How to dispose of radioactive waste
How to dispose of radioactive waste, radioactive waste in the disposal of strict requirements, because it will cause pollution of the environment, so in the disposal of the first need to be categorized, in accordance with the specific classification of the choice of way, the following I take you a brief understanding of how to dispose of radioactive waste.
How to dispose of radioactive waste 1Disposal of radioactive liquids
(1) radioactive waste liquid : need to utilize the radioactive wastewater special treatment devices or separated cesspools to store and discharge radioactive waste liquid in turn. Wastewater with a concentration of radioactivity less than or equal to the DIC (public) can be treated as non-radioactive wastewater and discharged into the sewer system.
Alternatively, the waste liquid may be filled into a container and stored for 10 half-lives before being discharged into the sewer system. If the waste liquid contains long half-life nuclides, it can be solidified and then disposed of as solid waste.
(2) the treatment of patient excreta: patients using radiopharmaceuticals in the consultation period should be used during the special bathroom with radiation protection signs, the implementation of unified collection and management of patient excreta.
Disposal of radioactive solid waste
(1) collection of radioactive solid waste:
Collection of waste according to the waste combustible and non-combustible, with or without pathogen toxicity classification. Waste collection drums should have an outer protective layer and ionizing radiation markings. Dirt barrels should be placed to avoid staff work and frequent access to the place. Special plastic bags should be placed inside the drums for direct collection of waste. When full, timely transfer to the storage room.
(2) radioactive solid waste storage:
Radioactive solid storage should be in line with the requirements of radiation hygiene and protection, radioactive storage room installed ventilation equipment, the entrance and exit of the ionizing radiation sign.
Waste bags, waste drums and other storage containers must be in a conspicuous position, labeled with the type of waste, nuclide type, specific activity range and storage date.
A jacket should be attached to the outside of waste bags for items such as syringes and broken glass.
(3) radioactive solid waste disposal:
Radioactive solid waste according to the length of half-life classification collection, placed in the radioactive storage room natural decay. Pollution with pathogens solid waste, must be disinfected, sterilized, and then treated as solid radioactive waste.
Short half-life nuclides (half-life <15 days) stored for 10 half-life, the specific activity of radioactivity reduced to 7.4 × 104Bq/kg, as non-radioactive waste disposal; long half-life radioactive waste temporarily stored in the decay chamber, to the specialized agencies for recycling.
Sealed radioactive sources below the GBq level must be stored in a facility with sufficient shielding capacity for external exposure.
The storage of radioactive waste must be labeled with the name, date of placement, and date of disposal, and registered. Determination of radioactivity activity is required before delivery, to meet the emission of the required level of sealed red plastic bags; handover is required to register the date of handover, the name of the waste, the weight, the production department, the person in charge, the handover unit. By the person placed in the hospital waste storage point.
Disposal of radioactive airborne waste
(1) Where the use of 133Xe diagnostic examination of the patient's premises, should have the recovery of the patient's exhaled breath in the 133Xe device can not be directly discharged into the atmosphere.
(2) Airborne waste with a concentration of radioactivity less than or equal to the DAC (public) is non-radioactive and can be discharged directly.
How to Dispose of Radioactive Waste2The methods used to date to dispose of uranium-containing tailings have been disposal in piles or backfilling of mines. Some countries are working on radical solutions. For example, in hydrometallurgical processing, underground leaching and in situ heap leaching technologies are proposed, whereby only the leach solution is sent to a hydrometallurgical plant to extract uranium metal. In addition, also studied the tailings slag solidification and granulation technology; the use of various chemicals and vegetation to make the tailings dam layer stabilization.
Disposal of radioactively contaminated artifacts For a variety of artifacts contaminated with artificial or natural radionuclides, their specific radioactivity is divided into two categories of high level and medium and low level; their properties are distinguished as combustible and non-combustible. The main treatment and disposal methods for this type of solid waste are:
Decontamination Radioactively contaminated equipment, utensils, instruments, etc., if the use of appropriate detergents, complexing agents or other solutions in a certain part of the wipe or impregnation decontamination, most of the radioactive material can be cleaned down. Although this treatment produces radioactive waste liquid that needs to be disposed of, the volume may be reduced if properly operated, and the decontaminated artifacts can continue to be used. In addition, the use of electrolysis and spray plating methods can also eliminate the radioactivity of some contaminated surfaces.
Compression Compressible 'radioactive solid waste' into metal or non-metallic containers and compressor. The volume can be significantly reduced, waste paper, broken cardboard shells, etc. can be reduced to 1 / 3 to 1 / 7. Glassware first broken, metal objects are first cut, and then put into the container compression, can also reduce the volume, easy transportation and storage.
Incineration combustible solid waste such as paper, cloth, plastic, wood products, etc., after incineration, the volume can generally be reduced to 1/10 to 1/15, up to 1/40. incineration to be carried out in the incinerator. The incinerator should be corrosion-resistant, and there should be a perfect exhaust gas treatment system to collect the escaping particles with radioactive, volatile aerosols and soluble substances. After incineration, the vast majority of the radioactive material is accumulated in the ash, and the residual ash and embers should be properly managed to prevent them from being blown away by the wind. The collected ash is generally placed in sealed metal containers or mixed into media such as cement, asphalt and glass. Incineration method due to the control of radioactive contamination surface requirements are very high, the cost is very large, the practical application of certain restrictions.
Burial The principles for selecting a burial site are: the impact on the environment is within the permissible range; can be regularly monitored; the area must not be productive activities; buried in the trench or groove can be covered with soil or concrete, etc.. Geological conditions of the site must meet:
① no surface water at the burial site;
② groundwater at the burial site does not lead to surface water
; ③ pre-measured radioactivity in the soil for hundreds of years of retention time, its hydrological system is simple and has a reliable predetermined retention period; ④ the burial site should be a few meters above the highest groundwater level.
In some countries, natural salt beds are considered to be more suitable as repositories for such wastes. The reason is that the salt layer of good hygroscopicity, less corrosive to the container, easy to excavate, time, it is possible to form a sealed whole, more secure for long-term storage. German Federal **** and the country is an abandoned Arthur salt mine for testing, the U.S. National Oak Ridge Laboratory (ORNL) proposed an ideal model of salt cavern repository.
Ocean Disposal Offshore countries use ocean disposal by drumming waste into deep water and off the continental shelf. Containers are required to have sufficient sinking weight to withstand impacts on the seafloor, resist high pressure in deep water, and prevent corrosion and reduce the amount of radioactive leaching. It has been practically recognized that disposal areas must be located away from coasts, tidally active areas and aquaculture farms. This method poses a potential hazard to the high seas and is internationally controversial.
Disposal of solid waste from radioactive waste streams The solidification of radioactive waste streams is converted into radioactive solid waste, which some countries prefer to dispose of by burying them, believing that this ensures safety. Depending on the self-generated heat of the contained radioactivity, low-level waste can be buried directly in a trench. Intermediate levels are buried in vertical concrete or steel pipes in the ground. High-level solid waste can generate up to 430 kcal/hour or more per cubic meter, and must be buried using a multiple barrier system: the first barrier is to transform the waste into an inert, insoluble solidified body, the second barrier is to place the solidified body in stable, impermeable containers; and the third barrier is to choose to be buried in favorable geological conditions.
Final Disposal The fundamental issue in radioactive solid waste management is final disposal. Currently being explored methods of final disposal of high-level radioactive waste include: placing important radionuclides such as cesium, strontium, krypton and iodine in reactors to irradiate them and convert them into short-lived nuclides that decay as quickly as possible, or into stable nuclides; using long-distance rockets to transport radioactive materials into space beyond the Earth's gravitational pull; or placing them on Antarctic ice and utilizing their heat release to dissolve the ice to form a well cavern and seal the waste. A well cavern to confine the waste. These ideas, involving international treaties and technical and economic difficulties, are difficult to realize in the near future.
Recycling of radioactive solid waste For uranium ore and waste slag, mainly to improve the recovery rate of uranium, radium and other resources and recycling of chemicals used in the refining process. As for a large number of fission products and the recovery of some transuranic elements must first separate them from the leachate of waste liquids or ashes, and then according to the nature and abundance of nuclides separately or uniformly purified, as a source of energy irradiation or other sources of heat, light, etc. to use, but also to consider the high level of radioactive solid wastes made of solid radiation sources for industry, agriculture and health.