Nuclear wastewater refers to wastewater containing radioactive substances produced during nuclear energy utilization. These radioactive substances mainly include tritium, uranium, plutonium, thorium, and radium. Nuclear wastewater primarily originates from nuclear power plants, nuclear weapons manufacturing, nuclear medicine research, and radioactive material production. Based on its radiation level and source, nuclear wastewater can be categorized into high-level radioactive wastewater and low-level radioactive wastewater.
1. Nuclear Power Plant Operations
- Reactor Cooling Water: Used to cool nuclear fuel, which may contain radioactive substances after contact with the fuel.
- Spent Fuel Reprocessing: Water used to extract recoverable nuclear fuel results in high-level radioactive liquid waste.
- Equipment Cleaning Water: Generated from maintenance and cleaning of nuclear plant equipment, often containing low-concentration radioactive substances.
- Condensate Discharge: Water condensed from the steam circulation system may carry small amounts of radioactive substances.
2. Nuclear Accident Leaks
- Large amounts of nuclear wastewater were produced during disasters like the Chernobyl and Fukushima nuclear accidents, requiring long-term storage and treatment.
3. Nuclear Fuel Cycle
- Uranium Mining: The extraction of uranium ore generates wastewater containing radioactive elements.
- Fuel Processing: The chemical processes involved in manufacturing nuclear fuel can lead to water contamination.
- Spent Fuel Reprocessing: The recycling and treatment of spent nuclear fuel produce high-level radioactive liquid waste.
4. Nuclear Medicine and Research
- Medical Diagnosis and Treatment: Procedures such as PET-CT scans and cancer radiotherapy use radioactive isotopes, generating low-level radioactive wastewater.
- Nuclear Laboratory Research: Experiments involving radioactive materials may release or discharge nuclear wastewater.
1. Low-Level Radioactive Wastewater (LLW)
- Contains small amounts of radioactive isotopes (e.g., tritium, iodine-131, cesium-137).
- Mainly originates from routine operations of nuclear power plants, research institutions, and the medical industry.
2. High-Level Radioactive Wastewater (HLW)
- Primarily generated from spent fuel reprocessing and contains high concentrations of radioactive substances (e.g., strontium-90, cesium-137, plutonium-239).
- Exhibits extremely strong radioactivity and long half-lives, requiring rigorous treatment and long-term storage.
1. Environmental Pollution
- If improperly managed, radioactive substances in nuclear wastewater may infiltrate soil, groundwater, rivers, and oceans, leading to long-term contamination.
2. Biological Impact
- Radioactive elements such as strontium-90 and cesium-137 can be absorbed by marine life, entering the food chain and ultimately affecting human health.
3. Human Health Risks
- Long-term exposure to radioactive wastewater increases risks of cancer, genetic mutations, and immune system damage.
Nuclear wastewater cannot be discharged directly into the environment and must undergo physical, chemical, biological, and long-term storage treatments, including:
1. Precipitation and Filtration (Removal of Suspended Radioactive Particles)
- The chemical coagulation-precipitation method involves adding precipitants (such as iron salts, aluminum salts, soda, phosphates) to nuclear wastewater. These react with radioactive nuclides, forming insoluble precipitates, effectively reducing radioactive content and purifying the wastewater.
2. Ion Exchange (Removal of Radioactive Ions)
- This method uses ion exchange resins to swap radioactive cations or anions with non-radioactive ions, significantly reducing the concentration of radioactive substances, ensuring the treated wastewater meets discharge standards.
3. Evaporation and Concentration (Reducing Wastewater Volume)
- Evaporation heating separates water from radioactive materials, allowing the condensed steam to be safely discharged, while the concentrated radioactive waste undergoes solidification for further treatment.
4. Biotechnology Treatment
- Microorganisms and plants can remove radioactive nuclides through absorption, accumulation, precipitation, and expansion mechanisms, reducing radioactive content to meet discharge standards.
