Wednesday, April 18, 2012

TEPCO Shows Water Level In Fukushima 1 Reactor 2 Fills Torus

The water level in unit 2 seemed to be consistent with water being up to the level of the downcomers which direct steam into the torus basement. Now they have released a drawing that shows indeed, they believe some water is at base of RPV, and that it fills the torus in the basement which then runs out to the turbine building basement. So what they have is a waterfall that runs into the basement. Presumably this water then is taken into the acres of water storage tanks where it will sit forever until they figure out some way to either process it or *gasp* dump it into the ocean.

We have confirmed that the water level of accumulated water inside of Primary Containment Vessel, Unit 2 is approx.60cm from bottom of the vessel, concluding that the inside of the vessel is cold enough.

April 5, 2012
On March 26, investigating inside of the PCV of Unit 2 by means of the industrial endoscope, it was confirmed that the water level was 60 cm from the bottom of the PCV, the water temperature was in the range of 48 to 50 ℃, and that the atmospheric temperature on the water surface was in the range of approx. 42 to 45 ℃. Some media reported, "the water level inside the PCV was only 60cm from the vessel's bottom," in spite of water injection to the vessel at the rate of 9m3/h. The level was lower than expected. But what is important here is twofold:
・It was visually confirmed using the industrial endoscope, not estimated from the outside of the vessel, that there was indeed accumulated water inside the Unit 2's PCV. In addition, the temperature of the water inside was measured using the thermometer calibrated outside.
・If the fuel which was melted down to the bottom of the vessel was not fully immersed in the water, the temperature inside the vessel should have been higher than measured this time. The measured water temperature as well as the atmospheric temperature show that the inside of the vessel has been cold enough.
While it is true that the water which was injected at the rate of 9m3/h was leaked from inside the vessel to the reactor building and to the turbine building, there has been no leakage of the water from each building to groundwater. We, TEPCO, will continue to stably operate the circulating injection cooling system which retrieves the leaked water from the turbine building, removes radioactive materials and salt out of the water, and injects it into the reactor again. By doing this, we make it sure to keep the cold shutdown status. We plan to suppress the leakage by various measures, including to check the degree of damage at torus room located on the first basement floor of the reactor building employing robots and to develop construction methods to block water among buildings.

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TEPCO never proposed a full evacuation.

March 1, 2012
The Media has widely alleged that TEPCO attempted a full-scale evacuation of all staff from Fukushima Daiichi Nuclear Power Station. However, this is a misrepresentation of the facts. On March 15, 2011, at approximately 6:30am, the former President Shimizu issued an order "to evacuate all staff except for the minimum number of staff needed". In response, the plant general manager ordered the "team leaders to appoint those who would be remaining". The staff of partner companies and TEPCO employees (approx. 650 people) who were not directly involved in the restoration work were temporarily moved to safer locations and the remaining staff (approx. 70 people) continued to implement the work.

The message TEPCO communicated to the Prime Minister's Office is that "TEPCO may begin considering the temporary evacuation of staff not directly related to the restoration work and who would eventually have to be evacuated anyway in light of the severe plant conditions". At around 4:30am on March 15th, former President Shimizu was summoned to the Prime Minister's Office and was questioned by former Prime Minister Kan concerning TEPCO's intentions regarding a possible site evacuation. Former President Shimizu replied that a full-scale evacuation was the last thing on his mind. Former Prime Minister Kan also subsequently related the contents of this conversation to the Budget Committee of the House of Councillors on April 18th, 25th, and May 2nd. Former President Shimizu also provided the same response at the press conference on April 13th that a "that a full-scale evacuation was the last thing on his mind".

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Damaged thermometer caused increase in temperature in the lower part of Reactor Pressure Vessel of Unit 2. Found out it remains cold shut down status.

February 16, 2012
At the beginning of February, it was found that one of the thermometers in the lower part of Reactor Pressure Vessel (RPV) indicated the temperature increase. TEPCO investigated both the possibilities; whether the temperature increased locally or the thermometer was damaged. We continuously monitor the situation while we increased the water injection up to double on step-by-step basis in order to prioritize the cooling of the Reactor.

We concluded from following two reasons that the increase in temperature was due to the damage of the thermometer and the lower part of the RPV is actually cooled adequately; all other thermometers in RPV and Primary Containment Vessel (PCV) indicated the temperature drop in line with increased the water injection, and higher resistance value than normal was measured when investigated the electric circuit.

It was also confirmed that Xenon concentration was below detection limit when gas sampling of PCV, which means there no re-criticality was happened. There is no difference of the concentration of the radioactive Cesium, compared with that measured before the temperature increase.

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→Xenon 135 was below detection limit mesured before and after the temperature increase.
Sampling date and time: Feb. 6, 12:34 
Sampling date and time: Feb. 12, 3:22 
Sampling date and time: Feb. 15, 11:06 
→Both Cesium 134 and 137 were no change before and after the temperature increase.
Sampling date: Feb. 13 
Sampling date: Feb. 6 
Sampling date: Jan. 13 

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