, it can be applied similarly.
Things. Next, a fourth embodiment of the device of the present invention will be described.
This will be described with reference to the drawings. This embodiment uses centering
14 to FIG. 14 to FIG.
16. FIG. 14 shows the centering drive mechanism 9 and the
The entire configuration including the drive system of the drive mechanism 9 is schematically shown.
FIG. In other words, this FIG.
Press and hold the installed spent fuel assembly 4 from both sides
, The gross gamma detectors 31, ...
Is equidistant from the spent fuel assembly 4.
And a control unit 61 installed on the land.
Water pressure or air pressure under the control of the control unit 61
Drive unit 62 installed on land and the pressure from this drive unit 62
Pressure guiding pipe 6 for introducing a force to the centering drive mechanism 9
It consists of three. The centering drive mechanism 9 is shown in FIG.
And a configuration as shown in FIG. That is,
The centering drive mechanism 9 is used in the mechanism frame 1.
Horizontally with the center point of the installed fuel assembly 4 as the center
A rotating ring-shaped gear 71 and the spent fuel assembly
4 on both sides, each receiving external pressure
Gear 72a meshing with the opposite side of the ring gear 71
And two sets of rotation transmitting mechanisms 72 for rotating
An assembly retainer disposed on each side of the fuel assembly 4
73 and a gear 72 a constituting the rotation transmission mechanism 72.
It rotates in conjunction with the rotation, converts it to linear motion, and pushes each assembly.
And a presser body driving mechanism 74 for moving the presser body 73 forward and backward.
Have been. The ring gear 71 is mounted on the mechanism frame 1
For example, at equal intervals and equal lengths from four places on the ceiling
Held by a sliding bearing 71a suspended by
It is installed rotatably. This ring gear 71 is
Spent fuel assembly 4 is located in the space inside gear
But maintain the required positional relationship.
If it is installed on the ceiling of the mechanism frame 1
Is also good. Each of the two sets of rotation transmitting mechanisms 72 is, for example,
Water pressure operated by the pressure (for example, water pressure) from the drive unit 62
Cylinder 72b, connected to this hydraulic cylinder 72b
A pinion 72d that rotates by the rack 72c
The rotation of the pinion 72d is performed by the connecting shaft 72e and the umbrella.
Transmission to gear 72a via gear 72f and drive shaft 72g
Configuration. Therefore, each rotation transmission mechanism 72 is driven
In response to water pressure from the moving part 62, the gears 72a, 72a
To rotate the ring-shaped gear 71,
The gear 71 is connected to the rotation transmitting mechanism 72 on the side receiving a large water pressure.
The gears 72a, 72 rotate depending on the rotational force, and thus rotate.
a is rotated by the same amount of rotation. 72h lotus
It is a plain bearing. The presser body driving mechanism 74 includes a driving shaft 72g.
For example, two pinions 74a are fixed at predetermined intervals.
The rack 74b is provided so as to mesh with them.
Is placed. Therefore, the rotation amount of the drive shaft 72g is
By transmitting to the rack 74b via the
The rack 74b is converted into a linear motion. At this time, the rack
An assembly pressing body 73 is attached to the tip of 74b.
Therefore, the spent fuel assembly is moved by the advance of the rack 74b.
Centering can be performed while pressing 4. 74c
It is a plain bearing. Each mechanical part is made of, for example, stainless steel.
Use Therefore, the centering drive
According to the configuration of the driving mechanism, the pressure of a pump or the like is used as a power source.
The hydraulic cylinder 72b is driven by the pressure 63 using an electromagnetic valve or the like.
Pressurizes and rotates the drive shaft 72g constituting the rotation transmission mechanism 72.
The rolling is changed to linear motion by the rack 74b of the presser body driving mechanism 74.
Since it is transmitted to the replacement assembly pressing body 73,
It is possible to advance the assembly presser 73 by an equal distance.
And by extension of the rack 74b the spent fuel
Centering can be reliably performed while pressing the aggregate 4. For example, the dimensions of the spent fuel assembly 4 are different.
However, since the moving range of the assembly pressing member 73 is large,
Centering is possible. Moreover, spent fuel assemblies
4 loaded in a tilted or off-center position
Even in such a case, the center position is
After pressing, hold it with both assembly pressing bodies 73 to securely
Can be interrogated. In addition, since it is under high radiation in water,
The main material is made of stainless steel, and the moving parts are sliding bearing materials.
No need for lubricants such as grease to improve durability
I have. The holding side shape of the assembly pressing body 73 is as follows.
As shown in FIG. 15, the shape is V-shaped.
Even if the dimensions of the spent fuel assembly 4 are different,
The present invention can be applied to various kinds of spent fuel assemblies 4. In the above embodiment, the radiation detector is used.
Gross gamma detector and emission neutron detector
However, other types of radiation detectors may be used,
It is stored in 6 and 7. The lifting drive mechanism 3
Uses the driving force of the electric motor 21a as a power source.
Water pressure may be used as power similarly to the mechanisms 8 and 9. Next, the fourth embodiment will be described.
FIGS. 17 and 1 show another modification of the centering drive mechanism.
This will be described with reference to FIG. In addition, the fourth shown in FIGS.
Parts having the same functions as those of the embodiment of FIG.
I have. Centering drive mechanism according to this modification
Is an adjusting force corresponding to the frictional force with respect to the aggregate pressing body 73.
And a pressing force adjusting mechanism for operating the pressing force. this
The pressing force adjusting mechanism is provided on the rear surface (push
One end of the wire rope 81 is connected to the surface facing the contact surface).
The intermediate part of the wire rope 81
Hook it on a pulley 83 provided at a position approximately the same height as 73
I have. Then, the wire suspended vertically by the pulley 83
Disc-shaped weights 82a, 82 are attached to the other end of the ear rope 81.
b, 82c. Cutting edge of wire rope 81
Is attached to the tip of the wire rope 81
And the other weights 82b and 82c are
The wire rope 81 is inserted through the through hole formed in the center
I have. The three disc-shaped weights 82a to 82c are
The outer diameter of the rib 82a is increased in the order of the smallest outer diameter.
You. Also, the pressing force adjustment mechanism has a weight suspended
A weight receiving portion 84 is provided in the vicinity. This receiving part 8
4 is smaller than the diameter of the largest weight 82c,
A cylindrical shape with a diameter larger than the diameter of the large weight 82b
Hole 85 is formed, and further in the center of the hole 85,
Weight 8 smaller than the diameter of large weight 82b but at the tip
A cylindrical hole 86 having a diameter larger than the diameter of 2c is concentric.
Is formed. Here, the force when the assembly presser body 73 advances and retreats
From the hydraulic cylinder 72b under pressure
The power transmission system from the
It is the value obtained by subtracting the frictional force applied. On the other hand, the frictional force is
The friction force at the start of motion (static friction force) is the largest,
As the moving speed of the pressing body 73 increases, the frictional force increases.
(Dynamic friction force) becomes smaller. Therefore, the hydraulic cylinder 72b is pressed at a constant pressure.
When driven by force, it moved slowly at the start of movement
When the assembly presser 73 holds the spent fuel assembly 4
When it comes to the time, it reaches a considerable speed and collides with a large impact
Will be. Severe collision breaks spent fuel assembly 4
It is not preferable because it may be damaged. Also, for the measurement system
However, noise is generated and has an adverse effect. In the present embodiment, the length of the wire rope 81 and
The depth of the holes 85 and 86 in the receiving portion 84 is set as follows.
I have decided. That is, the aggregate holding body 73 is
At the farthest position from the charge assembly 4, the intermediate weight 82
b rests on the step 86a of the hole 86 and only the weight 82a
It is made to hang on the yarope 81. Also, the set
Used a predetermined distance from the farthest position of the body presser body 73
When it is close to the fuel assembly 4, the intermediate weight 82
b is pulled up from the step portion 86a, but the maximum weight 82
c still remains on the step 85a
(The state shown in FIG. 18). In addition, the aggregate holding body
When the 73 approaches the spent fuel assembly 4, the maximum weight
So that the crest 82c can be pulled up from the step 85a.
I have. The weight of each of the weights 82a to 82c
The amount is related to the magnitude of the frictional force when each weight acts.
I can decide. At the start of centering, the assembly presser 73
Is determined by the following equation. F1 = (force in the pressing direction by the hydraulic cylinder 72b)
-(Static friction force)-(Adjustment force = Weight 82a) When the assembly pressing body 73 starts moving, the static friction force moves.
Instead of frictional force, the frictional force gradually decreases. Frictional
When it has decreased to the extent, the intermediate weight 82b
The weight is reduced by the weight 82b, which is added as drag and reduces the frictional force.
refill. Furthermore, the maximum weight 82c is added as drag.
The assembly presser 73 is used to collect spent fuel from the start of movement.
It will move at a nearly constant speed until it comes into contact with coalescing 4.
You. On the other hand, when the centering is released, the weight 82
The adjustment force by a to 82c functions as a return force. sand
That is, when the assembly pressing body 73 starts moving, the frictional force decreases.
Slightly, the weights 82c and 82b are sequentially formed in the stepped portion 85.
a, 86a, the return force is reduced. That
As a result, the assembly presser body 73 moves even when the centering is released.
The speed is kept constant. Further, the assembly presser body 73 is used for collecting spent fuel.
If the power is turned off during centering while holding
In this case, the pressing force against the pressing body 73 becomes zero.
The separation force by the hydraulic cylinder 72b can also be applied.
I can't. In this embodiment, in such a case, three
Automatic because the load of the weights 82a-82c acts as a return force
The centering can be released. For example, a rotation transmission mechanism
The weight of the 72 is 10 kg, and 14 kg of 40% increase
Weight (weight 82a = 4 kg, weight 82b = 5
kg, weight 82c = 5kg). The pressing force at the start of the centering operation is obtained.
(When the weights 82b and 82c do not work)
Assuming that the friction coefficient is 0.3, at least (10 kg + 3
kg + 4 kg = 17 kg) or more. Also, when the assembly presser 73 is moving
When the dynamic friction coefficient is 0.2,
Has at least (10kg + 2kg + 4kg = 16k
g) More force is required. When the weights 82b and 82c are added, dynamic
The pressing force during operation is at least 26 kg (= 10 kg
+ 2kg + 4kg + 5kg + 5kg) is a hydraulic syringe
Done 72b. To operate the rotation transmission mechanism 72,
Since at least 26 kg of power is required,
If the pressing force by the screw 72b is 27 kg, the center
Since the force at the start of the ring is 17kg, 10kg
And the operation can be reliably started. The return force required for opening the centering is as follows.
The weight of the rolling transmission mechanism 72 is 10 kg) + (the static friction force is 3 kg)
-(Total weight 14 kg) = -1 kg
Self-release at disconnection is possible. The normal centering release operation is performed by a hydraulic
Assuming that the opening force of the solder 72a is 9 kg, the cell
It becomes 10kg in total with the release force. Centering open
During operation, the weights 82c and 82b are sequentially lost.
Also has a total opening force of 8 kg. As described above, according to this modification, the pressing force
An adjustment mechanism is provided for use during centering operation.
The impact on the spent fuel assembly 4 can be greatly reduced.
And the shock is reduced, so the life of the detector
Measurement error due to noise or the like can be reduced. According to this modification, the power supply is cut off due to an accident or the like.
Automatic centering can be canceled even if
The fuel assembly 4 is easily removed.
be able to. The centering drive of the above-described modified example
In the mechanism, the wire rope 81 is directly attached to the
Exerted the force of the weights 82a to 82c through
Loads of weights 82a to 82c act on body presser 73 in the same manner
If it is a place, it may be another place in the power transmission system
No. For example, as shown in FIG.
To the connected rack 72c via the action member 90,
Is the suspension member 8 directly attached with the weights 82a to 82c.
Even if 1 'or a wire is connected, the same effect can be obtained.
Can be. The present invention is limited to the above-described embodiments and modified examples.
However, various modifications are possible. [0122] As described above, according to the present invention,
There are various effects as follows. That is, the shape and dimensions
Same measurement of various types of spent fuel assemblies with different characteristics
Measurement can be performed accurately under conditions, and radiation detection can be performed in a watertight container.
Water resistance is improved by storing the ejector, and maintainability is improved.
It is possible to provide a measuring device which is excellent in the above. Also, using a large number of single-line radiation detectors,
Reduce the number of cables and improve maintainability
Can be When using a one-line radiation detector
Can easily remove the effects of leakage current,
Bell measurements can be taken. Further, the same applies to a general radiation measurement device.
In this way, the effect of leakage current can be
You. Furthermore, used during centering operation
The impact on the fuel assembly can be greatly reduced and detected
To prevent measurement errors due to instrument life deterioration, noise, etc.
Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a first embodiment of a measuring device according to the present invention. FIG. 2 is a configuration diagram showing a specific example of a lifting drive mechanism shown in FIG. 1; FIG. 3 is a configuration diagram showing a specific example of the drive mechanism shown in FIG. FIG. 4 is a configuration diagram showing a specific example of the centering drive mechanism shown in FIG. 1; FIG. 5 is a schematic configuration diagram showing the present measuring device in a form close to completion. FIG. 6 is a configuration diagram showing a modification of the device of the present invention. FIG. 7 is a view showing a second embodiment of the measuring device according to the present invention, and particularly showing a measuring system when a one-line radiation detector is used. FIG. 8 is a diagram showing an entire configuration of a third embodiment of the measuring device according to the present invention. FIG. 9 is a diagram specifically showing the internal configuration of FIG. 8; 10 is a diagram showing a measurement system having a leak elimination function when a one-channel one-line radiation detector is used in the internal configuration of FIG. 9; 11 is an internal configuration diagram of the signal processing unit shown in FIG. FIG. 12 is a diagram showing an installation procedure of a spent fuel assembly and an example of removing a leak current. FIG. 13 is a diagram showing a measurement system having a leak removal function when a one-channel one-line radiation detector is used. FIG. 14 is a diagram showing the overall configuration of a fourth embodiment of the measuring apparatus according to the present invention. FIG. 15 is a schematic diagram showing another example of the centering drive mechanism. FIG. 16 is a diagram showing a specific mechanism of the centering drive mechanism shown in FIG. FIG. 17 is a top view of a modification of the centering drive mechanism. 18 is a side view of the centering drive mechanism shown in FIG. FIG. 19 is a diagram showing a main part of another modification of the centering drive mechanism. [Description of Signs] 1 ... Mechanical frame, 3 ... Elevation drive mechanism, 4 ... Spent fuel assembly, 6 ... Gloss gamma detector watertight container, 7 ... Emitted neutron detector watertight container, 8 ... Emitted neutron detector watertight container Drive mechanism, 9 centering drive mechanism, 31 single-line gross gamma detector, 32 cable, 33 high-voltage power supply,
34: DC amplifier, 35: Feedback circuit, 37: Field panel, 3
Reference numeral 8: measuring instrument panel, 40, 40a: signal processing unit, 52: voltage generating circuit, 53: bias element, 63: pressure guiding pipe, 71
... Ring-shaped gear, 72 ... Rotation transmission mechanism, 73 ... Assembly presser, 74 ... Presser drive mechanism, 81 ... Wire rope, 8
2a to 82c: weight, 83: pulley, 84: receiving part.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Fumiaki Kato 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant Co., Ltd. (56) References JP-A-4-29083 (JP, A) JP-A-4 -106498 (JP, A) JP-A-61-176876 (JP, A) JP-A-2-146353 (JP, U) JP-A-58-182103 (JP, U) JP-A-56-8865 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G21C 17/06

Claims (1)

(57) [Claim 1] A measuring device for measuring the radiation level of a spent fuel assembly in water, comprising: a mechanism frame having an insertion portion for inserting the fuel assembly in an upper part; A plurality of gamma ray detectors provided in the mechanism frame along the axial direction of the fuel assembly; and a sensitivity of each of the gamma ray detectors provided at the bottom of the mechanism frame by driving the fuel assembly up and down. Lifting and lowering driving means that enables calibration, a plurality of assembly pressing means provided at opposing positions around the fuel assembly in the mechanism frame, and by driving each of the assembly pressing means, Gamma-ray inspection of the fuel assembly inserted in the mechanism frame
A centering mechanism for adjusting the output device to a center position , which is a measurement position at an equal distance , connected to each of the assembly pressing means ,
When the control means approaches the fuel assembly, each of the assemblies is pushed.
Pressing force adjusting means for adjusting so as to reduce the force of the pressing means against the fuel assembly, and a distance between the fuel assembly and the fuel assembly inserted into the mechanism frame is provided so as to be adjustable and released from the fuel assembly. A neutron detector for measuring neutrons to be measured.