1、 The importance of nuclear and radiation safety
Nuclear and radiation safety supervision is an important field of ecological environment protection and an important part of maintaining national security. As an independent nuclear safety regulatory agency, the Ministry of ecological environment (National Nuclear Safety Administration) plays an important role in ensuring China's nuclear and radiation safety. Authoritative and effective supervision activities must be guaranteed by scientific and standardized management system and procedure system. Building a nuclear and radiation safety management system is an effective way to implement the nuclear safety law and promote the construction of legal supervision. In order to ensure the safety of nuclear facilities, the nuclear safety law has made a series of institutional arrangements for the safety licensing of nuclear facilities and nuclear safety supervision and inspection, and stipulated the nuclear and radiation safety supervision mechanism at the national legal level. To implement these systems, we need not only a set of clear, comprehensive, scientific and rigorous laws and regulations system for external supervision, but also a set of management system with clear division of labor, reasonable organization and effective operation for internal standardization, so as to realize the institutionalization, standardization and proceduralization of nuclear and radiation safety supervision.
1. The construction of nuclear and radiation safety management system is the internal need to strengthen the construction of nuclear safety culture of regulatory agencies. The construction of the management system is the self pressurization and self reform of the regulator, the practical embodiment of the concept of continuous improvement and the pursuit of excellence, and an important part of the construction of the regulator's nuclear safety culture. Build a relatively complete, systematic, scientific and strict management system, internalize and externalize the requirements of the management system, consciously implement the system requirements, supervise the implementation of the system, promote the improvement of the system, and continuously improve the level of nuclear safety culture within the regulatory system.
2. The construction of nuclear and radiation safety management system is an effective carrier to inherit the knowledge and experience of nuclear and radiation safety supervision. Over the past 30 years, the nuclear and radiation safety supervision system has gradually formed a complete set of supervision concepts, principles, methods and practices, which is the theoretical wealth extracted from the gradual exploration and continuous practice of generations of nuclear safety supervisors. By systematically combing, summarizing, summarizing, perfecting and sublimating the above practical experience, the nuclear and radiation safety management system can provide an effective carrier for nuclear and radiation safety supervision and spiritual inheritance, and build a good platform for the consolidation, transformation and re innovation of supervision theory.
3. The construction of nuclear and radiation safety management system is an inevitable choice in line with international safety standards and good practice. The construction of management system is a good practice to learn from international advanced experience, an effective channel to connect with the latest international safety standards, an important platform to share China's regulatory achievements, and plays an important role in establishing a domestic authoritative and world-class nuclear safety regulatory agency and helping nuclear safety and nuclear power "go global".
4. Building a nuclear and radiation safety management system is a realistic need to respond to the growing nuclear safety concerns of the state and the public. In recent years, the CPC Central Committee and the State Council have paid more attention to nuclear safety work, with an unprecedented number of instructions and specific concerns. Public concern about nuclear safety is growing, and public opinion related to nuclear safety is emerging. Facing the new situation, nuclear and radiation safety supervision needs to achieve leapfrog development and face "three changes" in the focus of work: in terms of work content, from construction project review and supervision to ensuring the continuous operation safety of nuclear facilities; In terms of working mode, from empirical supervision to standardized supervision; In terms of working methods, we have changed from top-level design to comprehensive implementation.
2、 Basic knowledge of radiation protection
1. According to the different effects of radiation on substances, radiation is divided into ionizing radiation and non ionizing radiation. Both ionizing radiation and non ionizing radiation belong to electromagnetic radiation.
2. Ionizing radiation refers to charged and uncharged particles that carry enough electrons in atoms or molecules of matter to become free states, thus ionizing these atoms or molecules.
3. Generally, photons with energy greater than 10ev are regarded as ionizing radiation, while photons with energy less than 10ev are called non ionizing radiation.
4. Ionizing radiation includes cosmic rays, X-rays and radiation from radioactive materials（ α Ray β Ray γ Rays, neutrons). Ultraviolet, visible, infrared, radio waves, microwaves, etc. with wavelengths greater than 100nm belong to non ionizing radiation.
5. Classification of ionizing radiation exposure:
（1） It can be divided into external radiation (external radiation, such as X γ、 Protons, neutrons and high energies β） And internal exposure (internal sources, e.g α、 Medium low energy β）；
（2） According to the predictable and accidental nature of exposure, it can be divided into normal exposure and potential exposure;
（3） According to the subject of exposure, it is divided into occupational exposure, public exposure and medical exposure.
6. The average effective dose limit of professional personnel for five consecutive years is 20msv/ year, and the effective dose limit of the public is 1msv/ year.
7. The equivalent dose limit of eye lens for professional personnel is 150msv/ year, and that of limbs (hands and feet) or skin is 500msv/ year.
8. The equivalent dose limit of eye lens for public personnel is 15msv/ year, and the equivalent dose limit of limbs (hands and feet) or skin is 50msv/ year.
9. For apprentices aged 16-18 who receive employment training involving radiation exposure and students aged 16-14 who need to use radioactive sources during their study, their occupational exposure shall be controlled to not exceed the following limits:
（1） Annual effective dose, 6msv.
（2） Equivalent dose of ocular lens, 50msv.
（3） Equivalent dose to limbs (hands and feet) or skin, 150msv.
10. Dose limits are applicable to occupational exposure and public exposure, excluding natural background exposure and medical exposure.
11. The basic principle of external radiation protection is to reduce or avoid external radiation to the human body as much as possible, so that the exposure does not exceed the dose limit specified by the state. The basic methods adopted include:
（1） Reduce exposure time; （2） Increase the irradiation distance; （3） Set shielding.
12. Time, distance and shielding are generally referred to as the three elements of external radiation protection, which are applicable to all radiation sources x γ、β、 Protection against protons, neutrons, etc.
13. In terms of penetration capability, α＜β＜γ And X.
14. For α， Commonly used shielding materials are paper, aluminum foil, plexiglass, etc.
15. The general measures for internal radiation protection are "containment", "isolation" and "purification" and "dilution". In pollution control, "containment" and "isolation" are the main measures. In open radiation operation, "containment", "isolation" and "purification" and "dilution" are often used in combination.
16. Containment refers to the containment of radioactive substances during operation, such as the use of fume hoods, glove boxes, etc.
17. Isolation means separation. The workplace shall be classified and divided according to the toxicity of radionuclides, the amount of operation and the mode of operation.
18. The ways of radioactive substances entering the human body include inhalation, ingestion and absorption through the skin.
19. According to the maximum equivalent daily operation quantity of operating radionuclides, open radioactive workplaces are divided into class A, class B and class C.
20. The potential danger of open type radiation work is related to the activity, relative toxicity and operation mode of radioactive substances.
21. If other conditions are the same, then α、β、γ In terms of the degree of radiation hazard caused by radiation, when external irradiation, γ＞β＞α， In case of internal irradiation, α＞β＞γ。
22. The dose that doubles the probability of natural mutation is called mutation doubling dose, which is about (0.1 ~ 1) gy, and the representative value is 0.7gy.
23. Acute radiation sickness can be divided into bone marrow radiation sickness, intestinal radiation sickness and brain radiation sickness according to the dose, main symptoms, course characteristics and severity.
24. Personal monitoring shall be carried out for any staff working in the controlled area, or who sometimes work in the controlled area and may receive significant occupational exposure, or whose occupational exposure dose may be greater than 5msv/a.
