About the prevention and control standards for radioactive pollutants in nuclear power plants from September 1

The website of the Ministry of Environmental Protection (hereinafter referred to as the “Ministry of Environmental Protection”) released on August 31 that the three issues involving environmental radiation and radioactive waste treatment of nuclear power plants issued by the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection and Quarantine on February 18 this year. The national standard for the prevention and control of radioactive pollutants will be implemented on September 1.

The three newly implemented standards are: "Environmental Radiation Protection Regulations for Nuclear Power Plants" (GB6249-2011), "Properties for Low-to-medium Level Radioactive Waste Solidified Parts - Cement Curing Body" (GB14569.1-2011) and "Nuclear Power Technical Requirements for Discharge of Radioactive Liquid Effluent (GB14587-2011) and the abolition of three old standards.

The Ministry of Environmental Protection said that the implementation of the three new standards aims to implement the "Environmental Protection Law of the People's Republic of China" and the "Law of the People's Republic of China on Prevention and Control of Radioactive Pollution" to prevent and control pollution and safeguard human health.

The environmental radiation regulations provide more specific details on the environmental radiation protection of nuclear power plants. The newly implemented standards stipulate the environmental radiation protection requirements for the selection, design, construction, operation, decommissioning, expansion and modification of land-based fixed nuclear power plants, and It was pointed out that this standard is applicable to land-based fixed nuclear facilities that use light water reactors or heavy water reactors for power generation. Other reactor-type nuclear power plants can be implemented by reference.

It is reported that the “Regulations on Environmental Radiation Protection for Nuclear Power Plants” (GB6249-2011) covers five aspects in the revision of the previous standard.

Reporters found that the reference to the original reference to the original standard: According to the size of the degree of harm that may lead to the environment, the accidents of the nuclear power plant are divided into expected operating events, major accidents, major accidents and maximum credible accidents. The new standard revised the classification of design basis accidents in the original standard to two types of rare accidents and extreme accidents. Meanwhile, the frequency of defining rare occurrences was 10-4-10-2 years, and the frequency of extreme accidents was 10-6-. 10-4 years old.

In addition, the new standard modifies the maximum credible incident of the accident release source item in the original site approval stage as a siting hypothetical accident, and gives the corresponding dose acceptance criteria. At the same time, the new standard implements the annual total discharge of radioactive effluent according to the reactor type and power, and also clearly stipulates the annual total discharge of carbon-14 in the liquid radioactive outflow of light water reactors, and increases the light water reactor and heavy water reactor gas. Contains control values ​​for carbon 14 and helium in radioactive effluents.

The “Environmental Radiation Protection Regulations for Nuclear Power Plants” (GB6249-2011) also stipulates that the concentration of radioactive nuclides other than thorium and carbon 14 in the radioactive effluent at the slot outlet of the coastal site shall not exceed 1000 Bq∕L, and the inland site Not more than 100Bq∕L.

An industry source close to the Ministry of Environmental Protection told reporters that the new environmental radiation standard was the first revision of the 1986 edition of the “Environmental Radiation Protection Regulations for Nuclear Power Plants” (GB6249-1986), and the revised content was more detailed and specific to nuclear power. The factory's requirements in site selection, construction, and later operation and decommissioning, “With decommissioning as an example, the new standard clearly clarified the requirements before, during, and after decommissioning, while the previous standard only mentions items after decommissioning. ."

Curing Waste Standard Application Scope Adjustment "Low-to-medium-level radioactive waste solidified body performance requirements-cement cured body" (GB14569.1-2011) standards stipulates low-to-medium-level radioactive waste cement solidified body (hereinafter referred to as "cement cured body") The minimum performance requirements and test methods.

According to the reporter, the new standard is applicable to solidified cement bodies near surface disposal, except for large-volume cement cast solids. The scope of application of the 1993 edition also includes cement solidification bodies that can be treated in accordance with the then-standard caverns. That is, the new standard has revised the normative references, that is, the newly issued normative documents, and removed the “low,” Medium-level radiological cabinet waste disposal regulations (GB13600). In addition, the performance requirements of the cement cured body against the ingression and the test methods for the compressive strength of the cement solid body have been revised.

In addition to the revised content, the new standard also adds the definition of “cement cured body” and “free liquid” and the conditions that do not perform the freeze-thaw resistance test of cement body.

With respect to the test method for the compressive strength of cement solidified bodies, the old standard only mentions that non-radioactive simulated wastes are used to prepare cement pastes in accordance with the prescribed formula. The cement slurry is poured directly into the test molds. The samples are cylinders with a diameter of 5 cm and a height of 5 cm. The sample was placed in a closed, room temperature of 25 ± 5 °C and kept out of direct sunlight. The compressive strength of the 28th day was measured. The new standard adopts the curing conditions specified in "Test method for strength of cement mortar (ISO method)" (GB ∕T17671), and it also increases the data processing requirements for test results, that is, the compressive strength performance test should cure at least six cements. The parallel samples were measured and the arithmetic average of a set of six compressive strength measurements was used as the experimental result.

Standards and concentrations for liquid waste control On radioactive liquid emissions, the new standard specifies the technical requirements for nuclear power plant emissions. This standard applies to the design and operation of radioactive liquid effluent discharge systems for light water reactors and heavy water reactor type nuclear power plants and to radioactivity. The management of liquid effluent discharges can also be referred to for other types of nuclear power plants and nuclear reactor facilities.

As with the previous two new standards, new standards for radioactive waste discharge have also been revised and increased. The first is to revise the name and scope of the standard, the principle of radioactive liquid effluent discharge management, as well as the management of discharge of radioactive liquid effluents, and the setting and monitoring of total discharge outlets. “According to the status quo for the upcoming construction of inland nuclear power plants such as the Binhe, Binhu and Binhu reservoirs in China, the new standards have particularly increased the requirements for these rivers, lakes and reservoirs.” The industry insiders told reporters.

The contents of the increase include the discharge concentration limits of radioactive liquid effluents and the online alarm thresholds, and the technical requirements for the design and operation management of liquid radioactive effluent discharge systems, especially the optimization requirements.

Through comparison, the old version of the principle of radioactive liquid effluent emission management is "can be reasonably achieved as low as possible", while the new standard is "radiation protection optimization" and "minimization of waste" principle, the key is the implementation of radioactive liquid effluent Total emission control and emission concentration control.