TEPCO says radiation level will be brought down in three months

Tokyo Electric Power Co. (TEPCO), which operates Japan's damaged nuclear plant at Fukushima, said on Sunday that radiation level at the plant will be brought down to a downward trend within three months.

The following is the latest update from TEPCO about the status of the Fukushima-Daiichi nuclear plant:

All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.

Unit 1(Shut down)

-Explosive sound and white smoke were confirmed after the big quake occurred at 3:36 pm on March 12th. It was assumed to be hydrogen explosion.
-At approximately 2:30 am on March 23rd, seawater injection to the nuclear reactor through the feed water system was initiated.
-From 3:37 pm on March 25th, we started injecting freshwater and are now injecting fresh water by a motor driven pump powered by the off-site transmission line.
-As it is suspected that hydrogen gas is accumulated inside reactor containment vessel, we commenced the valve opening operation concerning injection of nitrogen gas into the reactor container vessel at 10:30 pm April 6th and commenced injection at 1:31am April 7th.

Unit 2(Shut down)

-At approximately 6:00 am on March 15th, an abnormal noise began emanating from nearby Pressure Suppression Chamber and the pressure within the chamber decreased.
-From 10:10 am on March 26th, we started injecting freshwater to the reactor and are now injecting fresh water by a motor driven pump powered by the off-site transmission line.
-From 7:35 pm on April 12th, we started transferring the high level radioactive accumulated water in the trench of the turbine building to the condenser by an underwater pump. At 5:04pm on April 13th, the scheduled transfer was completed.

Unit 3(Shut down)

-Explosive sound and white smoke were confirmed at approximately 11:01am on March 14th. It was assumed to be hydrogen explosion.
-From 6:02 pm on March 25th, we started injecting fresh water to the reactor and are now injecting fresh water by a motor driven pump powered by the off-site transmission line.

Unit 4(outage due to regular inspection)

-At approximately 6:00 am on March 15th, we confirmed the explosive sound and the sustained damage around the 5th floor rooftop area of the Nuclear Reactor Building.
-At this moment, we do not consider any reactor coolant leakage inside the reactor happened.

Unit 5(outage due to regular inspection)

-Sufficient level of reactor coolant to ensure safety is maintained.
-At 5:00 am on March 19th, we started the Residual Heat Removal System Pump (C) in order to cool the spent fuel pool.
-At 2:30 pm on March 20th, the reactor achieved reactor cold shutdown. At around 5:24 pm on March 23rd, when we switched the temporary Residual Heat Removal System Seawater Pump, it has stopped automatically. At around 4:14 pm on March 24th we replaced the pump, and restarted cooling of reactor at around 4:35 pm.
-At this moment, we do not consider any reactor coolant leakage inside the reactor happened.

Unit 6(outage due to regular inspection)
-Sufficient level of reactor coolant to ensure safety is maintained.
-At 10:14 pm on March 19th, we started the Residual Heat Removal System Pump (B) of Unit 6 in order to cool the spent fuel pool.
-At 7:27 pm on March 20th, the reactor achieved reactor cold shutdown.
-In relation to the two seawater side pumps of the Residual Heat Removal System, we switched the power source from temporary to permanent at 3:38 pm and 3:42 pm, Mar 25 respectively.
-At this moment, we do not consider any reactor coolant leakage inside the reactor happened.

Operation for cooling the spent fuel pools
-From 2:30 pm to 6:29 pm on April 15th, we conducted spraying water to Unit 4 by the concrete pumping vehicle.
-From 10:13 am to 11:54 am on April 16th, we conducted injecting fresh water to Unit 2 by a temporary motor driven pump.
-We will conduct further water spray depending on the conditions of spent fuel pools, if needed.

Others
-The national government has instructed evacuation for those local residents within 20km radius of the periphery and evacuation to inside for those residents from 20km to 30km radius of the periphery, because it is possible that radioactive materials are discharged.
-From 7:03 pm on April 4th to 5:40 pm, April 10th, we discharged to the sea approximately 9,070 tons of the accumulated low level radioactive water stored in the Centralized Radiation Waste Disposal Facility. Also from 9:00 pm on April 4th to 6:52 pm, April 9th, we discharged to the ocean approximately 1,323 tons of the low level radioactive subsurface water stored in the sub drain pits of Unit 5 and 6.
Regarding radioactive concentrations at measuring points including those adjacent to the power station due to the discharge of the low level radioactive stored water to the ocean, no significant change has been found, though we compared them with the transition of concentrations for a week before the discharge.
The total amount of emitted radioactivity is approximately 1.5 x 1011 Becquerel. We evaluate approximately 0.6 mSv of effective radioactive doses per year per an adult as the impact on the discharge of the low radioactive stored water to the ocean if an adult eats adjacent fish and seaweeds every day. The amount (0.6 mSv of effective radioactive doses per year) is one-forth of annual radioactive dose (2.4 mSv) to which the general public is exposed from nature and equivalent to that when we evaluated before discharging the water to the ocean.
-From 2:30 pm to 3:45 pm on April 15th, we installed 3 sandbags containing zeolite (as an absorbent material) between the screen pump rooms of the Unit 3 and Unit 4.
-From 10:19 am to 5:00 pm on April 15th, we transferred distribution panels of the pumps to inject water to the reactors of Units 1 to 3 as a countermeasure against tsunami.
-We will continue to take all measures to ensure the safety and to continue monitoring the surrounding environment around the power station.