Category Archives: Passive Safety Systems and Natural Circulation in Water Cooled Nuclear Power Plants

Effects of non-condensable gases on condensation heat transfer

Condensation occurs when the temperature of vapor is reduced below its saturation temperature. Presence of even a small amount of Non-condensable gas (e. g. air, N2, H2, He, etc.) in the condensing vapor leads to a significant reduction in heat transfer during condensation. The buildup of non­condensable gases near the condensate film inhibits the diffusion of vapor from the bulk […]

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Condensation on containment structures

This phenomenon involves heat and mass transfer from the containment atmosphere towards the surrounding structures. This phenomenon would occur in existing reactors in case of a coolant release into the containment. It also occurs in advanced designs where containment surfaces are cooled externally, usually by natural mechanisms. Good examples are the designs of the AP series by Westinghouse, where the […]

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Description of passive reactor cooling system and passive containment cooling system

One of the new features of the ABWR-II safety design is the adoption of passive safety systems. The passive heat removal system (PHRS) consists of two dedicated systems, namely the passive reactor cooling system (PRCS: the same as Isolation condenser) and the passive containment cooling system (PCCS), that use a common heat sink pool above the containment allowing a one-day […]

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Passive residual heat removal heat exchangers (single-phase liquid)

Passive residual heat removal (PRHR) heat exchangers are incorporated into several advanced PWR designs. Their primary function is to provide extended periods of core decay heat removal by transferring heat using a single-phase liquid natural circulation loop as shown in Figure 6. The PRHR heat exchanger loop is normally pressurized and ready for service. Single-phase liquid flow is actuated by […]

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Behaviour of containment emergency systems

Nuclear power reactor containments are equipped with safety systems which protect the containment integrity under various accident conditions. The focus of this phenomenon is the natural circulation cooling and heat transfer in various containment passive cooling systems under accident conditions to remove the energy out of the containment by natural circulation and condensation heat transfer. Typical systems are the tube […]

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