Radioactive groundwater found in test wells at the site of the damaged Fukushima nuclear power plant is likely leaking into the Pacific ocean, Japan's Nuclear Regulation Authority said.
Officials with the watchdog agency said that a leak of radioactive water was "strongly suspected" and urged the power plant's operator, Tokyo Electric Power Co., to find the cause of any potential leaks and assess the environmental and health risks.
"We strongly suspect that high concentrations of contaminated water are leaking to the ground, and spreading to the sea," the agency said on Wednesday.
Samples taken from wells used to monitor water quality show an increase in radiation levels with some radioactive levels around 200 times the allowed limits.
The samples, tested by TEPCO on Tuesday, showed the highest levels recorded of two contaminants — cesium 134 and cesium 137 — that are suspected of increasing the risk of cancer.
TEPCO has denied that any radioactive water is making its way into the Pacific since the Fukushima Dai-ichi plant was crippled by the March 2011 earthquake and tsunami. The three nuclear reactors that were running at the time were heavily damaged. TEPCO used large amounts of seawater to cool the reactors after the accident.
The company's spokesman Noriyuki Imaizumi told the Associated Press that although cesium levels in the well samples have gone up, it doesn't necessarily mean that contaminated water is leaking into the Pacific. Imaizumi said that earlier spikes may have been caused by cesium-laced dust slipping into the samples.
But the watchdog agency said that samples taken from both the monitoring wells and the sea near the coastal nuclear plant showed the same high levels of radioactivity.
The Nuclear Regulation Authority's chairman Shunichi Tanaka said he thinks irradiated water has been leaking into the coastal waters since the accident, but that the contamination was worse earlier in the crisis.
"What's most important is to minimize the leak to the outside and reduce the impact on the human society," he said.
The safety of fish and seafood from the region is a big concern although anything caught off the Fukushima coast is off limits to both the domestic and international markets. TEPCO maintains that the problem is not spreading beyond the plant.
The Journal reported that TEPCO says there is no evidence of a significant increase in radioactive levels at the 16 sampling points it has in waters located just off the plant.
On Wednesday, the watchdog agency said it would form a panel of experts to look into ways to contain the problem.