Containment Buildings
A containment building is typically a reinforced steel, concrete, or lead structure that forms an airtight seal around a nuclear reactor. Its primary purpose is to prevent the escape of radioactive material during emergencies.
Preventing radioactive release: The containment building serves as the final barrier to prevent the release of radioactive materials from a nuclear reactor. Other barriers including the ceramic fuel pellets, the metal fuel cladding tubes, and the reactor vessel.
Shielding: The thick shell of the containment building also acts as a barrier to radiation, specifically gamma radiation. This reduces the radiation dose received by employees on the site, and to members of the public close to the site.
Protection: A further purpose of the reactor containment building is protecting the reactor itself from external threats. These include natural events such storms, earthquakes, or flooding and human-induced events such as terror attacks. To achieve this, the containment structure must be strong enough to withstand the impact of a fully loaded passenger airliner without rupture.
Fuel Handling and Storage
Fuel handling and storage activities are generally broken down into two separate categories:
Fresh Fuel Handling: Fresh fuel assemblies are received at the power plant. They undergo thorough inspection to ensure their quality and integrity. Once inspected, the fresh fuel is transferred into storage before being moved into the reactor core for use.
Irradiated Fuel Handling: When fuel assemblies are used up (typically after several years), they are removed from the reactor. The irradiated fuel is temporarily stored in a spent fuel pool where they are cooled down and shielded. Eventually, the fuel may be transferred to a dry cask for long-term storage.
To complete the different fuel movements, the following facilities and equipment are needed:
- Fuel Handling Machines: These machines handle fuel assemblies during loading and unloading.
- Fuel Transfer Systems: Used for moving fuel assemblies between the reactor core and storage areas.
- Spent Fuel Pools: Large pools with water to cool and store the highly radioactive irradiated fuel.
- Dry Cask Storage: Robust containers for long-term storage.
- Fuel Inspection Areas: Where fresh fuel is inspected before use.
- Fuel Loading/Unloading Areas: Where fuel assemblies are loaded into or removed from the reactor core.
Turbine Hall
The turbine hall is where electricity is generated from the heat produced by nuclear reactors. It houses the turbines, generators, and associated equipment necessary for converting steam energy into electrical power.
Components and Functions: The high-pressure turbine receives high-temperature, high-pressure steam from the reactor through steam pipes. Typically, there are two low-pressure turbines after the high-pressure turbine. They operate at lower pressures and temperatures. A turbine hall will usually contain multiple sets of turbines and generators.
Challenges in Boiling Water Reactors (BWRs): In BWRs, the steam passing through the turbines is radioactive due to its contact with the reactor core. As a result, the turbine hall must be slightly contained, and special maintenance procedures are necessary.
Cooling Towers / Intake & Outfall
Nuclear power stations require large amounts of cooling to turn steam back to water after it has been used to spin a turbine generator. This is usually done in one of two ways.
Cooling Towers: Water is pumped from a nearby source, typically a river, into the cooling tower basin. This water circulates through the plant’s condenser tubes, where it absorbs heat from the steam that has exited the turbine. The heated water then returns to the cooling tower where it is sprayed through the hollow core onto a grid in the centre. Cool air flows up from the hollow centre, causing some of the water to evaporate, taking the excess heat with it.
Intake & Outfall: Some power stations, typically ones located close to very large bodies of water, will suck up water and use it to extract heat from steam via a heat exchanger. Then, the heated water is simply released back into the source. This is usually done using pipelines or tunnels.
Is the water radioactive? In both cases, the cooling water which is released does not come into direct contact with the water inside the reactor, and is therefore not radioactive.
Auxiliary Buildings
The auxiliary building is often located adjacent to the reactor containment structure. It houses most of the auxiliary and safety systems associated with the reactor.
Key systems:
- Radioactive Waste Systems: These manage and process radioactive waste generated during reactor operation.
- Chemical and Volume Control Systems: These systems maintain water chemistry and control coolant volume.
- Emergency Cooling Water Systems: These provide cooling during emergency situations.
The auxiliary building also protects safety-related equipment against the consequences of internal and external events. Of particular importance is protection against earthquakes.
Administration
Administrative buildings can house a wide variety of different facilities.
Office Space: Offices where plant personnel, including managers, engineers, and administrative staff, work. These offices are essential for coordinating operations, maintenance, and safety.
Control Rooms: Control rooms where operators monitor and manage reactor systems, safety protocols, and emergency responses.
Meeting Rooms: Meeting spaces for discussions, briefings, and planning sessions.
Training Facilities: Training rooms where staff receive ongoing training related to nuclear safety, emergency procedures, and plant operations.
Documentation and Records: Areas to store important documents, records, and manuals related to plant operations, safety guidelines, and regulatory compliance.
Security
Security facilities safeguard against potential threats and ensuring the safe operation of the plant.
Physical Barriers and Robust Structures: Nuclear power plants are inherently secure and robust structures. They are designed to withstand natural disasters such as hurricanes, tornadoes, and earthquakes. The combination of these robust structures, well-armed professional security forces, and strict access controls creates multiple layers of safety and security.
Security Measures:
- Trained security personnel are stationed at nuclear power plants to prevent unauthorised access and respond to any security incidents.
- Intrusion Detection Systems monitor the plant perimeter and critical areas, alerting security personnel to any unauthorised entry.
- Area Surveillance Systems provide continuous monitoring of key locations within the plant.
- Strict access controls regulate entry into the plant, ensuring that only authorised personnel are allowed.
- Employees working inside the plant undergo thorough background checks and authorisation processes.
Emergency Preparedness: Security facilities play a crucial role during emergencies. They serve as coordination centres for responding to threats or incidents. Effective security measures are essential to prevent theft, sabotage, or unauthorised access to nuclear material and associated facilities.
Ove Schoeppner
Containment Building – Kindly provided by our partners at Energy Encyclopedia
Fuel Handling – IAEA Imagebank – Creative Commons Attribution 2.0 Generic
Fuel Handling Background – Nuclear Regulatory Commission – Creative Commons Attribution 2.0 Generic
Steam Turbine – US Department of Energy – Public Domain
Turbine Hall Background – ENERGY.GOV – Public Domain
Auxiliary Buildings Background – U.S. Department of Energy – Public Domain
