A method of value transfer

Abstract

The present application relates to the field of radioactive activity measurement, and provides a method for value transfer, the method comprising: m measurement standard devices correspondingly measure m sources to be measured, obtain the activities of the corresponding m sources to be measured, under the same measurement conditions of the same transfer standard device and the m measurement standard devices, the transfer standard device measures the same exempted reference source and the sources to be measured corresponding to each measurement standard device under the corresponding measurement conditions, obtains m reference source count rates and m sources to be measured count rates; according to the activities of the m sources to be measured, the reference source count rates and the sources to be measured count rates, obtains m equivalent activities; according to the m equivalent activities, determines the compliance results of the m corresponding measurement standard devices. By using the exempted reference source and the transfer standard device to transfer between multiple different measurement standard devices, the compliance results of multiple different measurement standard devices can be judged, the limitation of using standard sources or standard solutions for transfer for comparison can be eliminated, and the radiation safety risks in the circulation of radioactive sources can be reduced.

Description

Technical Field

[0001] The present application relates to the field of radioactivity measurement and provides a method for transferring a measurement value. Background Art

[0002] Comparison is an important means to ensure that laboratory values ​​are accurate and reliable. In the field of radioactivity measurement, the traditional method of value comparison is to transfer radioactive standard sources or standard solutions between laboratories, use the measurement standard devices of each laboratory to measure the same standard source or standard solution, and analyze the measurement results to determine whether each laboratory has reached the standard.

[0003] The key to the above-mentioned traditional comparison value transfer is to use radioactive standard sources or standard solutions to transfer between laboratories. Radioactive standard sources are radioactive nuclides whose properties and activities are known within a certain period of time and can be used as comparison standards. The types of radioactive standard sources or standard solutions vary with the purpose of comparison. For example, solid, liquid, gas, or volatile material standard sources; long-life or short-life nuclide standard sources or standard solutions; α, β or γ ray emitting radioactive standard sources or standard solutions, etc. However, due to the large radiation of radioactive standard sources or standard solutions, there are certain radiation safety risks when they are transferred and circulated between laboratories.

[0004] As radiation safety management continues to strengthen, nuclear safety departments at all levels have very strict supervision over the circulation of radioactive standard sources or standard solutions, which need to meet various management standards. It is becoming increasingly difficult to implement radioactive activity value comparison using radioactive sources or radioactive solutions. In order to ensure the accuracy and reliability of radioactive activity value transfer and make radioactive activity measurement more reliably serve all aspects of the nuclear industry, it is necessary to find a new method of comparison value transfer. Summary of the invention

[0005] In view of this, an embodiment of the present application provides a method for transferring a measurement value to get rid of the limitation of using a standard source or a standard solution for comparison and to reduce the radiation safety risk of the radioactive source during its circulation.

[0006] The present application provides a method for transferring a value, including:

[0007] m measurement standard devices measure m sources to be measured one by one, and obtain the corresponding activities A1 of the m sources to be measured, where m is a positive integer greater than 1;

[0008] When the same transfer standard device has the same measurement conditions as the m measurement standard devices, the transfer standard device measures the same exemption reference source under the corresponding measurement conditions to obtain m reference source count rates N2, and the transfer standard device measures the sources to be measured corresponding to each of the measurement standard devices to obtain m sources to be measured count rates N1;

[0009] Obtain m equivalent activities A2 according to m corresponding activities A1 of the source to be measured, the counting rate N1 of the source to be measured and the counting rate N2 of the reference source;

[0010] According to the m equivalent activities A2, the compliance results of the m corresponding measurement standard devices are determined.

[0011] In some implementation schemes, there is no correlation between the m sources to be detected.

[0012] In some embodiments, the m sources to be measured are unrelated to each other, which means that each source to be measured is a radioactive source with a different activity A1 of the source to be measured, prepared by using different original solutions at different times.

[0013] In some embodiments, the equivalent activity A2 is the ratio of the activity A1 of the source to be measured to the count rate N1 of the source to be measured, multiplied by the count rate N2 of the reference source.

[0014] In some implementation schemes, the efficiency ε of the transfer standard device is obtained based on the ratio of the count rate N1 of the source to be measured to the activity A1 of the source to be measured.

[0015] In some embodiments, determining the compliance results of the m measurement standard devices according to the m equivalent activities A2 includes:

[0016] According to the m equivalent activities A2, the corresponding m normalized deviations E are obtained. n ;

[0017] The m normalized deviations E n The values ​​are compared with the preset values ​​respectively to determine the compliance results of the corresponding measurement standard devices.

[0018] In some embodiments, the m normalized deviations E n The normalized deviation of the i-th measurement standard device is E ni , through Calculate, where: A2 i is the equivalent activity of the ith r is the reference value of m equivalent activities A2; U i For A2 i The expanded uncertainty of r For A2r The expanded uncertainty of .

[0019] In some embodiments, the transfer standard device comprises a NaI(Tl) digital gamma spectrometer.

[0020] In some embodiments, the exempt reference source is a long-lived nuclide 94 Nb.

[0021] In some embodiments, the exempt reference source and the source to be measured are both gamma radionuclides.

[0022] The embodiment of the present application provides a method for transferring a value, which utilizes an exempt reference source and a transfer standard device to transfer between multiple different metrology standard devices, and converts the activity A1 of the source to be measured measured by each metrology standard device into the equivalent activity A2 of each transfer standard device relative to the same exempt reference source, and compares the equivalent activity A2 to achieve the judgment of the compliance results of multiple different metrology standard devices. By transferring a transfer standard device (including an exempt reference source) that can circulate freely, the problem of strict and difficult implementation of circulation control in transferring radioactive standard sources is solved, and the radiation safety risks that may be caused by the source to be measured with radiation can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a method for transferring a value provided in this application;

[0024] Figure 2 A flowchart of another method for transferring a value provided in this application. DETAILED DESCRIPTION

[0025] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the embodiments of the present disclosure. Instead, they are merely examples of methods consistent with some aspects of the embodiments of the present disclosure as detailed in the appended claims.

[0026] This application embodiment provides a method for transferring a value. Figure 1 As shown, the value transfer method includes the following steps:

[0027] Step S1, m measurement standard devices measure m sources to be measured one by one, and obtain the corresponding activities A1 of the m sources to be measured, where m is a positive integer greater than 1;

[0028] Step S2, when the same transfer standard device has the same measurement conditions as the m measurement standard devices, the transfer standard device measures the same exemption reference source under the corresponding measurement conditions to obtain m reference source count rates N2, and the transfer standard device measures the sources to be measured corresponding to each of the measurement standard devices to obtain m sources to be measured count rates N1;

[0029] Step S3, obtaining m equivalent activities A2 according to m corresponding activities A1 of the source to be measured, the counting rate N1 of the source to be measured and the counting rate N2 of the reference source;

[0030] Step S4, determining the compliance results of the m corresponding measurement standard devices according to the m equivalent activities A2.

[0031] In the related art, in the field of radioactivity measurement, a single metrology standard device is generally configured in a single laboratory, that is, each metrology standard device is in a different space, for example, each metrology standard device is in a different laboratory, and there is a certain physical distance between them. According to the traditional comparison method, it is necessary to prepare the same radioactive standard source and distribute it to multiple metrology standard devices in different spaces to measure radioactivity. The radioactivity measurement results of multiple metrology standard devices are compared with each other to determine the compliance results of each metrology standard device. However, the transmission of radioactive standard sources in the related art not only faces the dilemma of strict circulation control and difficulty in implementation, but also faces greater radiation safety risks such as ionizing radiation damage and radiation source loss.

[0032] The method for transferring the value provided in the embodiment of the present application utilizes an exempt reference source and a transfer standard device to transfer between multiple different metrology standard devices, and converts the activity A1 of the source to be measured obtained by each metrology standard device into the equivalent activity A2 of each transfer standard device relative to the same exempt reference source, and compares the equivalent activity A2 to achieve the judgment of the compliance results of multiple different metrology standard devices. By transferring a transfer standard device (including an exempt reference source) that can circulate freely, the limitation of using direct radioactive standard sources or radioactive standard solutions for comparison is eliminated, and the problem of strict and difficult implementation of circulation control in transferring radioactive standard sources is solved, and the radiation safety risks that may be caused by the radioactive source to be measured can be avoided.

[0033] It should be noted that the source to be measured refers to a radioactive source with a certain radioactivity. Among them, the exempted reference source is a reference source that is sufficiently small for the public radiation dose and can be freely circulated. The counting rate refers to the nuclear radiation count recorded by the detector per unit time.

[0034] It can be understood that the compliance results include the accuracy of the measurement values ​​of the measurement standard device and the reliability of the value transfer.

[0035] See also Figure 2 As shown, the following is a detailed description of each step of the value transfer method provided in the embodiment of the present application. It should be noted that these detailed implementation steps can be selected and sorted according to different needs.

[0036] Step S1, m measurement standard devices measure m sources to be measured one by one, and obtain the corresponding activities A1 of the m sources to be measured, wherein m is a positive integer greater than 1.

[0037] That is to say, the number of m measurement standard devices includes two or more, and at the same time, one-to-one correspondence means that one measurement standard device corresponds to only one source to be measured, and each measurement standard device corresponds to measuring one source to be measured that matches it. For example, the first measurement standard device measures the first source to be measured corresponding to it, and obtains the activity A11 of the first source to be measured, the second measurement standard device measures the second source to be measured corresponding to it, and obtains the activity A12 of the second source to be measured, and the i-th measurement standard device measures the i-th source to be measured, and obtains the activity A1 of the i-th source to be measured. i And so on, we can obtain the corresponding m source activities A11, A12, ..., A1 i ,… Where i is a positive integer less than or equal to m.

[0038] Step S2, when the measurement conditions of the same transfer standard device are consistent with those of the m measurement standard devices, the transfer standard device measures the same exemption reference source under the corresponding measurement conditions to obtain m reference source counting rates N2, and the transfer standard device measures the sources to be measured corresponding to each of the measurement standard devices to obtain m sources to be measured counting rates N1.

[0039] This means that using the same transfer standard device and the same exemption reference source during the transfer process can ensure that the measurement benchmark remains unchanged. By circulating the exemption reference source and the transfer standard device between m different measurement standard devices and the corresponding m sources to be measured, the counting rate N1 of the m sources to be measured and the counting rate N2 of the m reference sources can be measured.

[0040] Specifically, in order to reduce the environmental error caused by the transfer standard device measuring different metrology standard devices each time and keep the measurement conditions relatively unchanged, each time the transfer standard device transfers from the previous metrology standard device to the next metrology standard device, it is necessary to re-measure the exempt reference source and obtain the reference source count rate N2 corresponding to each different metrology standard device to reduce the relative error caused by changes in the measurement environment.

[0041] For example, the same transfer standard device measures the source count rate N11 of the first source to be measured corresponding to the first metrological standard device. At the same time, the same transfer standard device measures the reference source count rate N21 of the same exempted reference source under the same measurement space and measurement conditions. Then, the same transfer standard device and the same exempted reference source are transferred to the measurement space of the second source to be measured corresponding to the second metrological standard device. While keeping the second measurement conditions relatively consistent, the source count rate N12 of the second source to be measured and the reference source count rate N22 of the same exempted reference source are measured. And so on, m source count rates N11, N12, ..., N1 are obtained. i , ..., and the corresponding m reference source count rates N21, N22, ..., N2 i ,… Where i is a positive integer less than or equal to m.

[0042] Step S3, obtaining m equivalent activities A2 according to the m corresponding activities A1 of the source to be measured, the counting rate N1 of the source to be measured and the counting rate N2 of the reference source.

[0043] That is to say, each set of the activity A1 of the source to be measured, the counting rate N1 of the source to be measured and the counting rate N2 of the reference source can be calculated or derived to obtain a corresponding equivalent activity A2.

[0044] In one embodiment, the equivalent activity A2 is the ratio of the activity A1 of the source to be measured to the count rate N1 of the source to be measured, multiplied by the count rate N2 of the reference source.

[0045] For example, among m equivalent activities A2, the i-th equivalent activity A2 i Calculated by formula (1):

[0046]

[0047] Where i is a positive integer less than or equal to m; A1 i is the activity of the i-th source to be measured; N1 i is the counting rate of the i-th source to be measured; N2 i is the counting rate of the i-th reference source.

[0048] In one embodiment, the efficiency ε of the transfer standard device can also be obtained according to the ratio of the count rate N1 of the source to be measured to the activity A1 of the source to be measured. For example, for the same transfer standard device, the efficiency ε of the transfer standard device relative to the source to be measured is fixed. Therefore, under the premise of ensuring the stability of the transfer standard device, the count rate N1 of the i-th source to be measured is i and the reference source count rate N2 i Stable; once the activity A1 of the source to be measured is measured by the i-th measurement standard device i If unreliable, then A1i / N1 i Change, and then A2 i That is, A2 i It can reflect the radioactivity measurement capability of the i-th measurement standard device participating in the comparison.

[0049] Step S4, determining the compliance results of the m corresponding measurement standard devices according to the m equivalent activities A2.

[0050] That is to say, the equivalent activities of each metrological standard device A21, A22, ..., A2 i , …, A2 m After they are determined, a variety of comparison methods can be used to compare the m equivalent activities, so as to determine whether the measurement capability of each measurement standard device meets the standards based on the judgment criteria.

[0051] In one embodiment, step S4 further includes the following steps:

[0052] Step S41, according to the m equivalent activities A2, obtain the corresponding m normalized deviations E n Specifically, each of the m measurement standard devices has its own normalized deviation E n , normalized deviation E n It is the ratio of the difference between the measurement result of the measurement standard device and the reference value to the uncertainty of the difference, where the uncertainty of the difference is the combined standard uncertainty of the two.

[0053] Exemplarily, in one embodiment, m normalized deviations E n The normalized deviation of the i-th measurement standard device is E ni , E ni Calculated by formula (2):

[0054]

[0055] Among them, A2 i is the ith equivalent activity, A2 r is the reference value of m equivalent activities A2; U i For A2 i The expanded uncertainty of r For A2 r The expanded uncertainty of For A2 i and A2 r The combined standard uncertainty of

[0056] It should be noted that A2 rIt is the reference value of m equivalent activities A2, which is determined according to the measurement plan. It can be the measurement value of the leading metrological standard device or the average value of the measurement results of m metrological standard devices. The leading metrological standard device is often set up in the leading laboratory. Specifically, the leading laboratory is a laboratory that plays a leading role in the comparison. It usually needs to have corresponding qualifications and assume corresponding responsibilities, such as having legal qualifications and impartial status, providing transfer standards, formulating comparison plans, controlling the comparison process, processing comparison data, writing comparison reports, personnel with corresponding technical capabilities, and stable and reliable metrological standard devices whose technical indicators involved in the comparison field meet the requirements.

[0057] Step S42: m normalized deviations E n The normalized deviation E n Compare with the preset value to determine the compliance result of the measurement standard device.

[0058] The preset value is set according to convention. For example, in one embodiment, the i-th normalized deviation E ni When the absolute value of is less than or equal to the preset value, the compliance result of the i-th measurement standard device meets the requirements. Among them, the preset value in some embodiments is 1, that is, |E ni |≤1, the measurement capability of the i-th measurement standard device meets the requirements.

[0059] In one embodiment, the value transfer method provided in the embodiment of the present application further includes step S5 before step S1, preparing corresponding sources to be measured in the laboratories of m measurement standard devices respectively, one measurement standard device corresponds to one source to be measured, thereby obtaining m sources to be measured.

[0060] Specifically, the source to be measured is prepared according to the standard point source requirements. The standard point source is sandwiched between two layers of transparent organic membranes with a thickness of less than 10 mg.cm -2 The diameter of the source active spot is less than 5mm, the eccentricity is less than 1.5mm, the heavy peak interference gamma ray impurities are less than 0.2%, and the radioactive source has certain mechanical strength and chemical stability.

[0061] Exemplarily, in one embodiment, there is no correlation between the m sources to be measured. That is to say, the m sources to be measured used in the present application have no correlation in terms of the radioactive materials used to prepare the sources to be measured, the preparation environment, and the preparation time. In this way, it is possible to avoid the transfer of radioactive materials used to prepare the sources to be measured between various laboratories and reduce the transfer safety risk, making the comparison easier to implement.

[0062] Specifically, in one embodiment, the lack of correlation between the m sources to be measured means that each source to be measured is a radioactive source with a different source activity A1 prepared by different original solutions at different times. The radioactive activities A1 of the m unrelated sources to be measured are different, so that the values ​​of the m sources to be measured count rates N1 and the m reference source count rates N2 of the transfer standard device are different, thereby improving the authenticity and accuracy of the compliance results. It is understandable that the preparation of the source to be measured meets the requirements for the preparation of the standard point source. For example, the specific preparation requirements of the source to be measured may include but are not limited to the composition of the source to be measured, the impurity content, the activity size, the geometric dimensions, etc. The requirements for preparing the source to be measured are usually comprehensively considered based on the comparison measurement object, the comparison measurement standard, and the performance of the measuring device.

[0063] It should be noted that step S1 and step S2 can be performed sequentially, interspersed, or simultaneously according to actual conditions. Sequentially means that step S1 is performed first, and step S2 is performed after step S2 is completed; or step S2 is performed first, and step S1 is performed after step S2 is completed.

[0064] Interleaved means that step S1 and step S2 are performed in sequence in the first laboratory, and then step S1 and step S2 are performed in sequence in the second laboratory, and so on until the measurement of the last laboratory is completed.

[0065] Simultaneously means that step S2 is performed while step S1 is performed. For example, the metrology standard devices of m laboratories simultaneously perform m A1 measurements on the corresponding m sources to be measured, and at the same time, the transfer standard device simultaneously performs N1 measurements on the m sources to be measured in turn, and performs N2 measurements on the exempt reference source.

[0066] It is understandable that after the processing of steps S1 and S2 of any group of laboratories is completed, step S3 of the group can be performed. For example, step S1 and step S2 are processed in an interleaved manner. When A1 of the i-th group of laboratories is i 、N1 i 、N2 i After all are obtained, you can proceed to step S3 to obtain A2 i .

[0067] In one embodiment, both the exempted reference source and the source to be measured are gamma radionuclides. Since the gamma rays produced by gamma radionuclides have strong penetrating properties and the circulation of radioactive source materials causes great harm, the value transfer method of the embodiment of the present application is particularly suitable for the measurement value comparison of the measurement standard device for gamma radionuclides.

[0068] There are many types of gamma spectrometers, for example, gamma spectrometers such as high-purity germanium, sodium iodide, lanthanum bromide, and cadmium zinc telluride are commonly used as a measuring device in the field of radioactive activity. Exemplarily, in one embodiment, the transfer standard device includes a NaI (Tl) digital gamma spectrometer. That is, the transfer standard device uses a NaI (Tl) digital gamma spectrometer, that is, a sodium iodide (NaI) gamma spectrometer containing a small amount of thallium (Tl) as an activator, and the NaI (Tl) digital gamma spectrometer measures the counting rate of the source to be measured and the exempt reference source.

[0069] The NaI (Tl) digital gamma spectrometer is easy to store and use, has a small size, is easy to carry, has high detection efficiency, is widely applicable, has relatively low use and measurement costs, and is economical. This makes it easy for operators to carry the NaI (Tl) digital gamma spectrometer and the exempted reference source between laboratories for transfer and measurement, which is convenient, fast, and safe, greatly improving work efficiency.

[0070] In one embodiment, the exempt reference source is a long-lived nuclide 94 Nb. That is, the exempt reference source is niobium with a mass number of 94. It should be noted that long-lived nuclides refer to nuclides with a long life and a half-life greater than 10 hours.

[0071] 94 Nb has the following advantages as an exemption reference source:

[0072] on the one hand, 94 Nb has a long half-life (T 1 / 2 =2.03×10 4 a) At the same time, during the comparison 94 The count rate decay correction of Nb can be ignored, which can reduce the impact of non-comparison sources.

[0073] on the other hand, 94 Nb ray emission has the following advantages:

[0074] The X-ray energy is 17keV, which is used to set the lower threshold of the energy spectrum measurement and indicate whether the energy spectrum drifts.

[0075] The gamma ray energies of 703keV and 871keV are located in the middle region of the NaI(Tl) energy spectrum, and the peaks do not overlap, making it easy to measure. In addition, the two gamma ray branch ratios are large (>99%), resulting in a high measurement count rate, saving measurement time.

[0076] On the other hand, 94 Nb exempt reference sources can be freely circulated, ensuring that measurements can be easily implemented; from a safety perspective, the radiation dose to the public is sufficiently small. However, other nuclides cannot simultaneously meet the above advantages as reference sources.

[0077] Now, the following examples are provided in combination with the above embodiments:

[0078] Two of the two comparison laboratories 137 Take the Cs standard point source as an example. The two point sources are prepared at different times and with different original solutions and different activities. 137 Cs point source, but they are all prepared according to the requirements of standard point source, that is, they meet the requirements of no correlation with the source to be measured for comparison.

[0079] Two gamma spectrometers were used to measure the 137 The source activity A1 of the Cs standard point source to be measured is then measured on the NaI (Tl) digital γ spectrometer of the transfer standard device. 137 The source count rate N1 of the Cs standard point source to be measured, and 94 The reference source count rate N2 of the Nb exempt reference source is calculated according to formula (1) 94 Nb equivalent activity A2, and one of 94 The Nb equivalent activity is taken as the reference value, and the comparison results are shown in Table 1.

[0080] Table 1 137 Analysis of Cs equivalent activity comparison data

[0081]

[0082] In Table 1, 1# and 2# represent the numbers of the comparison laboratories; Bq is the legal unit of measurement for radioactivity, becquerel; s -1 is counts per second; k represents the coverage factor of uncertainty. In this embodiment, k is 2. Then, according to the product of the uncertainty of the activity of the source to be measured and k, we can get 94 Nb equivalent activity uncertainty.

[0083] If A22 is used as the reference value, the comparison laboratory No. 2# is the leading laboratory, and the measurement standard device No. 2# meets the requirements by default. The normalized deviation E can be calculated according to formula (2) from Table 1: n1 ;

[0084]

[0085] |E n1 |≈0.067<1, which means that the measurement standard device No. 1 measures 137 The results of Cs point source meet the requirements.

[0086] If the average value of A21 and A22 is used as the reference value, then A2 r =8.74×10 3 According to Table 1, the normalized deviation E can be calculated according to formula (2): n1 、E n2 ;

[0087]

[0088]

[0089] |E n1 |≈0.034<1,|E n2 |≈0.034<1; then it means that the measurement standard devices No. 1# and No. 2# measure 137 The results of Cs point sources all meet the requirements.

[0090] The various embodiments / implementations provided in this application can be combined with each other without causing any contradiction. The above description is only a preferred embodiment of this application and is not intended to limit this application. For those skilled in the art, this application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the protection scope of this application.

Claims

1. A method for transferring a value, characterized in that: include: m measurement standard devices measure m sources to be measured one by one, and obtain the corresponding activities A1 of the m sources to be measured, where m is a positive integer greater than 1; When the same transfer standard device has the same measurement conditions as the m measurement standard devices, the transfer standard device measures the same exemption reference source under the corresponding measurement conditions to obtain m reference source count rates N2, and the transfer standard device measures the sources to be measured corresponding to each of the measurement standard devices to obtain m sources to be measured count rates N1; According to the m corresponding activities A1 of the source to be measured, the counting rate N1 of the source to be measured and the counting rate N2 of the reference source, m equivalent activities A2 are obtained, wherein the equivalent activity A2 is the ratio of the activity A1 of the source to be measured to the counting rate N1 of the source to be measured, and multiplied by the counting rate N2 of the reference source; According to the m equivalent activities A2, the compliance results of the m corresponding measurement standard devices are determined.

2. The value transfer method according to claim 1, characterized in that: There is no correlation between the m sources to be measured.

3. The value transfer method according to claim 2, characterized in that: The lack of correlation between the m sources to be measured means that each source to be measured is a radioactive source with a different source activity A1 prepared by using different original solutions at different times.

4. The value transfer method according to claim 1, characterized in that: The efficiency ε of the transfer standard device is obtained according to the ratio of the counting rate N1 of the source to be measured to the activity A1 of the source to be measured.

5. The value transfer method according to claim 1, characterized in that: Determining the compliance results of the m measurement standard devices according to the m equivalent activities A2, including: According to the m equivalent activities A2, the corresponding m normalized deviations E are obtained. n ; The m normalized deviations E n The values ​​are compared with the preset values ​​respectively to determine the compliance results of the corresponding measurement standard devices.

6. The value transfer method according to claim 5, characterized in that: m said normalized deviations E n The normalized deviation of the i-th measurement standard device is E ni , through Calculate, where: A2 i is the equivalent activity of the ith r is the reference value of m equivalent activities A2; U i For A2 i The expanded uncertainty of r For A2 r The expanded uncertainty of .

7. The method for transferring a value according to any one of claims 1 to 6, characterized in that: The transfer standard device includes a NaI (Tl) digital gamma spectrometer.

8. The method for transferring a value according to any one of claims 1 to 6, characterized in that: The exempt reference source is a long-lived nuclide 94 Nb.

9. The method for transferring a value according to any one of claims 1 to 6, characterized in that: The exempted reference source and the source to be measured are both gamma radionuclides.

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