Just In: Reactor 2 RPV Temperature at 78.3 Degrees Celsius as of 10AM, Feb 12, 2012

From TEPCO's plant parameter - Reactor 2 RPV bottom hourly temperature table (Japanese, for now):

2/11 17:00 69.5
2/11 18:00 71.2
2/11 19:00 71.1
2/11 20:00 70.9
2/11 21:00 73.3
2/11 22:00 72.5
2/11 23:00 71.2
2/12 0:00 71.1
2/12 1:00 69.5
2/12 2:00 71.9
2/12 3:00 74.1
2/12 4:00 75.7
2/12 5:00 74.0
2/12 6:00 74.4
2/12 7:00 76.3
2/12 8:00 74.5
2/12 9:00 77.1
2/12 10:00 78.3 (at TEPCO's morning press conference, 2/12/2012)

2/12 11:00 74.9

TEPCO do not give morning presser on weekends any more, but today is the exception due to the concern over the Reactor 2 RPV temperature. Matsumoto is doing the press conference, instead of the usual junior manager of PR department.

Q: What happens if the temperature here exceeds 80 degrees Celsius?
A: Further increase of water to be injected into the RPV. But the cold shutdown state should take other parameters of the reactor into consideration.

Q: Possible causes?
A: Unstable cooling at the location. Some movement inside RPV of melted fuel, possibly, disturbing the flow of water. We don't think it's likely because we haven't been working near the reactor. Instrument failure is another possibility.

Q: What evidence to verify the accuracy of the thermometer?
A: Difficult.

Q: Containment Vessel's temperature?
A: Dry Well 39.5 degrees Celsius as of 5AM February 12. Other parameters about Reactor 2 is stable, trending down, except for this particular location at the RPV.

A: We're watching out for Xe-135 for any indication of recriticality, so far there is no detection from the gas management system of Reactor 2.

Q: Are municipalities around the plant informed?
A: Yes. We've been informing them of the temperature and the amount of water being injected.

Q: Which is more likely, the unstable water flow or the instrument failure?
A: Not sure. We're on the safety side (that there is actually a rise in temperature), so we're increasing the amount of water.

Q: Current decay heat?
A: We estimate it to be 0.6 megawatt, but we're not sure whether the temperature rise like this is possible, given the uncertainty of how the water flows through the reactor.

74.9 degrees Celsius at 11AM.

Q: Is this the only location that shows abnormality?
A: No abnormal numbers anywhere else.

Q: Amount of boric acid solution to be injected?
A: 1000 kilograms, as before.

Amount of water from feed water system 7.8 tonnes/hour (from 6.8 tonnes/hour), core spray ssytem 10 tonnes/hour.

If the temperature doesn't respond to increased water, then the instrument failure may be suspected.

Q: When are you going to decide on the cause - instrument failure or water flow?
A:

Q: What does the manufacturer of the thermometer say?
A: Nothing so far.

Q: Why is it taking so long to figure out the cause?
A: The problem is that we cannot enter the Containment Vessel. So we do everything we can from outside the CV to figure it out.

(Press conference just ended.)

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