JP2005308419A - Condition detector for radiation substance container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for more securely detecting the abnormality of the sealing performance of a radioactive substance container accommodating radioactive substances. <P>SOLUTION: A condition detector for the radioactive substance container in this invention includes temperature sensors 31 and 32 which get the surface temperature T<SB>i</SB>of canisters 11 accommodating radioactive substances and an arithmetic unit 34 which determines the abnormality of the canisters 11 on the basis of the surface temperature T<SB>i</SB>. The arithmetic unit 34 determines the abnormality of one of the canisters 11 on the basis of the surface temperature T<SB>i</SB>of the one and that of the other canisters 11. Specifically, the arithmetic unit 34 determines the abnormality of the one of the canisters 11 by comparing the tendency of the characteristic amount of the surface temperature T<SB>i</SB>of the one of the canisters 11 with that of the other canisters 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a state detection device that detects the state of a radioactive material container that contains, transports, or stores radioactive materials such as spent fuel assemblies and radioactive waste.

  Technology for safe and long-term storage of spent fuel assemblies that have been burned in a nuclear reactor is one of the important technologies for establishing a nuclear fuel cycle. After the spent fuel assembly is generated, it takes some time before it is reprocessed by the reprocessing facility. Specifically, spent fuel assemblies can be stored for up to 60 years before being reprocessed after they are generated. Therefore, spent fuel assemblies need to be stored safely for a long time before being reprocessed by a reprocessing facility.

  Wet storage and dry storage are techniques for preserving spent fuel assemblies for a long period of time, and concrete cask, metal cask and vault storage are known as dry storage. The concrete cask is generally composed of a metal canister (inner cylinder) that accommodates a spent fuel assembly and a concrete outer cylinder that accommodates the canister. The spent fuel assembly is accommodated in a sealed space formed inside the canister. The metal cask is generally composed of a metal body portion that contains a radioactive substance, and a lid portion including a primary lid and a secondary lid. The spent fuel assembly is accommodated in a sealed space formed by the body portion and the lid portion. On the other hand, vault storage is a method in which metal canisters that contain spent fuel assemblies are arranged at high density in a building in consideration of heat removal and radiation shielding. The spent fuel assembly is accommodated in a sealed space formed inside the canister.

  As a matter to be considered when storing the spent fuel assembly, it is mentioned that the spent fuel assembly includes radioactivity and heat generation in a highly radioactive substance such as FP (fission product). The main role of the cask and canister is to reduce the radioactivity and heat generation of the spent fuel assembly. In order to reduce the heat generation of the spent fuel assembly, the following three techniques are generally adopted. First, in order to diffuse the heat generated locally by the spent fuel assembly, helium gas is sealed in a sealed space (that is, inside the canister and the metal cask) that houses the spent fuel assembly. Second, the cask is cooled during storage of the spent fuel assembly. In addition, the cask itself is designed to withstand heat generation.

  In addition, in order to store the spent fuel assembly more safely, the sealing performance of the sealed space that houses the spent fuel assembly, that is, the sealing performance of the cask and the canister is checked. As the most effective means for confirming the sealing performance, there are a radiation detector for detecting radiation leaking from the cask and a helium leak detector for detecting leak of helium gas. However, the use of these devices is not suitable for continuously confirming the sealing performance of the sealed space for storing the spent fuel assembly for a long period of time without radiation leakage. For this reason, there is a demand for the development of a device for confirming the sealability of the cask easily and at low cost without radiation leakage.

  Patent Document 1 discloses a monitoring device for confirming the sealing performance of a cask simply and at low cost. The known monitoring device detects deterioration of the sealing performance from the temperature change and pressure change of the cask. When helium gas leaks due to deterioration of the cask sealing, the temperature and pressure of the cask drop abnormally. The known monitoring device detects the abnormality of the cask by detecting this abnormal drop in temperature and pressure. Confirming the sealing performance of the cask from changes in temperature and pressure makes it possible to simplify the monitoring device, and to confirm the sealing performance of the cask easily at an early stage without radiation leakage and at low cost. It is effective for.

  It is important to improve the accuracy of detection of abnormalities in cask sealing in monitoring devices that check cask sealing from temperature and pressure changes. More specifically, it is important that even when a minute leak occurs in the cask, the minute leak can be detected. In the case of a minute leak, the temperature change and pressure change per time of the cask are small, so it is important to accurately detect the temperature change and pressure change caused by the minute leak. On the other hand, it is also important to correctly conclude that non-abnormal temperature changes and pressure changes are not caused by deterioration of the cask sealing performance.

Against this background, there is a need to provide a technique for more reliably detecting an abnormality in the sealing property of a radioactive substance container that contains a radioactive substance.
JP 2002-48898 A

  An object of the present invention is to provide a technique for more reliably detecting an abnormality in the sealing property of a radioactive substance container containing a radioactive substance.

  In order to achieve the above object, the present invention employs the following means. In the description of technical matters included in the means, in order to clarify the correspondence between the description of [Claims] and the description of [Best Mode for Carrying Out the Invention] Number / symbol used in the best mode for doing this is added. However, the added numbers and symbols shall not be used for the interpretation of the technical scope of the invention described in [Claims].

In one aspect, the state detector for a radioactive substance container according to the present invention is a state quantity acquisition means for acquiring the state quantities (T _i , P) of a plurality of radioactive substance containers (11, 2 ′) containing radioactive substances. 31, 32, 71) and abnormality detection means (34-9, 73-9) for determining abnormality of the plurality of radioactive substance containers (11, 2 ′) based on the state quantities (T _i , P). ing. The abnormality detection means (34-9, 73-9) detects an abnormality of one radioactive substance container (11, 2 ') among the plurality of radioactive substance containers (11, 2'). 'state quantity) _(T i, P) and other radioactive material container (11, 2' 11,2 state quantity) _(T i, is determined on the basis of the P). Specifically, the anomaly detection means (34-9, 73-9) determines the tendency of the feature quantity corresponding to the state quantity (T _C , P) of the one radioactive substance container (11, 2 ′), and others. of determining the abnormality of the radioactive substance container (11,2 ') amount state of (T _{C, P)} is compared with the trend of the feature amount corresponding to the one of the radioactive substance container (11,2').

The radioactive substance container state detection device adds an abnormality of one radioactive substance container (11, 2 '), which is an object of abnormality determination, to the one radioactive substance container (11, 2'), Since the determination is made based on the corrected state quantity (T _i , P) of the radioactive substance container (11, 2 ′), the abnormality can be determined more accurately.

Preferably, the state detection device for a radioactive substance container includes an environmental temperature (T ₀ ) for measuring the environmental temperature (T ₀ ) and an environmental temperature (T) for each of the plurality of radioactive substance containers (11). ₀ ) and the corrected state quantities by correcting the state quantities (T _i , P) based on the positions of the plurality of radioactive substance containers (11) in the storage building (1) containing the plurality of radioactive substance containers (11). Correction state quantity calculating means (34-2) for calculating (T _Ci , P _C ), and the abnormality detecting means (34-9, 73-9) detects the abnormality of the radioactive substance container (11, 2 '). , It is preferable to determine from the correction state quantity (T _Ci , P _C ). More specifically, the corrected state quantity calculating means (34-1, 73-1) and the state quantity (Ti, P) and the corrected state quantity are closer to the upstream side of the cooling air flow inside the storage building. It is preferable to calculate the correction correction state quantity (T _Ci , P _C ) so that the difference from (T _Ci , P _C ) becomes large. Such a method is particularly effective in detecting an abnormality in the sealing property of the radioactive material container (11) in the vault storage in which the cooling air greatly affects the state quantity.

In another aspect, the state detection device for a radioactive substance container according to the present invention is a state quantity acquisition means (31, 31) for acquiring the state quantity (T _i , P) of the radioactive substance container (11, 2 ′) containing the radioactive substance. 32, 71), environmental temperature measuring means (33, 72) for measuring the environmental temperature (T ₀ ), state quantity corresponding terms corresponding to the state quantities (T _i , P), and environmental temperature (T ₀ ) A corrected state quantity (T _Ci , P _C ) using an equation including a response waveform corresponding term representing a response to the state quantity (T _i , P) and an environmental temperature correction term that is a linear function of the environmental temperature (T ₀ ). Correction state quantity calculating means (34-1, 73-1) for calculating the error, and abnormality determination means for judging an abnormality of the radioactive substance container (11, 2 ') based on the correction state quantity (T _Ci , P _C ) 34-2, 73-2). Such a radioactive substance container state detection apparatus calculates an environmental temperature by calculating a correction state quantity (T _Ci , P _C ) using an equation including an environmental temperature correction term that is a linear function of the environmental temperature (T ₀ ). The influence of (T ₀ ) on the state quantity (T _i , P) without passing through the radioactive substance container (11, 2 ′) can be reflected in the corrected state quantity (T _Ci , P _C ). As a result, it is possible to calculate a correction state quantity (T _Ci , P _C ) appropriate for determining an abnormality.

In still another aspect, the state detector for a radioactive substance container according to the present invention is a state quantity acquisition means (31) for acquiring a state quantity (T _i , P) of a radioactive substance container (11, 2 ′) containing a radioactive substance. , 32, 71), environmental temperature measuring means (33, 72) for measuring the environmental temperature (T ₀ ), state quantity corresponding terms corresponding to the state quantities (T _i , P), and the environmental temperature (T _0). ) Correction state quantity calculating means (34-1, 73-1) for calculating the correction state quantity (T _Ci , P _C ) using an expression including a correction term that is a function of), and correction state quantity (T _Ci , Abnormality determination means (34-2, 73-2) for determining abnormality of the radioactive substance container (11, 2 ′) based on P _C ). The correction state quantity calculating means (34-1, 73-1) determines the coefficient of the correction term so that the environmental temperature (T ₀ ) and the correction state quantity (T _Ci , P _C ) are uncorrelated. By determining the coefficient of the correction term so that the environmental temperature (T ₀ ) and the correction state quantity (T _Ci , P _C ) are uncorrelated, the environmental temperature (T _Ci , P _C ) is The influence due to T ₀ ) is eliminated. It is possible to accurately determine the abnormality of the radioactive substance container (11, 2 ′) by determining the abnormality of the radioactive substance container (11, 2 ′) using the corrected state quantity (T _Ci , P _C ). become.

In still another aspect, the state detector for a radioactive substance container according to the present invention is a state quantity acquisition means (31, 31) for acquiring a state quantity (T _i , P) of a radioactive substance container (11, 2 ′) containing a radioactive substance. and 32,71), and the environmental temperature measuring means (33,72) for measuring the environmental temperature _{(T 0),} the frequency spectrum of the state quantity _(T i, P), the frequency spectrum of the environmental temperature _{(T 0)} Spectrum calculation means (34-1, 73-1) for calculating a correction spectrum calculation means for obtaining a correction frequency spectrum from the frequency spectrum of the state quantity (T _i , P) and the frequency spectrum of the ambient temperature (T ₀ ) and (34-1,73-1), the correction state quantity by inverse Fourier transform of the corrected frequency spectrum _(T Ci, _{P C)} correction state quantity calculating means for calculating a (34-1,73- ) And the amount of compensation state _(T Ci, and a abnormality determining means (34-2,73-2) for determining the abnormality of the radioactive substance container (11,2 ') based on the _{P C).} By calculating a corrected frequency spectrum from the frequency spectrum of the state quantity (T _i , P) and the frequency spectrum of the environmental temperature (T ₀ ), and calculating the corrected state quantity (T _Ci , P _C ) from the corrected frequency spectrum. , The influence of the environmental temperature (T ₀ ) is removed from the correction state quantities (T _Ci , P _C ). It is possible to accurately determine the abnormality of the radioactive substance container (11, 2 ′) by determining the abnormality of the radioactive substance container (11, 2 ′) using the corrected state quantity (T _Ci , P _C ). become.

The correction spectrum calculation means preferably obtains the correction frequency spectrum by subtracting at least part of the frequency spectrum of the ambient temperature (T ₀ ) from the frequency spectrum of the state quantity (T _i , P).

In still another aspect, the state detector for a radioactive substance container according to the present invention is a state quantity acquisition means (31) for acquiring a state quantity (T _i , P) of a radioactive substance container (11, 2 ′) containing a radioactive substance. , 32, 71), an environmental temperature measuring means (33, 72) for measuring the environmental temperature (T ₀ ), a normal period in which the radioactive substance containers (11, 2 ′) are normal, and a radioactive substance container (11, 2 ′) includes a state quantity corresponding term corresponding to the state quantity (T _i , P) and a correction term that is a function of the environmental temperature (T ₀ ) for each of the determination target periods that are the targets of the abnormality determination. Correction state quantity calculating means (34-1, 73-1) for calculating a correction state quantity (T _Ci , P _C ) using an equation, and abnormality determination means (34-4, 73-4) are provided. . The correction state quantity calculating means (34-1, 73-1) determines the coefficient of the correction term so that the environmental temperature (T ₀ ) and the correction state quantity (T _Ci , P _C ) are uncorrelated. The abnormality determination means (34-3, 73-3) calculates the radioactive substance container (11, 2 ') from the coefficient of the correction term obtained for the normal period and the coefficient of the correction term obtained for the determination target period. Judge abnormalities. Also with this radioactive substance container state detection device, it is possible to accurately determine the abnormality of the radioactive substance container (11, 2 '). In this case, the correction term includes a plurality of terms corresponding to a plurality of different transfer functions, and the abnormality determination means (34-3, 73-3) determines the coefficients of the plurality of terms obtained for the normal period and the determination. It is preferable to determine the abnormality of the radioactive substance container (11, 2 ') from the coefficients of a plurality of terms obtained for the target period.

In still another aspect, the radioactive substance container state detection device according to the present invention is a state quantity measuring means (31, 31) for measuring the quantity (T _i , P) of the radioactive substance container (11, 2 ′) containing the radioactive substance. and 32,71), and the environmental temperature measuring means (33,72) for measuring the environmental temperature _{(T 0),} the state quantity of the radioactive substance container (11,2 ') based on the environmental temperature _{(T 0)} (T _i, P the normal value of the corresponding state quantity characteristic quantity), the state of the ambient temperature (T ₀₎ (T _i, the state quantity estimation means for estimating using a physical model representing the response to _P) (34-4 73-4), the estimated normal value, and the state quantity feature quantity corresponding to the state quantity (T _i , P) measured by the state quantity obtaining means (31, 32, 71). Detection means for determining the abnormality of the radioactive material container (11, 2 ') 34-4,73-4) and a.

In still another aspect, the state detector for a radioactive substance container according to the present invention is a state quantity acquisition means (31, 31) for acquiring a state quantity (T _i , P) of a radioactive substance container (11, 2 ′) containing a radioactive substance. , 32, 71), frequency spectrum calculating means (34-5, 73-5) for calculating the frequency spectrum of the state quantity feature quantity corresponding to the state quantity (Ti, P), and the radioactive substance container based on the frequency spectrum And an abnormality determining means (34-5, 73-5) for determining an abnormality of (11, 2 '). Examples of the state quantity feature quantity include a corrected state quantity (T _Ci , P _C ) obtained by correcting the state quantity (T _i , P) based on the environmental temperature (T ₀ ), and a corrected state quantity ( T _Ci , P _C ) and the corresponding feature quantity may be used.

Specifically, the frequency spectrum calculated by the frequency spectrum calculation means (34-5, 73-5) is the same as that of the radioactive substance container (11, 2 ') when the radioactive substance container (11, 2') is normal. The normal frequency spectrum of the state quantity feature amount corresponding to the state quantity (T _i , P) and the radioactive substance container (11, 2 ') in the period that is the target of the abnormality determination of the radioactive substance container (11, 2') The state quantity feature quantity determination target period frequency spectrum corresponding to the state quantity (T _i , P), and the abnormality determination means (34-5, 73-5) includes the normal frequency spectrum and the determination target period frequency spectrum. It is preferable to determine abnormality of the radioactive substance container (11, 2 ') based on the above.

In still another aspect, the state detector for a radioactive substance container according to the present invention comprises a state quantity measuring means for measuring the state quantity (T _i , P) of the radioactive substance container (11, 2 ′) containing the radioactive substance, environmental temperature environment temperature measuring means _{(T 0)} to measure (33,72), has environmental temperature _{(T 0)} as an exogenous input, ARX with state quantity _(T i, P) as an output (auto- ARX model identification means (34-6, 73-6) for identifying a regressive exogenous) model, and an environmental temperature (T _i , P) of the state quantity (T _i , P) of the radioactive substance container (11, 2 ′) from the ARX model ₀ ) A component that does not depend on the above is obtained, a whiteness test is performed on the obtained component, and an abnormality determination means (34-6, 73-6) for determining the abnormality of the radioactive substance container (11, 2 ') from the result of the whiteness test Are preferably provided. The influence of the environmental temperature (T ₀ ) on the state quantities (T _i , P) is generally noise. However, the state detection device for a radioactive substance container positively utilizes the influence of the environmental temperature (T ₀ ) on the state quantity (T _i , P), thereby sealing the radioactive substance container (11, 2 ′). Can be judged.

In still another aspect, the state detector for a radioactive substance container according to the present invention is a state quantity acquisition means (31) for acquiring a state quantity (T _i , P) of a radioactive substance container (11, 2 ′) containing a radioactive substance. , 32, 71) and the state quantity feature quantity corresponding to the state quantity (T _i , P) obtained by the state quantity acquisition means (31, 32, 71) is normal in the radioactive substance container (11, 2 ′). A set of state quantity feature quantities of the radioactive substance container (11, 2 ′) at a certain time and the radioactive substance container (11, 2 ′) when the sealing property of the radioactive substance container (11, 2 ′) is abnormal ) And an abnormality detection means (34-7, 73-7) for determining an abnormality of the radioactive substance container (11, 2 ') by determining which one belongs to the state quantity feature quantity group by discriminant analysis. And has. As the state quantity feature quantity, for example, a corrected state quantity (T _Ci , P _C ) obtained by correcting the state quantity (T _i , P) based on the environmental temperature (T ₀ ), or a corrected state quantity ( It can be a feature quantity obtained from T _Ci , P _C ). Specifically, the abnormality detection means (34-7, 73-7) has a state quantity feature value corresponding to the state quantity (T _i , P) obtained by the state quantity acquisition means (31, 32, 71). It is preferable to calculate the Mahalanobis generalized distance and to determine the abnormality of the radioactive substance container (11, 2 ') based on the calculated Mahalanobis generalized distance.

In still another aspect, the radioactive substance container state detection apparatus according to the present invention is a state quantity measuring means (31, 31) for measuring the quantity (T _i , P) of the radioactive substance container (11, 2 ′) containing the radioactive substance. and 32,71), determined the environmental temperature measuring means (33,72) for measuring the environmental temperature _{(T 0),} the state of the ambient temperature _{(T 0) (T} i, the impulse response for P), the impulse response Abnormality determining means (34-8, 73-8) for determining an abnormality of the radioactive substance container (11, 2 ′) from the feature amount of As the characteristic value of the impulse response, a reduction ratio of the impulse response and a time constant obtained from the step response corresponding to the impulse response can be used.

  According to the present invention, it is possible to more reliably detect an abnormality in the sealing property of a radioactive substance container that contains a radioactive substance.

Configuration of first concrete cask and state detection device In one embodiment of the present invention, as shown in FIG. Is detected by the state detection device 3. In the following, after the configuration of the concrete cask 2 that is the target of state detection is described, the configuration and operation of the state detection device 3 of the present embodiment will be described in detail.

1. Configuration of Concrete Cask As shown in FIG. 2, the concrete cask 2 is generally composed of a canister 11 and a concrete container 21 that houses the canister 11. The canister 11 includes a body portion 12, a primary lid 13a, and a secondary lid 13b. The body portion 12, the primary lid 13a, and the secondary lid 13b are all made of stainless steel or carbon steel. The upper opening of the body portion 12 is sealed with a primary lid 13 a and a secondary lid 13 b, whereby a cavity 14 is formed inside the canister 11. A basket 16 for storing the spent fuel assembly 15 is stored in the cavity 14. The canister 11 is filled with helium gas in order to diffuse the heat generated locally by the spent fuel assembly 15 throughout. When the spent fuel assembly 15 generates heat, the temperature of the helium gas in the vicinity thereof increases. Due to this temperature rise, helium gas is circulated and heat is diffused throughout the canister 11. Since heat is diffused using natural circulation, the temperature at the top of the canister 11 is high and the temperature at the bottom is low. That is, the temperature is different at a position where the height of the canister 11 is different.

  Each of the concrete containers 21 includes a concrete support 22, a side wall 23, and a lid 24. Air circulation holes 25 are formed in the upper and lower portions of the side wall 23. The air inside the facility that houses the concrete cask 2 can flow to the canister 11 through the air flow hole 25, thereby cooling the canister 11.

  The side wall 23 and the lid 24 of the concrete container 21 are formed with inspection holes 26 and 27 penetrating therethrough, respectively. As will be described later, the inspection holes 26 and 27 are used for inserting a temperature sensor for measuring the surface temperature of the canister 11.

2. Configuration of State Detection Device 3 The state detection device 3 includes temperature sensors 31 and 32, an environmental temperature sensor 33, a calculation device 34, and a display device 35.

The temperature sensors 31 and 32 are used to sequentially measure the surface temperature of the canister 11. The temperature sensors 31 and 32 are inserted into inspection holes 26 and 27 provided in the concrete container 21 and fixed so as to contact the surface of the canister 11. The temperature sensors 31 and 32 have different heights. That is, the temperature sensor 31 is in contact with the upper part of the canister 11 and is used for measuring the surface temperature of the upper part. On the other hand, the temperature sensor 32 is in contact with the central portion of the canister 11 and is used to measure the surface temperature of the central portion. As the temperature sensors 31 and 32, typically, a thermocouple, a Peltier element, a resistance temperature detector, an infrared thermometer, and a heat radiation thermometer can be used. Surface temperature measured by the temperature sensor 31 (i.e., the surface temperature of the top of the canister 11) are hereinafter described as the surface temperature T _1, the surface temperature measured by the temperature sensor 32 (i.e., the central portion of the canister 11 surface temperature), thereafter, it is described as the surface temperature T _2. In particular, when it is desired to specify the time, the surface temperatures T ₁ and T _{2 at} the time t are expressed as T ₁ (t) and T ₂ (t), respectively.

The environmental temperature sensor 33 measures the environmental temperature T ₀ around the concrete cask 2. The environmental temperature T _{0 at} time t is expressed as T ₀ (t).

The arithmetic unit 34 uses the surface temperatures T ₁ and T ₂ sequentially measured by the temperature sensors 31 and 32 and the environmental temperature T ₀ sequentially measured by the environmental temperature sensor 33 to determine whether the canister 11 is abnormal. It is a computer that detects The arithmetic unit 34 includes a correction temperature calculation module 34-1, a correction temperature determination module 34-2, a correction coefficient determination module 34-3, a physical model determination module 34-4, a spectrum analysis module 34-5, A software program including an ARX model determination module 34-6, a discriminant analysis module 34-7, an impulse response determination module 34-8, and a group management module 34-9 is installed.

The correction temperature calculation module 34-1 is a program for calculating the correction temperatures T _C1 and T _C2 from the surface temperatures T ₁ and T ₂ . Here, the correction temperatures T _C1 and T _C2 are virtual temperatures introduced to cancel the influence of the change in the environmental temperature T _{0 on} the surface temperatures T ₁ and T ₂ . Correcting the temperature _{T C1, T C2,} from the surface temperatures _T 1, _{T 2,} is obtained by removing the component corresponding to the change of the surface temperature _T 1, _{T 2} due to a change in environmental temperature _{T 0.}

Correction temperature determination module 34-2, correction coefficient determination module 34-3, physical model determination module 34-4, spectrum analysis module 34-5, ARX model determination module 34-6, discriminant analysis module 34-7, and impulse response determination The module 34-8 is a program module for determining an abnormality in the sealing performance of each canister 11. The correction temperature determination module 34-2 is a program for detecting an abnormality in _the canister 11 using the correction temperatures T _C1 and T _C2 calculated by the correction temperature calculation module 34-1. The correction coefficient determination module 34-3 is a program for determining the above of the canister 11 using the correction coefficient calculated in the process of calculating the correction temperatures T _C1 and T _C2 . Physical model determination module 34-4 is a program for detecting an abnormality of the canister 11 using a physical model describing the response to the surface temperature T _1, T ₂ of the environmental temperature T _0. The spectrum analysis module 34-5 is a program for determining an abnormality in the sealing performance of the canister 11 from the frequency spectra of the surface temperatures T ₁ and T ₂ and / or the correction temperatures T _C1 and T _C2 . The ARX model determination module 34-6 identifies an ARX model having the environmental temperature T ₀ as an exogenous input and outputs the surface temperatures T ₁ and T ₂ , and uses the identified ARX model to determine the sealing performance of the canister 11. This is a program for judging abnormalities. The discriminant analysis module 34-7 is a program for determining an abnormality in the sealing performance of the canister 11 by discriminating and analyzing the feature values of the surface temperatures T ₁ and T ₂ . Impulse response determination module 34-8 is to identify the impulse response of the transfer function from the ambient temperature T ₀ to the surface temperatures T _1, T _2, the program determines an abnormality in the sealing of the canister 11 by using the impulse response is there. The operations performed by these modules will be described in detail later.

  The group management module 34-9 is a program for determining whether there is an abnormality in the sealing performance of a certain canister 11 by comparing the tendency of the one canister 11 with the tendency of the canister 11 located in the vicinity thereof. is there. The group management module 34-9 includes a correction temperature determination module 34-2, a correction coefficient determination module 34-3, a physical model determination module 34-4, a spectrum analysis module 34-5, an ARX model determination module 34-6, and a discriminant analysis module. For the canister 11 determined to be abnormal by the 34-7 and the impulse response determination module 34-8, an abnormality in the sealing performance of the canister 11 is determined. The group management module 34-9 is used to confirm with high accuracy that there is an abnormality in the sealing performance of the canister 11.

  The display device 35 is used for displaying the detection result by the arithmetic device 34. When an abnormality is detected in the canister 11 by the arithmetic device 34, a message to that effect is displayed on the display device 35.

Second Canister State Determination Method FIG. 3 is a flowchart showing a state determination method of the canister 11 in the present embodiment.

Step S11:
In each predetermined measuring time, temperature sensors 31 and 32, the surface temperature _{T 1} of the upper part of the canister 11, and measuring the surface temperature _{T 2} of the central portion of the canister 11, the environmental temperature sensor 33 is the environmental temperature _{T 0} taking measurement. In the following, the latest measurement time is described as time t _k , and the surface temperatures T ₁ and T ₂ measured at the time t _k are described as T ₁ (t _k ) and T ₂ (t _k ), respectively. Is done.

Step S12:
The corrected temperatures T _C1 and T _C2 are calculated from the measured surface temperatures T ₁ and T ₂ and the environmental temperature T ₀ . As described above, the correction temperatures T _C1 and T _C2 are virtual temperatures obtained by removing components corresponding to fluctuations in the environmental temperature T ₀ from the surface temperatures T ₁ and T ₂ . The correction temperatures T _C1 and T _C2 are calculated by the correction temperature calculation module 34-1. As a calculation method of the correction temperatures T _C1 and T _C2 ,
A method of calculating the correction temperatures T _C1 and T _C2 by correcting the surface temperatures T ₁ and T ₂ by a correction formula;
A method of calculating the correction temperatures T _C1 and T _C2 using the frequency spectra of the surface temperatures T ₁ and T ₂ and the environmental temperature T ₀ can be used. In the following, these two methods will be described in detail.

(A) Calculation Method of Correction Temperatures T _C1 and T _C2 by Correction Equation In this calculation method, the correction temperatures T _C1 (t) and T _C2 (t) at time t are expressed by the following equation (1A):
T _Ci (t) = T _i (t) −ΣK _ij · f _ij (T ₀ (t)), (1A)
Is calculated by Here, i is 1 or 2, j is an integer of 1 to m (m is an integer of 1 or more), Σ represents the sum of j, and f _ij is the environmental temperature It is a function of T ₀ , and each K _{ij in} equation (1) is a correction coefficient. That is, the correction temperature T _Ci is calculated using the sum of m functions f _ij .

Correction coefficient _{K ij} of equation (1), the time _{t k, t k-1,} t k-2, ···, so that the _{t k-n} in the correction temperature _{T Ci} and the ambient temperature _{T 0} is uncorrelated To be determined. Here, t _k is the latest measurement time, and t _k−1 , t _k−2 ,..., T _k−n are 1 time before, 2 times before,. This is the previous measurement time. The fact that the corrected temperature T _Ci (t) and the environmental temperature T ₀ (t) are uncorrelated means that the corrected temperature T _Ci (t) is changed from the surface temperature T _i (t) to the environmental temperature T ₀ (t). It means that it is a component excluding the influence. The corrected temperatures T _C1 (t) and T _C2 (t) determined in this way are suitable indexes for evaluating the presence or absence of leakage of the canister 11.

The function f _ij (T ₀ (t)) is _preferably a function T _cij (T ₀ (t)) representing the response of the environmental temperature T _{0 to} the surface temperature T _i . That is, the correction temperatures T _C1 (t) and T _C2 (t) at time t are expressed by the following formula (1B):
T _Ci (t) = T _i (t) −ΣK _ij · T _cij (T ₀ (t)), (1B)
Is preferably obtained by Specifically, the function T _cij (T ₀ (t)) is an expression (2) using the transfer function X _ij (s) of the response of the environmental temperature T _{0 to} the surface temperature T _i :
T _cij (T ₀ (t)) = L ⁻¹ [X _ij (s) · T ₀ (s)], (2)
Is preferably obtained by Here, T ₀ (s) is a Laplace transform of the environmental temperature T ₀ (t), and L ⁻¹ is a symbol indicating an inverse Laplace transform.

The response of the surface temperatures T _1, T ₂ against the ambient temperature T _0, the correction coefficient be different be approximated as the sum of (no one) m-number of transfer function, the surface temperature T ₁ of the environmental temperature T ₀ , T ₂ is preferable in evaluating the influence on T ₂ more appropriately. The concrete cask 2 is composed of a plurality of members having different heat capacities, that is, a plurality of members having different time constants of temperature change. Accordingly, approximating the response of the surface temperatures T ₁ and T ₂ as the sum of a plurality of transfer functions having different coefficients approximates the response of the environmental temperature T _{0 to} the surface temperatures T ₁ and T ₂ more appropriately. Makes it possible to do.

As X _ij (s) in equation (2), the transfer function of the first-order lag element having the time constant τ _ij can be used most simply. When a transfer function of a first order lag element having a time constant τ _ij is used as X _ij (s), the time constant τ _ij is preferably determined by a correlation method.

FIG. 4 is a flowchart showing a procedure for determining the time constant τ _ij by the correlation method. For each time constant τ _ij , the period Π _j used to calculate the transfer function X _ij (s) is determined. The period _{ｊ j} is commonly used to determine the time constant τ _{1j of} the transfer function X _1j (s) corresponding to the surface temperature T ₁ and the time constant τ _2j of the transfer function X _C2j (s) corresponding to the surface temperature T _2. used. The length of the period _{ｊ j} is determined according to the length of the time constant to be evaluated; if you want to find a time constant that represents short-term fluctuations, the length of the period _{ｊ j} is short and long-term fluctuations When it is desired to obtain a time constant representing, the length of the period _{ｊ j} is taken long. For example, like the concrete container 21, in order to determine the time constant representing the influence of the member having a large heat capacity, for example, the long period [pi _j as a seven day length is determined. As the canister 11, in order to determine the time constant representing the influence of the members with moderate heat capacity, for example, a period [pi _j moderate as its length is 2 days is determined.

Further, after the offset component is removed from the measured environmental temperature T ₀ (t), surface temperature T ₁ (t), T ₂ (t) (step S01), noise is removed by the whitening filter (step S01). Step S02). The environmental temperature T ₀ and the surface temperatures T ₁ and T ₂ from which the offset component and the noise component have been removed are expressed as the environmental temperature T _f0 (t), the surface temperature T _f1 (t), and T _f2 (t), respectively. The

Subsequently, a cross-correlation function R _Cij (τ) for the period _{ｊ j} between the environmental temperature T _f0 (t) from which the offset component and the noise component have been removed and the surface temperature T _fi (t) is obtained (step) S03).

Further, an impulse response is obtained from the cross-correlation function R _cij (τ) (step S04), and a step response is obtained by integrating the impulse response (step S05). By approximating the step response as a first-order lag element, a time constant τ _ij is calculated (step S06). The time constants τ _i1 , τ _i2 ,... Calculated in such a process calculate the transfer functions X _i1 (t), X _i2 (t) _,. It is used to calculate the correction temperature T _Ci (t).

When the correction temperature T _Ci is calculated using the equation (1B), in order to calculate a more appropriate correction temperature T _Ci , a term representing the influence of the environmental temperature T ₀ directly on the temperature sensors 31 and 32. Is preferably introduced. Since the temperature sensors 31 and 32 are exposed to the atmosphere in the storage building 4, the environmental temperature T ₀ is equal to the surface temperatures T ₁ and T ₂ measured by the temperature sensors 31 and 32 (without going through the concrete cask 2. ) Directly affects. Specifically, instead of formula (1B),
T _Ci (t) = T _i (t) −ΣK _ij · T _Cij (T ₀ (t)) − K ′ · {(T _i (t) −μ _T0j },
... (1C)
Thus, it is preferable that the correction temperatures T _C1 and T _C2 are calculated. Here, mu _T0j is the average value of the environmental temperature _{T 0} in the period [pi _j. Instead of the average value μ _T0j, it is also possible to average values of the ambient temperature T ₀ of the past fixed period (e.g. one year) is used.

Although not an essential problem, when the correction temperature T _Ci is calculated by the equations (1B) and (1C), in order to make the correction temperature T _{Ci a} meaningful value as an index representing the temperature of the canister 11, It is preferred that the average value of the temperature T ₀ is subtracted from T _τij (t _k ); that is, the corrected temperature T _Ci (k) is obtained by correcting the equations (1B) and (1C) as follows: 1B ′) or (1C ′):
_{T Ci (t) = T i} (t) -ΣK ij · {T τij (t) -μ T0j}, ··· (1B ')
_{T Ci (t) = T i} (t) -ΣK ij · {T τij (t) -μ T0j}
−K ′ · {(T _i (t) −μ _T0j } (1C ′)
It is preferable to be calculated by Here, μ _T0j is an average value of the environmental temperature T ₀ in the period _{ｊ j} as described above. Instead of the average value μ _T0j, it is also possible to average values of the ambient temperature T ₀ of the past fixed period (e.g. one year) is used. As a result, the correction temperature T _Ci becomes a value close to the temperature of the canister 11.

(B) calculation method Figure 5 of the surface temperature _T 1, _{T 2} and correcting the temperature _T C1 using the frequency spectrum of the environmental temperature _{T 0, T C2,} the frequency spectrum of the surface temperature _T 1, _{T 2} and the ambient temperature _{T 0} It is a functional block diagram which shows the method of calculating correction temperature T _C1 and T _C2 using The correction temperatures T _C1 and T _C2 are obtained by filtering out the frequency components of the fluctuation of the environmental temperature T ₀ from the surface temperatures T ₁ and T ₂ . Specifically, the surface temperature _T 1, _{T 2} Fast Furue transform (FFT) is performed (step S12-1), the frequency spectrum of the surface temperature _T 1, _{T 2} is calculated. Similarly, the frequency spectrum of the environmental temperature _{T 0} is calculated by a Fast Furue conversion (step S12-2). The obtained frequency spectrum of the ambient temperature T ₀ is used to determine the filtering coefficient. Further, a frequency spectrum obtained by subtracting the frequency spectrum of the ambient temperature T ₀ from the frequency spectrum of the surface temperatures T ₁ and T ₂ is obtained by filtering (step S12-3). The frequency spectrum obtained in step S12-3 is a frequency spectrum of fluctuations in the surface temperatures T ₁ and T ₂ corresponding to the sealing performance abnormality of the canister 11. The correction temperatures T _C1 and T _C2 are calculated by inverse fast Fourier transform of the frequency spectrum (step S12-4).

In the filtering performed in step S12-3, it is not necessary to reduce the frequency spectrum of the environmental temperature T ₀ in the entire frequency region. Only in the desired frequency range, the frequency spectrum of the ambient temperature T ₀ can be subtracted from the frequency spectrum of the surface temperatures T ₁ and T ₂ to obtain the frequency spectrum.

Step S13:
As shown in FIG. 3, after the correction temperatures T _C1 and T _C2 are calculated, it is determined whether or not there is an abnormality in the sealing performance of each canister 11. In step S13, an abnormality in the sealing performance of each canister 11 is determined by the following determination method:
・ Abnormality judgment based on correction temperature ・ Abnormality judgment based on correction coefficient ・ Abnormality judgment by physical model simulation ・ Abnormality judgment by spectrum analysis ・ Abnormality judgment using ARX model ・ Abnormality judgment by discriminant analysis ・ By abnormality judgment using impulse response Determined. The abnormality determination based on the correction temperature is performed by the correction temperature determination module 34-2, and the abnormality determination based on the correction coefficient is performed by the correction coefficient determination module 34-3. The abnormality determination by the physical model simulation is performed by the physical model determination module 34-4, and the abnormality determination by the spectrum analysis is performed by the spectrum analysis module 34-5. Similarly, abnormality determination using the ARX model is performed by the ARX model determination module 34-6, and abnormality determination by discriminant analysis is performed by the discriminant analysis module 34-7. The abnormality determination using the impulse response is performed by the impulse response determination module 34-8. In the following, these determination methods will be described in detail.

(A) Abnormality determination based on correction temperature In the abnormality determination based on the correction temperature, the canister 11 is calculated from the correction temperature T _C1 (t _k ), T _C2 (t _k ) calculated in step S12 or the characteristic amount obtained from these. Judgment of abnormal sealability. Correction temperature _{T C1 (t k), T} C2 The feature amount obtained from _{(t k),} the correction temperature _{T C1,} the time rate of change _dT C1 of _{T C2, dT C2,} the difference ΔT correction temperature _{T C1, T C2 C (= T C1 -T C2)} , the correction temperature _{T C1,} the difference between the past value _{^T p} ^{C1, T} _{p C2} with the current value _{^T c} ^{C1, T} _{c C2} of ^{_{T C2 ΔT cp C1 (= T}} p C1 -T ^c _C1 ), T ^cp _C2 (= T ^p _C2 −T ^c _C2 ). Specifically, when the correction temperature T _C1 (t _k ), T _C2 (t _k ) of a certain canister 11 or the feature quantity obtained from these is not within a predetermined normal region, the correction temperature determination module 34-2 Determines that the canister 11 is abnormal. A preferred embodiment of the abnormality determination based on the corrected temperature will be described later.

(B) Abnormality determination by abnormality determination based on correction coefficient In the abnormality determination based on the correction coefficient, the sealability of the canister 11 is calculated using the correction coefficient _Kij calculated in the process of calculating the correction temperatures T _C1 and T _C2 in step S12. Judge abnormalities. As described above, the correction coefficient K _ij is determined so that the environmental temperature T ₀ and the correction temperatures T _C1 and T _C2 are uncorrelated. Since the value of the correction coefficient _{K ij} to uncorrelated when leakage occurs between the environmental temperature _{T 0} and the correction temperature _{T C1, T C2} of the canister 11 is varied, the sealing performance of the canister 11 from the variation of the correction coefficient _{K ij} abnormal Can be detected. More specifically, the correction coefficient K _ij calculated for the determination target period that is the target of the abnormality determination of the canister 11 is calculated for the period (normal period) in which it is known that there is no abnormality in the sealability of the canister 11. It is compared with the corrected correction coefficient K _ij, and the abnormality of the sealing performance of the canister 11 is determined from the comparison result. For example, the magnitude of the difference between the vector having the correction coefficients K _{i1 to} K _im calculated for the determination target period as elements and the vector having the correction coefficients K _{i1 to} K _im calculated for the normal period as elements is a predetermined value. Is larger than that, it is determined that the sealing performance of the canister 11 is abnormal.

(C) Physical Model Simulation With reference to FIG. 6, in the abnormality determination by the physical model simulation, the sealability of the canister 11 is determined using a physical model representing the response of the environmental temperature T _{0 to} the surface temperatures T ₁ and T ₂ . Judge abnormalities. Specifically, first, using the measured environmental temperature T ₀ and the physical model, the estimated values of the surface temperatures T ₁ and T ₂ when there is no abnormality in the sealing performance of the canister 11, that is, the estimated normal value T ₁ ^, _{T 2} ^ is calculated. As the physical model, the transfer function of the response of the environmental temperature T _{0 to} the surface temperatures T ₁ and T ₂ obtained by system identification can be used most simply. Subsequently, the surface temperatures T ₁ and T ₂ actually measured by the temperature sensors 31 and 32 are compared with the estimated normal values T ₁ and T _2, and from this comparison result, the presence or absence of an abnormality in the sealing performance of the canister 11 is confirmed. Is judged. Specifically, the absolute values | T ₁ ^ −T ₁ | and | T ₂ ^ −T ₂ | of the difference between the estimated normal values T ₁ ^ and T ₂ ^ and the measured surface temperatures T ₁ and T ₂ If at least one is greater than a predetermined value, it is determined that the sealing performance of the canister 11 is abnormal. When the absolute values | T ₁ ^ −T ₁ | and | T ₂ ^ −T ₂ | are both larger than a predetermined value, it is possible to determine that the sealing performance of the canister 11 is abnormal.

In the abnormality determination based on the physical model simulation described above, it is possible to determine that the sealing performance of the canister 11 is abnormal in consideration of the influence of the fluctuation of the environmental temperature T ₀ on the surface temperatures T ₁ and T ₂ .

(D) Abnormality determination by spectrum analysis As shown in FIG. 7, in the abnormality determination by spectrum analysis, an abnormality in the sealing performance of the canister 11 is determined from the frequency spectrum of the surface temperatures T ₁ and T ₂ . If an abnormality occurs in the sealing performance of the canister 11, the frequency spectrum of the surface temperatures T ₁ and T ₂ changes. Therefore, the abnormality of the sealing performance of the canister 11 is detected from the change in the frequency spectrum of the surface temperatures T ₁ and T _2. be able to.

More specifically, the surface temperature T ₁ for each of a determination target period that is a target of abnormality determination of the canister 11 and a period (normal period) in which it is known that there is no abnormality in the sealing performance of the canister 11, frequency spectrum of T ₂ is calculated by the fast Fourier transform. Further, the frequency spectrum of the surface temperatures T ₁ and T ₂ calculated for the determination target period is compared with the frequency spectrum calculated for a period (normal period) in which it is known that there is no abnormality in the sealing performance of the canister 11, From the comparison result, an abnormality in the sealing performance of the canister 11 is determined. For example, when an abnormality occurs in the sealing performance of the canister 11, the peak position in the specific frequency region of the frequency spectrum of the surface temperatures T ₁ and T ₂ changes. From the difference between the peak position of the frequency spectrum during the determination target period and the peak position of the frequency spectrum during the normal period, an abnormality in the sealing performance of the canister 11 is determined.

The abnormality determination based on the spectrum analysis of the surface temperatures T ₁ and T ₂ can determine the sealing performance of the canister 11 by comparing the frequency spectrum in the frequency region in which no component corresponding to the fluctuation of the environmental temperature T ₀ exists. This is suitable for eliminating the influence of the environmental temperature T ₀ .

Instead of the frequency spectra of the surface temperatures T ₁ and T _2, the frequency spectrum of the feature quantity obtained from the surface temperatures T ₁ and T ₂ can be used. For example, instead of the frequency spectrum of the surface temperatures T ₁ and T ₂ , the frequency spectrum of the correction temperatures T _C1 and T _C2 can be used. Similar to the surface temperatures T ₁ and T ₂ , if an abnormality occurs in the sealability of the canister 11, the frequency spectra of the correction temperatures T _C1 and T _C2 vary. Therefore, an abnormality in the sealing performance of the canister 11 can be detected from the variation in the frequency spectrum of the correction temperatures T _C1 and T _C2 .

(E) Abnormality determination using the ARX model Referring to FIG. 8, in the abnormality determination using the ARX model, the environmental temperature T ₀ is an exogenous input, and the surface temperature T _i (i is any one of 1 and 2). Is used to detect an abnormality in the sealing performance of the canister 11. The The ARX model, the components of the change of the surface temperature T _i due to abnormal sealing of the canister 11 (leakage component) is considered as a disturbance w. If there is no abnormality in the sealing performance of the canister 11, the disturbance w should be white noise. However, when the sealability of the canister 11 is abnormal, the disturbance w does not become white noise. Using this phenomenon, an abnormality in the sealing performance of the canister 11 is detected.

Specifically, first, an ARX model is estimated from the measured value of the surface temperature T _{i and} the measured value of the environmental temperature T ₀ . A response transfer function B (z) / A (z) of the response of the environmental temperature T _{0 to} the surface temperature T _i is calculated, and the disturbance w is obtained using the denominator A (z) of the transfer function. Further, a white test for disturbance w is performed. The ARX model determination module 34-5 determines that there is no abnormality in the sealing performance of the canister 11 when the disturbance w is white noise. On the other hand, when the disturbance w is not white noise, the ARX model determination module 34-5 determines that the sealing performance of the canister 11 is abnormal.

In the abnormality determination using the ARX model described above, it is possible to determine that the sealing performance of the canister 11 is abnormal in consideration of the influence of the fluctuation of the environmental temperature T ₀ on the surface temperatures T ₁ and T ₂ . .

(F) Abnormality determination by discriminant analysis Referring to FIG. 9, in the abnormal determination by discriminant analysis, the sealability abnormality of the canister 11 is determined by discriminant analysis on a plurality of feature amounts obtained from the surface temperatures T ₁ and T ₂ . Presence or absence is determined. As the feature amount, for example, the surface temperature _T 1, _{T 2} itself, the time rate of change of the surface temperatures _T 1, _{T 2,} the difference between the surface temperatures _T 1, _{T 2,} the correction temperature _{T C1, T C2,} the correction temperature _{T C1} , T _C2 , and the difference between the correction temperatures T _C1 and T _C2 can be used.

  A feature value used for discriminant analysis is calculated for each of when the canister 11 is normal and when the sealability of the canister 11 is abnormal. As a result, a group of data based on the characteristic amount when the canister 11 is normal and a group of data based on the characteristic amount when the sealability of the canister 11 is abnormal are defined. Below, the former is called a normal group, and the latter is called an abnormal group.

When the surface temperatures T ₁ and T ₂ are newly measured, a feature amount is calculated from the surface temperatures T ₁ and T _2, and data based on the feature amount, that is, discrimination target data is the difference between the normal group and the abnormal group. Which one belongs is determined by discriminant analysis. Specifically, the Malahanobis general distance of the discrimination target data (that is, data based on the newly measured feature values of the surface temperatures T ₁ and T ₂ ) is calculated for each of the normal group and the abnormal group. It is determined that the discrimination target data belongs to the group with the shorter calculated general distance of Malahanobis.

  When it is determined that the determination target data belongs to the normal group, the canister 11 is determined to be normal. When the determination target data is determined to belong to the abnormal group, the sealability of the canister 11 is abnormal. It is judged that there is.

  Instead of calculating the general distance of Malahanobis, a discriminant for discriminating whether the discrimination target data belongs to a normal group or an abnormal group may be prepared in advance. This discriminant defines a boundary 36 between an area where the discrimination target data is judged to belong to the normal group and an area judged to belong to the abnormal group.

  The abnormality determination by such discriminant analysis can determine the abnormality of the canister 11 based on various feature values, and is excellent in the reliability of the abnormality determination.

(G) Abnormal judgment using impulse response Referring to FIG. 10, in the abnormal judgment using impulse response, the impulse response of the transfer function from the environmental temperature T ₀ to the surface temperatures T ₁ and T ₂ is identified. An abnormality in the sealing performance of the canister 11 is determined using the impulse response. Since the impulse response of the transfer function from the environmental temperature T ₀ to the surface temperatures T ₁ and T ₂ varies depending on the presence or absence of the sealability abnormality of the canister 11, the abnormality of the sealability of the canister 11 can be determined from the impulse response. . The identification of the impulse response is preferably performed by the correlation method as in the calculation of the correction temperatures T _C1 and T _C2 .

Specifically, the environmental temperature T ₀ and the surface for each of a determination target period that is a target of abnormality determination of the canister 11 and a period (normal period) in which it is known that there is no abnormality in the sealing performance of the canister 11. A cross-correlation function R _i (τ) with the temperature T _i is obtained, and an impulse response for each of the determination target period and the normal period is identified from the cross-correlation function R _cij (τ). It is determined whether or not the sealability of the canister 11 is abnormal by comparing the feature values obtained from the identified impulse responses.

  As the feature amount obtained from the impulse response, for example, an attenuation ratio and a time constant of a step response corresponding to the impulse response can be used. When the impulse response is compared using the time constant of the step response, the step response is obtained by integrating the obtained impulse response, and the time constant is obtained by approximating the step response to the first-order lag element .

The abnormality determination using the impulse response is advantageous in that it can be determined that the sealability of the canister 11 is abnormal in consideration of the influence of the fluctuation of the environmental temperature T ₀ on the surface temperatures T ₁ and T ₂ . .

Steps S14 and S15:
Returning to FIG. 3, when no abnormality is found in the sealing performance of all the canisters 11 in step S13, the display device 35 displays that all the canisters 11 are normal (steps S14 and S15). . On the other hand, if there is a canister 11 in which an abnormality is found in the sealing performance, step S16 is performed.

Step S16:
In step S16, the presence of an abnormality in the canister 11 in which an abnormality is found in the sealing performance in step S13 is confirmed by comparing the tendency of the canister 11 with the tendency of the canister 11 located in the vicinity thereof. The canister 11 in which an abnormality is found in the sealing performance in step S13 is hereinafter referred to as an abnormality determination canister, and the canister 11 positioned around the abnormality determination canister is referred to as a peripheral canister.

Specifically, the tendency of the feature quantity of the surface temperature T ₁ , T ₂ of the abnormality determination canister and the tendency of the feature quantity of the peripheral canister are compared. The characteristic of the surface temperatures _T 1, _{T 2,} for example, the surface temperature _T 1, _{T 2} itself, the time rate of change of the surface temperatures _T 1, _{T 2,} the difference between the surface temperatures _T 1, _{T 2,} the correction temperature _{T C1} , _{T C2,} the time rate of change of the correction temperature _{T C1, T C2,} the difference between the corrected temperature _{T C1, T C2} may be used. As a result of the comparison, if it is determined that the tendency of the feature values of the surface temperatures T ₁ and T ₂ of the abnormality determination canister is different from the tendency of the feature values of the peripheral canisters, finally, the sealability of the abnormality determination canister is determined. It is judged that there is an abnormality. If it is not determined that the tendency of the characteristic amounts of the surface temperatures T ₁ and T ₂ of the abnormality determination canister is different from the tendency of the characteristic amounts of the peripheral canisters, it cannot be concluded that the abnormality determination canister is abnormal.

Step S17:
In step S17, the result of determination in step S16 is displayed on the display device 35. Finally, when it is determined that there is an abnormality in the sealing performance of the abnormality determination canister, it is displayed that any of the canisters 11 has been determined to be abnormal. If it is not possible to conclude that there is an abnormality in the sealing performance of the abnormality determination canister, this is displayed.

Third Canister Abnormality Determination Based on Correction Temperature A preferred embodiment of abnormality determination based on the correction temperature will be described below. The abnormality determination based on the corrected temperature has the following four determination methods:
And correcting the temperature _{T C1, T} abnormality determination by the statistical processing of the _{C2-correction} temperature _{T C1,} the temperature difference of the abnormality judgment and corrected temperature due to the statistical processing of the time rate of change _dT C1, _{dT C2} of _{T C2 T C1, T C2 ΔT} C It is composed of abnormality determination / abnormality determination based on long-term changes in the correction temperatures T _C1 and T _C2 by statistical processing of (= TC ₁ −TC ₂ ). In the following, each of the four determination methods is explained.

例えば，一定期間Γ_ｋは，その始期である時刻ｔ_ｋ−Ｎが測定時刻ｔ_ｋの２日前になるように設定される。 (A) State Determination by Statistical Processing of Correction Temperatures T _C1 and T _C2 FIG. 13 is a flowchart showing processing for detecting an abnormality of the canister 11 by statistical processing of the correction temperatures T _C1 and T _C2 . In this process, the average value _{mu TC1,} mu _TC2 and standard deviation sigma _TC1 of correction in a most-recent fixed period of time gamma _k of the measurement time _{t k} temperature _{T C1, T C2,} σ _TC2 are calculated (step S21, S22). Most typically, the period Γ _k is defined as a period of t _k−N ≦ t ≦ t _k−1 . Here, the time _{t k-1} is the measurement time of the immediately preceding measurement time _{t k,} likewise, the time _{t k-N} is N times before the measurement time of the measurement time _{t k.} In this case, the average values μ _TC1 and μ _TC2 and the standard deviations σ _TC1 and σ _TC2 are expressed by the following equations (3a) and (3b).

For example, the fixed period Γ _k is set so that the time t _k-N that is the start time is two days before the measurement time t _k .

Subsequently, the normal temperature region is determined from the average values μ _TC1 and μ _TC2 and the standard deviations σ _TC1 and σ _TC2 calculated in steps S21 and S22 (step S23). The normal temperature range is a range of correction temperatures T _C1 and T _C2 at which the canister 11 is determined to be normal. In the present embodiment, the normal temperature regions R _TC1 and R _Tc2 of the correction temperatures T _C1 and T _C2 are respectively
R _TC1 : μ _TC1 −n · σ _TC1 < _{TC 1} <μ _TC1 + n · σ _TC1 , (4a)
R _TC2 : μ _TC2 −n · σ _TC2 < _{TC 2} <μ _TC2 + n · σ _TC2 , (4b)
Is calculated. n is empirically preferably 2 or 3. However, n can take any optimum value.

It should be noted that the fixed period Γ _k used for calculating the average value and the standard deviation of the correction temperatures T _C1 and T _C2 is shifted every time the measurement time arrives. Usually, it changes every time the measurement time arrives. For example, for the next measurement time _{t k + 1} at time _{t k,} the period gamma _{k + 1 is} defined as _{t k-N + 1 ≦ t} ≦ t k becomes period. Therefore, when the next measurement time t _{k + 1} arrives, average values μ _TC1 and μ _TC2 and standard deviations σ _TC1 and σ _TC2 are newly calculated, and normal temperature regions R _TC1 and R _TC2 are also newly determined. In order to clarify this, when necessary, the normal temperature regions determined for the time t _k are described as R _TC1 (t _k ) and R _TC2 (t _k ), respectively.

Subsequently, the correction temperature determination module 34-2 determines whether the correction temperatures T _C1 (t _k ) and T _C2 (t _k ) are lower than the lower limits of the normal temperature regions R _TC1 (t _k ) and R _TC2 (t _k ). Whether or not the canister 11 is normal is determined according to whether or not (step S24). Specifically, the correction temperature determination module 34-2 determines that the canister 11 is abnormal when at least one of the correction temperatures T _C1 and T _C2 is below the lower limit of the normal temperature range for the past m times including the current time. That is, the correction temperature determination module 34-2 determines that at least one of the correction temperatures T _C1 and T _C2 is “correction temperature T _Ci for any p of 0 or more and m−1 or less”. _{(t k-p)} is judged to be normal temperature region _R TCi _{(t k-p)} falls below the lower limit of "when satisfying the condition that there is abnormality in the sealing performance of the canister 11. Instead, it may be determined that there is an abnormality in the canister 11 when both of the correction temperatures T _C1 and T _C2 are out of the normal temperature range for the past m times including the current time. On the other hand, when the correction temperature T _Ci (t _k ) exceeds the upper limit of the normal temperature region R _TCi (t _k ) continuously m times including the current time, the correction temperature determination module 34-2 performs sensor abnormality or measurement. Judge that there is a system abnormality. When these conditions are not satisfied, the correction temperature determination module 34-2 determines that each canister 11 is normal (step S26).

FIG. 14 is a graph showing a specific example of a state determination method based on statistical processing of the correction temperature T _C1 . The correction temperature T _C1 is sequentially calculated, and the average value μ _TC1 and the standard deviation σ _TC1 are sequentially calculated using the calculated correction temperature T _C1 . Using this average value μ _TC1 and standard deviation σ _TC1 , the normal temperature region R _TC1 is sequentially determined. In this case, leakage occurs in the canister 11 at time t _1, the internal gas pressure is beginning to decrease. In response to this, the correction temperature T _C1 starts to decrease rapidly. Change of the correction temperature _T normothermic region _{R TC1} with the variation of _C1 are the gradual correction temperature _{T C1} deviates from the normal temperature region _{R TC1.} In this case, at time _{t 2, the} correction temperature _{T C1} deviates from the normal temperature region _{R TC1.} Thereafter, when the event that the correction temperature T _C1 deviates from the normal temperature region R _TC1 occurs m times continuously, that is, when the correction temperature T _C1 deviates from the normal temperature region R _TC1 is maintained to some extent, the correction temperature determination The module 34-2 determines that a leak has occurred in the canister 11.

The effectiveness of determining the sealing performance of the canister 11 in this way is that the normal temperature regions R _TC1 and R _Tc2 can be determined accurately and sequentially. Even if the temperature of the canister 11 is normal, the temperature of the canister 11 gradually decreases while being stored for a long time. This means that it is difficult to determine whether the surface temperature of the canister 11 has abnormally decreased by determining a certain fixed threshold. In the state determination method based on the statistical processing of the correction temperatures T _C1 and T _{C2 according to} the present embodiment, the fluctuation of the normal range in the fixed period Γ _k , that is, the fluctuation between the upper and lower n · σ _TC1 centered on the average value. If a large fluctuation occurs, it is determined that an abnormality has occurred in the sealing performance of the canister 11. As a result, the criteria for determining the sealing performance of the canister 11 can be determined dynamically and accurately, and the sealing performance of the canister 11 can be determined accurately.

(B) State Determination by Statistical Processing of Corrected Temperature Change Rates dT _C1 and dT _C2 FIG. 15 is a flowchart showing processing for detecting an abnormality of the canister 11 by statistical processing of the corrected temperature change rates dT _C1 and dTC ₂ . In this method, from the time _t corrected temperature _T C1 calculated for _{k, T C2,} the time _t the rate of change of the correction temperature in _{k dT C1 (t k),} dT C1 (t k) is calculated (step S31) .

Then the processing is performed, except that the correction temperature _{T C1,} instead corrected temperature change rate _dT C1 of _{T C2, dT C2} is used, is performed in a state determination method according to the statistical processing of the correction temperature _{T C1, T C2} It is the same as processing. Specifically, the average value _{mu DTC1} of measurement time _t corrected in a most-recent fixed period of time gamma _k of _k temperature change rate _{dT C1, dT C2,} μ dTC2 and standard deviation sigma _DTC1, sigma _DTC2 is calculated (step S32, S33).

Subsequently, the normal temperature change rate regions R _dTC1 and R _dTC2 are determined from the average values μ _dTC1 and μ _dTC2 and the standard deviations σ _dTC1 and σ _dTC2 calculated in steps S32 and S33 (step S34). In this embodiment, the correction rate of temperature change _dT C1, _{dT C2} respective normal temperature change rate region _{R DTC1, R DTC2} is
R _dTC1 : μ _dTC1 −n · σ _{dTC 1} < _{dTC 1} <μ _dTC1 + n · σ _{dTC 1} , (5a)
R _dTC2 : μ _{dTC 2} −n · σ _{dTC 2} < _{dTC 2} <μ _TdC 2 + n · σ _{dTC 2} , (5b)
Is determined. For example, n is preferably 2 or 3. However, n can take any optimum value.

Subsequently, the correction temperature determination module 34-2 determines that the correction temperature change rates dT _C1 (t _k ) and dT _C2 (t _k ) are lower limits of the normal temperature regions R _dTC1 (t _k ) and R _dTc2 (t _k ). It is determined whether or not the canister 11 is normal depending on whether or not it is lower (step S35). Specifically, the correction temperature determination module 34-2, at least one of the correction temperature change rate _dT C1, _{dT C2} is below the lower limit of the normal temperature region _{R DTC1, R DTC2} successively past m times including the current In this case, it is determined that the sealability of the canister 11 is abnormal (step S36); that is, the correction temperature determination module 34-2 determines that at least one of the correction temperatures T _C1 and T _C2 is “0 or more and m−1 or less. When the condition that the corrected temperature change rate dT _Ci (t _k−p ) is lower than the lower limit of the normal temperature change rate region R _dTCi (t _k−p ) for an _{arbitrary p} is satisfied, the sealing performance of the canister 11 is improved. Judge that there is an abnormality. Alternatively, the correction temperature determination module 34-2, when the correction both the temperature change rate _dT C1, _{dT C2} is continuously past m times including this time is out of the normal temperature region _{R DTC1, R DTC2,} It may be determined that the sealability of the canister 11 is abnormal. On the other hand, if the corrected temperature change rate dT _Ci (t _k ) exceeds the upper limit of the normal temperature region R _TCi (t _k ) continuously including the current m times in the past m times, Alternatively, it is determined that there is an abnormality in the measurement system. If these conditions are not satisfied, the correction temperature determination module 34-2 determines that the canister 11 is normal (step S37).

Figure 17 is a graph showing a specific example of a state determination method according to the statistical processing of correcting the temperature change rate dT _C1. Correcting the temperature change rate _{dT C1} is calculated sequentially by using the calculated correction temperature change rate _{dT C1,} the average value _{mu DTC1,} standard deviation sigma _DTC1 is calculated sequentially. Using this average value μ _dTC1 and standard deviation σ _dTC1 , the normal temperature change rate region R _dTC1 is sequentially determined. In this case, leakage occurs in the canister 11 at time t _3, the surface temperature T ₁ is beginning to decrease. In response to this, the correction temperature T _C1 starts to decrease rapidly, and the correction temperature change rate dT _C1 changes greatly accordingly. Change of the correction temperature change rate normal temperature change rate region _{R DTC1} by _{dT C1} are the gradual correction rate of temperature change _{dT C1} deviates from the normal temperature change rate region _{R DTC1.} In this case At time _{t 3, the} correction rate of temperature change _{T C1} is out of the normal temperature change rate region _{R DTC1.} Thereafter, the correction when the event that the temperature change rate _{dT C1} deviates from the normal temperature change rate region _{R DTC1} occurs continuously m times, that is, a state where the correction temperature change rate _{dT C1} deviates from the normal temperature change rate region _{R DTC1} to some extent If maintained, the correction temperature determination module 34-2 determines that a leak has occurred in the canister 11.

Advantage of the state determination method according to the statistical processing of correcting the temperature change rate dT _C1 is thereafter leaks of the canister 11 is generated, is that short time to required to detect the abnormality of the canister 11. As understood from FIG. 17, the leakage of the canister 11 is generated, the correction rate of temperature change dT _C1 is instantaneously changed, rapidly out of the normally temperature change rate region R _DTC1. Therefore, the state determination method according to the statistical processing of correcting the temperature change rate dT _C1 can detect the abnormality of the canister 11 in a short time.

(C) the temperature difference _{ΔT C (= T C1 -T C2} ) state judgment 18 according to statistical processing indicates a process of detecting an abnormality of the canister 11 by the statistical processing of the difference [Delta] T _C of the correction temperature _{T C1, T C2} It is a flowchart. Since the surface temperatures T ₁ and T ₂ of the canister 11 change when an abnormality occurs in the sealing performance of the canister 11, the correction temperatures T _C1 and T _C2 also change with changes in the surface temperatures T ₁ and T ₂ . The correction temperature determination module 34-2 detects an abnormality in the sealing performance of the canister 11 by capturing changes in the correction temperatures T _C1 and T _C2 .

In this process, the time _t from the correction temperature _{T C1, T C2} calculated for _k, the time _t the difference between the correction in _k temperature _{T C1, T C2 ΔT C (} t k) (= T C1 (t k) -T C2 (T _k )) is calculated. (Step S41).

Then the processing is performed, except that the temperature difference [Delta] T _C instead of the correction temperature T _C1, T _C2 is used, is the same as the process executed by the state determination method according to the statistical processing of the correction temperature T _C1, T _C2 . Specifically, the average value mu _.DELTA.TC and standard deviation sigma _.DELTA.TC temperature difference [Delta] T _C in a most-recent fixed period of time gamma _k of the measurement time _{t k} is calculated (step S42, S43).

Subsequently, the normal temperature difference region R _ΔTC is determined from the average value μ _ΔTC and the standard deviation σ _ΔTC calculated in steps S42 and S43 (step S44). In the present embodiment, the normal temperature difference region R _ΔTC is
_{R ΔTC: μ ΔTC -n · σ} ΔTC <ΔT C <μ ΔTC + n · σ ΔTC, ··· (6)
Is determined. n is empirically preferably 2 or 3. However, n can take any optimum value.

Subsequently, the correction temperature determination module 34-2 determines whether or not the canister 11 is normal depending on whether or not the temperature difference ΔT _C (t _k ) is below the lower limit of the normal temperature difference region R _ΔTC (t _k ). Is determined (step S45). Specifically, the correction temperature determination module 34-2, the temperature difference [Delta] T _C is, if successively past m times including the current falls below the lower limit of the normal temperature difference region R _.DELTA.TC, abnormal sealing of the canister 11 determines that (step S46); that is, the correction temperature determination module 34-2, for any p temperature difference [Delta] t _C is "0 or more m-1 or less, the temperature difference ΔT _{C (t k-p)} is, When the condition “below the lower limit of the normal temperature difference region R _ΔTC (t _k−p )” is satisfied, it is determined that the sealability of the canister 11 is abnormal. On the other hand, the correction temperature determination module 34-2, when the temperature difference ΔT _{C (t k)} is exceeded successively past m times including the current upper limit of the normal temperature difference region _R ΔTC _{(t k),} sensor abnormality Alternatively, it is determined that there is an abnormality in the measurement system. When these conditions are not satisfied, the correction temperature determination module 34-2 determines that the canister 11 is normal (step S47).

(D) State determination based on detection of long-term change FIG. 18 is a flowchart showing processing for detecting an abnormality of the canister 11 by detecting long-term changes in the correction temperatures T _C1 and T _C2 .

In this process, the standard deviations σ ^S _TC1 and σ ^S _TC2 of the correction temperatures T _C1 and T _{C2 in} the predetermined reference period Γ ^S are calculated (step S51). As the reference period Γ ^S , a period in which the sealing performance of the canister 11 is found to be stably maintained is selected. That is, the standard deviations σ ^S _TC1 and σ ^S _TC2 are variations in the correction temperatures T _C1 and T _C2 when the canister 11 is in a stable state. The reference period Γ ^S can be fixed. For example, a predetermined period immediately after the start of storage can be determined as the reference period Γ ^S. It is also possible to be relatively determined from the measurement time t _k. For example, a period of two years up to a year before the time t _k is, it is possible to be determined as the reference period gamma ^S. When the reference period Γ ^S is fixed, the standard deviations σ ^S _TC1 and σ ^S _TC2 do not need to be calculated every time the measurement time arrives; the standard deviations σ ^S _TC1 and σ ^S _TC2 are calculated once. If done, it is sufficient.

Subsequently, from the correction temperatures T _C1 and T _C2 , the current values T ^c _C1 and T ^c _{C2 of} the correction temperature and the past values T ^p _C1 and T ^p _C2 are determined (step S52). The current value ^T _{c Ci,} a value determined from the most recent measurement time _{t k} of the correction temperature _T Ci _{(t k),} the past value ^T _{p Ci,} time from the latest measuring time _{t k} given τ _This value is determined from the corrected temperature T _Ci (t _{k ′} ) at the measurement time t _{k ′} (= t _k −τ _STD ) just before _STD . Typically, one month from the current measurement time t _k, 6 months, 1 year ago, two years ago, the time such as three years ago, is selected as the time t _{k '.} The current value T ^c _Ci and the past value T ^p _Ci can be the correction temperatures T _Ci (t _k ) and T _Ci (t _{k ′} ), respectively.

によって算出されることが好適である。 To eliminate the effects of variation, N obtained to date 'average of pieces of the correction temperature T _Ci is used as the current value T ^c _Ci, time t _k'-N-1 after time t _k' obtained by It is preferable that the average value of the N ′ correction temperatures T _Ci to be used is used as the past value T ^p _Ci ; that is, the current value T ^c _Ci and the past value T ^p _Ci are respectively expressed by the following formula (7a): , (7b):

It is preferable to be calculated by

Subsequently, the difference between the current value ^T _{c C1} correction temperature _{T C1} and past value _{^{T p C1 ΔT cp C1 (=}} T c C1 -T p C1), the current value ^T _{c C2} and past values of the correction temperature _{T C2} T the difference between the _{^{p C2 ΔT cp C2 (= T}} c C2 -T p C2) is calculated (step S53).

The difference [Delta] T ^cp _Ci is the decreased amount of the correction temperature T _Ci from the time t _{k 'to} time t _k, therefore, is a suitable parameter to detect that there is a small leakage in the canister 11. If the time difference τ _STD (= t _k −t _{k ′} ) is set appropriately, for example, if τ _STD is set to about 1 to 6 months, and if there is no abnormality in the canister 11, the difference ΔT ^cp _Ci is It is expected that the value will be close to 0; since the temperature drop of the canister 11 is substantially 0 in about 1 to 6 months. Conversely, as shown in Figure 20, the phenomenon that the difference [Delta] T ^cp _Ci is increased, from time t _{k 'to} the time t _k to the correct temperature T _Ci indicates that reduced, thus , Means that there is a minute leak in the canister 11 such that the pressure decreases in the order of the time difference τ _STD .

The corrected temperature determination module 34-2 determines whether or not the canister 11 is abnormal based on the changes in the difference ΔT ^cp _C1 and the difference ΔT ^cp _C2 calculated in step S53 (step S54). Specifically, the correction temperature determination module 34-2 calculates the normal temperature difference region R ^cp _C1 , R from the standard deviations σ ^S _TC1 and σ ^S _TC2 of the correction temperatures T _C1 and T _{C2 in} a predetermined reference period Γ ^S. Determine ^cp _C2 . Typically, the correction temperature determination module 34-2 converts the normal temperature difference regions R ^cp _C1 and R ^cp _C2 into R ^cp _C1 : −n · σ ^S _TC1 <ΔT ^cp _C1 <n · σ ^S _TC1 ,
R ^cp _C2 : −n · σ ^S _TC2 <ΔT ^cp _C2 <n · σ ^S _TC2 ,
And decide. n is empirically preferably 2 or 3. However, n can take any optimum value. Then, the correction temperature determination module 34-2 determines that at least one of the difference ΔT ^cp _C1 and the difference ΔT ^cp _C2 exceeds the upper limit of the normal temperature difference regions R ^cp _C1 and R ^cp _{C2 in} the past m times including this time. If, it is determined that there is an abnormality in the sealing performance of the canister 11 (step S55); that is, the correction temperature determination module 34-2, a difference [Delta] T ^cp _C1, at least one of the difference [Delta] T ^cp _C2 is "0 or more m-1 For the following arbitrary p, if the condition that the difference ΔT ^cp _Ci exceeds the upper limit of the normal temperature difference region R ^cp _Ci is satisfied, it is determined that the sealability of the canister 11 is abnormal. Instead, the corrected temperature determination module 34-2 determines that the difference ΔT ^cp _C1 and the difference ΔT ^cp _C2 are set to the upper limit of the normal temperature difference regions R ^cp _C1 and R ^cp _C2 continuously m times including the current time. If it exceeds, it may be determined that there is an abnormality in the sealing performance of the canister 11. When these conditions are not satisfied, the correction temperature determination module 34-2 determines that the canister 11 is normal (step S56).

The advantage of detecting an abnormality in the sealing performance of the canister 11 based on the difference ΔT ^cp _Ci between the current value T ^c _Ci and the past value T ^p _Ci described above is that the canister 11 takes about time τ _STD. That is, it is possible to detect minute leaks in which the pressure continues to decrease. This advantage is difficult to achieve in principle by the three methods described above, and using the above three methods in combination with the state determination by detecting a long-term change makes it possible to improve the sealing performance of the canister 11. This is suitable for further ensuring the detection of abnormalities.

Fourth Supplement and Modification 1 Application to Vault Storage The state detection device 2 of the present embodiment can also be used to determine whether or not the canister 11 has leaked during vault storage. The vault storage is a storage method in which the canisters 11 are arranged inside the storage building 1 without using the concrete container 21. Also in this case, the surface temperature of the canister 11 is measured, and an abnormality in the sealing performance of the canister 11 is detected from the surface temperature by the same calculation as described above.

However, when an abnormality in the sealing performance of the canister 11 in the vault storage is detected, it is preferable to add a correction term depending on the position of the canister 11 when calculating the correction temperature. This is because in the vault storage, the surface temperatures T ₁ and T ₂ of the canister 11 are easily affected by the position of the canister 11 due to the presence of the cooling air flowing inside the storage building 1. As shown in FIG. 11, in the vault storage, the canister 11 is exposed inside the storage building 1 and the cooling air directly touches the canister 11. This is because the surface temperature of the canister 11 located on the upstream side of the cooling air is relatively low regardless of whether or not the canister 11 leaks, and the surface temperature of the canister 11 located on the downstream side depends on whether or not the canister 11 leaks. It means that it is relatively expensive regardless. Therefore, in order to cancel the influence of the flow of the cooling air, it is preferable to include a correction term depending on the position of the canister 11 in the calculation formula for calculating the correction temperature.

Specifically, when calculating the correction temperature of each canister 11 based on the equation (1A), the following equation (3A):
T _Ci (t) = T _i (t) −ΣK _ij · f _ij (T ₀ (t)) + g _i (x),
... (3A)
It is preferable that the correction temperature of each canister 11 is calculated by Here, x is the position of the canister 11 where the correction temperature is calculated, and g _i (x) is a function of the position x of the canister 11. The function g _i (x) is determined so as to increase as the position x of the canister 11 is located upstream of the cooling air. The same applies to the case where the corrected temperature of each canister 11 is calculated based on other equations (1B), (1C), (1B ′), and (1C ′).

2. Application to a Metal Cask It is obvious to those skilled in the art that the state detection device 3 of the present embodiment can also be applied to the detection of an abnormality in the sealing property of a metal cask.

  When detecting an abnormality in the sealability of a metal cask, it is possible to detect an abnormality in the sealability from the internal pressure instead of the surface temperature, and it is preferable to use the pressure. is there. Unlike a concrete cask canister, a metal cask can directly measure its internal pressure. Since the occurrence of leakage of the metal cask 3 directly leads to a change in pressure as it is, detecting an abnormality in the sealing property of the metal cask 3 based on the pressure inside the metal cask 3 causes the occurrence of the abnormality in the sealing property. It is suitable for sure detection.

FIG. 12 is a block diagram showing the configuration of the metal cask 2 ′ and the state detection device 3 ′ that detects an abnormality in sealing performance from the pressure inside the metal cask 2 ′.
The metal cask 2 'schematically includes a trunk portion 61, a primary lid 62a, and a secondary lid 62b. The body 61, the primary lid 62a, and the secondary lid 62b are all made of stainless steel or carbon steel. The upper opening of the body 61 is sealed by the primary lid 62a, and the secondary lid 62b is fixed so as to cover the primary lid 62a. A cavity 63 is formed by the body 61 and the primary lid 62 a, and a basket 65 for storing the spent fuel assembly 64 is stored in the cavity 63. A pressure barrier 66 that is a space for buffering pressure is formed between the primary lid 62a and the secondary lid 62b. The secondary lid 62b is provided with an inspection hole 67 passing therethrough. As will be described later, the inspection hole 67 is an opening for inserting a pressure sensor for measuring the pressure of the pressure barrier 66. The cavity 63 and the pressure barrier 66 are filled with helium gas. The helium gas serves to diffuse the heat generated by the spent fuel assembly 64 throughout the cavity 63 by convection.

The state detection device 3 ′ includes a pressure sensor 71, an environmental temperature sensor 72, a calculation device 73, and a display device 74. The pressure sensor 71 is used for sequentially measuring the pressure P of the pressure barrier 66. The pressure sensor 71 is inserted into an inspection hole 67 provided in the secondary lid 62 b, and the tip thereof is fixed to the secondary lid 62 b so as to reach the pressure barrier 66. The pressure sensor 71 and the secondary lid 66 are sealed by a sealing structure, and the inspection hole 67 is completely sealed. Since the pressure inside the pressure barrier 66 is constant at any position, the pressure sensor 71 does not need to be provided at different height positions (unlike the temperature sensors 31 and 32). The environmental temperature sensor 72 measures the environmental temperature T ₀ around the metal cask 1.

The computing device 73 is a computer that detects the presence or absence of abnormality of the metal cask 3 using the pressure P sequentially measured by the pressure sensor 71 and the environmental temperature T ₀ sequentially measured by the environmental temperature sensor 33. . The arithmetic device 73 includes a correction temperature calculation module 73-1, a correction temperature determination module 73-2, a correction coefficient determination module 73-3, a physical model determination module 73-4, a spectrum analysis module 73-5, A computer program including an ARX model determination module 73-6, a discriminant analysis module 73-7, an impulse response determination module 73-8, and a group management module 73-9 is installed. These modules use the pressure P in place of the surface temperature _{T i,} except that replaced the correction temperature _{T Ci} to correct the pressure _{P C,} the correction temperature calculation module 34-1, a correction temperature determination module 34-2, Correction coefficient determination module 34-3, physical model determination module 34-4, spectrum analysis module 34-5, ARX model determination module 34-6, discriminant analysis module 34-7, impulse response determination module 34-8 And the same calculation as in the group management module 34-9. Corrected pressure P _C, as well as the correct temperature T _Ci, a virtual pressure from the pressure of the metal cask 3 remove the influence of the environmental temperature T _0. The pressure P of the metal cask 2 'is measured, corrected pressure P _C is calculated from the pressure P. Based on the pressure P, and corrected pressure P _C, the presence of occlusive abnormality metal cask 3 is determined. This calculation is possible because the pressure P and temperature T are approximately
PV = nRT,
It is self-evident to those skilled in the art considering the relationship.

FIG. 13 is a flowchart showing a method for determining the state of the metal cask 2 ′. At each predetermined measurement time, the pressure P of the pressure barrier 66 of the metal cask 2 ′ is measured (step S11 ′). Furthermore, the measured pressure P, the environmental temperature _{T 0,} corrected pressure _{P C} is calculated (step S12 '). Corrected pressure _{P C} is being read as the surface temperature _{T Ci} pressure P, wherein the correction temperature _{T Ci} was read as corrected pressure _{P C} (1A) to (1C), (1B '), calculated from (1C) As with the correction temperature T _Ci , the frequency P can be selected from the frequency spectrum of the pressure P and the ambient temperature T ₀ .

Furthermore, the pressure P and the corrected pressure P _C, the metal cask 2 'sealability is determined from whether it is abnormal (step S13'). The determination of the abnormality in the sealing property of each metal cask 2 ′ is performed by the correction temperature determination module 34-2, the correction coefficient determination module 34-3, the physical model determination module 34-4, the spectrum analysis module 34-5, and the ARX. This is performed by the model determination module 34-6, the discriminant analysis module 34-7, and the impulse response determination module 34-8.

  If no abnormality is found in the sealability of the all-metal cask 2 ′ in step S13 ′, the display device 74 displays that the all-metal cask 2 ′ is normal (steps S14 ′, S15 ′). ). On the other hand, if there is a metal cask 2 'in which an abnormality is found in the sealing performance, step S16' is performed.

  In step S16 ′, the abnormality of the metal cask 2 ′ in which an abnormality is found in the sealing performance in step S13 ′ indicates the tendency of the characteristic amount of the metal cask 2 ′ and the characteristic amount of the metal cask 2 ′ located in the vicinity thereof. Confirmed by comparing trends. The specific procedure is the same as the procedure for checking the abnormality of the abnormality determination canister described above.

  In step S17, the result of determination in step S16 'is displayed on the display device 74. When it is finally determined that there is an abnormality in the sealing performance of a certain metal cask 2 ', it is displayed that any metal cask 2' is determined to be abnormal. If it cannot be concluded that there is an abnormality in the sealing performance of the metal cask 2 ', this is displayed.

FIG. 1 is a conceptual diagram showing an embodiment of a state detection apparatus according to the present invention. FIG. 2 is a block diagram showing the configuration of the concrete cask and the state detection device in the present embodiment. FIG. 3 is a flowchart showing a canister state determination method according to the present embodiment. FIG. 4 is a flowchart showing the procedure for identifying the time constant of the first-order lag element that approximates the response of the environmental temperature to the surface temperature. FIG. 5 is a flowchart showing a procedure for calculating the correction temperature. FIG. 6 is a conceptual diagram illustrating an abnormality determination procedure by physical model simulation. FIG. 7 is a graph for explaining abnormality determination by spectrum analysis. FIG. 8 is a conceptual diagram illustrating abnormality determination using the ARX model. FIG. 9 is a conceptual diagram illustrating abnormality determination using discriminant analysis. FIG. 10 is a conceptual diagram illustrating abnormality determination using an impulse response. FIG. 11 is a conceptual diagram of vault storage. FIG. 12 is a block diagram illustrating a configuration of a state detection device for determining an abnormality of a metal cask. FIG. 13 is a flowchart for explaining a state detection method for determining abnormality of the metal cask. FIG. 14 is a flowchart showing a process for detecting an abnormality in the sealing performance of the canister by the statistical process of the correction temperature in the preferred embodiment. FIG. 15 is a graph showing a specific example of detection of an abnormality in the sealing performance of the canister by statistical processing of the correction temperature. FIG. 16 is a flowchart showing a process of detecting an abnormality in the sealing performance of the canister by a statistical process of the change rate of the correction temperature in the preferred embodiment. FIG. 17 is a graph showing a specific example of an abnormality in the sealability of the canister by statistical processing of the change rate of the correction temperature. FIG. 18 is a flowchart showing a process for detecting an abnormality in the sealing performance of the canister by a statistical process of a difference between correction temperatures obtained for two points having different heights. FIG. 19 is a flowchart showing a process for detecting an abnormality in the sealing performance of the canister by detecting a long-term temperature change. FIG. 20 is a graph showing a specific example of an abnormality in the sealing performance of a canister by detecting a long-term temperature change.

Explanation of symbols

1: Storage building 2: Concrete cask 2 ': Metal cask 3, 3': Condition detection device 11: Canister 12: Body 13a: Primary lid 13b: Secondary lid 14: Cavity 15: Spent fuel assembly 16: Basket 21: Concrete container 22: Support body 23: Side wall 24: Cover body 25: Air circulation hole 26, 27: Inspection hole 31, 32: Temperature sensor 33: Environmental temperature sensor 34: Arithmetic device 34-1: Correction temperature calculation module 34 -2: Correction temperature determination module 34-3: Correction coefficient determination module 34-4: Physical model determination module 34-5: Spectrum analysis module 34-6: ARX model determination module 34-7: Discriminant analysis module 34-8: Impulse Response determination module 34-9: Group management module 35: Display device 61: Body 62 : Primary lid 62b: Secondary lid 63: Cavity 64: Spent fuel assembly 65: Basket 66: Pressure barrier 67: Inspection hole 71: Pressure sensor 72: Environmental temperature sensor 73: Computing device 73-1: Corrected pressure calculation module 73-2: Correction pressure determination module 73-3: Correction coefficient determination module 73-4: Physical model determination module 73-5: Spectrum analysis module 73-6: ARX model determination module 73-7: Discriminant analysis module 73-8: Impulse response determination module 73-9: Group management module 74: Display device

Claims (23)

State quantity acquisition means for acquiring the state quantities of a plurality of radioactive substance containers containing radioactive substances;
An abnormality detecting means for determining an abnormality of the plurality of radioactive substance containers based on the state quantity;
The abnormality detection means determines an abnormality of one radioactive substance container among the plurality of radioactive substance containers based on the state quantity of the one radioactive substance container and the state quantity of another radioactive substance container. Status detector for radioactive material containers. A state detection device for a radioactive substance container according to claim 1,
The abnormality detecting means compares the tendency of the feature amount corresponding to the state quantity of the one radioactive substance container with the tendency of the feature quantity corresponding to the state quantity of the other radioactive substance container. Radioactive material container condition detection device that determines the abnormality of the radioactive material container. A state detection device for a radioactive substance container according to claim 2,
In addition,
Environmental temperature measuring means for measuring environmental temperature;
For each of the plurality of radioactive substance containers, the corrected state quantity is corrected by correcting the state quantity based on the environmental temperature and the position of the plurality of radioactive substance containers in a storage building that houses the plurality of radioactive substance containers. Correction amount calculation means for calculating,
The abnormality detection means detects an abnormality of the radioactive substance container based on the correction state quantity. A state detection device for a radioactive substance container according to claim 3,
The corrected state quantity calculating means calculates the corrected state quantity so that a difference between the state quantity and the corrected state quantity becomes larger as it is upstream of the flow of cooling air inside the storage building. Substance container state detection device. State quantity acquisition means for acquiring the state quantities of a plurality of radioactive substance containers containing radioactive substances;
Environmental temperature measuring means for measuring environmental temperature;
Correction state quantity calculating means for calculating a correction state quantity by correcting the state quantity based on the environmental temperature;
An abnormality detecting means for determining an abnormality of the plurality of radioactive substance containers based on the corrected state quantity;
The corrected state quantity calculating means calculates the corrected state quantity of the plurality of radioactive substance containers based on positions of the plurality of radioactive substance containers in a storage building that houses the plurality of radioactive substance containers. Detection device. The state detection device for a radioactive substance container according to claim 5,
The corrected state quantity calculating means calculates the corrected state quantity so that a difference between the state quantity and the corrected state quantity becomes larger as it is upstream of the flow of cooling air inside the storage building. Substance container state detection device. A state quantity acquisition means for acquiring a state quantity of a radioactive substance container containing radioactive substances;
Environmental temperature measuring means for measuring environmental temperature;
A corrected state using an equation including a state quantity corresponding term corresponding to the state quantity, a response waveform corresponding term representing a response of the environmental temperature to the state quantity, and an environmental temperature correction term which is a linear function of the environmental temperature. A radioactive substance container state detection device comprising: a corrected state quantity calculating means for calculating a quantity; and an abnormality determining means for judging an abnormality of the radioactive substance container based on the corrected state quantity. A state quantity acquisition means for acquiring a state quantity of a radioactive substance container containing radioactive substances;
Environmental temperature measuring means for measuring environmental temperature;
A correction state quantity calculating means for calculating a correction state quantity using an equation including a state quantity correspondence term corresponding to the state quantity and a correction term that is a function of the environmental temperature; and the radioactive substance based on the correction state quantity An abnormality judging means for judging an abnormality of the container,
The radioactive state container state detection device, wherein the correction state quantity calculating means determines a coefficient of the correction term so that the environmental temperature and the correction state quantity are uncorrelated. A state quantity acquisition means for acquiring a state quantity of a radioactive substance container containing radioactive substances;
Environmental temperature measuring means for measuring environmental temperature;
A frequency spectrum calculating means for calculating a frequency spectrum of the state quantity and a frequency spectrum of the environmental temperature;
A corrected spectrum calculating means for obtaining a corrected frequency spectrum from the frequency spectrum of the state quantity and the frequency spectrum of the environmental temperature;
Correction state quantity calculating means for calculating a correction state quantity from the correction frequency spectrum;
An apparatus for detecting a state of a radioactive substance container, comprising: an abnormality determination unit that determines an abnormality of the radioactive substance container based on the correction state quantity. The state detection device for a radioactive substance container according to claim 9,
The radioactive substance container state detection device, wherein the correction spectrum calculation means obtains the correction frequency spectrum by subtracting at least a part of the frequency spectrum of the environmental temperature from the frequency spectrum of the state quantity. A state quantity acquisition means for acquiring a state quantity of a radioactive substance container containing radioactive substances;
Environmental temperature measuring means for measuring environmental temperature;
It is a function of the state quantity correspondence term corresponding to the state quantity and the environmental temperature for each of a normal period in which the radioactive substance container is normal and a determination target period that is a target of determination of abnormality of the radioactive substance container. A correction state quantity calculating means for calculating a correction state quantity using an equation including a correction term and an abnormality determination means,
The correction state quantity calculating means determines a coefficient of the correction term so that the environmental temperature and the correction state quantity are uncorrelated;
The abnormality determination means determines an abnormality of the radioactive substance container from the coefficient of the correction term obtained for the normal period and the coefficient of the correction term obtained for the determination target period. State detection device. It is a state detection apparatus for radioactive substance containers of Claim 11, Comprising:
The correction term includes a plurality of terms corresponding to a plurality of different transfer functions,
The abnormality determining means determines an abnormality of the radioactive substance container from the coefficients of the plurality of terms obtained for the normal period and the coefficients of the plurality of terms obtained for the determination target period. State detection device. A state quantity measuring means for measuring a state quantity of the radioactive substance container containing the radioactive substance,
Environmental temperature measuring means for measuring environmental temperature;
A state quantity estimating means for estimating a normal value of the state quantity of the radioactive substance container based on the environmental temperature using a physical model indicating a response to the state quantity of the environmental temperature;
Radioactivity comprising an abnormality detection means for judging an abnormality of the plurality of radioactive substance containers based on the estimated normal value and a state quantity feature quantity corresponding to the state quantity measured by the state quantity acquisition means Substance container state detection device. State quantity acquisition means for acquiring a state quantity of a radioactive substance container containing the radioactive substance;
Frequency spectrum calculating means for calculating a frequency spectrum of a state quantity feature corresponding to the state quantity;
An apparatus for detecting a state of a radioactive substance container, comprising: an abnormality determination unit that determines an abnormality of the radioactive substance container based on the frequency spectrum. It is a state detection apparatus for radioactive substance containers of Claim 14, Comprising:
The state quantity feature quantity is one value selected from a correction state quantity obtained by correcting the state quantity based on the environmental temperature and a feature quantity corresponding to the correction state quantity. Substance container state detection device. It is a state detection apparatus for radioactive substance containers of Claim 14, Comprising:
The frequency spectrum calculated by the frequency spectrum calculation means is:
A normal frequency spectrum of a state quantity feature corresponding to the state quantity of the radioactive substance container when the radioactive substance container is normal;
A determination target period frequency spectrum of a state quantity feature amount corresponding to the state quantity of the radioactive substance container in a period which is a target of determination of abnormality of the radioactive substance container,
The said abnormality determination means determines the abnormality of the said radioactive substance container based on the said normal time frequency spectrum and the said determination object period frequency spectrum The radioactive substance container state detection apparatus. A state quantity measuring means for measuring a state quantity of the radioactive substance container containing the radioactive substance,
Environmental temperature measuring means for measuring environmental temperature;
ARX model identification means for identifying an ARX (auto-regressive exogenous) model having the environmental temperature as an exogenous input and the state quantity as an output;
A component that does not depend on the environmental temperature in the state quantity of the radioactive substance container is obtained from the ARX model, a white test is performed on the obtained component, and an abnormality of the radioactive substance container is determined from a result of the white test. A state detection device for a radioactive substance container comprising an abnormality determination means. A state quantity acquisition means for acquiring a state quantity of a radioactive substance container containing radioactive substances;
A state quantity feature corresponding to the state quantity obtained by the state quantity acquisition means includes a group of state quantity feature quantities of the radioactive substance container when the radioactive substance container is normal, and a sealing property of the radioactive substance container. Radioactive substance comprising abnormality detection means for determining abnormality of the radioactive substance container by determining by discrimination analysis which of the state quantity feature quantity group of the radioactive substance container when the substance is abnormal Container state detection device. The state detection device for a radioactive substance container according to claim 18,
The state quantity feature quantity is a corrected state quantity obtained by correcting the state quantity based on the environmental temperature, or a feature quantity obtained from the corrected state quantity. The state detection device for a radioactive substance container according to claim 18,
The abnormality detection means calculates a Mahalanobis general distance for a state quantity feature corresponding to the state quantity obtained by the state quantity acquisition means, and based on the calculated Mahalanobis general distance, the radioactive substance container Status detector for radioactive material containers to judge abnormalities. A state quantity measuring means for measuring a state quantity of the radioactive substance container containing the radioactive substance,
Environmental temperature measuring means for measuring environmental temperature;
A radioactive substance container state detection apparatus comprising: an abnormality determination unit that obtains an impulse response to the state quantity of the environmental temperature and determines an abnormality of the radioactive substance container from a feature quantity of the impulse response. The state detection device for a radioactive substance container according to claim 21,
The feature amount includes a reduction ratio of the impulse response,
The abnormality determination means determines an abnormality of the radioactive substance container from the reduction ratio. The state detection device for a radioactive substance container according to claim 21,
The feature amount is a time constant obtained from a step response corresponding to the impulse response,
The abnormality determination means determines an abnormality of the radioactive substance container from the time constant.

Images