Radiation Protection Regulations for Particle Accelerators

GB 5172-85

1. General Provisions

1.1 In order to strengthen the management of radiation protection of particle accelerators, protect the environment and ensure Iran and safety of staff members and neighbouring residents, this regulation is formulated in accordance with GBJ 8-74, Radiation Protection Regulations, with reference to relevant international standards for radiation protection and in combination with the radiation protection status of domestic accelerators.

1.2 These Provisions apply to particle accelerators (excluding medical accelerators and mobile accelerators such as sealed neutron tubes) where the single nucleus energy of accelerating particles is less than 100 MeV.

1.3 All units with particle accelerators shall, in accordance with the requirements of this Regulation and in accordance with the characteristics of their accelerators, formulate rules for their implementation.

1.4 In the radiation protection of accelerators, a trade-off should be made between the benefits obtained by reducing the dose and the costs paid for it, so as to keep the collective dose equivalent produced in the operation of the facility at the lowest level reasonably achievable, and to ensure that the dose equivalent accepted by individuals does not exceed the equivalent limit.

1.5 Units that build, expand and rebuild accelerator facilities must prepare an evaluation report on the impact of such facilities on environmental quality and submit it it to the local environmental protection department for approval, otherwise they may not design and/or construct. At the same time, it is necessary to register with the local public security department.

1.6 We should pay attention to the health of people working on accelerators and strengthen health management. Such personnel shall enjoy the labor insurance treatment prescribed by the labor protection department and other departments.

1.7 These Provisions shall be supervised and implemented by the local competent radiation protection authorities.

2. Dose equivalent limit

2.1 The dose equivalent of uniform whole body irradiation or the effective dose equivalent of non-uniform whole body irradiation for occupational radioactive workers and personnel shall not exceed 50 mSv (5 rem); and the individual in the public shall not exceed 5 mSv (0.5 rem) per year.

2.2 The dose equivalent of ocular lens for occupational radiation workers should not exceed 50 mSv (5 rem) per year, and the dose equivalent of other tissues or organs should not exceed 500 mSv (50 rem) per year. The dose equivalent of any organ or tissue in the public should not exceed 50 mSv (5 rem) per year.

2.3 In the case of external exposure only, the deep dose equivalent index should be lower than 50 mSv (5 rem) per year.

2.4 In the case of internal exposure only, the annual intake of radioactive substances should be lower than the ALI listed in Appendix C (Supplement).

2.5 In the case of combined internal and external irradiation, the following two formulas must be satisfied simultaneously in order to ensure that the annual dose equivalent limit is not exceeded:

(1)

(2)

Formula: Hid - annual deep dose equivalent index. Sv (rem);

HL - Annual Deep Tangent Dose Equivalent Limit, Sv (rem);

Ii - Annual Intake of Radionuclear Nuclide J, Bq (Ci); (ALI) J - Annual Intake Limit of Radionuclide j, Bq (Ci); His - Annual Dose Equivalent Index, Sv (rem); HSKL - Annual Dose Equivalent Limit of Skin, 500mSv (50rem).

2.6 Occupational radiological workers may be allowed to receive irradiation beyond the annual dose equivalent limit on duty if necessary with the approval of radiation safety agencies. However, the negative dose equivalent or dose equivalent received in one event shall not exceed twice the annual value, and the total dose equivalent or dose equivalent burden received during the whole life of such exposure shall not exceed five times the annual value.

Women with fertility and those under 18 years of age are not allowed to receive such exposure.

2.7 Pregnant women, lactating women and interns aged 16 to 18 who are engaged in radiation work. It should be operated under the condition that one year's irradiation does not exceed the annual dose equivalent limit of 3/10, and the dose equivalent rate should be uniform.

Those under the age of 16 are prohibited from engaging in radioactive work.

2.8 The average annual dose equivalent for all radiation workers working in accelerators should be less than 5 mSv (0.5 rem).

2.9 The level of surface contamination by radioactive substances shall be lower than the values listed in Appendix D (Supplement).

The effective dose equivalent of stray radiation, radioactive gas and radioactive wastewater produced by 2.10 accelerator to individuals in key residential groups should be less than 0.1 mSv (10 rem) per year.

3. Design Principles of Radiation Protection Facilities

3.1 General requirements

3.1.1 During the planning and design stage of accelerator facilities, full consideration must be given to the contents of radiation protection facilities, including shield, required equipment, experiment and staffing.

3.1.2 The radiation protection facilities of the accelerator must be designed, constructed and put into operation simultaneously with the main project.

3.1.3 During the design phase of the accelerator facility, full consideration should be given to the possibility that the accelerator will increase the beam flow, increase fertility and expand its application in the future, so there should be appropriate room for radiation protection facilities.

3.1.4 Radiation protection engineers should be involved in the design of accelerator facilities. During the construction stage, radiation protection personnel should check the engineering quality of radiation protection facilities to ensure the design requirements.

3.2 Radiation shielding

3.2.1 The shield thickness of the accelerator must be considered comprehensively according to the type of accelerating particles, energy, beam strength and target material.

It is designed according to its possible maximum radiation output.

3.2.2 The shield thickness of the accelerator should also be determined according to the type of the adjacent area and the number of its population, so that the collective dose equivalent of the accelerator population can be maintained at the lowest level reasonably achievable. It is also necessary to ensure that the dose equivalent received by an individual does not exceed the corresponding dose equivalent limit.

3.2.3 When calculating the shielding thickness, two times the number of safety systems should be given.

3.3 Radiation Safety System

3.3.1 The main control system that determines the radiation generation of the accelerator should be controlled by a switch key.

3.3.2 Interlocking devices should be installed in the doors of accelerator hall and target hall. Radiation can only be generated after the doors are closed.

3.3.3 Emergency shutdown or shutdown switch should be installed in the easily accessible places of accelerator hall and target hall, and the switch should have a striking sign.

3.3.4 Flash or rotary red warning lights and sound warning devices shall be installed in the areas easily seen by the personnel in the accelerator hall and target hall, and working state heat indicators shall be installed in corridors, entrances and consoles leading to the radiation area.

3.3.5 In high radiation and radiation areas, remote control radiation monitoring system should be installed. The digital display device of the system should be installed on the console or in the monitoring position. When the radiation exceeds the predetermined level, the sound and/or light warning device of the system should give a warning signal.

3.3.6 Each accelerator must be equipped with other radiation monitoring devices according to its characteristics, such as personal dosimeters, portable monitors, gas monitors, etc.

3.3.7 The components of the radiation safety system are of good quality and the installation must be solid and reliable. The components of the system shall be resistant to radiation damage.

3.4 Ventilation System

3.4.1 In order to emit toxic gases (such as ozone) and airborne radioactive substances, ventilation devices must be installed in the accelerator facilities.

3.4.2 The exhaust rate of the ventilation system shall be determined according to the amount of harmful gases that may be produced and the working requirements.  The intake of the ventilation system should be avoided from being polluted by the exhaust gas.

3.4.3 When ventilation ducts pass through the shield, measures must be taken to ensure that the shielding effect of the shield is not significantly weakened.

4. Radiation safety in operation

4.1 Acceptance of Radiation Protection Facilities

4.1.1 After the completion of the accelerator facility, the radiation protection facility shall be checked and accepted. These include: radiation shielding; interlocking and warning systems; radiation monitoring systems; ventilation systems; laboratories or facilities for radiation protection. These projects meet the design requirements and are licensed by the local radiation protection authority before the accelerator can be officially put into operation.

4.2 Running procedures

4.2.1 All operators of accelerators must be trained in basic knowledge of radiation protection before working, master the use methods of the radiation safety system (including radiation measuring instruments) of the machine, and pass the examination before they can be turned into formal operators.

4.2.2 The boot shall be completed in the middle at the same time under the following conditions:

A. The types of accelerating particles and accelerating voltage are consistent with the predicted values.

B. The digital display device on the console can work normally;

C. Interlocking and warning systems can work properly;

D. Accelerator hall and target hall shall not be manned;

E. All protective doors in the accelerator hall and target hall have been closed.

4.2.3 The startup and shutdown of the accelerator must be operated by a control switch. The shutdown shall not be carried out by cutting off the interlocking unless the palladium is tightened.

4.2.5 When interlocking or palladium switch is cut off, the cut-off part must be reset manually before the accelerator can be restarted on the console with the main control switch.

4.2.6 No bypass interlocking system shall be allowed without special reasons. When the bypass interlocking system is needed for work, the following must be done:

A. With the approval of duty personnel and radiation safety personnel;

B. Display it on the console and register it in the running log;

C. Reposition as soon as possible;

D. Take other security measures.

4.3 Operation and storage of radioactive materials.

4.3.1 When operating radioactive materials (such as changing targets, processing activated parts, processing and welding radioactive materials, etc.), it should be carried out in designated places, strictly abide by the operating procedures, and do a good job of radiation monitoring, and take certain personal protective measures and ventilation measures when necessary.

4.3.2 Radioactive materials must be stored in designated places or special receptacles with appropriate shielding and radiation hazard marks. Radioactive materials must be registered and kept by special persons.

4.3.3 Tritium targets shall be stored in special containers, which shall be placed in ventilation cabinets with good ventilation, waste vacuum pump oil shall be stored in special containers, and leakage shall be strictly prevented. Storage places shall be well ventilated. If these substances are not used, they should be treated as radioactive waste.

4.4 Overhaul

4.4.1 Before the repair of the accelerator, the radiation safety personnel shall carry out the radiation measurement, and according to the specific conditions, the radiation protection measures to be taken in the repair shall be put forward, and the repair shall be carried out in accordance with the safety regulations.

4.4.2 When repairing the vacuum pump of the accelerator, proper working ground must be provided, corresponding personal protective measures and ventilation measures should be taken to strictly control the spread of pollution.

4.4.3 After the overhaul, surface contamination monitoring should be carried out for the persons participating in the overhaul, such as the clothes, tools and ground.

4.5 Ventilation

4.5.1 After the shutdown of the accelerator, before entering the airborne radioactive area, the area should be properly ventilated so that its concentration is lower than the derived air concentration listed in Appendix C. However, under the principle that the internal and external irradiation of terrestrial symbols is lower than the annual effective dose equivalent limit, the concentration of radioactive substances in the air may be allowed to be inhaled one or more times than the derived air concentration listed in Appendix C.

4.6 Emergency procedures

4.6.1 According to the actual situation of the accelerator, the emergency procedures needed to deal with major accidents (or errors) that may occur should be formulated, including evacuation of personnel, determination of individual doses, medical tracking, environmental assessment, etc.

4.7 Reliability Testing

4.7.1 The radiation safety system must be regularly inspected or maintained at intervals of no more than six months, and the inspection records should be kept.

5. Radiation monitoring

5.1 Contents and requirements of radiation monitoring

5.1.1 Personal dose monitoring

5.1.1.1 Personal dose monitoring of external irradiation shall be carried out for the operators, maintenance personnel and experimental personnel of the accelerator.

5.1.1.2 If it is known or suspected that a person has inhaled or ingested radionuclides, internal radiation monitoring should be carried out, such as urine sample analysis or whole body counter measurement.

5.1.2.1 During the commissioning stage after the completion of the accelerator facility and the operation to the maximum radiation emissivity state, a comprehensive radiation level measurement must be carried out in the relevant areas with the participation of radiation protection personnel to evaluate the radiation safety situation.

5.1.2.2 If the operating parameters of the accelerator, the shielding condition or the residence of the area have changed, and the radiation safety may be affected, the radiation field must be re-measured. When necessary, measures should be taken to ensure that the requirements of radiation protection can still be met under the new conditions.

5.1.2.3 After radiation measurement, the workplace should be classified according to radiation level, and corresponding measures should be taken in particular for the following areas:

A. Monitoring areas: When working continuously in these areas, the dose equivalent received by personnel for one year may exceed the annual dose equivalent limit of occupational radiological workers by one-tenth. Radiation monitoring should be strengthened in such areas.

B. Control zones: When working continuously in these areas, the annual dose equivalent received by personnel may exceed the annual dose equivalent limit of occupational radiological workers by 3/10. In addition to strengthening radiation monitoring in these areas, radiation hazard signs should also be set at their entrances or borders.

5.1.2.4 During the operation of the accelerator, the radiation level of any area equipped with remote control monitoring system shall be continuously recorded when exceeding the predetermined threshold.

The system shall issue sound and/or light warning signals when the value is set. Necessary radiation patrols should be carried out in other areas.

5.1.2.5 After the shutdown of the accelerator, when personnel enter the accelerator hall or target hall, they should cooperate with radiation monitoring.

5.1.3 Surface Pollution Monitoring

5.1.3.1 Surface contamination must be monitored regularly where tritium targets (or tritium-containing substances) are stored and used, and where there may be Tritium surface contamination.

5.1.3.2 The contamination level of equipment, walls and ground should be monitored regularly in areas where surface contamination may occur due to exfoliation of activated materials.

5.1.3.3 After the personnel have operated the radioactive material, they should monitor the surface pollution of their body surface and clothing.

5.1.3.4 When the surface contamination level of various s exceeds the corresponding limit, protective unveiling or timely decontamination should be adopted to prevent the contamination from spreading.

5.1.4 Airborne Radioactive Monitoring

5.1.4.1 Airborne radioactivity concentrations in areas where airborne radioactive substances exist should be continuously monitored or regularly monitored.

5.2 Options for measuring devices

5.2.1 The types and quantities of radiation monitoring and recognition instruments or devices that should be equipped in the accelerator facilities mainly depend on the size, complexity and use of the accelerator. However, for any accelerator, at least two (class) measuring instruments must be equipped for each type of radiation produced by the accelerator.

5.2.2 The equipped radiation measuring instruments must have the following functions:

A. Correct response to radiation measurements;

B. Measurements of the instrument are less than 2.5 *mSv.h-1 (0.25 merm.h-1).

C. The instrument has an adequate upper measurement limit to indicate the radiation level in the monitored area.

5.3 Radiometric Records

5.3.1 Radiation measurements shall be recorded, including:

A. Time, place and purpose of measurement;

B. Type, energy and beam strength of accelerated particles;

C. Type of target;

D. Position of collimator and magnet;

E. Radiation detectors used;

F. Results and recommendations;

G. Personnel participating in the measurement.

5.4 The Degree and Maintenance of Instruments

5.4.1 In order to use the instrument reasonably, we must be familiar with its performance and limitations. Therefore, for each instrument, we must give the following performance data:

A. The response of the instrument to the measured radiation;

B. Energy response;

C. Screening capacity for other types of radiation;

D. Responses to humidity, temperature and pressure;

E. Directional response.

5.4.2 Radiometric instruments must be periodically calibrated at intervals not exceeding one year. Calibration is also required after each overhaul.

5.4.3 For frequently used or continuously used instruments, work performance must be tested once a day or once a week.

6. Radiation safety management

6.1 Radiation Safety Institutions and Duties

6.1.1 Every unit with an accelerator must establish a radiation safety agency or appoint a full-time (part-time) radiation safety officer according to the number and complexity of the accelerators it has.

6.1.2 The responsibilities of the radiation safety agency are:

(a) To formulate and supervise the implementation of the Rules in collaboration with the relevant agencies in accordance with the requirements of these Provisions;

B. Education and training on radiation safety for operators and experimenters;

C. To report the monitoring results regularly to the competent authorities of the unit, and to put forward radiation safety assessment and suggestions for improvement;

D. Participate in the investigation and treatment of radiation safety accidents;

E. Check radiation safety facilities, monitor radiation levels, control radiation hazards and inform operators and experimenters of necessary circumstances; report major abnormalities to the competent authorities of the unit in time;

F. For radiation safety reasons, radiation safety personnel have the right to propose the suspension of the accelerator operation.

6.1.3 Qualifications of radiation safety personnel

A. Radiation safety design and evaluation of accelerators must be attended by engineer-level radiation protection personnel;

B. Radiation safety personnel must be radiation protection personnel with technical or above;

C. The head of the radiation safety agency shall be a radiation protection officer at or above the Engineer level.

6.2 Health Management

6.2.1 Medical examinations before employment are required for those who are ready to work on accelerators. Only those who are qualified for health can take part in this work.

6.2.2 Medical examinations should be carried out regularly for those who have been engaged in accelerator work, health records should be established, and whether the radiation work they are engaged in is suitable or should be restricted according to their health status.

6.2.3 Personnel who have received emergency or accidental radiation should conduct reasonable medical follow-up study and take certain treatment measures (including labor insurance treatment) according to the degree of exposure.

6.2.4 Personnel who have been diagnosed with radiation occupational diseases should be given necessary labor insurance treatment in accordance with relevant regulations, and perfect medical measures should be taken to make them recover at an early date.

6.3 Technical Archives

6.3.1 In addition to properly preserving the archives of the original radiation protection design of the accelerator, the following resource-sharing materials should also be preserved.

Personal dosage records. When personnel are transferred, a copy should be copied and transferred to a new job. After the death of a person, other persons can be kept for another 10 years, except those who have disputes about the cause of death.

B. Reporting and co-processing opinions on radiation accidents, evaluation reports on radiation protection and valuable monitoring results, as well as background investigation data. These data should be kept for a long time.

C. Maintenance and calibration records of radiometer. The preservation life of the data should be the same as that of the instrument.

D. Recording of maintenance and modification of radiation interlocking lines. The storage life of these data depends on its reference value to the operation of the accelerator and should generally be the same as that of the accelerator.

7. Environmental protection and waste management

7.1 All units with accelerators should do a good job in environmental protection, strive to reduce the production of radioactive "three wastes" and discharge as little radioactive substances as possible to the environment.

7.2 Units with accelerators shall establish corresponding storage sites or treatment facilities for radioactive wastewater and wastes according to the production of radioactive "three wastes".

7.3 Radioactive waste should be classified according to its half-life and incinerability. Special incinerators should be used to incinerate radioactive waste, such as waste vacuum pump oil.

7.4 The discharge of radioactive wastewater (mainly activated cooling water) from accelerator facilities must be strictly controlled. Before discharge, decay measures must be taken, purification and filtration measures must be taken, and radiation monitoring must be carried out.

7.5 Deuterium target with high tritium content or accelerator with high airborne radioactive level should be used. The discharge port or ventilation system of the front stage pump should adopt purification and filtration measures.

7.6 The environmental hazards of accelerator facilities should be investigated or evaluated once a year, and environmental monitoring and evaluation should be carried out in time under special circumstances.

Appendix A

Except for the following nouns, the other nouns used in this regulation can be found in GB 4960-85 "Terminology of Nuclear Science and Technology".

A.1 Target

A substance that interacts with accelerated charged particles to produce useful radiation.

A.2 High Radiation Area

It refers to an area where the radiation level may cause the effective dose equivalent of more than 1 mSv (100 merm) to be received by the human body in any one hour.

A.3 Radiation Zone

An area accessible to workers in which radiation levels may cause the human body to receive an excessive effective dose equivalent within an hour.

Over 5 x 10-2 mSv (5 merm) or over 1 mSv (100 merm) of effective dose equivalent received in any five consecutive days.

A.4 Key Residential Groups

The residents with the highest exposure level were the residents living and living around the accelerator facilities.