Wastewater from nuclear power plants contains radiation.
Wastewater discharged from nuclear power plants is mainly divided into two types. One is cooling water, which is very large and has the same function as the cooling tower water of ordinary thermal power plants. power plants, but is used for cooling. Those used do not come into contact with radioactive materials, so radioactive materials from the nuclear power plant have not been removed. The other concerns wastewater, which is in very small quantities. According to national regulations, this wastewater must undergo special treatment to bring its radioactivity level below a certain limit, so that it does not affect the environment.
The natural environment itself is also radioactive. If the radioactivity of the effluent is equivalent to the radioactivity of the natural environment, there is nowill have no impact. But even after treatment, wastewater from nuclear power plants can still contain radioactive materials.
The working principle of nuclear power plants
Burning water is basically energy conversion, and other energy is converted into energy thermal water. Nuclear power plants use nuclear energy to “boil water” and are carried out in reactors. This step is much more complicated than using boilers in thermal power plants to "boil water" because it involves nuclear fission reactions.
As we all know, thermal power plants use coal, oil or natural gas to generate electricity, hydroelectric power plants use hydropower to generate electricity, and power plants Nuclear power uses the fission energy of atomic nuclei to produce electricityelectricity. . At present, more than 60% of the world's nuclear power plants are pressurized water reactor nuclear power plants, which mainly consist of reactors, steam generators, turbines, generators and related system equipment .
What cooling methods are available for transformers?
Increased bearing temperature may be caused by lubricating oil or cooling water system failure
1. First check if it is a false alarm, check the oil level, cooling water volume, is the water temperature normal?
2. Is the unit charging normal?
3. Is the unit axis normal?
4. . Unit oscillation exceeds standard;
5. The gap between the rolling pads is unevenly adjusted.
Commonly used cooling methods for transformers arethe following:
1. Oil-immersed self-cooling (ONAN)
2. cooling (ONAF);
3. Forced Oil Circulating Water Cooling (OFWF); Forced Guided Oil Circulating Air Cooling (ODAF);
6. ODWF forced-guided oil circulation water cooling).
According to the requirements of the transformer selection guidelines, the selection of cooling methods is recommended as follows:
1. Oil-immersed self-cooling
31,500 kVA. and below, 35 kV products and below;
50,000 kVA and below, 110 kV products.
2. Oil-immersed air cooling
12,500 kVA ~ 63,000 kVA products, 35 kV ~ 110 kV;
Below 75,000 kVA, 110 kV products;
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40,000 kVA and less, 220 kV products.
3. Forced oil circulation air cooling
50,000 ~ 90,000 kVA, 220 kV products.
4. Circulating water coolingForced oil ulation
Generally used in booster transformers of 220 kV and above, 60 MVA and above in hydroelectric power stations.
5. Forced guided oil circulation air or water cooling (ODAF or ODWF)
75,000 kVA and above, 110 kV products
120,000 kVA and above, 220 products kV; ;
330kV and 500kV products.
When using powerful air and oil cooling method, when the oil pump and fan lose power supply, the transformer cannot work for a long time. It cannot work for a long time even if it is discharged. Therefore, two independent power supplies should be selected for the cooler.
When using the powerful oil-water cooling method, the oil pump cannot work when the cooling water loses power. The power supply must choose two power supplies independent.