From IAEA, the latest update as of 4 April 2011, 12:15 UTC, excerpt :
" 1. Current Situation
Power supply to the temporary electric pumps for water supply to the Reactor Pressure Vessels (RPV) of Units 1, 2 and 3 was switched from the temporary mobile power supply to the off-site power supply on 3 April.
Lighting in a part of Units 1 - 4 Turbine Building was restored on 2 April.
On 2 April, transferring of water from the Unit 1 condenser storage tank to the surge tank of the suppression pool was completed in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser. Also on 2 April, transferring of water from the Unit 2 condenser to the condenser storage tank was started in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser.
A second US Navy barge arrived on 2 April carrying fresh water that is being transferred to the first barge which is pumping water to the "filtered water tank".
TEPCO has identified a possible leakage path from the Turbine Building of Unit 2 to the sea via a series of trenches/tunnels used to provide power to the sea water intake pumps and supply of service water to the reactor and turbine buildings. Initial attempts on 2 April to stop the leak, by pouring concrete into the pit, were not successful. On 3 April, the top of the trench was broken open and polymer was poured into the trench in an attempt to stop the leakage of water to the sea through the pit, but leakage has not stopped as of 00:00 UTC on 4 April.
NISA have advised the IAEA that TEPCO have been given permission by the Government of Japan to discharge 10 000 ton of low level contaminated water from their radioactive waste treatment facility to the sea. This is in order to have sufficient capacity to store highly contaminated water found in the basement of the Unit 2 Turbine Building.
In addition TEPCO will discharge 1 500 ton of low level contaminated water in the sub-drain pit for Units 5 and 6 to prevent the water in the pit from leaking into the reactor buildings and potentially damaging safety-related equipment.
TEPCO has estimated that the potential additional annual dose to a member of the public would be approximately 0.6 millisieverts (mSv), if they ate seaweed and seafood caught, from near the plant, every day for a year.
As of 07:00 UTC, 4 April the discharge had not yet commenced. The IAEA have asked NISA for additional information.
In Unit 1 fresh water has been continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 6 m3/h using off-site power. In Unit 2 and Unit 3 fresh water is being injected continuously into the reactor pressure vessels through the fire extinguisher line indicated rates of 8 m3/h and 7 m3/h respectively using off-site power.
In Unit 1 the indicated temperature at the feed water nozzle of the RPV decreased from 253 °C to 243 °C and at the bottom of RPV it was stable at 113 °C. The RPV pressure indications are fluctuating and Drywell pressure is slightly increasing. The reliability of RPV pressure indications is in question. In Unit 2 the indicated temperature at the feed water nozzle of the RPV has decreased from 153 °C to 140 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. In Unit 3 the indicated temperature at the feed water nozzle of the RPV is stable at 114 °C and at the bottom of RPV is about 90 °C. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation."
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