Identify the flow type described by: consists of steam with some drops of entrained moistures, exists in PWRs only under abnormal conditions such as LOCA.

Identify the flow type described by: consists of steam with some drops of entrained moistures, exists in PWRs only under abnormal conditions such as LOCA.

• A. Mist Flow
• B. Slug Flow
• C. Subcooled Boiling
• D. Bubble Flow

Answer: (A)

In two‑phase flow, the regime where the gas phase dominates and a fine spray of liquid droplets is carried along is described as mist flow. This matches the situation in a PWR during abnormal events like LOCA, where boiling creates steam that carries small entrained moisture droplets but there isn’t a continuous liquid slug or a bulk liquid core. Slug flow would show large liquid slugs separated by gas pockets, which isn’t implied here. Bubble flow is vapor bubbles in a liquid, not steam with dispersed droplets in a mostly gas stream. Subcooled boiling involves boiling near heated walls in a largely liquid core, not a steam stream with entrained droplets. Therefore, the described flow is mist flow.

In two‑phase flow, the regime where the gas phase dominates and a fine spray of liquid droplets is carried along is described as mist flow. This matches the situation in a PWR during abnormal events like LOCA, where boiling creates steam that carries small entrained moisture droplets but there isn’t a continuous liquid slug or a bulk liquid core. Slug flow would show large liquid slugs separated by gas pockets, which isn’t implied here. Bubble flow is vapor bubbles in a liquid, not steam with dispersed droplets in a mostly gas stream. Subcooled boiling involves boiling near heated walls in a largely liquid core, not a steam stream with entrained droplets. Therefore, the described flow is mist flow.