Cooling systems in nuclear power plants must support more than ordinary temperature control. Electrical buildings, control rooms, cable areas, and other critical spaces rely on stable thermal conditions to protect sensitive equipment and maintain suitable operating environments. When cooling equipment is selected for these applications, engineers must consider low-temperature operation, load variation, corrosion resistance, seismic requirements, and long-term maintenance.

Air-cooled chiller and heat pump equipment can be a practical option for projects where heat rejection through an air-cooled condenser fits the site design. However, nuclear power applications place demanding requirements on equipment design and verification. The selection process should therefore begin with the function of the cooling system and the conditions it must withstand throughout its service life.

1. Start with the Cooling Requirements of Critical Areas

Different areas within a nuclear power plant have different cooling priorities. The main control room, electrical engineering building, and cable layer may all require chilled water, but their operating conditions and consequences of cooling interruption are not identical.

For example, the control room HVAC system must maintain suitable environmental conditions for operators and relevant electronic equipment. Electrical rooms need temperature control to help prevent excessive heat from affecting equipment performance. Cable areas also require appropriate ventilation and cooling to limit the thermal stress that can accelerate insulation aging.

Before selecting a chiller, project teams should establish the required cooling capacity, chilled-water temperatures, flow rates, operating schedule, and allowable temperature fluctuations. The design should also identify which loads must remain supported under specified abnormal or emergency conditions.

This assessment helps determine whether a single unit, multiple units, or a dual-system configuration is appropriate. Capacity alone is not enough; the cooling arrangement must match the plant's operating philosophy and reliability requirements.

2. Evaluate Low-Ambient-Temperature Performance

Air-cooled equipment rejects heat directly to the outdoor environment, so ambient temperature has a significant influence on condenser pressure and overall operating conditions. In cold climates, low outdoor temperatures can create challenges during startup and operation, particularly when the refrigeration circuit requires sufficient condensing pressure to function correctly.

For nuclear power projects, engineers should check the manufacturer's stated operating envelope rather than relying on a general low-temperature rating. Relevant details include the minimum permitted ambient temperature, startup conditions, control strategy, and protective functions.

The Dunham-Bush nuclear power air-cooled heat pump unit uses condenser-area adjustment and variable-frequency fan control to manage operating pressure under low-ambient conditions. According to the product information, the design addresses startup and operation at ambient temperatures as low as -15°C.

This feature is relevant to sites exposed to winter temperature swings. During technical evaluation, however, project teams should confirm the specified performance against the actual site design conditions, required chilled-water output, and approved operating procedures.

3. Match Compressor Control to Changing Loads

Cooling demand in an electrical building is not necessarily constant throughout the year. Outdoor conditions, equipment operating schedules, ventilation requirements, and the number of active systems can all affect the load placed on a chiller.

A unit that cannot respond appropriately to changing demand may cycle too frequently or operate inefficiently at partial load. Repeated starts and stops can also place additional demands on components and controls.

The Dunham-Bush DEL air-cooled unit is described as using a vertical, fully enclosed screw compressor with stepless capacity regulation. Its dual-compressor, dual-system configuration and hot-gas bypass technology are intended to support a broad operating range, with the supplied product information specifying load regulation from 15% to 100%.

For engineers, the important question is how the equipment performs across the project's actual load profile. Review the minimum stable operating load, control accuracy, compressor staging, restart logic, and response to rapid changes in demand. These details help determine whether the unit can maintain stable chilled-water conditions without unnecessary cycling.

Energy efficiency should also be assessed at representative operating points rather than through a single rated value. Part-load performance, annual operating hours, and the local climate can all influence lifecycle energy consumption.

4. Consider Corrosion Protection and Service Life

Nuclear power plant equipment may need to remain in service for decades, making material selection and environmental protection important parts of the procurement process. Corrosion can affect heat-transfer surfaces, structural components, electrical connections, and protective coatings, particularly in coastal or otherwise corrosive environments.

When reviewing air-cooled refrigeration equipment, engineers should examine the materials used in the condenser and evaporator, the corrosion protection applied to exposed surfaces, and the maintenance requirements for those components. Coating performance should be supported by documented test results and acceptance criteria relevant to the project.

The Dunham-Bush DEL unit's published product information identifies tin-plated copper condenser fins, thick-walled evaporator heat-exchange tubes, and specialized protective coating processes among its design features. The supplier also reports a 2,000-hour salt-spray test for its specified coating process.

Such information provides a starting point for technical review. Buyers should request the relevant test reports, clarify which components and coating systems were tested, and confirm that the results correspond to the equipment configuration being offered. A test duration should not be treated as a direct prediction of service life in the field.

5. Review Nuclear Project Qualification Requirements

Equipment intended for nuclear power applications requires a more detailed qualification process than ordinary commercial HVAC equipment. The applicable requirements depend on the equipment's assigned function, installation location, safety classification, and project-specific design basis.

Procurement teams should establish the required seismic qualification, environmental qualification, material traceability, inspection records, and testing documentation before finalizing the technical specification. If radiation exposure is relevant to the installation location, the required dose level and the suitability of materials should also be reviewed.

The DEL air-cooled unit's product information describes seismic analysis, radiation-resistant material selection, and verification testing as part of its design approach. These claims should be assessed through project-specific documentation, including the applicable calculation reports, test evidence, qualification scope, and acceptance criteria.

A supplier's general statement that a product meets nuclear-grade requirements does not replace the project's formal qualification and approval process. Engineers should verify that the offered model, configuration, and installation arrangement meet the requirements established by the plant owner and relevant authorities.

6. Check System Integration and Maintenance Access

Even a well-designed chiller can become difficult to operate if it is poorly integrated into the wider chilled-water system. The equipment review should cover chilled-water pumps, valves, piping arrangements, control interfaces, alarms, and connections to the plant's building management or monitoring systems.

Maintenance access is equally important. Engineers should check whether compressors, fans, electrical panels, heat exchangers, and service points can be inspected safely without creating unnecessary disruption to nearby equipment. The maintenance plan should identify routine inspections, cleaning requirements, spare parts, and the procedures used to return the unit to service after maintenance.

For critical applications, the overall system arrangement also deserves attention. Redundancy, standby capacity, isolation capability, and recovery procedures should be considered at the system level rather than assumed from the design of an individual chiller.

These checks help reduce operational difficulties after commissioning and make it easier for plant teams to maintain consistent cooling performance over time.

7. Consider Equipment with Relevant Nuclear Power Experience

Experience in comparable projects can help buyers assess whether a supplier understands the documentation, manufacturing controls, and coordination demands associated with nuclear power work. Reference projects should be reviewed for similarities in application, equipment configuration, environmental conditions, and qualification requirements.

Dunham-Bush identifies applications of its DEL air-cooled units in Unit 3 of the Ningde, Yangjiang, and Hongyanhe nuclear power plant projects. These references may provide a basis for further supplier evaluation. Project teams should request confirmation of the supplied scope, operating history where available, and the relevance of each reference to the new project.

For more information about the equipment's configuration and stated design features, see the Dunham-Bush Nuclear Power Air-Cooled Heat Pump Units product page.

Selecting air-cooled refrigeration equipment for a nuclear power plant requires a coordinated review of cooling demand, low-temperature performance, compressor control, corrosion protection, qualification evidence, and long-term maintenance. Each factor affects the suitability of the equipment for its intended operating environment.

The Dunham-Bush DEL air-cooled unit incorporates design features aimed at addressing these requirements, including low-ambient-temperature control, stepless capacity regulation, corrosion-resistant materials, and nuclear-project-oriented verification. The final selection should still be based on the plant's technical specification, documented qualification evidence, and review by the responsible engineering and procurement teams.

A careful evaluation at the procurement stage helps ensure that the selected cooling equipment fits the system design and supports dependable operation throughout the planned service period.

www.great-hvac.com
​China HVAC Refrigeration