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Radiation Safety and Protection on Electron Accelerator Irradiation Facilities
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HJ 979-2018
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Standard similar to HJ 979-2018 HJ 511 HJ 945.3 HJ 943
Basic data | Standard ID | HJ 979-2018 (HJ979-2018) | | Description (Translated English) | Radiation Safety and Protection on Electron Accelerator Irradiation Facilities | | Sector / Industry | Environmental Protection Industry Standard | | Word Count Estimation | 22,296 | | Date of Issue | 2018-11-30 | | Date of Implementation | 2019-03-01 | | Regulation (derived from) | Ministry of Ecology and Environment Announcement No.60 of 2018 | | Issuing agency(ies) | Ministry of Ecology and Environment |
HJ 979-2018: Radiation Safety and Protection on Electron Accelerator Irradiation Facilities---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Radiation Safety and Protection on Electron Accelerator Irradiation Facilities
National Environmental Protection Standard of the People's Republic
Electron accelerator irradiation device radiation safety and protection
Published on.2018-11-30
2019-03-01 implementation
Ministry of Ecology and Environment
Content
Foreword..I
1 Scope..1
2 Normative references..1
3 Terms and Definitions.1
4 General requirements..1
4.1 Radiation safety requirements.1
4.2 Radiation protection requirements. 2
5 Radiation shielding of electron accelerator irradiation device.3
5.1 Shield design principles.3
5.2 Shield design calculation.3
6 Safety design of electron accelerator irradiation device.3
6.1 Interlocking requirements 3
6.2 Safety facilities 3
6.3 Other requirements 4
7 Daily maintenance (management) and records.5
7.1 Maintenance and repair of the device..5
7.2 Recording..5
Appendix A Shielding Protection Calculation for Electron Accelerator Irradiation Devices 7
Appendix A Example 10MeV Electron Accelerator Irradiation Device Radiation Shielding Calculation.12
Appendix B Calculation of the generation and emission of harmful gases. 18
I preface
To implement the Law of the People's Republic of China on Prevention and Control of Radioactive Pollution and the Safety and Protection of Radioisotopes and Radiation Devices
This Regulation is established to protect the environment, protect human health, and regulate the radiation safety of electron accelerators (electron beam and X-ray) irradiation devices.
This standard specifies the radiation safety and protection principles of electron accelerators (electron beam and X-ray) irradiation devices, including
Requirements for dose control, radiation workplace division, radiation shielding, safety design, routine maintenance (management) and documentation.
The technical content of this standard refers to the International Atomic Energy Agency (IAEA) "gamma, electron beam and X-ray irradiation devices.
Radiation Safety (IAEA SSG-8,.2010), with reference to international and domestic standards, combined with the practice of radiation processing in China.
Appendix A and Appendix B of this standard are informative annexes.
This standard was proposed by the Radiation Source Safety Supervision Department of the Ministry of Ecology and Environment.
This standard is formulated by the Nuclear Equipment Safety Supervision Department of the Ministry of Ecology and Environment and the Science and Technology Standards Department.
This standard is mainly drafted by. Beijing Top Three Nuclear Radiation Engineering Technology Co., Ltd., Ministry of Environmental Protection Nuclear and Radiation Safety
Center, Beijing Municipal Environmental Protection Bureau, Shandong Lanfu High Energy Physics Technology Co., Ltd., China Guangdong Nuclear Power Co., Ltd.
Ltd., China Institute of Atomic Energy and China Nuclear Power Engineering Co., Ltd.
This standard is approved by the Ministry of Ecology and Environment on November 30,.2018.
This standard has been implemented since March 1,.2019.
This standard is explained by the Ministry of Ecology and Environment.
1 Electron accelerator irradiation device radiation safety and protection
1 Scope of application
This standard specifies the radiation safety and protection principles of electron accelerators (electron beam and X-ray) irradiation devices, including
Requirements for dose control, radiation workplace division, radiation shielding, safety design, routine maintenance (management) and documentation.
This standard is applicable to electron beam irradiation devices with energy not higher than 10 MeV for radiation processing and energy not higher than 5 MeV.
X-ray irradiation device. Self-shielding irradiation devices are not suitable for this standard.
2 Normative references
The contents of this standard refer to the following documents or their terms. For undated references, the valid version is appropriate.
Used in this standard.
GB 3095 Ambient Air Quality Standard
GB 5172 particle accelerator radiation protection regulations
GB 18871 Basic standards for ionizing radiation protection and radiation source safety
GBZ 2.1 Occupational exposure limits for workplace hazards Part 1. Chemically harmful factors
GBZ 2.2 Occupational exposure limits for workplace hazards Part 2. Physical factors
3 Terms and definitions
3.1 electron accelerator irradiation device electron accelerator spraying facilities
It consists of an electron accelerator, an irradiation chamber, a transmission device, a safety device, and a control system to implement a radiation processor.
Art installation.
3.2 Under-beam equipment under beam equipment
The beam is led out of the window (outside), and the independent control unit that receives the irradiation in the material transport device.
3.3 main room main machine room
Place a device such as an electron accelerator electron beam generating device (electron gun) and a beam acceleration structure (such as an accelerating tube).
3.4 Irradiation room
The electron accelerator emits radiation to form a radiation field, which is used to complete the radiation processing process.
3.5 interlocking interlock
Refers to the electronic accelerator can automatically cut off the power or beam immediately in a certain dangerous state, and does not meet the set safety
Electrical devices that ensure that no radiation is produced under conditions.
3.6 tenth value layer tenth-value layer
Also called tenth of a thickness. Thickness of a given material that reduces the level of radiation to 1/10 when placed on a beam path
degree. It can be further divided into the first tenth value layer and the subsequent tenth value layer, the latter called the balanced tenth value layer.
4 General requirements
4.1 Radiation safety requirements
4.1.1 Security Principles
4.1.1.1 Defense in depth
2 to take appropriate multi-layer protection against the application of the electron accelerator irradiation device and the size and possibility of potential illumination
And security measures (ie defense in depth) to ensure that when a level of defense measures fails, the next level of defense can be
Make up or correct it to.
(1) Prevent accidents that may cause exposure;
(2) mitigate the consequences of any similar accidents that may occur;
(3) Return the unit to a safe state after any such incident.
4.1.1.2 Redundancy
The items used should be more than the minimum number of items necessary to complete a security function, in case of operation
If the item fails or does not work, it will not lose its function as a whole. For example, the entrance and exit of the irradiation room and the main room should be
Set 3 or more interlocks.
4.1.1.3 Diversity
Diversity can improve the safety and reliability of the device and reduce common cause failures. System diversity and multiple dose monitoring
To use different operating principles, different physical variables, different operating conditions, different components and so on. For example. irradiation
The safety interlocks between the entrance and exit of the room and the main room can be mechanical, electrical, electronic and dose interlocked, respectively.
4.1.1.4 Independence
Independence means that when a safety component fails, it does not cause malfunction or loss of function of other safety components.
use. Safety agencies gain independence through functional separation and physical isolation. To increase the independence of the system, it can be taken
The following measures.
(1) Ensuring independence between the components of redundancy (multiple interlocks);
(2) Ensuring independence between components in depth defense;
(3) Ensure the independence between the various components;
(4) Ensure the independence between important items of safety and non-safety important items.
4.1.2 Division of radiation workplaces
According to the provisions of GB 18871, the workplace of the electron accelerator irradiation device is divided into.
Control areas, such as the main room and the irradiation room, and areas within the respective entrances and exits;
Supervised areas, such as equipment operating rooms, electronic accelerator irradiation equipment auxiliary facilities not included in the control area, and other needs
Areas where monitoring and evaluation of occupational exposure conditions are often performed.
4.1.3 A warning sign in accordance with GB 18871 shall be established at the entrance and exit of the control area and other necessary places.
4.1.4 Documents such as manuals, operating procedures and emergency procedures, as well as key safety component identification and safety signs, should be in Chinese.
4.2 Radiation protection requirements
4.2.1 Radiation protection principles
(1) Legitimacy of radiation practice
The construction of the electron accelerator irradiation device must be justified to determine the legitimacy of the project.
(2) Optimization of radiation protection
3 The design and construction of the electron accelerator irradiation device requires that all irradiation doses remain within the specified limits and are under consideration.
After social and economic factors, the size of the individual’s exposure, the number of people exposed, and the likelihood of exposure should remain
The lowest level that can reasonably be achieved, namely the ALARA (As Low As Reasonably Achievable) principle.
(3) Personal dose constraints
The dose limits for occupational exposure and public exposure of radiation workers shall meet the requirements of GB 18871.
In the engineering design of the electron accelerator irradiation device, the dose constraint value of the radiation protection is specified as.
a) The annual effective dose of the radiation worker is 5mSv;
b) The annual effective dose of a member of the public is 0.1 mSv.
4.2.2 Radiation shielding design basis
The shielding design of the electron accelerator irradiation device must be based on the highest energy of the accelerator and the maximum beam intensity.
The dose equivalent rate around the outer surface of the externally shielded surface of the electron accelerator irradiation device at 30 cm and beyond
Can not exceed 2.5μSv/h. If the shielding is outside the public area, the shielding design must comply with the individual member's personal dose constraint value.
This standard applies to electron beams with an energy not higher than 10 MeV and X-rays with energy not higher than 5 MeV.
There is no need to consider the resulting neutron protection issues in the design.
5 Radiation shielding of electron accelerator irradiation device
5.1 Shield design principles
The electron accelerator irradiation device should not only consider the shielding requirements when the maximum beam power is used in the shielding design, but also in the energy and
Where the beam intensity is adjustable, the difference in shielding at the maximum energy and/or maximum beam intensity combination is also considered.
5.2 Shield design calculation
5.2.1 The design of the shield design shall include. the irradiation room and the main engine room and their respective lost roads, roofs, holes, etc.
5.2.2 Shielding design and calculation results should be stated in the design document.
5.2.3 The shielding calculation method of the electron accelerator irradiation device can be found in Appendix A. For special X-ray irradiation equipment,
Calculated according to the conversion target parameters or X-ray emissivity provided by the accelerator manufacturer. For both electron beam irradiation and
Irradiation devices that can be used for X-ray irradiation should be calculated according to the shielding calculation method of the electron accelerator irradiation device.
6 Safety design of electron accelerator irradiation device
6.1 Interlocking requirements
In the design of the electron accelerator irradiation device, a safety interlock protection device with complete functions and reliable performance must be provided.
Effective access interlocking and monitoring of the entrance and exit doors of the control area, the opening and closing of the accelerator, and the beam-down device.
The safety interlock must automatically cut off the high voltage when the accelerator is stopped.
The accelerator cannot operate when the safety interlock is broken. Safety interlocks must not be bypassed and must be restored to their original condition after maintenance and repair.
6.2 Safety facilities
(1) Key control. The accelerator's master key switch must be interlocked with the main room door and the irradiation room door. As from the console
Remove the key and the accelerator should stop automatically. The key must be accompanied by an effective portable radiation monitoring report
The police are connected. The key is unique during operation and can only be used by the running monitor;
4(2) Door machine interlocking. The doors of the irradiation chamber and the main chamber must be interlocked with the beam control and the accelerator high pressure. Irradiation room door or
The accelerator cannot be turned on when the main unit door is open. The accelerator should be automatically stopped when the accelerator is running and the door is opened.
(3) The interlocking device is interlocked. The control of the electron accelerator irradiation device and the control of the beam device must establish a reliable connection.
Port and protocol documents. When the beam device deviates from normal operation or stops running due to malfunction, the accelerator should automatically
Downtime
(4) Signal warning device. Light and sound warning signals should be set at the entrance and exit of the control area for booting
Pre-warning of the host room and the personnel in the irradiation room. Main room and irradiation room entrance and exit setting working status indication
Set and interlock with the electron accelerator irradiation device;
(5) Patrol button. A “patrol button” should be set in the main room and the irradiation room, and interlocked with the console. Accelerator on
Before the machine, the operator enters the main room and the irradiation room and presses the “patrol button” in order to check whether there are any personnel missing.
(6) Preventing people from entering the device. Three anti-missing safety settings are set in the entrance and exit passages of the main room and the irradiation room.
Interlocking device (usually using photoelectric device), and interlocking with the opening and closing of the accelerator;
(7) Emergency stop device. Set emergency stop device (usually pull switch) on the console and in the main room and irradiation room
Or button) to terminate the operation of the accelerator in an emergency. Irradiation room and emergency stop in the lost road
The pull switch should be used to cover all areas. There should also be a door opening mechanism in the main room and the irradiation room so that
Personnel leave the control area;
(8) Dose interlocking. Set a fixed radiation monitor, irradiation chamber and host in the labyrinth of the irradiation room and the main room
The entrance and exit doors of the room are interlocked. When the radiation level in the main room and the irradiation room is higher than the threshold set by the instrument,
The main room and the irradiation room door cannot be opened;
(9) Ventilation interlocking. The main room, the irradiation room ventilation system is interlocked with the control system, and only after the accelerator is stopped
The door can be opened after a preset time to ensure that the concentration of harmful gases such as indoor ozone is lower than the allowable value;
(10) Smoke alarm. The irradiation room should be equipped with a smoke alarm device. In the event of fire hazard, the accelerator should stop immediately and stop.
Ventilation.
6.3 Other requirements
6.3.1 Electrical system
(1) Must be designed according to the power supply conditions of the accelerator device and plant construction and public works to ensure the stability of voltage and current
degree.
(2) Emergency lighting system should be installed in the main room, irradiation room and control room.
(3) Each power supply system and related equipment should have a reliable grounding system.
(4) Where there is danger of high voltage, high voltage interlocking and high voltage discharge protection devices shall be provided.
6.3.2 Water supply system
(1) A certain amount of water flow and water pressure should be provided according to the total water requirements of the accelerator unit.
(2) Designed according to the water quality, water temperature and heat exchange load required by the equipment such as the accelerator device and the beam device.
6.3.3 Ventilation system
(1) Ventilation system should be installed in the main room and the irradiation room to ensure that the concentration of harmful gases such as ozone generated by radiation decomposition meets the requirements of GBZ 2.1.
The emission of harmful gases should meet the requirements of GB 3095.
(2) The generation and emission of ozone, the calculation mode and parameters are shown in Appendix B.
(3) The main exhaust port in the irradiation room should be placed in a position where ozone is easily discharged, such as the position below the scanning window.
5(4) The height of the exhaust vent should be calculated and determined according to the provisions of GB 3095, the amount of harmful gas emissions and the environment and meteorological data near the irradiation device.
6.3.4 Fire protection system
The fire resistance of the irradiation room and the main room should not be lower than the second level, and a fire alarm device and an effective fire extinguishing facility should be provided.
7 Daily maintenance (management) and records
7.1 Maintenance and repair of the device
The operating unit of the irradiation device must establish a maintenance and repair system for the irradiation device, and regularly inspect (inspect) each acceleration.
The main safety equipment of the device maintains the effectiveness and stability of the main safety equipment of the irradiation device.
Changes to safety facilities must be approved by the design unit and approved by the regulatory authorities.
7.1.1 Daily inspection
Common safety equipment on the electron accelerator irradiation device should be inspected every day, and must be repaired in time when abnormal conditions are found.
complex. The regular day inspection project should include at least the following.
(1) Working status indicator, warning light and emergency lighting;
(2) The irradiation device safety interlock control display status;
(3) Working condition of personal dose alarm device and portable radiation monitoring instrument.
7.1.2 month check
Important safety equipment or safety procedures on the electron accelerator irradiation device should be checked regularly every month to find abnormal conditions.
It must be repaired or corrected in time. The monthly inspection project should at least include.
(1) The operating conditions of the irradiated indoor fixed radiation monitor equipment;
(2) Console and all other emergency stop buttons;
(3) The effectiveness of the ventilation system;
(4) Verify the validity of the safety interlock function;
(5) The smoke alarm function is normal.
7.1.3 Half year inspection
The safety status of the electron accelerator irradiation device should be checked regularly every 6 months.
Take corrective measures. The scope of inspection should at least include.
(1) Cooperate with the inspection of annual inspection;
(2) All safety equipment and control system operating conditions.
7.2 Recording
The operating unit of the irradiation device must establish a strict operation and maintenance record system, which should be pressed during operation and maintenance.
It is required to complete the record of the operation log, record important activities related to the device and save the log file. Recording matters
Not less than the following.
(1) Operating conditions;
(2) The situation of irradiated products;
(3) Faults and troubleshooting methods;
(4) The situation of outsiders entering the control area;
(5) The wearing situation of the personal dosimeter;
6(6) Radiation monitoring results for individual doses, workplaces and surrounding environments;
(7) Contents and results of inspection and maintenance;
(8) Other.
7 Appendix A Calculation of Shielding Protection for Electron Accelerator Irradiation Devices
(informative appendix, based on NCRP-51 and NCRP-151 reports)
A.1 Radiation source item
Electron beam bombardment targets, various structural materials, and irradiated products all produce bremsstrahlung (X-rays), and X-rays are electrons.
The main radiation source in the radiation protection design of the speed irradiator.
Table A.1 shows the X-ray emissivity Q at which a single-energy electron is incident on a high-Z thick target (Z >73) at a distance of 1 m from the target.
Table A.1 X-ray emissivity (unit. Gy·m2·mA-1·min-1)
Incident electron energy (MeV) 0.5 1.0 1.5 2.0 2.5 3.0 4.0 5.0 7.5 10.0
Forward 0° 0.008 0.26 1.3 3.3 7.0 14.0 30.0 63.2 170 450
Lateral 90° 0.07 0.4 1.0 1.6 2.5 3.2 4.8 6.5 10.0 13.5
X-rays are approximately exponentially attenuated as they pass through the material. The shielding calculation must first determine the X-ray transmittance Bx.
After the dose rate is passed through the thickness of the shield, the value of the transmittance is reduced to an allowable value.
A.2 Direct X-ray shielding
The data given in Table A.1 is the data of the electron beam hitting high Z target, and the usually irradiated material is rarely high Z material, so
The target needs to be corrected. When the irradiated target material is "iron, copper", the correction coefficient fe in the 0° direction is 0.7, 90° square.
The correction coefficient fe of the direction is 0.5; when the irradiated target material is "aluminum, concrete", the correction coefficient fe in the 0° direction is 0.5,
The correction factor fe in the 90° direction is 0.3.
8A.2.2 Solution of shielding thickness
There are two methods for calculating the thickness of the shield. the curve plot method and the tenth-value layer method. Only give tenths here
The one-value layer method, the curve diagram method can be found in the NCRP-51 report.
Shield thickness is indicated by a tenth value layer of the shielding material
Bx=10-n or n=log10(1/Bx) (A-3)
Calculating the thickness of the shield can be conservatively estimated as.
S=T1 (n-1)Te (A-4)
In the formula.
S-- thickness of the shield (cm);
T1-- in the shielding thickness, the first tenth of the layer (cm) towards the radiation source;
Te-- balances the tenth-value layer, which approximates a constant (cm);
N-- is the number of tenths of the value layer.
Tables A.2 and A.3 give the T1 and Te values for ordinary concrete, steel and lead.
Table A.2 The thickness of the first tenth of the broad beam X-ray in several major materials (unit. cm)
Incident electron energy
Quantity (MeV)
0.5 1.0 1.5 2.0 2.5 3.0 4.0 5.0 7.5 10.0
Concrete 15.2 18.5 20.4 22.1 24.2 26.1 30.5 32.5 36.8 41
Iron 3.8 5.5 6.8 7.7 8.3 8.7 9.2 9.7 10.3 10.5
Lead 0.5 1.5 2.6 3.35 4.7 4.5 5.0 5.3 5.6 5.7
Table A.3 Balance of wide beam X-rays in several major materials. Layer thickness (unit. cm)
Incident electron energy
Quantity (MeV)
0.5 1.0 1.5 2.0 2.5 3.0 4.0 5.0 7.5 10.0
Concrete 11.9 15.0 18.3 20.1 22.5 24.7 30.5 32.5 36.8 38.6
Iron 3.3 5.0 6.2 7.0 7.7 8.2 9.2 9.7 10.3 10.5
Lead 1.2 2.6 3.65 4.2 4.1 4.9 5.3 5.5 5.7 5.6
A.2.3 Shielding of lateral X-rays
For electron accelerator irradiation devices, in many cases, lateral (relative to the electron beam 90° direction) X-rays need to be considered.
Shielding, the equivalent incident electron energy should be used as the energy of the lateral incident electrons, as shown in Table A.4 below, and then equivalent
The characteristic parameters of incident electron energy are calculated according to the method of direct X-ray shielding.
Table A.4 Corresponding equivalent energies of electrons in the 90° direction (unit. MeV)
Incident electron energy 1.0 1.5 2.0 2.5 3.0 4.0 5.0 7.5 10.0
Equivalent incident electron energy 0.7 1.0 1.3 1.6 1.9 2.5 3.1 4.6 6.0
A.3 Shielding of scattered radiation
In the shielding design of the accelerator device, there are three cases in which the scattered radiation must be considered.
(1) lost and protective doors;
9(2) sky backscattering;
(3) Holes.
A.3.1 Lost and protective doors
A.3.1.1 The obscurity of protecting electrons, in order to prevent the illumination of electrons at the entrance of the lost channel,...
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