Japan’s nuclear watchdog is proposing raising the risk level of a radioactive water leak at the crippled Fukushima nuclear power plant from “an anomaly” to a “serious incident”.
The operator said about 300 tons of contaminated water has leaked from of the steel tanks around the wrecked Fukushima Dai-ichi plant. Tokyo Electric Power suspects it leaked through a faulty seam.
Officials now fear that this could be the beginning an even bigger disaster. Four other tanks of the same design have leaked and around 350 of the 1,000 steel tanks containing nearly 300,000 tons of contaminated water are less-durable and have only rubber seams.
“That’s what we fear the most. We must remain alert. We should assume that what has happened once could happen again, and prepare for more,” watchdog chairman Shunichi Tanaka said. “We are in a situation where there is no time to waste.”
The watchdog proposes to raise the rating of the leak to level three from an earlier level one on an International Nuclear and Radiological event scale of eight. However it plans to consult the UN nuclear agency over whether it is appropriate to use the evaluation scale on the already wrecked Fukushima plant.
The watchdog has urged TEPCO to step up monitoring.
Officials also revealed that plant workers apparently have overlooked several signs of leaks, suggesting that their twice-daily patrols were largely just a walk. They have not monitored water levels inside tanks, obviously missed a puddle forming at the bottom of the tank earlier, and kept open a valve on an anti-leakage barrier around the tanks.
TEPCO initially said the leaked water is believed to have mostly seeped into the ground after escaping from the barrier around the tank. It initially said the leak did not pose an immediate threat because it is 500 yards from the coastline but high radioactivity has now been found in a gutter extending to the ocean.
The company also said the tank may have been leaking slowly for weeks. That could create extensive soil contamination and a blow to plans to release untainted underground water into the sea.
Contaminated water is already entering the Pacific Ocean at a rate of hundreds of tons per day.
The plant suffered multiple meltdowns following a massive earthquake and tsunami in March 2011 – rated at level seven “major accident,” the highest on the INES rating and the worst since Chernobyl in 1986.