Induced radioactivity assessment method suitable for particle accelerator beam tube

Abstract

The invention relates to the technical field of accelerator radiation protection, in particular to an induced radioactivity assessment method suitable for a particle accelerator beam tube. The method aims at providing reference for radiation protection and operation mode optimization of an accelerator and maintenance plan making for workers by evaluating induced radioactivity of an accelerator beam tube in a multi-cycle operation mode. According to the method, the operation mode of an accelerator is considered, Monte Carlo simulation software is adopted, and the radionuclide activity concentration, the focus dose rate and the dose received by a worker during long-time maintenance of a focus in a beam tube in different operation periods and different cooling time are calculated through an activation formula in a multi-period operation mode; and future induced radioactivity is predicted, so that application of the Monte Carlo method in the field of radiation protection of the accelerator is effectively promoted, and technical support is provided for radiation protection and operation maintenance of the accelerator.

Description

Technical Field

[0001] The invention relates to the technical field of accelerator radiation protection, in particular to an induced radioactivity assessment method applicable to a particle accelerator beam tube. Technical Background

[0002] During the operation of large accelerators, beam tubes generate induced radioactivity due to beam losses during acceleration and transport. This induced radioactivity is one of the main causes of radiation exposure for accelerator workers, posing a potential health threat. The impact of external radiation exposure on workers is particularly significant for beam tubes that are long, have a wide distribution area, and generate a large amount of radioactivity.

[0003] Existing methods for assessing induced radioactivity in particle accelerator beam tubes typically use cumulative exposure time for calculation. However, in actual accelerator operation, multiple exposure cycles are often involved. Therefore, using cumulative exposure time for calculations often overestimates induced radioactivity and fails to accurately reflect the induced radioactivity under actual accelerator operation.

[0004] To address these issues, a method suitable for assessing induced radioactivity in particle accelerator beam tubes is needed. This method needs to account for the cyclical nature of accelerator operation, as well as factors such as the half-life and decay patterns of the radionuclides in the beam tube, enabling a more accurate assessment of the induced radioactivity level. Furthermore, the method should be able to predict future trends in induced radioactivity, providing strong support for optimizing accelerator operating modes and maintaining worker safety. Summary of the Invention

[0005] In response to the defects in the prior art, the present invention provides a method for evaluating the induced radioactivity of a particle accelerator beam tube. The method aims to evaluate the induced radioactivity of the accelerator beam tube under a multi-cycle operation mode, so as to provide a reference for the radiation protection of the accelerator, the optimization of the operation mode, and the formulation of a maintenance plan for the staff. The method takes into account the operation mode of the accelerator, adopts Monte Carlo simulation software, and calculates the activity concentration of radionuclides in the beam tube under different operation cycles and different cooling times, the dose rate of the point of interest, and the dose received by the staff during long-term maintenance at the point of interest through the activation formula under the multi-cycle operation mode, and 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 the radiation protection and operation and maintenance of the accelerator.

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

[0007] S1. Determine the accelerator operation mode: The accelerator operation mode is a mode of multiple operation cycles, including the accelerator operation time t i , cooling time t c1 , number of operations per year n, cooling time after each operation t c2 , and the number of years the accelerator program has been running, k.

[0008] S2. Constructing geometric model and inputting parameters: using Monte Carlo simulation software to construct the geometric model of the accelerator beam tube, and inputting the radiation source term, the running time t i and cooling time t c , calculate different cooling times t c The activity concentration of each radionuclide is shown below.

[0009] S3. Selection of important radionuclides: Select important radionuclides based on the proportion of the activity concentration of each radionuclide at different cooling times to the total activity concentration.

[0010] S4. Calculate the activity concentration of important radionuclides: Use the activation formula under the multi-cycle operation mode to calculate the activity concentration of the important radionuclides in different operation cycles and different cooling times.

[0011] S5. Calculate the dose rate of the point of interest: Calculate the dose rate of the point of interest using the important radioactive nuclides as radiation source items, and obtain the conversion coefficient between the activity concentration of each nuclide and the dose rate.

[0012] S6. Predicting dose rate changes at the point of interest: Calculating the dose rate at the point of interest under different operating cycles and cooling times according to the conversion coefficient.

[0013] S7. Determine the shutdown waiting time: Based on the preset dose limit and in combination with the relationship between the dose rate of the focus point and the cooling time, determine the shutdown waiting time of the accelerator.

[0014] S8. Evaluate maintenance doses for workers: Calculate the doses received by workers when performing long-term maintenance at the points of interest under different operating cycles.

[0015] S9. Develop a maintenance plan: Determine a maintenance plan for the accelerator based on the dose received by the staff during long-term maintenance.

[0016] S10. Evaluation of technical effects: By using Monte Carlo simulation software combined with the activation formula under the multi-cycle operation mode to evaluate the induced radioactivity of the accelerator beam tube, it is verified that the present invention can accurately evaluate the induced radioactivity of the accelerator beam tube under the multi-cycle operation mode, thereby obtaining the activity concentration of radionuclides and the dose rate of the point of interest in the beam tube at different operation cycles and different cooling times.

[0017] The specific operation mode of the accelerator in S1 is: the accelerator runs for 16 hours for 6 days a week and is shut down for 8 hours. It runs for 40 weeks a year and is shut down for 85 days and 8 hours. It is planned to operate for 30 years.

[0018] The radiation source term includes information such as the type, energy, number, direction, and position of beam loss particles. Considering that the beam tube is a circular cylinder, the beam loss particle position and direction sampling model is used for calculation during the transportation of accelerator particles.

[0019] The important radioactive nuclides are nuclides whose activity concentration accounts for a relatively high proportion of the total activity concentration at different cooling times and whose half-life is relatively long.

[0020] The activation formula in the S4 multi-cycle operation mode is as follows: Assuming the accelerator runs m times and cools down for t time, the activity concentration of the radionuclide is:

[0021]

[0022] In the kth year of operation, the nth operation, and the cooling time t, the activity concentration of the radionuclide is:

[0023] Among them, S sat is the saturation activity concentration of the radionuclide, and T is the half-life of the radionuclide.

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

[0025] D f =D rate / S·V

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

[0027] The preset dose limits of S7 are: when the dose rate is less than 0.1mSv / h at 30cm from the equipment surface, manual maintenance is not subject to time restrictions; when the dose rate is between 0.1 and 1mSv / h, manual maintenance needs to be time controlled; the quarterly dose does not exceed 2.5mSv, and the annual dose does not exceed 10mSv.

[0028] In the step S8 of evaluating the maintenance dose of the staff, the total dose received during each maintenance is calculated by taking into account the number of daily maintenance and annual maintenance performed by the staff each year, as well as the time and dose rate of each maintenance.

[0029] In the step of formulating a maintenance plan S9, the daily maintenance and annual maintenance plans for the accelerator are determined based on the dose received by the staff during long-term maintenance and the accelerator downtime waiting time.

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

[0031] The beneficial effects of the present invention are as follows: the induced radioactivity assessment method for a particle accelerator beam tube provided by the present invention has significant beneficial effects, which are specifically reflected in the following aspects:

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

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

[0034] Optimizing accelerator operating modes: This method can predict future trends in induced radioactivity, providing a basis for determining the optimal operating mode for the accelerator. By adjusting parameters such as operating cycle and cooling time, the induced radioactivity level in the beam tube can be effectively reduced, improving the accelerator's operating efficiency and safety.

[0035] Supporting safe maintenance for workers: This method can calculate the dose received by workers during extended maintenance near the beam tube under different operating cycles, providing a reference for developing safe and reasonable maintenance plans. By rationally scheduling maintenance times and taking necessary protective measures, worker safety can be effectively guaranteed.

[0036] Promoting the Development of Accelerator Radiation Protection Technology: The proposal and application of this invention will help promote the application and development of Monte Carlo simulation methods in the field of accelerator radiation protection, promoting related research and advancement of new technologies. Furthermore, the methods and technical ideas of this invention also provide a useful reference for radiation protection analysis of other similar devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a logic principle diagram of the present invention.

[0038] Figure 2 This is the relationship between the dose rate and the cooling time, which is the focus of the present invention. DETAILED DESCRIPTION

[0039] The following describes a specific embodiment of a method for evaluating induced radioactivity of a particle accelerator beam tube according to the present invention with reference to the accompanying drawings.

[0040] Determine the accelerator operation mode. Use Monte Carlo simulation software to construct a geometric model, input radiation source terms, operating time, and cooling time, and calculate the activity concentration of each radioactive nuclide at different cooling times. Select important radioactive nuclides. Use the activation formula under the multi-cycle operation mode to calculate the activity concentration of important radioactive nuclides in the beam tube at different operating cycles and different cooling times. Using radioactive nuclides as radiation source terms, calculate the dose rate of the point of interest and obtain the conversion coefficient between the activity concentration of the nuclide and the dose rate. Calculate the dose rate of the point of interest at different cooling times in different operating cycles. Determine the downtime waiting time based on the dose limit. Calculate the dose received by staff during long-term maintenance in different operating cycles and determine the maintenance plan.

[0041] The accelerator operation mode is: a large particle accelerator, the operation mode is generally multiple cycles, assuming that the accelerator runs t i Time, downtime t c1 Time, runs n times a year, and stops after each year's operation c2 Time, the accelerator program runs for k years.

[0042] The input radiation source term, running time and cooling time are used to calculate the activity concentration of each radioactive nuclide at different cooling times: the radiation source term includes information such as the type, energy, number, direction and position of the beam loss particles. Considering that the beam tube is a circular cylinder, the beam loss particle position and direction sampling model during the accelerator particle transport process 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 cosine vectors of the particle sampling position coordinates and 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 coordinates and minimum z-axis coordinates of the particle sampling. θ is the particle sampling angle relative to the beam centerline. The running time is t i , cooling time is 0~t c2 Several in between.

[0043] The selection of important radionuclides is as follows: different radionuclides have different half-lives, resulting in different proportions of the activity concentration of each nuclide to the total activity concentration at different cooling times. Important radionuclides are those whose activity concentrations account for a higher proportion of the total activity concentration at different cooling times.

[0044] The activation formula in the multi-cycle operation mode is used to calculate the activity concentration of important radionuclides in different operation cycles and different cooling times. The following method is used to calculate the activity concentration of important radionuclides in different operation cycles and different cooling times: Assuming that the accelerator runs m times and stops for t time, the activity concentration of radionuclides is:

[0045]

[0046] In the kth year of operation, the nth time, and the shutdown time t, the activity concentration of radionuclides is:

[0047]

[0048] Among them, S sat is the saturation activity concentration of the radionuclide, and T is the half-life of the radionuclide.

[0049] The specific characteristics of the radionuclide radiation source term are as follows: When a radionuclide decays, the contribution of low-energy gamma rays and beta rays to the dose is negligible compared to high-energy gamma rays. The dose contribution of gamma rays, which have a low emission probability, is also negligible. The beam tube wall is thin, and the effect of wall self-shielding on the dose rate at the point of interest is negligible. The nuclides are assumed to be uniformly distributed within the beam tube. The emitted gamma rays are uniformly distributed over a 4π solid angle. The gamma ray energy sampling model is:

[0050]

[0051] Where 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 probability gamma rays emitted when radioactive nuclides decay, respectively.

[0052] The location sampling model is:

[0053]

[0054] x=R·cos(2πε1)

[0055] y=R·sin(2πε1)

[0056] z=z1+(z2-z1)·ε2

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

[0058] The direction sampling model is:

[0059] u=sin(2πε1)·cos(2πε2)

[0060] v=sin(2πε1)·sin(2πε2)

[0061] w=cos(2πε1)

[0062] Where (u, v, w) are the cosine vectors of the particle emission direction, and ε and ε1 are random numbers.

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

[0064] The calculation of the dose rate of the focus point at different operating cycles and different cooling times is specifically as follows:

[0065] Assume that the accelerator runs m times and cools down for t time. The dose rate at the point of interest is: D 1,m =S 1,m ×V×D f

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

[0067] The calculation of the dose received by the staff during long-term maintenance in different operation cycles is as follows: Assuming that the accelerator runs m times, the staff is at the focus point from t m1 Time maintenance to t m2 Time, the dose received is:

[0068]

[0069] Run the kth year, the nth time, the staff at the focus point from t k1 Maintenance starts at time, and the total work time is 1 day, starting from t k1 Time to t k2 time, the dose received during this period is:

[0070]

[0071]

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

[0073] like Figure 1-2 FIG. 1 shows an implementation of an induced radioactivity assessment method applicable to a particle accelerator beam tube according to this embodiment, which specifically includes:

[0074] Step 1: Determine the operating mode of the accelerator: In this embodiment, the accelerator operates for 16 hours for 6 days a week and is shut down for 8 hours for daily maintenance of each system. It operates for 40 weeks a year and is shut down for 85 days and 8 hours for annual maintenance of each system. It is planned to operate for 30 years.

[0075] Step 2: Use a Monte Carlo simulation program to construct a geometric model, input the radiation source term, irradiation time, and cooling time, and calculate the activity concentration of each radionuclide at different cooling times. Specifically, the beam tube is a cylindrical pipe. During particle acceleration or transport in the accelerator, particles deviate from the beam centerline and strike the inner wall of the beam tube at a small angle, resulting in loss. To determine the contribution of each radionuclide in the beam tube at different cooling times, the activity concentration of radionuclides in the beam tube was calculated for different cooling times (0 seconds, 1 hour, 1 day, and 85 days and 8 hours) over a 6-day 16-hour run.

[0076] Step 3: Select the most important radionuclides from the radionuclides obtained in Step 2. The induced radioactivity is determined by those that contribute significantly to the total concentration. Considering that some nuclides have short half-lives and decay rapidly, their contribution to the total concentration will quickly disappear. Nuclides with a contribution greater than 1% to the total concentration and a half-life greater than 20 seconds at different cooling times are selected as the key nuclides for beam tube induced radioactivity assessment.

[0077] Step 4: Using the activation formula under the multi-cycle operation mode, calculate the activity concentrations of important radionuclides in the beam tubes for different operating cycles and cooling times: Assuming that the linear, LRBT, RCS, and RTBT accelerators operate for 29 years and 40 weeks, with shutdowns of 4 hours, 20 minutes, 1 hour, and 20 minutes, respectively, the activity concentrations of radionuclides in the accelerator beam tubes are shown in Table 1.

[0078] Table 1 Activity concentrations of important radionuclides in accelerator beam tubes

[0079]

[0080]

[0081]

[0082]

[0083] Step 5: Calculate the dose rate at the point of interest using the radionuclide as the radiation source term, and obtain the conversion coefficient between the activity concentration of the nuclide and the dose rate: 57 Taking Ni as an example, the focus point is 30 cm away from the surface of the accelerator beam tube, and the conversion coefficient between the activity concentration of the nuclide and the dose rate at the focus point is 1.27e-4pSv / Bq / s.

[0084] Step 6: Calculate the dose rate at the point of interest with different operating cycles and cooling time: Assuming that the linear, LRBT, RCS and RTBT accelerators have been running for 29 years and 40 weeks, the relationship between the dose rate at the point of interest and the cooling time is calculated as follows: Figure 2 shown.

[0085] Step 7: Determine downtime waiting time based on dose limit: CSNS requirements for radiation workers during maintenance: 30cm away from the equipment surface, the dose rate is less than 0.1mSv / h, and manual maintenance is not subject to time limits. The dose rate is 0.1-1mSv / h, and manual maintenance needs to be time controlled. The quarterly dose does not exceed 2.5mSv, and the annual dose does not exceed 10mSv. During routine maintenance, the maintenance time of the workers is relatively short, and the dose limit and Figure 2 Considering the attenuation trend of the linear accelerator, LRBT, RCS and RTBT, the downtime waiting time is 4 hours, 20 minutes, 1 hour and 20 minutes respectively. Figure 2 The attenuation trend and dose limit in the data were considered, and the waiting time for the linear accelerator, LRBT, RCS and RTBT were 1 month, 1 week, 1 week and 1 week respectively.

[0086] Step 8: Calculate the doses received by workers during long maintenance periods during different operating cycles: Assuming the linear accelerator, LRBT, RCS, and RTBT operate for 29 years and 40 weeks, the doses received by workers during routine maintenance for 20 minutes are shown in Table 2 below. During annual maintenance, the doses received by workers during five days of maintenance, four hours per day, are shown in Table 3 below. Assuming that workers perform 40 routine maintenance operations and one annual maintenance operation per year, the maximum annual dose received is 5.89 mSv, which meets the annual dose management target.

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

[0088]

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

[0090]

[0091]

[0092] Step 9: Evaluate the technical effectiveness of this method: The radionuclide activity concentrations and dose rates at points of interest in the beam tubes were calculated using both conventional and this method. Assuming the linear accelerator, LRBT, RCS, and RTBT operate for 29 years and 40 weeks, with downtimes of 4 hours, 20 minutes, 1 hour, 20 minutes, 1 month, 1 week, 1 week, and 1 week, respectively, the radionuclide activity concentrations and dose rates at points of interest in the beam tubes were calculated as shown in Table 4. As can be seen, compared to the present method, the conventional evaluation method overestimates the radionuclide activity concentrations by 13.3% to 22.4% and the dose rates by 5.1% to 31.4%. Furthermore, the conventional evaluation method fails to predict the doses to workers during extended maintenance periods.

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

[0094]

[0095]

[0096] Step 10: The induced radioactivity of the accelerator beam tube is evaluated by using Monte Carlo simulation software combined with the activation formula under the multi-cycle operation mode, verifying that the present invention can accurately evaluate the induced radioactivity of the accelerator beam tube under the multi-cycle operation mode, thereby obtaining the radionuclide activity concentration and the dose rate of the point of interest in the beam tube under different operation cycles and different cooling times.

[0097] This embodiment proposes for the first time the use of an activation formula under a multi-cycle operating mode combined with a Monte Carlo simulation method to evaluate the induced radioactivity of an accelerator beam tube. This method obtains induced radioactivity evaluation results for beam tubes with different operating cycles and different cooling times, solving the problem of overestimation of induced radioactivity caused by the use of cumulative irradiation time in existing analyses. Compared with the existing technology, the present invention can accurately evaluate the induced radioactivity of an accelerator beam tube under "multiple cycles" of irradiation time, and the results obtained can be used to predict future induced radioactivity. This provides a basis for determining the optimal operating mode for the accelerator and a reference for staff in formulating maintenance plans. This effectively promotes the application of the Monte Carlo method in the field of accelerator radiation protection. It provides technical support for accelerator radiation protection and operation and maintenance, and promotes the development of related research and new technologies.

Claims

1. A method for evaluating induced radioactivity in a particle accelerator beam tube, characterized by: The following steps are involved: S1. Determine the accelerator operation mode: The accelerator operation mode is a mode of multiple operation cycles, including the accelerator operation time t i , cooling time t c1 , number of operations per year n, cooling time after each operation t c2 , and the number of years the accelerator program has been running, k. S2. Constructing geometric model and inputting parameters: using Monte Carlo simulation software to construct the geometric model of the accelerator beam tube, and inputting the radiation source term, the running time t i and cooling time t c , calculate different cooling times t c The activity concentration of each radionuclide. S3. Selection of important radionuclides: Select important radionuclides based on the proportion of the activity concentration of each radionuclide at different cooling times to the total activity concentration. S4. Calculate the activity concentration of important radionuclides: Use the activation formula under the multi-cycle operation mode to calculate the activity concentration of the important radionuclides in different operation cycles and different cooling times. S5. Calculate the dose rate of the point of interest: Calculate the dose rate of the point of interest using the important radioactive nuclides as radiation source items, and obtain the conversion coefficient between the activity concentration of each nuclide and the dose rate. S6. Predicting dose rate changes at the point of interest: Calculating the dose rate at the point of interest at different operating cycles and cooling times based on the conversion coefficient. S7. Determine the shutdown waiting time: Based on the preset dose limit and in combination with the relationship between the dose rate of the focus point and the cooling time, determine the shutdown waiting time of the accelerator. S8. Evaluate maintenance doses for workers: Calculate the doses received by workers during long-term maintenance at the points of interest during different operating cycles. S9. Develop a maintenance plan: Determine a maintenance plan for the accelerator based on the dose received by the staff during long-term maintenance. S10. Evaluation of technical effects: By using Monte Carlo simulation software combined with the activation formula under the multi-cycle operation mode to evaluate the induced radioactivity of the accelerator beam tube, it is verified that the present invention can accurately evaluate the induced radioactivity of the accelerator beam tube under the multi-cycle operation mode, thereby obtaining the activity concentration of radionuclides and the dose rate of the point of interest in the beam tube at different operation cycles and different cooling times.

2. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: The accelerator operation mode in S1 is specifically as follows: the accelerator is shut down for cooling after running for a long time, and then runs for a long time again after cooling, and the cycle continues.

3. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: The radiation source term includes information such as the type, energy, number, direction, and position of beam loss particles. Considering that the beam tube is a circular cylinder, during the transportation of accelerator particles, particles will deviate from the center line and hit the inner wall of the beam tube at a small angle, causing beam loss. The beam loss particle position and direction sampling model is used for calculation.

4. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: The important radioactive nuclides are nuclides whose activity concentrations at different cooling times account for a relatively high proportion of the total activity concentration and whose half-lives are relatively long.

5. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: The activation formula in the S4 multi-cycle operation mode is as follows: Assuming that the accelerator runs m times and stops for t time, the activity concentration of the radionuclide is: In the kth year of operation, the nth operation, and the cooling time t, the activity concentration of the radionuclide is: Among them, S sat is the saturation activity concentration of the radionuclide, and T is the half-life of the radionuclide.

6. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: The conversion coefficient between the S5 nuclide activity concentration and dose rate is: D f =D rate / S·V Among them, D f is the conversion coefficient, D rate is the radiation dose rate at the point of interest, S is the radionuclide activity concentration in the beam tube, and V is the volume of the beam tube.

7. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: The preset dose limits of S7 are: when the dose rate is less than 0.1mSv / h at 30cm from the equipment surface, manual maintenance is not subject to time restrictions; when the dose rate is between 0.1 and 1mSv / h, manual maintenance needs to be time controlled; the quarterly dose does not exceed 2.5mSv, and the annual dose does not exceed 10mSv.

8. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: In the step S8 of evaluating the maintenance dose of the staff, the total dose received during each maintenance is calculated by taking into account the number of daily maintenance and annual maintenance performed by the staff each year, as well as the time and dose rate of each maintenance.

9. The method for evaluating induced radioactivity of a particle accelerator beam tube according to claim 1, wherein: In the step of formulating a maintenance plan S9, the daily maintenance and annual maintenance plans for the accelerator are determined based on the dose received by the staff during long-term maintenance and the accelerator downtime waiting time.

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

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