Context: Recently, France’s Gravelines Nuclear Power Station (Europe’s largest) had to shut down four reactors after a massive swarm of jellyfish clogged its cooling system.
Relevance of the Topic: Prelims: How do Jellyfish disrupt Nuclear Plants; Jellyfish.
Similar incidents have been reported globally since the 1990s. In 2011 alone, jellyfish paralysed plants in Israel, Japan, and Scotland. Such incidents are now on the rise as climate change and marine pollution have increased the jellyfish population.
How do Jellyfish disrupt Nuclear Plants?
- Nuclear power plants require a continuous inflow of millions of gallons of water per minute to cool their reactors, turbines, and boilers.
- To ensure smooth functioning, the water intake pipes of these plants are fitted with screens that block solid waste and aquatic organisms from entering.
- The problem arises when a massive bloom of jellyfish (millions of individuals) is sucked into the intake system. Within minutes, these jellyfish clog the intake screens, cutting off the essential flow of cooling water.
- A sudden disruption in water flow creates a risk of overheating and potential reactor damage, forcing operators to shut down the reactors to avoid accidents.
- The situation worsens when dead jellyfish decompose into a gel-like substance, which can sometimes bypass the screens and reach deeper parts of the plant’s cooling system.
- Cleaning these clogged pipes is a time-consuming process that may take up to 48 hours, during which power generation remains suspended.
Why are such incidents rising?
- Climate Change: Rising ocean temperatures have boosted plankton growth, the main food of jellyfish, and extended their breeding season leading to population surges.
- Overfishing: Depletion of predators like tuna and turtles has removed natural checks on jellyfish, while reducing competition for plankton.
- Plastic Pollution: Jellyfish tolerate low-oxygen waters caused by pollution. Floating plastic waste often serves as a breeding surface, enabling jellyfish to reproduce close to coastlines and near power plant intake systems.
About Jellyfish
- Jellyfish are marine invertebrates. They are spineless, soft-bodied, and mostly transparent.
- About 95-98% of their body consists of water.
- Jellyfish have two main stages in life: the polyp (attached to surfaces) and the medusa (free-swimming).
- They are tolerant to low-oxygen environments and polluted waters which allows them to thrive where other species decline.
- Some jellyfish can glow in the dark due to bioluminescence.
- Some species are edible and used in Asian cuisine.
- Their numbers increase rapidly during “blooms”, often triggered by warm waters (climate change), abundant plankton, or low predation (due to overfishing) and marine pollution.
Ecological role:
- They feed on plankton, small fish, and other microscopic organisms.
- Serve as food for sea turtles, some fish, and other predators.
- Act as bioindicators of changes in marine ecosystems.
