In high-vacuum applications like these, vacuum systems that combine turbomolecular pumps with cryogenic pumps are commonly used. The turbomolecular pump works by transferring momentum to gas molecules via a高速ly rotating rotor, enabling highly efficient pumping even at extremely low pressures—allowing the centrifuge's internal pressure to be rapidly reduced to remarkably low levels. Meanwhile, the cryogenic pump captures gas molecules through condensation on its低温 surface, further driving down system pressure. For instance, a uranium enrichment plant employs a vacuum system capable of maintaining the centrifuge’s internal pressure consistently between 10⁻⁵ Pa and 10⁻⁶ Pa. In this ultra-high vacuum environment, the efficiency of uranium isotope separation is significantly enhanced, producing enriched uranium products with purity levels exceeding 90%, thus meeting the stringent nuclear fuel requirements of power plants. Moreover, during the post-processing of nuclear fuel, extracting valuable nuclear materials from spent fuel also necessitates operations conducted under vacuum conditions. This prevents radioactive substances from coming into contact with air and spreading, ensuring both the safety of operators and the protection of the surrounding environment.

Maintaining a specific vacuum environment during nuclear reactor operation is one of the key factors ensuring the normal fission reaction of nuclear fuel. Take a pressurized water reactor (PWR) power plant as an example—vacuum levels on the secondary side of the steam generator significantly influence the entire energy conversion process. In practice, when the vacuum is maintained between -0.08 MPa and -0.09 MPa, steam generation efficiency can improve by approximately 15% to 20% compared to atmospheric pressure conditions. This is because, at a certain vacuum level, the boiling point of water decreases, allowing it to more efficiently absorb heat transferred from the primary side and convert it into steam—thereby enhancing overall energy conversion efficiency.

To stably maintain this vacuum range, a typical setup involves an oil-sealed mechanical vacuum pump paired with a Roots vacuum pump. The oil-sealed mechanical pump serves as the forepump, initially reducing the system pressure from atmospheric levels to a lower baseline—creating optimal conditions for the subsequent Roots vacuum pump to operate efficiently. The Roots pump, known for its rapid pumping speed and ability to function across a wide pressure range, quickly evacuates non-condensable gases such as air and hydrogen from the secondary side of the steam generator. For instance, during operation at a large pressurized water reactor nuclear power plant, a sudden failure in the vacuum unit caused the secondary-side vacuum level of the steam generator to drop sharply to -0.05 MPa. This led to a significant reduction in steam production, resulting in lower turbine power output and an overall decline in the plant’s electricity generation by approximately 30%. Such an incident clearly underscores the critical role of the vacuum unit in maintaining a stable vacuum environment within the steam generator during reactor operations—a factor essential for ensuring the safe and efficient functioning of the entire nuclear power plant.

4.2 Nuclear Fuel Handling Conditions

Key processing steps for nuclear fuel—such as enrichment and purification—must be carried out under vacuum conditions to ensure both the quality and safety of the fuel. In the uranium enrichment stage, the widely used centrifugal method relies on highly sophisticated, vacuum-sealed centrifuges to achieve separation. Given that uranium isotopes require an extremely controlled environment for separation, even a slight trace of air can lead to uranium oxidation, compromising the enrichment process and ultimately affecting the quality of the nuclear fuel.

In high-vacuum applications like these, vacuum systems that combine turbomolecular pumps with cryogenic pumps are commonly used. The turbomolecular pump works by imparting momentum to gas molecules via a高速ly rotating rotor, enabling highly efficient pumping even at extremely low pressures—allowing the centrifuge's internal pressure to be rapidly reduced to remarkably low levels. Meanwhile, the cryogenic pump captures gas molecules through condensation on its低温 surface, further driving down system pressure. For instance, a uranium enrichment plant employs a vacuum system capable of maintaining the centrifuge’s internal pressure consistently between 10⁻⁵ Pa and 10⁻⁶ Pa. In this ultra-high vacuum environment, the efficiency of uranium isotope separation is significantly enhanced, producing enriched uranium products with purity levels exceeding 90%, thus meeting the stringent nuclear fuel requirements of power plants. Moreover, during the post-processing of nuclear fuel, extracting valuable nuclear materials from spent fuel also necessitates operations conducted under vacuum conditions. This prevents radioactive substances from coming into contact with air and spreading, ensuring both the safety of operators and the protection of the surrounding environment.

4.3 Nuclear Facility Maintenance and Overhaul Conditions

During the maintenance and inspection of nuclear facilities, vacuum pumps play an indispensable role. By evacuating the inside of equipment, these pumps not only make it easier for personnel to access the system for inspections and repairs but also effectively prevent air from entering, thereby mitigating potential safety risks. For instance, during routine maintenance of a nuclear reactor pressure vessel, a vacuum pump is first used to reduce the internal pressure to near-vacuum levels—typically requiring a vacuum degree below 10⁻³ Pa.
At this point, rotary vane vacuum pumps are often the preferred choice. These pumps boast a simple design and convenient operation, enabling rapid evacuation of pressure within containers to the desired range. This process not only prevents air from entering and reacting with residual radioactive materials, potentially generating hazardous gases, but also allows personnel to more clearly inspect the internal structure of equipment under low-pressure conditions—enabling them to spot hidden cracks, wear, or other issues in time. For instance, during a recent pressure vessel maintenance at a nuclear power plant, a tiny crack was discovered after applying a vacuum, prompting immediate repairs and averting what could have been a serious safety incident. Similarly, when maintaining certain radioactive waste-handling equipment, creating a vacuum environment effectively minimizes the risk of radioactive dust and aerosols spreading into the surrounding area, ensuring both the safety of maintenance staff and the protection of the broader environment.