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Saturday, April 2, 2011

Iodine-131 found in groundwater

Tepco hit for failing to supply dosimeters


Staff writer

Tokyo Electric Co. came under further fire Friday after it was revealed that many of its employees at the damaged Fukushima No. 1 power plant have been working without the protection of dosimeters. It also said radioactivity in groundwater under the compound spiked.

News photo
Wiped off the map: These twin images show the city of Miyako, Iwate Prefecture, on Monday, following the devastating tsunami, and in March last year. KYODO PHOTO

Tepco said the groundwater sample, which contains 10,000 times the legal limit of radioactive iodine-131, was taken from one of 15 water tanks buried 15 meters below the compound near the No. 1 reactor. The tanks are designed to collect much of the runoff from rainwater and other sources that sinks into the ground.

The water is usually pumped from the tanks into the sea, but the pumps have been halted to prevent seawater pollution, the Nuclear and Industrial Safety Agency said.

NISA earlier cast doubt on details of the analysis, which was announced Thursday, causing Tepco to scramble to verify the information. But on Friday, Tepco confirmed that its previous statement was accurate.

"People are extremely worried right now and the data must be trustworthy. It is a problem that (Tepco) is not answering people's expectations," senior NISA official Hidehiko Nishiyama said the same day.

Tepco officials said they believe the possibility is high that iodine-131, earlier released on the ground from some of the three crippled reactors, seeped underground along with rainwater.

This is the second time in less than a week Tepco has had to amend radiation readings from the plant.

On Sunday, it said the level of radioactive material in the water in the turbine building of the No. 2 reactor was "10 million" times the normal level, only to correct it later and say the number was actually 100,000 times higher than normal.

The quake and killer tsunami that shattered the northeastern coastline also destroyed thousands of the nuclear plant's supply of dosimeters, which each employee should carry to warn of excessive radiation.

This means workers were forced to share dosimeters, the Nuclear and Industrial Safety Agency said Thursday. Since dosimeter readings vary greatly by position, it is difficult for a single dosimeter to protect everyone in a group if anyone strays. How many workers were forced to share dosimeters was not immediately known.

Tepco had 5,000 dosimeters but only 320 survived the quake and tsunami.

NISA issued Tepco a strong warning, prompting the utility to immediately send another 100 dosimeters to the workers at Fukushima No. 1. Tepco said 420 dosimeters is enough to protect everyone there.

Echoing an incident last week in which three workers stepped into dangerously radioactive floods they weren't warned about, NISA "warned Tepco to take all possible measures to manage the level of radiation exposure on the workers," Nishiyama said, adding from now on, "those who do not have dosimeters on will not be allowed to continue working."

Separately, NISA also announced Thursday the number of workers who had been exposed to more than 100 millisieverts of radiation at the plant had risen to 21.

In another flip-flop, the health ministry announced Friday that beef from a cow from Tenei, Fukushima Prefecture, that it initially reported contained 510 becquerels of radioactive cesium, upon a second test came up devoid of radiation, indicating the meat may not be contaminated. The legal limit for cesium is 500 becquerels.



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