Plutonium detected in soil at Fukushima nuke plant

TOKYO, March 29, Kyodo News

Plutonium has been detected in soil at five locations at the crippled Fukushima Daiichi nuclear power plant, Tokyo Electric Power Co. said Monday.

The operator of the nuclear complex said that the plutonium is believed to have been discharged from nuclear fuel at the plant, which was damaged by the devastating March 11 earthquake and tsunami.

While noting that the concentration level does not pose a risk to human health, the utility firm said it will strengthen monitoring on the environment in and around the nuclear plant.

Meanwhile, high levels of radiation exceeding 1,000 millisieverts per hour have been detected in water in a trench outside the No. 2 reactor's building at the nuclear plant, with the contaminated water suspected to have come from the reactor's core, where fuel rods have partially melted, authorities said Monday.

The government's Nuclear and Industrial Safety Agency said the electric power company, known as TEPCO, is expected to pump out similarly highly contaminated water that has been building up in the basement of the No. 2 reactor's turbine building, which is connected to the trench, to eventually remove the water.

The company said the high radiation level in water in the trench connected to the No. 2 complex was detected Sunday, adding that the radiation level in the air in the trench stood at 100 to 300 millisieverts.

At a radiation level of 1,000 millisieverts per hour, people could suffer a decrease in the number of lymphocytes -- a type of white blood cell -- in just 30 minutes, and half could die within 30 days by remaining in such conditions for four hours.

TEPCO also found Sunday afternoon that the radiation level at the surface of the trench water adjacent to the No. 1 complex was 0.4 millisievert per hour. But it could not measure the level at the gutter linked to the No. 3 unit as rubble prevented the firm from checking it, the company added.

Although it remains unknown whether the contaminated water has flowed into the sea from the trenches that are 55 to 70 meters away from the shore, TEPCO suspects the high concentration of radioactive substances found in seawater near the plant reactors' drainage outlets may be linked to the trench water.

Earlier in the day, the nuclear agency said radioactive iodine-131 at a concentration 1,150 times the maximum allowable level was detected Sunday in a seawater sample taken around 1.5 kilometers north of the drainage outlets of the troubled No. 1-4 reactors.

Haruki Madarame, chairman of the Nuclear Safety Commission of Japan, a government panel, told reporters he is ''very worried'' about the high-level radiation detected in water in the trenches, which is outside the radiation-controlled area set by TEPCO.

Maradame said he cannot predict when the ongoing nuclear emergency will end and pointed to the possibility that fuel rods in the No. 2 reactor, which were temporarily exposed to the atmosphere, have been significantly damaged.

''We must control the water well so it won't ever go outside'' the complex, said Sakae Muto, vice president of TEPCO, at a news conference.

TEPCO revealed the elevated radiation levels in trench water a day after it first detected them, but Muto denied any intention of withholding information from the public.

On Monday, TEPCO continued to remove highly radioactive water from inside reactor buildings at the crisis-hit plant, in an effort to enable engineers to restore the power station's crippled cooling functions. The turbine buildings are equipped with electric equipment necessary to cool down the reactors.

TEPCO has found the concentration of radioactive substances in a pool at the No. 2 reactor's basement was 100,000 times higher than usual for water in a reactor core.

Chief Cabinet Secretary Yukio Edano told a press conference the highly radioactive water found at the basement of the No. 2 reactor's turbine building is ''believed to have temporarily had contact with fuel rods (in the reactor's core) that have partially melted.''

The safety commission chaired by Madarame said in its recommendations to Prime Minister Naoto Kan that highly radioactive water in the No. 2 reactor's containment vessel could have directly leaked, raising concerns that polluted water could spread to the building's underground and to the sea.

Hidehiko Nishiyama, a spokesman for the nuclear agency, however, denied the possibility that the No. 2 reactor's vessel has cracks or holes, saying no data suggest such conditions. It is rather likely that radioactive water has leaked from pipes or valves, he said.

Nishiyama said it is now necessary to strike a balance between two missions -- injecting coolant water into the reactor cores and spent nuclear fuel pools to prevent them from overheating, and removing radioactive water in the turbine buildings and trenches.

He said the water contamination may have been caused by operations to pour massive amounts of coolant water into the reactors and pools.

Since Sunday, TEPCO has been trying to move the radioactive water in the basement of the No. 1 reactor's turbine building to a tank in the unit by using three pumps.

But the operator has yet to start this work at the remaining three reactor buildings due to difficulties in securing enough space in tanks to accommodate the polluted water, according to the nuclear agency.

Removal of highly radioactive water is also meant to reduce the risk of more workers being exposed to radioactive substances. The number of workers who have been exposed to radiation exceeding 100 millisieverts at the plant came to 19 as of Monday, TEPCO said.

Exposure to 100 millisieverts is the legal limit for nuclear plant workers dealing with an emergency, but the limit has been raised to 250 millisieverts during the ongoing crisis, the worst Japan has seen, at the plant some 220 kilometers northeast of Tokyo.

Among the 19, three received treatment at a radiation research center in Chiba Prefecture after they were exposed to radiation of 173 to 180 millisieverts Thursday. They were discharged Monday, with officials of the center saying the exposure has not affected their health.

==Kyodo