Robot probe detects high radiation at No.3 reactor

The operator of the Fukushima Daiichi nuclear plant has detected high levels of radiation in the basement of the No. 3 reactor, with a maximum dose of 360 millisieverts per hour. Tokyo Electric Power Company sent in a robot on Wednesday to the room where the suppression chamber is located. It was the first robot to probe this area of the plant. TEPCO released video taken inside. They show that a door on the southwestern side is broken. There is no other apparent damage or sign of water leakage. But high levels of radiation were detected. Readings exceeded 100 millisieverts per hour in a number of locations. Average levels were higher than those in the No.2 reactor. Engineers lost control of the remote-controlled robot after around 3 hours of operation. They say there are problems with the connecting cable and they've been unable to regain control. TEPCO officials say they have no option but to leave the robot where it is for the time being. This may pose a problem to the utility's efforts to decommission the reactor. The operators are in a hurry to identify and repair damage to the reactor's suppression chamber and containment vessel. They want to pump in water in order to remove the melted fuel lying at the bottom.

Workers cannot approach reactor buildings

At the Fukushima Daiichi nuclear plant, high levels of radiation have kept workers from approaching the buildings housing the first 3 reactors, which lost their cooling functions in the March 11th earthquake and tsunami.

On Friday, the highest radiation level measured outside the double-entry doors of the Number 1 to 3 reactor buildings was 2 to 4 millisieverts per hour.

Radiation levels measured between the double doors of those reactor buildings was 270 millisieverts in the Number One reactor, 12 in Number 2, and 10 in Number 3.
The radiation level detected at the Number One reactor exceeds the national exposure limit of 250 millisieverts for nuclear contract workers.

Tokyo Electric Power Company, TEPCO, has started using a remote-controlled robot inside the reactor buildings.

But issues remain as radioactive water has been found in turbine buildings and the utility tunnel outside the reactors.

At the Number 2 reactor, the level of highly contaminated water in the tunnel is still rising. To prevent overflow, TEPCO is stepping up the inspection of the nuclear waste processing facility, to which it aims to transfer contaminated water.

Underground water at the plant is also contaminated.
On Wednesday, the level of radioactive substances sharply increased at facilities where underground water from the Number 1 and 2 reactors is collected.

On Friday, workers kept on monitoring the situation.
They say the level of radioactive substances has stabilized or decreased in every reactor from 1 to 6.

So they say it's unlikely that highly radioactive water is still seeping into underground water.
Monday, Apri

No radiation change observed after water release

Japan's nuclear safety agency says no major changes have been observed in the concentration of radioactive substances in the sea around the Fukushima Daiichi nuclear power plant after the release of low-level contaminated water.

Tokyo Electric Power Company, or TEPCO, discharged a total of 10,393 tons of low-level radioactive wastewater from its damaged Fukushima plant between April 4th and 10th.

The government's Nuclear and Industrial Safety Agency says the amount of wastewater disposed of was 1,100 tons less than originally planned, resulting in the reduced release of radioactive substances.

To assess the effect of the contaminated water, the power company collected sea water samples from around the plant as well as from 15 kilometers offshore.

The nuclear safety agency says it has concluded that the data shows no major change in the concentration of radioactive substances.

But the agency also directed TEPCO to carry out long-term monitoring over a wider area and to assess the impact of the discharge by measuring radiation levels in fish and shellfish caught in nearby waters.

When releasing the wastewater, TEPCO had said that even if a person were to eat seafood from nearby waters every day for one year, the radiation exposure would total 0.6 millisieverts, which is below the annual permissible level of one millisievert.
Friday, April 15, 2

Radiation levels in underground water rise

The operator of the troubled Fukushima Daiichi nuclear power plant says radiation levels in underground water gathered in so-called sub-drain pits rose by up to 38 times during the past week.

Tokyo Electric Power Company, or TEPCO, is working to remove contaminated water from the basements of the turbine buildings and tunnels. The contaminated water is hindering efforts to restore the reactors' cooling systems.

TEPCO said that in its monitoring on Wednesday, it found 400 becquerels of iodine-131 and 53 becquerels of cesium-134 per cubic centimeter in the No. 1 reactor's sub-drain pit. These levels are 6 times and 38 times higher than a week ago respectively.

In the No.2 reactor's pit, 610 becquerels of iodine-131 and 7.9 becquerels of cesium-134 per cubic centimeter were detected. These levels are 17 times and 8 times higher than a week ago respectively.

TEPCO says the sub-drain pits of the 2 reactors are connected by a pipe and that the highly radioactive water in the No. 2 reactor could be leaking underground.

TEPCO is to increase its radiation readings to 3 times per week from Saturday on the instructions of the Nuclear and Industrial Safety Agency.
Friday, April 15, 2011 10:43 +0900 (JST)