A sort of 252 Estimation Method of Cf Source Age

Abstract

The present application embodiment provides a 252 The estimation method of Cf source age is more convenient for 252 The method involves estimating the age of Cf sources, which involves the field of nuclear technology. 252 The total radioactivity A of the first nuclide in the Cf source 11 ,and 252 The total radioactivity A of the second nuclide in the Cf source 12 ;according to 252 The total radioactivity A of the first nuclide produced by spontaneous fission of at least one nuclide in the Cf source 21 and 252 The relationship between the age t of the Cf source and the sum of the radioactivity A of the second nuclides 22 The relationship between and t, and let A 21 =A 11 , A 22 =A 12 , calculate t; wherein any one of the at least one nuclide has a long-lived fission product of the same type as the first nuclide and a short-lived fission product of the same type as the second nuclide, and the at least one nuclide includes at least 252 Cf, the second nuclide is 138 Cs is 136 Any one of I. This method is used to estimate 252 Age of the Cf source.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202210725690.1 and application date June 23, 2022 “A 252 Cf source age estimation method" and Chinese patent application number 202210723639.7 and application date June 23, 2022 "A 252 The present invention proposes a method for estimating the age of Cf source and claims the priority of the two Chinese patent applications, the entire contents of the two Chinese patent applications are hereby incorporated into the present application by reference. Technical Field

[0003] The present application relates to the field of nuclear technology, in particular to a 252 Method for estimating Cf source age. Background Art

[0004] 252 The main components of Cf source are 252 Cf nuclides have a wide range of applications in medicine, scientific research, industry, nuclear science education and many other fields, such as: they can be used for nuclide analysis of the human body, instrument calibration, neutron imaging, nuclear reactor starting sources, nuclear fuels and explosives, etc. 252 The age estimation of Cf sources has important significance and practical application value, for example: 252 Cf source can be traced to its source and production date, etc. 252 The neutron intensity of the Cf source is accurately determined, so that the relevant instruments can use 252 Higher accuracy is achieved when calibrating the Cf source, etc.

[0005] 252 Cf source 252 The gamma rays emitted by Cf are difficult to measure, which makes it difficult for researchers to measure them using gamma spectroscopy. 252 The amount of Cf is estimated by 252 The age of the Cf source, 252 The estimation of the age of Cf sources is difficult. Summary of the invention

[0006] In view of this, the present application embodiment provides a 252 The estimation method of Cf source age is more convenient to estimate 252 Age of the Cf source.

[0007] The embodiments of the present application provide 252 The method for estimating the Cf source age includes: obtaining 252 The total radioactivity A of the first nuclide in the Cf source11 ,and 252 The total radioactivity A of the second nuclide in the Cf source 12 ;according to 252 The total radioactivity A of the first nuclide produced by spontaneous fission of at least one nuclide in the Cf source 21 and 252 The relationship between the source age t of Cf and 252 The total radioactivity A of the second nuclide produced by spontaneous fission of at least one nuclide in the Cf source 22 The relationship between and t, and let A 21 =A 11 , A 22 =A 12 , calculate t; wherein any one of the at least one nuclide has a long-lived fission product of the same type as the first nuclide, any one of the at least one nuclide has a short-lived fission product of the same type as the second nuclide, and the at least one nuclide includes at least 252 Cf, the second nuclide is 138 C and 136 Any one of I.

[0008] In some optional embodiments of the present application, obtaining A 12 Includes: Determination 252 The energy of the second nuclide in the Cf source is the peak net count rate I(E1) of the characteristic γ energy peak of E1; using A 12 Calculate the relationship between A and I(E1) 12 Among them, A 12 The relationship between it and I(E1) is:

[0009] I(E1)=A 12 ×Br(E1)×η(E1)

[0010] Where η(E1) is 252 The detection efficiency of the total energy peak of the second nuclide in the Cf source with the energy of E1, Br(E1) is 252 The energy of the second nuclide in the Cf source is the branching ratio of the characteristic gamma energy peak of E1.

[0011] In some optional embodiments of the present application, when the second nuclide is 136 I, E1 = 1313.02keV; when the second nuclide is 138 When Cs, E1 = 1435.77keV.

[0012] In some optional embodiments of the present application, when the second nuclide is 136 I, by measuring 252The gamma spectrum of the Cf source in the energy range of 0 to 2 MeV is obtained I(E1); when the second nuclide is 138 Cs, by measuring 252 The gamma energy spectrum of the Cf source in the energy range of 0 to 2.1 MeV is obtained I(E1).

[0013] In some optional embodiments of the present application, determining 252 The energy of the second nuclide in the Cf source is the characteristic γ energy peak of E1, and the peak net count rate is determined by using a high purity germanium detector. 252 The energy of the second nuclide in the Cf source is the peak net count rate of the characteristic gamma energy peak of E1.

[0014] In some optional embodiments of the present application, the first nuclide is 137 Cs.

[0015] In some optional embodiments of the present application, obtaining A 11 Includes: Determination 252 Cf source 137 The energy of Cs is the peak net count rate I(E2) of the characteristic γ energy peak of E2; using A 11 Calculate the relationship between A and I(E2) 11 Among them, A 11 The relationship between it and I(E2) is:

[0016] I(E2)=A 11 ×Br(E2)×η(E2)

[0017] Where η(E2) is 252 Cf source 137 The detection efficiency of the full energy peak of Cs with energy E2 is Br(E2) 252 Cf source 137 The energy of Cs is the branching ratio of the characteristic γ energy peak of E2.

[0018] In some optional embodiments of the present application, E 2＝ 661.66keV.

[0019] In some optional embodiments of the present application, 252 Cf source 252 The relationship between the total radioactivity of the first nuclides produced by spontaneous fission of Cf and t is:

[0020]

[0021] In the formula, for 252 Cf source 252 The total radioactivity of the first nuclides produced by spontaneous fission of Cf, is the decay constant of the first nuclide, for 252 The decay constant of Cf, For the initial moment 252 Cf source 252 The total radioactivity of Cf, for 252 Spontaneous fission branching ratio of Cf, for 252 Cf source 252 The cumulative yield of the first nuclide produced by spontaneous fission of Cf.

[0022] In some optional embodiments of the present application, 252 Cf source 252 The relationship between the total radioactivity of the second nuclides produced by spontaneous fission of Cf and t is:

[0023]

[0024] In the formula, For the 252 Cf source 252 The radioactivity of the sum of the second nuclides produced by spontaneous fission of Cf, For the initial moment 252 Cf source 252 The total radioactivity of Cf, for 252 Spontaneous fission branching ratio of Cf, For the 252 Cf source 252 The cumulative yield of the second nuclide produced by spontaneous fission of Cf, for 252 The decay constant of Cf.

[0025] The embodiments of the present application provide 252 The Cf source age estimation method is to use 252 Cf source 252 The activity of a long-lived fission product of Cf is related to 252 The relationship between the Cf source age and the 252 The age of the Cf source does not need to be measured directly 252 Cf source 252 The amount of Cf, obtained 252 Cf source 252 The activity of Cf fission products is relatively easy to make 252 The process of estimating the Cf source age is relatively simple. Specifically, 252 Cf undergoes spontaneous fission, and 252 Cf source age252 The long-lived fission products of Cf will 252 The accumulation of the age of the Cf source, i.e. 252 Cf source age 252 The amount of long-lived fission products of Cf is related to 252 There is a clear relationship between the age of the Cf source and the 252 Cf source 252 In the case of Cf, the current 252 Cf source 252 The amount of long-lived fission products in Cf is estimated by 252 The current age of the Cf source. 252 In the process of Cf source age, the initial moment 252 Cf source 252 The quantity Cf is usually unknown, but 252 Cf will produce a variety of fission products, which can be 252 Cf source 252 The activity of a long-lived fission product of Cf is related to 252 The relationship between the age of the Cf source and 252 The activities of other fission products produced by the fission of Cf are similar to 252 The relationship between the age of the Cf source is combined, so there is no need to obtain the initial time 252 Cf source 252 The amount of Cf can also be 252 The age of the Cf source can be estimated. 252 Cf source 252 The fission of Cf 138 Cs and 136 The activity of any one of I 252 The relationship between the age of Cf sources and 252 The activity of the long-lived fission products of Cf is related to 252 Combined with the relationship between the age of the Cf source, the estimation result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 In some embodiments of this application 252 One of the flow charts of the method for estimating the Cf source age;

[0027] Figure 2 For obtaining in some embodiments of this application 252 Schematic diagram of the total radioactivity of the second nuclide in the Cf source;

[0028] Figure 3 For obtaining in some embodiments of this application 252 Schematic diagram of the flow chart of the total radioactivity of the first nuclide in the Cf source;

[0029] Figure 4 In the first embodiment of this application 252 Schematic diagram of the process of estimating the Cf source age;

[0030] Figure 5 In the second embodiment of this application 252 Schematic diagram of the flow chart of the Cf source age estimation method. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other, and the detailed description in the specific implementation method should be understood as an explanation of the purpose of the present application and should not be regarded as an improper limitation on the present application.

[0032] In the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more.

[0033] In addition, in the embodiments of the present application, directional terms such as "up", "down", "left" and "right" are defined relative to the orientation of the components in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they may change accordingly according to the changes in the orientation of the components in the drawings.

[0034] In the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0035] In the embodiments of the present application, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0036] In the embodiments of the present application, words such as "exemplarily" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplarily" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplarily" or "for example" is intended to present related concepts in a specific way.

[0037] The present application embodiment provides a 252 The Cf source age estimation method is used to estimate 252 Age of the Cf source. 252 The age of the Cf source is 252 The time that has passed since the Cf source was last separated and purified.

[0038] The present application embodiment provides 252 The estimation method of Cf source age includes obtaining 252 The total radioactivity A of the first nuclide in the Cf source 11 ,and 252 The total radioactivity A of the second nuclide in the Cf source 12 ;according to 252 The total radioactivity A of the first nuclide produced by spontaneous fission of at least one nuclide in the Cf source 21 and 252 The relationship between the source age t of Cf and 252 The total radioactivity A of the second nuclide produced by spontaneous fission of at least one nuclide in the Cf source 22 The relationship between A and t, and let A 21 =A 11 , A 22 =A 12 , calculate t; wherein any one of the at least one nuclide has a long-lived fission product of the same type as the first nuclide, any one of the at least one nuclide has a short-lived fission product of the same type as the second nuclide, and the at least one nuclide includes at least 252 Cf, the second nuclide is 138 Cs and 136 Any one of I.

[0039] That is, please refer to Figure 1 , the present application embodiment provides 252 The method for estimating the Cf source age includes the following steps:

[0040] Step S101, obtain A 11 With A 12 ;

[0041] Step S102, according to A 21The relationship between t1 and A 22 The relationship between t1 and A 21 =A 11 , A 22 =A 12 , calculate t1.

[0042] The embodiments of the present application provide 252 The Cf source age estimation method is to use 252 Cf source 252 The activity of a long-lived fission product of Cf is related to 252 The relationship between the Cf source age and the 252 The age of the Cf source does not need to be measured directly 252 Cf source 252 The amount of Cf, obtained 252 Cf source 252 The activity of Cf fission products is relatively easy to make 252 The process of estimating the Cf source age is relatively simple. Specifically, 252 Cf undergoes spontaneous fission, and 252 Cf source age 252 The long-lived fission products of Cf will 252 The accumulation of the age of the Cf source, i.e. 252 Cf source age 252 The amount of long-lived fission products of Cf is related to 252 There is a clear relationship between the age of the Cf source and the 252 Cf source 252 In the case of Cf, the current 252 Cf source 252 The amount of long-lived fission products in Cf is estimated by 252 The current age of the Cf source. 252 In the process of Cf source age, the initial moment 252 Cf source 252 The quantity Cf is usually unknown, but 252 Cf will produce a variety of fission products, which can be 252 Cf source 252 The activity of a long-lived fission product of Cf is related to 252 The relationship between the age of the Cf source and 252 The activities of other fission products produced by the fission of Cf are similar to 252 The relationship between the age of the Cf source is combined, so there is no need to obtain the initial time 252 Cf source 252 The amount of Cf can also be 252 The age of the Cf source can be estimated. 252Cf source 252 The fission of Cf 138 Cs and 136 Any activity in I 252 The relationship between the age of Cf sources and 252 The activity of the long-lived fission products of Cf is related to 252 Combined with the relationship between the age of the Cf source, the estimation result is more accurate.

[0043] It should be explained that the total radioactivity A of the first nuclide in the spontaneous fission source is obtained. 11 It refers to obtaining the radioactive activity of the sum of the first nuclides existing in the spontaneous fission source at the current moment, and the same is true for obtaining the activity of the second nuclide in the spontaneous fission source. In addition, the sum of the first nuclides produced by the spontaneous fission of at least one nuclide in the spontaneous fission source refers to the sum of all the first nuclides produced by the fission of at least one nuclide from the initial moment to the current moment, which are still present in the spontaneous fission source at the current moment. Each nuclide in at least one nuclide will spontaneously fission to produce the first nuclide, and the same is true for the second nuclide. In addition, the initial moment refers to the moment when the age of the spontaneous fission source is zero.

[0044] It should be explained that the long-lived fission product of a certain nuclide refers to the fission product of the nuclide with a longer half-life, which is not easy to decay into other nuclides and will accumulate as the parent nuclide continues to spontaneously fission. The short-lived fission product of a certain nuclide refers to the fission product of the nuclide with a shorter half-life, which is easy to decay into other nuclides. In the embodiment of the present application, the short-lived fission product can be defined as follows: in the process of spontaneous fission of the parent nuclide, a short-lived fission product of the parent nuclide and the parent nuclide will gradually reach a radioactive equilibrium state and last until the end. The long-lived fission product can be defined as follows: all other spontaneous fission products of the parent nuclide except the short-lived fission product can be used as long-lived fission products.

[0045] 252 The first and second nuclides in the Cf source may not be completely caused by 252 Cf fission produced, specifically, in some optional embodiments of the present application, at least one nuclide also includes 252 Impurity nuclides in Cf source, 252 Cf source 252 Any one or more of at least one decay product of Cf and at least one decay product of an impurity nuclide. 252 Impurity nuclides in Cf source such as 250 Cf and 254 Cf, etc. 252 The decay products of Cf are 248 Cm and 244Pu, etc., and some decay products of impurity nuclides such as 250 Cf decay produces 246 Cm and others may also undergo fission to produce the first nuclide and the second nuclide. 252 The first and second nuclides in the Cf source are mostly composed of 252 Cf source 252 The smaller part is produced by the fission of Cf and the impurity nuclides, 252 The decay products of Cf and the decay products of impurity nuclides are produced by fission. It can be understood that the 21 With A 22 The more types of nuclides there are, 252 The more accurate the estimate of the Cf source age.

[0046] It needs to be explained that 252 The impurity nuclide of the Cf source refers to the initial moment, i.e. 252 When the age of the Cf source is zero 252 Other nuclides in Cf sources other than the main nuclides are not included in 252 As the Cf source ages, 252 Decay products and fission products of various nuclides in the Cf source.

[0047] It should be noted that the decay in the embodiments of the present application can be either single decay or continuous decay. 252 One of all decay daughters of the nuclide in the Cf source. If the decay of the nuclide is a continuous decay, the decay product of the nuclide refers to one of all decay daughters in the decay chain of the nuclide. 252 Cf source 252 Cf can also refer to 252 Impurity nuclides in Cf source.

[0048] Get A 12 There are many methods, for example, it can be an absolute measurement method of radioactivity or a relative measurement method of radioactivity. In some optional embodiments of the present application, the peak net count rate of the characteristic γ energy peak of the nuclide to be measured with the energy E is obtained by using the gamma energy spectrum to obtain A 12 For details, please refer to Figure 2 In some optional implementations of the present application, A is obtained 12 The following steps are involved:

[0049] S201, determination 252 The peak net count rate I(E1) of the characteristic gamma energy peak of the second nuclide in the Cf source with the energy E1;

[0050] S202, use A12 Calculate the relationship between A and I(E1) 12 ;

[0051] Among them, A 12 The relationship between it and I(E1) is:

[0052] I(E1)=A 12 ×Br(E1)×η(E1) (1)

[0053] Where η(E1) is 252 The detection efficiency of the total energy peak of the second nuclide in the Cf source with the energy of E1, Br(E1) is 252 The energy of the second nuclide in the Cf source is the branching ratio of the characteristic gamma energy peak of E1.

[0054] Thus, the determination of I(E1) does not require destruction of 252 Cf source, 252 The Cf source can continue to be used, and the entire acquisition A 12 The process is relatively simple, efficient, and easy to operate. On this basis, optionally, in some optional embodiments of the present application, when the second nuclide is 136 I, E1 = 1313.02keV; when the second nuclide is 138 When Cs, E1 = 1435.77keV.

[0055] In some optional embodiments of the present application, determining 252 The energy of the second nuclide in the Cf source is the peak net count rate of the characteristic γ energy peak of E1, which is measured using a high-purity germanium detector. 252 The energy of the second nuclide in the Cf source is the peak net count rate of the characteristic γ energy peak of E1. The high purity germanium detector is used to measure 252 The energy of the second nuclide in the Cf source is the peak net count rate of the characteristic γ energy peak of E1, which can make the measurement result more accurate. Specifically, a high-energy germanium detector can be set according to the selected parameters to be measured, and the energy calibration, efficiency calibration and background measurement of the set high-energy germanium detector can be performed, and then 252 The Cf source is placed at a suitable distance between the center line of the high-energy germanium detector and the end face for measurement.

[0056] In some optional embodiments of the present application, when the second nuclide is 136 I, by measuring 252 The gamma spectrum of the Cf source in the energy range of 0 to 2 MeV is obtained I(E1); when the second nuclide is 138 Cs, by measuring 252 The gamma spectrum of the Cf source in the energy range of 0 to 2.1 MeV is used to obtain I(E1). In this way, the obtained I(E1) result is more accurate.

[0057] Further, in some optional embodiments of the present application, the first nuclide is 137 Cs. Experiments have shown that the selection 137 Cs as the first nuclide is beneficial to 252 The estimated results of Cf source age are relatively accurate.

[0058] The first nuclide is 137 Cs basis, please refer to Figure 3 In some optional implementations of the present application, A is obtained 11 The following steps are involved:

[0059] S301, determination 252 Cf source 137 The energy of Cs is the peak net count rate I(E2) of the characteristic γ energy peak of E2;

[0060] S302, use A 11 Calculate the relationship between A and I(E2) 11 ;

[0061] Among them, A 11 The relationship between it and I(E2) is:

[0062] I(E2)=A 11 ×Br(E2)×η(E2) (2)

[0063] Where η(E2) is 252 Cf source 137 The detection efficiency of the full energy peak of Cs with energy E2 is Br(E2) 252 Cf source 137 The energy of Cs is the branching ratio of the characteristic γ energy peak of E2.

[0064] Thus, the determination of I(E2) does not require destruction of 252 Cf source, 252 The Cf source can continue to be used, and the entire acquisition A 11 The process is relatively simple, efficient, and easy to operate. On this basis, optionally, in some optional implementations of the present application, E2=661.66keV.

[0065] Further, in some optional embodiments of the present application, 252 Cf source 252 The relationship between the total radioactivity of the first nuclides produced by spontaneous fission of Cf and t is:

[0066]

[0067] In the formula, for 252 Cf source 252 The total radioactivity of the first nuclides produced by spontaneous fission of Cf, is the decay constant of the first nuclide, for 252 The decay constant of Cf, For the initial moment 252 Cf source 252 The total radioactivity of Cf, for 252 Spontaneous fission branching ratio of Cf, for 252 Cf source 252 The cumulative yield of the first nuclide produced by spontaneous fission of Cf.

[0068] In this way, Add the radioactivity of the first nuclide produced by spontaneous fission of other nuclides except the main nuclide in at least one nuclide to obtain A. 21 The relationship between t.

[0069] It should be explained that e in the embodiments of the present application refers to a natural constant.

[0070] Further, in some optional embodiments of the present application, 252 Cf source 252 The relationship between the total radioactivity of the second nuclides produced by spontaneous fission of Cf and t is:

[0071]

[0072] In the formula, for 252 Cf source 252 Cf spontaneous fission 252 The total radioactivity of the second nuclide in the Cf source, For the initial moment 252 Cf source 252 The total radioactivity of Cf, for 252 Spontaneous fission branching ratio of Cf, for 252 Cf source 252 Cf spontaneous fission 252 The cumulative yield of the second nuclide in the Cf source, for 252 The decay constant of Cf.

[0073] In this way, Add the radioactivity of the second nuclide produced by spontaneous fission of other nuclides except the main nuclide in at least one nuclide to obtain A. 22 The relationship between A and t is used to calculate 21 With A 22 The ratio R2 between them can be used to calculate t.

[0074] The following is a detailed description of the embodiments of the present invention. 252 The estimation method of Cf source age is explained. 252 Impurities in Cf source include 250 Cf, in the first embodiment, please refer to Figure 4 , 252 The estimation method of Cf source age mainly includes the following steps:

[0075] S401, select 137 The peak net count rate of the characteristic γ energy peak of Cs at 661.66 keV is 136 The peak net count rate of the characteristic γ energy peak with energy of 1313.02keV is taken as the parameter to be measured;

[0076] S402, setting a high energy germanium detector according to the selected parameters to be measured;

[0077] S403, performing energy calibration, efficiency calibration and background measurement on the high energy germanium detector;

[0078] S404, 252 The Cf source is placed at a preset position on the center line of the high-energy germanium detector, and then the gamma energy spectrum measurement in the range of 0 to 2 MeV is performed;

[0079] S405, calculating the obtained measured parameter in the mathematical model 252 The age of the Cf source, the mathematical model is as follows:

[0080]

[0081] Where R is the measured 137 The peak net count rate of the characteristic γ energy peak of Cs with an energy of 661.66keV is similar to the measured 136 The energy of I is the ratio of the peak net count rate of the characteristic γ energy peak of 1313.02keV, I Cf252 (y1), I Cf250 (y1), I Cm248 (y1), I Cm246 (y1) and I Pu244 (y1) are produced by spontaneous fission of various nuclides 137 The time expression of the peak net count rate of the characteristic gamma energy peak of Cs with an energy of 661.66keV, multiple nuclides including 252Cf 250 Cf 252 Cf decay produces 248 Cm, 250 Cf decay produces 246 Cm and 252 Cf decay produces 244 Pu. I Cf252 (y2), I Cf250 (y2), I Cm248 (y2), I Cm246 (y2) and I Pu244 (y2) are produced by spontaneous fission of various nuclides 136 The time expression of the peak net count rate of the characteristic gamma energy peak of I with an energy of 1313.02keV, multiple nuclides including 252 Cf 250 Cf 252 Cf decay produces 248 Cm, 250 Cf decay produces 246 Cm and 252 Cf decay produces 244 Pu.

[0082] The final estimated 252 The age of the Cf source is 25.5 years, and the certified age of the neutron source is 26.2 years, and the estimated results are relatively accurate.

[0083] In the second embodiment, please refer to Figure 5 , 252 The estimation method of Cf source age mainly includes the following steps:

[0084] S501, select 137 The peak net count rate of the characteristic γ energy peak of Cs at 661.66 keV is 138 The peak net count rate of the characteristic γ energy peak of Cs with an energy of 1435.77keV is the parameter to be measured;

[0085] S502, setting a high energy germanium detector according to the selected parameters to be measured;

[0086] S503, performing energy calibration, efficiency calibration and background measurement on the high energy germanium detector;

[0087] S504, 252 The Cf source is placed at a preset position on the center line of the high-energy germanium detector, and then the gamma energy spectrum measurement in the range of 0 to 2.1 MeV is performed;

[0088] S505, calculating the obtained measured parameter in the mathematical model 252 The age of the Cf source, the mathematical model is as follows:

[0089]

[0090] Where R is the measured 137 The peak net count rate of the characteristic γ energy peak of Cs with an energy of 661.66keV is similar to the measured 138 The ratio of the peak net count rate of the characteristic γ energy peak of Cs with an energy of 1435.77 keV, I Cf252 (y1), I Cf250 (y1), I Cm248 (y1), I Cm246 (y1) and I Pu244 (y1) are produced by spontaneous fission of various nuclides 137 The time expression of the peak net count rate of the characteristic gamma energy peak of Cs with an energy of 661.66keV, multiple nuclides including 252 Cf 250 Cf 252 Cf decay produces 248 Cm, 250 Cf decay produces 246 Cm and 252 Cf decay produces 244 Pu. I Cf252 (y3), I Cf250 (y3), I Cm248 (y3), I Cm246 (y3) and I Pu244 (y3) are produced by spontaneous fission of various nuclides 138 The time expression of the peak net count rate of the characteristic gamma energy peak of Cs with an energy of 1435.77 keV, multiple nuclides including 252 Cf 250 Cf 252 Cf decay produces 248 Cm, 250 Cf decay produces 246 Cm and 252 Cf decay produces 244 Pu.

[0091] The final estimated 252 The age of the Cf source is 24.9 years, and the certified age of the neutron source is 26.2 years, and the estimated results are relatively accurate.

[0092] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A 252 The method for estimating the Cf source age is characterized by: include: Get the 252 The total radioactivity A of the first nuclide in the Cf source 11 , and 252 The total radioactivity A of the second nuclide in the Cf source 12 ; According to the 252 The radioactivity A of the sum of the first nuclides produced by spontaneous fission of at least one nuclide in the Cf source 21 With the 252 The relationship between the source age t of Cf and the 252 The radioactivity A of the sum of the second nuclides produced by the spontaneous fission of the at least one nuclide in the Cf source 22 The relationship between A and t, and let A 21 =A 11 , A 22 =A 12 , calculate t; Wherein, any one of the at least one nuclide has a long-lived fission product of the same type as the first nuclide, any one of the at least one nuclide has a short-lived fission product of the same type as the second nuclide, and the at least one nuclide includes at least 252 Cf, the second nuclide is 138 Cs and 136 Any one of I; Said 252 Cf source 252 The relationship between the radioactivity of the sum of the second nuclides produced by spontaneous fission of Cf and t is: In the formula, For the 252 Cf source 252 The spontaneous fission of Cf 252 The radioactivity of the sum of the second nuclides in the Cf source, For the initial moment 252 Cf source 252 The total radioactivity of Cf, for 252 Spontaneous fission branching ratio of Cf, For the 252 Cf source 252 Cf spontaneous cleavage produces 252 The cumulative yield of the second nuclide in the Cf source, for 252 The decay constant of Cf.

2. according to claim 1 252 The method for estimating the Cf source age is characterized by: Get A 12 include: Determination of the 252 The peak net count rate I(E1) of the characteristic gamma energy peak of the second nuclide in the Cf source whose energy is E1; Use A 12 Calculate the relationship between A and I(E1) 12 ; Among them, A 12 The relationship between it and I(E1) is: I(E1)=A 22 ×Br(E1)×η(E1) Wherein, η(E1) is 252 The energy of the second nuclide in the Cf source is the detection efficiency of the total energy peak of E1, Br(E1) is the 252 The energy of the second nuclide in the Cf source is the branching ratio of the characteristic gamma energy peak of E1.

3. According to claim 2 252 The method for estimating the Cf source age is characterized by: When the second nuclide is 136 I, E1 = 1313.02keV; when the second nuclide is 138 When Cs, E1 = 1435.77keV.

4. according to claim 2 252 The method for estimating the Cf source age is characterized by: When the second nuclide is 136 I, by measuring 252 The gamma spectrum of the Cf source in the energy range of 0 to 2 MeV is obtained I(E1); when the second nuclide is 138 Cs, by measuring 252 The gamma energy spectrum of the Cf source in the energy range of 0 to 2.1 MeV is obtained I(E1).

5. According to claim 2 252 The method for estimating the Cf source age is characterized by: The determination 252 The energy of the second nuclide in the Cf source is the characteristic γ energy peak of E1, and the peak net count rate is measured by using a high purity germanium detector. 252 The energy of the second nuclide in the Cf source is the peak net count rate of the characteristic gamma energy peak of E1.

6. According to claim 1 252 The method for estimating the Cf source age is characterized by: The first nuclide is 137 Cs.

7. According to claim 6 252 The method for estimating the Cf source age is characterized by: Get A 11 include: Determination of the 252 Cf source 137 The energy of Cs is the peak net count rate I(E2) of the characteristic γ energy peak of E2; Use A 11 Calculate the relationship between A and I(E2) 11 ; Among them, A 11 The relationship between it and I(E2) is: I(E2)=A 21 ×Br(E2)×η(E2) Wherein, η(E2) is 252 Cf source 137 The energy of Cs is the detection efficiency of the full energy peak of E2, and Br(E2) is 252 Cf source 137 The energy of Cs is the branching ratio of the characteristic γ energy peak of E2.

8. According to claim 7 252 The method for estimating the Cf source age is characterized by: IN 2＝ 661.66keV。 9. The method according to any one of claims 1 to 7 252 The method for estimating the Cf source age is characterized by: Said 252 Cf source 252 The relationship between the radioactivity of the sum of the first nuclides produced by spontaneous fission of Cf and t is: In the formula, For the 252 Cf source 252 The radioactivity of the sum of the first nuclides produced by spontaneous fission of Cf, is the decay constant of the first nuclide, for 252 The decay constant of Cf, For the initial moment 252 Cf source 252 The total radioactivity of Cf, for 252 Spontaneous fission branching ratio of Cf, For the 252 Cf source 252 The cumulative yield of the first nuclide produced by spontaneous fission of Cf.

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