Beware of rain (1)

October 21, 2013

Rainwater flows over tank barriers at Fukushima No. 1

JIJI

http://www.japantimes.co.jp/news/2013/10/21/national/rainwater-flows-over-tank-barriers-at-fukushima-no-1/#.UmTOl1M0_9k

Simultaneous overflows had not previously taken place at so many tank areas at the plant.

The possibility cannot be ruled out that overflowed water has leaked into the sea, according to Tepco.

Tepco also discovered water leaks from a concrete joint of a barrier at another tank area where above-limit radioactive substances have been found in the past.

As a result, contaminated water inside such barriers has leaked from more than half of the plant’s 23 tank areas.

In the past, radioactive materials in excess of the provisional limits set by Tepco have been detected in water inside some tank-surrounding barriers.

The overflows and leaks are the latest in a series of radioactive water problems at the plant.

On Sunday, the utility started draining water from inside the barriers at six tank areas, including five of the 11 overflow areas, after confirming that radiation levels have fallen below the provisional limits.

At two other tank areas, Tepco transferred barrier area water to sunken reservoirs. Although the utility stopped using the reservoirs after the discovery of radioactive water leaks from some of them in April, it took the emergency step this time, as it did in preparation for heavy rain caused by Typhoon Wipha last week.

The total amount of water that overflowed and leaked Sunday is not known, the company said.

In one location among the 11 tank areas, a maximum of 29,000 becquerels per liter of strontium and other radioactive materials emitting beta-ray particles were detected in the past.

Tepco’s provisional limit on radiation is 10 becquerels per liter for strontium-90, a substance that is believed to account for about half of beta ray-emitting radioactive materials.

Airborne radioactive materials have fallen inside the tank-surrounding barriers at the plant, while contaminated water is thought to have leaked into some of the areas. Therefore, rainwater inside the barriers contains a certain amount of radioactive substances.

After plant workers patrolling tank areas discovered the overflows late Sunday afternoon, Tepco started pumping water from inside the barriers to storage facilities, including tanks.

Rainwater flowed over the barriers around storage tanks containing radioactive water in 11 tank areas of the stricken Fukushima No. 1 nuclear power plant Sunday, Tokyo Electric Power Co. said.

TEPCO: Strontium tops safety standards in 6 spots

http://www3.nhk.or.jp/nhkworld/english/news/20131021_16.html

The operator of the Fukushima Daiichi nuclear power plant says radioactive strontium in 6 barriers, around tanks storing contaminated water, exceeded the government safety limit.

Workers found on Sunday that heavy downpours caused water to flow over 11 of the barriers.

Tokyo Electric Power Company says levels of radioactive strontium in 6 of them were above the government-approved limit for releasing the substance.

The highest reading was 71 times the set standard of 10 becquerels per liter.

TEPCO says the water that overflowed may have reached the ocean.

Pumps could not keep up with the rising water levels in the barriers after last week's typhoon and Sunday's downpours. The barriers are 30 centimeters high.

TEPCO plans to double the number of pumps as another typhoon is expected to approach Japan this week.

Oct. 21, 2013 - Updated 04:41 UTC