New Threat to Ocean-Cooled Datacenters: Jellyfish

Anyone involved in datacenters is concerned about disaster recovery, but only once in a while.

Disaster-recovery technology doesn’t change as quickly as in other datacenter disciplines, largely on purpose. Who wants to have to evacuate a flooding datacenter, fleeing to a hot site with rescued tapes filled with transaction data, only to find the shiny new systems won’t run the backups quite as effectively as they did nine months and two firmware revs ago?

It is a good idea to keep up on the latest weather or disaster news, but only in season. October in North Carolina? Hurricane watch. August in Colorado? Fire news. Nome in April? Bear reports. Any time at all in California? Keep an eye out for news on earthquakes, windstorms, wildfires, tsunamis, mudslides, avalanches and deadly fronts of witheringly envious scorn raining down from Washington and Oregon. (If you work in datacenters in Washington or Oregon, keep an eye out for mobs of WTO protesters and close the damn windows, it’s raining.)

Just in time for the start of major winter disaster season in the U.S., however, comes news of a new seaborne disaster threat to make life even more interesting for datacenter- and disaster-recovery managers with facilities anywhere near an ocean.

One of the largest nuclear-power plants in the world was forced to shut down temporarily Sept. 29, after pipes that bring Baltic Sea water in to cool the plant’s turbines became clogged with tons of jellyfish.

The sudden influx of common moon jellyfish overwhelmed the screens and filters that keep flotsam and most sea life out of the Oskarshamn nuclear plant in southeastern Sweden. The plant was forced to shut down its No. 3 reactor – the largest boiling-water reactor in the world, which generates 1,400 megawatts of electricity when it is jellyfish-free and running at full power.

The reactor stayed down until earlier today, Oct. 1, after the jellyfish had been cleared out and engineers approved the cooling system as invertebrate-free.

It’s not easy to overwhelm the cooling system for a nuclear power plant, but Oskarshamn’s is unusually resilient. There is a separate intake- and cooling system for each reactor, all of which were designed for the brackish, polluted water in that area of the Baltic Sea, according to a report from the Nickel Institute, a trade organization for companies that mine and smelt nickel commercially. (PDF)

The pollution and high chloride content of the water is corrosive even to the rubber-coated carbon steel pipes of the intake system. Crustaceans do get into the pipes to nest, especially during July and August, but the plant has limited the incursions with pesticides and by installing a high-pressure water strainer with holes .12 inch in diameter behind the intake pumps to filter out crustaceans (or anything else that wants to come visit).

The three boiling-water reactors at Oskarshamn are the same basic type as those at Japan’s Fukushima Daiichi plan, which failed catastrophically in 2011 after a tsunami broke its walls and flooded the plant.

Unfortunately, aside from occasional population surveys, there are few efforts to track jellyfish populations in real time anywhere in the world’s oceans, and none at all on the Baltic Sea, Moller said.

It’s not common for nuclear power plants to be shut down by “jellyfish blooms,” but it does happen, especially in marine environments that are overfished, have low oxygen content, algae blooms or other phenomena that threaten most marine life but welcome jellyfish, according to Lene Moller, of the Swedish Institute for the Marine Environment, who was quoted in the Oskarshamn announcement. “The fish leave and (the moon jelly) can really take over the ecosystem,” she said.

In 2012 California’s Diablo Canyon nuclear power plant had to shut down after gobs of gelatinous, jellyfish-like sea salp clogged intake pipes. Oskarshamn had a similar but less serious incident in 2005.

There’s no solid evidence that jellyfish populations are growing as oceans warm due to global climate change, according to Rob Condon, marine scientist at the Dauphin Island Sea Lab in Alabama, as quoted in a National Science Foundation article Jan. 24. Indeed, a study published in the Proceedings of the National Academy of Sciences in 2012 showed populations of jellies wax and wane over time.

A cyclical rise in jellyfish populations, angst over environmental changes and unexpected swarms of jellies has fueled the perception that jellyfish blooms contribute to the perception that the jellies are taking over, Condon said. During the past two years, waves of box jellyfish have swarmed near Hawaii, where the species had rarely appeared in such numbers. Off the coast of France, sudden jellyfish blooms have sunk the nets of French seiners; in Japan, blooms have shut down power plants.

Other blooms have been reported in the Black Sea, Gulf of Mexico, Yellow Sea and Japan Sea – where “refrigerator-sized gelatinous monsters called Nomuras, weighing 485lb (220 kg) and measuring 6.5ft (2m) in diameter, have swarmed the Japan Sea annually since 2002, clogging fishing nets, overturning trawlers and devastating coastal livelihoods,” according to an April 2012 BBC.com story.

Most datacenters are too far inland to worry about jellyfish in their cooling water, though Green-IT-promoters Vertatique estimated that a 5,000-sq.-ft. datacenter would consume almost 9 million gallons of water for cooling.

Ocean-side datacenters that use sea water for cooling are just as susceptible to jellyfish attacks as nuclear power plants, however.

Google’s data center in Hamina, Finland was built in an old paper mill on the Baltic Sea. It uses raw sea water piped through tunnels bored for the paper mill to cool its servers. Internexion, a colocation company based in the Netherlands, also uses Baltic Sea water to cool its datacenter near Stockholm, though “jellyfish are an occasional hazard” there as well, according to a May 16 IDG News Service story. Seawater-coolant systems for datacenters more common in European datacenters than in the U.S., according to a June 12 Datacenter Journal article.

Cornell Univ. uses water from Lake Cayuga in upstate New York for cooling, but the jellyfish problem there is considered trivial by comparison with the Baltic.

Image: Wikimedia Commons/ André Karwath aka Aka

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