How Jellyfish Disrupt Nuclear Power Plants

Context: Since the 1990s, several nuclear power plants worldwide have faced shutdowns after jellyfish clogged their cooling systems. In recent years, the frequency of such disruptions has grown, driven by climate change and marine pollution that have led to a surge in jellyfish populations.

What are Jellyfish?

• Nature: Jellyfish are soft-bodied, spineless marine animals belonging to the phylum Cnidaria.
• Structure: They have a gelatinous umbrella-shaped bell and trailing tentacles armed with stinging cells (cnidocytes) used for capturing prey.
• Reproduction: They reproduce both sexually and asexually. Under favourable conditions (like warm water and abundant plankton), their populations can rapidly increase, forming blooms (large swarms).
• Adaptability: Unlike many marine animals, jellyfish can survive in low-oxygen and polluted waters, which gives them an edge in degraded ecosystems.

How Jellyfish Disrupt Nuclear Power Plants

• Cooling Water Requirement: Nuclear power plants need a constant flow of water from nearby seas, rivers, or lakes to cool reactors, turbines, and condensers.
  • Intake pipes draw millions of gallons of water per minute, passing through screening areas designed to block debris and marine life.
• Jellyfish Swarm Problem: When a massive bloom occurs near coastal nuclear plants, millions of jellyfish get sucked into the intake pipes.
  • They clog the screens within minutes, blocking water flow.
• Consequences of Blockage: Reduced cooling water supply raises the risk of overheating.
  • Critical components like turbines, condensers, and boilers may get damaged.
  • To avoid accidents, reactors are forced to shut down temporarily.
• Dead Jellyfish Issue: Dead jellyfish often turn into a gelatinous mass that can slip past screens and cause problems deeper inside the cooling system.
• Operational Challenges: Clearing clogged intake pipes is complex and dangerous.
  • Workers may face stings while removing jellyfish.
  • In some cases, cleaning can take up to two days, leading to significant power loss and financial impact.

Why Incidents Are Rising

• Climate Change: Warmer waters increase plankton (jellyfish food) and extend breeding seasons.
• Overfishing: Fewer predators (like tuna and turtles) allow jellyfish populations to surge.
• Plastic Pollution: Plastic debris provides surfaces for jellyfish to breed, pushing them closer to coastlines and nuclear plants.
• Pollution Tolerance: Jellyfish can thrive in low-oxygen, degraded marine environments where other species struggle.

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