Japan nuclear watchdog may raise leak to 'serious'

Japan's nuclear watchdog today said it is taking the leakage of highly radioactive water at the crippled Fukushima nuclear power plant seriously, and proposed raising the rating to describe it from "an anomaly" to a "serious incident."
The operator of the plant said about 300 tons of contaminated water has leaked from one of hundreds of steel tanks around the wrecked Fukushima Dai-ichi plant.
Tokyo Electric Power Co hasn't figured out how or where the water leaked, but suspects it did so through a seam on the tank.
The leak, the fifth since last year involving tanks of the same design, also raised concerns that this could be the beginning a new disaster, contaminated water leaking from storage tanks one after another.

"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 told a news conference. "We are in a situation where there is no time to waste."
The watchdog proposed at a weekly meeting today to raise the rating of the leak to level 3 from an earlier level 1 on an International Nuclear and Radiological event scale of eight.

The watchdog, however, plans to consult with the UN nuclear regulatory agency over whether it is appropriate to use the evaluation scale on the already wrecked Fukushima plant.

The watchdog urged TEPCO to step up monitoring for leaks and take precautionary measures.
During the meeting, 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 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 to the sea because of its distance, about 500 meters from the coastline.

But TEPCO reversed that view today and acknowledged a possible leak to the sea after detecting high radioactivity inside a gutter extending to the ocean.
The company also said the tank may have been leaking slowly for weeks through a possible flaw on its bottom. That could create extensive soil contamination and a blow to plans to release untainted underground water into the sea as part of efforts to reduce the amount of radioactive water.