A method for induced radioactivity assessment for a beam tube of a particle accelerator

Abstract

The present application relates to the technical field of accelerator radiation protection, and particularly relates to a method for evaluating induced radioactivity of a beam tube of a particle accelerator; the method aims to evaluate the induced radioactivity of the beam tube of the accelerator under a multi-cycle operation mode, to provide a reference for radiation protection of the accelerator, optimization of the operation mode, and development of a maintenance plan for the staff; the method considers the operation mode of the accelerator, adopts Monte Carlo simulation software, calculates the activity concentration of radionuclides in the beam tube, the dose rate of a focus point, and the dose received by the staff at the focus point during long-time maintenance, predicts the future induced radioactivity, thereby effectively promoting the application of the Monte Carlo method in the field of accelerator radiation protection, and providing technical support for radiation protection and operation maintenance of the accelerator.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of accelerator radiation protection, and particularly relates to a method for evaluating induced radioactivity of a beam tube of a particle accelerator. TECHNICAL BACKGROUND

[0002] During the operation of a large accelerator device, the beam tube has induced radioactivity due to the loss of beam along the way during acceleration and transportation. This induced radioactivity is one of the main reasons for the radiation exposure of accelerator staff, which poses a potential threat to the health of the staff. In particular, for some beam tubes with a relatively long length, a relatively wide distribution of radioactivity, and a relatively large total amount, the external exposure formed by the beam tube has a particularly significant impact on the staff.

[0003] In the existing method for evaluating the induced radioactivity of the beam tube of the particle accelerator, the cumulative exposure time is usually used for calculation. However, in the actual operation of the accelerator, there is often a "multiple cycle" exposure time. Therefore, the calculation using the cumulative exposure time often leads to overestimation of the induced radioactivity, and cannot accurately reflect the induced radioactivity of the accelerator under the actual operation mode.

[0004] In order to solve the above problems, a method for evaluating the induced radioactivity of the beam tube of the particle accelerator is needed. This method needs to consider the periodic characteristics of the operation of the accelerator, as well as the half-life and decay law of the radionuclides in the beam tube, so as to more accurately evaluate the induced radioactivity level of the beam tube. In addition, this method should also be able to predict the future trend of induced radioactivity, and provide strong support for the optimization of the operation mode of the accelerator and the safety maintenance of the staff. SUMMARY

[0005] In view of the defects in the prior art, the present application provides a method for evaluating the induced radioactivity of the beam tube of the particle accelerator, which aims to evaluate the induced radioactivity of the beam tube of the accelerator under the multi-cycle operation mode, and provide a reference for the radiation protection of the accelerator, the optimization of the operation mode, and the development of the maintenance plan for the staff; this method considers the operation mode of the accelerator, uses the Monte Carlo simulation software, calculates the activity concentration of the radionuclides in the beam tube, the dose rate at the point of interest, and the dose received by the staff during long-term maintenance at the point of interest under different operation cycles and different cooling times through the activation formula under the multi-cycle operation mode, predicts the future induced radioactivity, and thus effectively promotes the application of the Monte Carlo method in the field of accelerator radiation protection, and provides technical support for the radiation protection and operation maintenance of the accelerator.

[0006] The technical scheme adopted by the present application is as follows: a method for evaluating the induced radioactivity of the beam tube of the particle accelerator, comprising the following steps:

[0007] S1, determining an accelerator operation mode: the accelerator operation mode is a mode of multiple operation periods, including accelerator each operation time t i , cooling time t c1 , annual operation frequency n, cooling time t c2 after annual operation, and planned accelerator operation years k.

[0008] S2, constructing a geometric model and input parameters: using Monte Carlo simulation software to construct a geometric model of the accelerator beam tube, and inputting radiation source terms, the operation time t i and the cooling time t c , and calculating the activity concentration of each radionuclide under different cooling time t c .

[0009] S3, selecting important radionuclides: according to the proportion of the activity concentration of each radionuclide at different cooling time in the total activity concentration, important radionuclides are selected.

[0010] S4, calculating the activity concentration of important radionuclides: using the activation formula under the mode of multiple operation periods, the activity concentration of the important radionuclides under different operation periods and different cooling time is calculated.

[0011] S5, calculating the dose rate of the point of interest: taking the important radionuclides as the radiation source term, the dose rate of the point of interest is calculated, and the conversion coefficient of the activity concentration of each radionuclide and the dose rate is obtained.

[0012] S6, predicting the change of the dose rate of the point of interest: according to the conversion coefficient, the dose rate of the point of interest under different operation periods and different cooling time is calculated.

[0013] S7, determining the shutdown waiting time: based on the preset dose limit value, combined with the change relationship of the dose rate of the point of interest with the cooling time, the shutdown waiting time of the accelerator is determined.

[0014] S8, evaluating the dose of the staff maintenance: the dose of the staff in the long time maintenance at the point of interest under different operation periods is calculated.

[0015] S9, making a maintenance plan: according to the dose of the staff in the long time maintenance, the maintenance plan of the accelerator is determined.

[0016] S10, evaluating the technical effect: by using Monte Carlo simulation software combined with the activation formula under the mode of multiple operation periods to evaluate the induced radioactivity of the accelerator beam tube, it is verified that the present application can accurately evaluate the induced radioactivity of the accelerator beam tube under the mode of multiple operation periods, so as to obtain the activity concentration of radionuclides in the beam tube under different operation periods and different cooling time, and the dose rate of the point of interest.

[0017] The S1 accelerator operation mode is specifically: the accelerator is operated for 16 hours per day for 6 days per week, and is stopped for 8 hours per day, is operated for 40 weeks per year, and is stopped for 8 hours per day for 85 days per year, and is planned to be operated for 30 years.

[0018] The radiation source term includes the information of the kind, energy, number, direction and position of the beam loss particles, and the beam loss particle position and direction sampling model is used for calculation in the process of the accelerator particle transportation, considering that the beam tube is a circular ring cylinder.

[0019] The important radionuclide is a radionuclide with a relatively high proportion of the nuclide activity concentration in the total activity concentration and a relatively long half-life at different cooling times.

[0020] The activation formula in the S4 multi-cycle operation mode is specifically: assuming that the accelerator is operated for m times and is cooled for t time, the activity concentration of the radionuclide is:

[0021]

[0022] The activity concentration of the radionuclide is cooled for t time in the kth year and the nth time is:

[0023] Wherein, S sat is the saturated activity concentration of the radionuclide, and T is the half-life of the radionuclide.

[0024] The conversion coefficient of the S5 nuclide activity concentration and the dose rate is:

[0025] D f = D rate / S·V

[0026] Wherein, D f is the conversion coefficient, D rate is the radiation dose rate of the point of interest, S is the nuclide activity concentration in the beam tube, and V is the volume of the beam tube.

[0027] The S7 preset dose limit is: when the dose rate is less than 0.1 mSv / h at a distance of 30 cm from the surface of the device, manual maintenance is not time-limited; when the dose rate is between 0.1 and 1 mSv / h, manual maintenance needs to control the time; the dose received in a quarter is not more than 2.5 mSv, and the dose received in a year is not more than 10 mSv.

[0028] In the S8 step of evaluating the maintenance dose of the worker, the total dose received in each year is calculated by considering the number of daily maintenance times and the number of annual maintenance times of the worker per year, and the time and dose rate of each maintenance.

[0029] In the step of formulating the maintenance plan by the S9, the daily maintenance and annual maintenance plan of the accelerator is determined according to the dose received by the staff during long-time maintenance and the accelerator downtime waiting time.

[0030] The Monte Carlo simulation software is at least one of MCNPX or FLUKA

[0031] The method for evaluating induced radioactivity of a particle accelerator beam tube has the following advantages:

[0032] Precise analysis of induced radioactivity in multi-cycle operation mode: By introducing the activation formula in multi-cycle operation mode and combining the Monte Carlo simulation method, the present application can accurately calculate the activity concentration of radionuclides in the beam tube under different operation cycles and cooling times, thereby accurately reflecting the induced radioactivity of the accelerator in the actual operation mode and solving the overestimation problem caused by the cumulative irradiation time in the existing method.

[0033] Improving the safety of radiation protection: By accurately evaluating the induced radioactivity level of the beam tube, the present application can provide scientific basis for radiation protection during the operation of the accelerator, which helps to reduce the radiation dose received by the staff and ensure their health and safety.

[0034] Optimizing the operation mode of the accelerator: The method of the present application can predict the future trend of induced radioactivity, which provides a basis for determining the optimized operation mode of the accelerator. By adjusting the operation cycle, cooling time and other parameters, the induced radioactivity level of the beam tube can be effectively reduced, and the operation efficiency and safety of the accelerator can be improved.

[0035] Supporting the safe maintenance of staff: The method of the present application can calculate the dose received by the staff during long-time maintenance near the beam tube under different operation cycles, which provides a reference for formulating a safe and reasonable maintenance plan. By reasonably arranging the maintenance time and taking necessary protective measures, the safety of the staff can be effectively guaranteed.

[0036] Promoting the development of accelerator radiation protection technology: The proposal and application of the present application can promote the application and development of the Monte Carlo simulation method in the field of accelerator radiation protection, and promote the progress of related research and new technology. At the same time, the method and technical idea of the present application also provide beneficial reference and reference for the radiation protection analysis of other similar equipment. BRIEF DESCRIPTION OF DRAWINGS

[0037] Fig. 1 is the logic diagram of the present application.

[0038] Fig. 2 is the change relationship of the concern point dose rate with cooling time in the present application. DETAILED DESCRIPTION

[0039] The application is described below in detail with reference to the accompanying drawings, which illustrate a specific embodiment of a method for evaluating induced radioactivity of a beam tube of a particle accelerator:

[0040] The accelerator operation mode is determined. A geometric model is constructed using Monte Carlo simulation software, and the radiation source term, operation time and cooling time are inputted. The activity concentration of each radionuclide at different cooling times is calculated. Important radionuclides are selected. The activity concentration of important radionuclides in the beam tube at different operation cycles and different cooling times is calculated using the activation formula in the multi-cycle operation mode. The dose rate at the point of interest is calculated using the radionuclides as the radiation source term, to obtain the conversion coefficient of the radionuclide activity concentration and the dose rate. The dose rate at the point of interest at different operation cycles and different cooling times is calculated. The shutdown waiting time is determined according to the dose limit. The dose received by the staff during long-term maintenance at different operation cycles is calculated to determine the maintenance plan.

[0041] The accelerator operation mode is: a large particle accelerator, which generally has a multi-cycle operation mode. It is assumed that the accelerator is operated for t i time each time, shut down for t c1 time, operated n times per year, and shut down for t c2 time after the operation of each year. The accelerator is planned to be operated for k years.

[0042] The radiation source term, operation time and cooling time are inputted, and the activity concentration of each radionuclide at different cooling times is calculated. The radiation source term includes the type, energy, number, direction and position of the beam loss particles, and the beam tube is considered to be a circular cylindrical body. During the transport of the accelerator particles, the sampling model of the position and direction of the beam loss particles is: x=R·cos(2πε1), y=R·sin(2πε1), z=z1+(z2-z1)·ε2, u=sinθ·cos(2πε3), v=sinθ·sin(2πε3), w=cosθ, where (x, y, z) and (u, v, w) are the sampling position coordinates and the unit vector of the emission direction, respectively; ε1, ε2 and ε3 are random numbers; R is the inner radius of the beam tube; z1 and z2 are the maximum z-axis coordinate and the minimum z-axis coordinate of the particle sampling; and θ is the sampling angle of the particles relative to the beam center line. The operation time is t i , and the cooling time is several between 0 and t c2 .

[0043] The important radionuclides are selected. Different radionuclides have different half-lives, resulting in different proportions of the activity concentration of each radionuclide in the total activity concentration at different cooling times. The important radionuclides are the radionuclides with a higher proportion of the activity concentration in the total activity concentration at different cooling times.

[0044] The activity concentration of important radionuclides in different cooling time in different operation period is calculated by using the activation formula in the multi-period operation mode, and the activity concentration of radionuclides is obtained by assuming that the accelerator is operated m times, and the shutdown t time is:

[0045]

[0046] The activity concentration of radionuclides in the kth year, the nth time, the shutdown t time is:

[0047]

[0048] Wherein, S sat is the saturated activity concentration of radionuclides, and T is the half-life of radionuclides.

[0049] The radionuclide as the radiation source item specifically is: when the radionuclide decays, the contribution of low-energy gamma rays and beta rays to the dose can be ignored compared with high-energy gamma rays, and the dose contribution of gamma rays with low emission probability can also be ignored. The beam tube wall is thin, and the influence of the tube wall self-shielding on the dose rate of the focus can be ignored, and it is considered that the radionuclides are uniformly distributed in the beam tube. The emitted gamma rays are uniformly distributed in 4π solid angle. The gamma ray energy sampling model is:

[0050]

[0051] Wherein, ε is a random number. P1, P2……P n-1 , P n , E1, E2……E n-1 , E n are the probability and energy of high-energy and high-emission-probability gamma rays when the radionuclide decays.

[0052] The position sampling model is:

[0053]

[0054] x=R·cos(2πε1)

[0055] y=R·sin(2πε1)

[0056] z=z1+(z2-z1)·ε2

[0057] Wherein, z direction is the axial direction of the beam tube. (x, y, z) is the particle sampling position coordinate. R0 is the inner radius of the beam tube. R1 is the outer radius of the beam tube. z1 and z2 are the maximum z-axis coordinate and the minimum z-axis coordinate of particle sampling. ε, ε1, ε2, ε3, ε4, ε5 are random numbers.

[0058] The direction sampling model is:

[0059] u = sin(2p e1) cos(2p e2)

[0060] v = sin(2p e1) sin(2p e2)

[0061] w = cos(2p e1)

[0062] where (u, v, w) are the direction cosines of the particle emission direction, and e, e1, are random numbers.

[0063] The conversion coefficient of the nuclide activity concentration and the dose rate is: where D f is the conversion coefficient of the nuclide activity concentration and the dose rate, D rate is the radiation dose rate of the point of interest, S is the nuclide activity concentration in the beam tube, and V is the volume of the beam tube.

[0064] The dose rate of the point of interest at different running periods and different cooling times is specifically calculated as:

[0065] Assuming that the accelerator is operated m times, and the cooling time is t, the dose rate of the point of interest is: 1,m D 1,m = S f × V × D

[0066] The dose rate of the point of interest at the kth year, the nth time, and the cooling time t is: k,n D k,n = S f × V × D

[0067] The dose received by the staff during long-term maintenance at different running periods is specifically calculated as: Assuming that the accelerator is operated m times, and the staff maintains the point of interest from t m1 time to t m2 time, the dose received is:

[0068]

[0069] The dose received by the staff during long-term maintenance at the kth year, the nth time, and the point of interest from t k1 time to t k1 time, and the staff works for a total of l days, from t k2 time to t

[0070]

[0071]

[0072] Embodiment: implemented in the China Spallation Neutron Source (CSNS) high-energy proton accelerator, which consists of a linear accelerator, a linear-to-ring beam transport line (LRBT), a fast-cycling synchrotron ring accelerator (RCS), and a ring-to-target station transport line (RTBT).

[0073] As shown in the implementation of the evaluation method for induced radioactivity of a particle accelerator beam tube involved in the embodiment, specifically includes: Figs. 1-2

[0074] Step 1: Determine the operation mode of the accelerator: in this embodiment, the accelerator is operated for 16 hours a day for 6 days a week, and is shut down for 8 hours for daily maintenance of each system, and is operated for 40 weeks a year, and is shut down for 8 hours for annual maintenance of each system, and is planned to be operated for 30 years.

[0075] Step 2: Use the Monte Carlo simulation program to build a geometric model, input the radiation source term, the irradiation time and the cooling time, and calculate the activity concentration of each radionuclide at different cooling times, specifically including: the beam tube is a cylindrical pipe, and during the acceleration or transport of particles, the particles will deviate from the beam center line and hit the inner wall of the beam tube at a small angle. In order to obtain the proportion of each radionuclide in the beam tube at different cooling times, the activity concentration of the radionuclide in the beam tube at different cooling times (0 seconds, 1 hour, 1 day, 85 days and 8 hours) is calculated when the accelerator is operated for 6 days and 16 hours.

[0076] Step 3: Select important radionuclides from the radionuclides obtained in step 2: the radionuclides that determine the induced radioactivity are those that contribute more to the total nuclide concentration, while considering that individual nuclides with shorter half-lives and faster decay will also quickly disappear. The contribution of the total nuclide concentration to the total nuclide concentration is greater than 1%, and the half-life is greater than 20 seconds. The radionuclides are selected as important radionuclides for the evaluation of induced radioactivity of the beam tube.

[0077] Step 4: Calculate the activity concentration of the important radionuclides in the beam tube at different cooling times in different operation cycles using the activation formula in the multi-cycle operation mode: assuming that the linear accelerator, LRBT, RCS and RTBT are operated for 29 years and 40 weeks, respectively, and are shut down for 4 hours, 20 minutes, 1 hour and 20 minutes, respectively, the activity concentration of the radionuclides in the accelerator beam tube is shown in Table 1.

[0078] Table 1 Activity concentration of important radionuclides in the accelerator beam tube

[0079]

[0080]

[0081] ​

[0082]

[0083] Step 5: Calculate the dose rate of the point of interest with radionuclide as the radiation source term, get the conversion coefficient of the radionuclide activity concentration and the dose rate: in the beam tube of the linac 57 Take Ni as an example, the point of interest is 30 cm away from the surface of the accelerator beam tube, and the conversion coefficient of the radionuclide activity concentration and the dose rate of the point of interest is 1.27e-4 pSv / Bq / s.

[0084] Step 6: Calculate the dose rate of the point of interest at different cooling times in different operation periods: Assume that the linac, LRBT, RCS and RTBT accelerators are operated for 29 years and 40 weeks, and the relationship between the dose rate of the point of interest and the cooling time is calculated as shown in Fig. 2 .

[0085] Step 7: Determine the shutdown waiting time according to the dose limit: The dose control requirements for radioactive workers during maintenance of CSNS: The dose rate at a distance of 30 cm from the surface of the device is less than 0.1 mSv / h, and manual maintenance is not time-limited. The dose rate is 0.1-1 mSv / h, and manual maintenance needs to be controlled in time. The dose received in a quarter is not more than 2.5 mSv, and the dose received in a year is not more than 10 mSv. During routine maintenance, the maintenance time of workers is short, combined with the decay trend in Fig. 2 , the shutdown waiting time of the linac, LRBT, RCS and RTBT is considered to be 4 hours, 20 minutes, 1 hour and 20 minutes respectively. During annual maintenance, the maintenance time is longer, combined with the decay trend in Fig. 2 and the dose limit, the shutdown waiting time of the linac, LRBT, RCS and RTBT is considered to be 1 month, 1 week, 1 week and 1 week respectively.

[0086] Step 8: Calculate the dose received by workers during long-term maintenance in different operation periods: Assume that the linac, LRBT, RCS and RTBT are operated for 29 years and 40 weeks, and the dose received by workers during routine maintenance for 20 minutes is shown in Table 2. During annual maintenance, the dose received by workers during 5 days of maintenance, 4 hours per day is shown in Table 3. Considering that workers perform routine maintenance 40 times per year and annual maintenance once per year, the highest dose received by workers per year is 5.89 mSv, which meets the requirements of the annual dose management target value.

[0087] Table 2 Dose received by workers during routine maintenance

[0088]

[0089] Table 3 Dose received by workers during annual maintenance

[0090]

[0091]

[0092] Step 9: Evaluate the technical effect of the method: calculate the radionuclide activity concentration and the dose rate of the concern point in the beam tube by using the traditional evaluation method and the method. Assuming that the linear accelerator, the LRBT, the RCS and the RTBT, run for 29 years and 40 weeks, and the downtime waiting time is 4 hours, 20 minutes, 1 hour, 20 minutes and 1 month, 1 week, 1 week and 1 week respectively, the radionuclide activity concentration and the dose rate of the concern point in the beam tube are shown in Table 4. It can be seen that, compared with the present application, the traditional evaluation method overestimates the radionuclide activity concentration by 13.3% to 22.4%, and overestimates the dose rate by 5.1% to 31.4%. At the same time, the traditional evaluation method cannot predict the dose received by the staff during long-term maintenance.

[0093] Table 4 Comparison of calculation results of the present embodiment with the traditional simulation method and the method

[0094]

[0095]

[0096] Step 10: Evaluate the induced radioactivity of the accelerator beam tube by using the Monte Carlo simulation software combined with the activation formula under the multi-cycle operation mode, verify that the present application can accurately evaluate the induced radioactivity of the accelerator beam tube under the multi-cycle operation mode, and thus obtain the radionuclide activity concentration and the dose rate of the concern point in the beam tube under different operation cycles and different cooling times.

[0097] In the present embodiment, the activation formula under the multi-cycle operation mode is used in combination with the Monte Carlo simulation method to evaluate the induced radioactivity of the accelerator beam tube, and the induced radioactivity evaluation results of the beam tube under different operation cycles and different cooling times are obtained, solving the problem of overestimation of induced radioactivity caused by the use of cumulative irradiation time in the existing analysis. Compared with the prior art, the present application can accurately evaluate the induced radioactivity of the accelerator beam tube under the irradiation time of "multiple cycles", and the obtained results can predict the future induced radioactivity. It provides a basis for determining the optimized operation mode of the accelerator. It provides a reference for formulating the maintenance plan for the staff. Thus, it effectively promotes the application of the Monte Carlo method in the field of accelerator radiation protection. It provides technical support for the radiation protection and operation and maintenance of the accelerator, and promotes the development of related research and new technologies.

Claims

1. A method for assessing induced radioactivity suitable for use in a beam tube of a particle accelerator, characterized by: Comprise the following steps: S1, determining an accelerator operation mode: the accelerator operation mode is a mode of multiple operation periods, including accelerator each operation time t i , cooling time t c1 , annual operation frequency n, cooling time t c2 after the end of annual operation, and accelerator planned operation years k; S2, constructing a geometric model and inputting parameters: using Monte Carlo simulation software to construct a geometric model of the accelerator beam tube, and inputting the radiation source term, the running time t i and the cooling time t c , calculating the activity concentration of each radionuclide at different cooling times t c ; S3, selecting important radionuclide: according to the proportion of the activity concentration of each radionuclide at different cooling time in the total activity concentration, important radionuclide is selected; S4, calculating the activity concentration of important radionuclide: using the activation formula under multi-cycle operation mode, the activity concentration of important radionuclide at different operation cycle and different cooling time is calculated; the activation formula under multi-cycle operation mode is specifically: assuming that the accelerator is operated m times, stopped t time, the activity concentration of radionuclide is: = In the kth year, the nth time, the cooling t time, the activity concentration of radionuclide is: = where S sat is the saturation activity concentration of the radionuclide and T is the half-life of the radionuclide. S5, calculating the dose rate of the point of interest: taking the important radionuclide as the radiation source term, the dose rate of the point of interest is calculated, and the conversion coefficient of the activity concentration of each radionuclide and the dose rate is obtained; S6, predicting the dose rate change of the point of interest: according to the conversion coefficient, the dose rate of the point of interest at different operation cycle and different cooling time is calculated; S7, determining the waiting time of shutdown: based on the preset dose limit, combined with the change relationship of the dose rate of the point of interest with the cooling time, the waiting time of accelerator shutdown is determined; S8, evaluating the dose of staff maintenance: the dose received by the staff in long time maintenance at the point of interest in different operation cycle is calculated; S9, making maintenance plan: according to the dose received by the staff in long time maintenance, the maintenance plan of the accelerator is determined; S10, evaluating the technical effect: through the Monte Carlo simulation software combined with the activation formula under multi-cycle operation mode, the induced radioactivity of the accelerator beam tube is evaluated, it is verified that the present application can accurately evaluate the induced radioactivity of the accelerator beam tube under multi-cycle operation mode, so as to obtain the activity concentration of radionuclide in the beam tube at different operation cycle and different cooling time, the dose rate of the point of interest.

2. A method for assessing induced radioactivity for use in a beam tube of a particle accelerator according to claim 1, characterized in that: The operation mode of the accelerator in S1 is specifically: after long time continuous operation, the accelerator is stopped for cooling, after cooling, long time continuous operation is carried out again, and the cycle is repeated.

3. A method for assessing induced radioactivity in a beam tube of a particle accelerator according to claim 1, characterized in that: The radiation source term includes the type, energy, number, direction and position information of beam loss particles, considering that the beam tube is a circular ring cylinder, in the process of particle transport, the particles will deviate from the center line and hit the inner wall of the beam tube at a small angle to cause beam loss, the position and direction sampling model of beam loss particles is used for calculation.

4. A method for assessing induced radioactivity for use in a beam tube of a particle accelerator according to claim 1, characterized in that: The important radionuclide is the radionuclide with higher proportion of activity concentration at different cooling time and longer half-life period.

5. A method for assessing induced radioactivity in a beam tube of a particle accelerator according to claim 1, characterized in that: The conversion coefficient of radionuclide activity concentration and dose rate in S5 is: D f =D rate / S V where D f is the conversion coefficient, D rate is the radiation dose rate of interest, S is the activity concentration of the nuclide in the beam tube, and V is the volume of the beam tube.

6. A method for assessing induced radioactivity suitable for use in a beam tube of a particle accelerator according to claim 1, characterized in that: The preset dose limit in S7 is: when the dose rate is less than 0.1 mSv / h at the position 30 cm away from the surface of the device, manual maintenance is not limited by time; when the dose rate is between 0.1 and 1 mSv / h, manual maintenance needs to control time; the dose received in a quarter is not more than 2.5 mSv, and the dose received in a year is not more than 10 mSv.

7. A method for assessing induced radioactivity suitable for use in a beam tube of a particle accelerator according to claim 1, characterized in that: In the step of evaluating the maintenance dose of staff in S8, the total dose received by the staff in each year is calculated by considering the number of daily maintenance and annual maintenance of the staff, and the time and dose rate of each maintenance.

8. A method for assessing induced radioactivity suitable for use in a beam tube of a particle accelerator according to claim 1, characterized in that: In the step of formulating the maintenance plan by the S9, a daily maintenance and an annual maintenance plan of the accelerator are determined according to the dose received by the staff during long-time maintenance and the waiting time of the accelerator shutdown.

9. A method for assessing induced radioactivity for use in a beam tube of a particle accelerator according to any one of claims 1 to 8, characterized in that: The Monte Carlo simulation software is at least one of MCNPX or FLUKA.

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