Why Japan Is Releasing Fukushima Water Into the Sea

Japanese utility Tepco has started to release about 1.3 million cubic meters (343 million gallons) of treated radioactive water — enough to fill about 500 Olympic-size swimming pools — from the wrecked Fukushima Dai-Ichi nuclear power plant into the Pacific Ocean, part of its nearly $150 billion effort to clean up the worst atomic accident since Chernobyl. The decision was made because storage tanks at the site were forecast to be full as early as 2024, and space for building more is scarce. Scary as it sounds, discharges are common practice in the industry, and the plan has been ruled to be in line with global guidelines. That hasn’t assuaged angry locals or neighboring China and South Korea.

A 2011 earthquake, the strongest ever recorded in Japan, and ensuing tsunami caused structural damage to Fukushima’s reactor buildings, about 220 kilometers (137 miles) north of Tokyo. While Tepco cycles in water to keep fuel and debris cool, roughly 130 cubic meters of water becomes contaminated daily, including groundwater and rain. The tainted water is pumped out and run through something called the Advanced Liquid Processing System, or ALPS, then stored in one of roughly 1,000 tanks at the site. The processing removes most of the radioactive elements except for tritium.