New TEPCO Admission On Damage To Reactors; July 29, 2013

TEPCO buried new admissions about the reactor units and their damage in a couple of obscure reports.

New unit 1 reactor & containment leakage:

TEPCO buried this admission on a latter page of a document on nitrogen injection of unit 1.
There is a possibility of correlation between upward flow and “injected nitrogen – exhaust = leak amount.”

It included this schematic

The schematic shows a gas escape route out the reactor vessel to the containment vessel and out via the containment cap indicating they assume both vessel caps leak continually. (TEPCO incorrectely labeled the RPV as PCV in the diagram) While many have assumed all along that this leak out of the top of containment was going on and likely contributed to TEPCO’s rush to cover unit 1, this is the first time TEPCO admits this publicly. TEPCO announced recently they want to remove the tent cover of unit 1 for an extended period of time to remove the debris from the refueling floor. Worker Happy also pointed out that the frame they used over unit 1 can not hold the needed crane and defueling equipment so it will need another structure.

New failures of torus at all 3 units:

In this obscure past progress document buried inside was this revelation:

Based on the results of field investigations using robots and fiberscopes, the status of leaks from the pressure suppression chambers at Units 1~3 were estimated. (It was estimated that leaks have occurred from the pressure suppression chambers at Units 1 and 2, and that the pressure suppression chamber at Unit 3 is mostly sound.)” 

So now they admit that units 1 and 2 have leaks but they do not clarify what kind or where. This could be significant yet TEPCO buries a vague mention where most would not see it including the media. How the suppression chambers leak could be providing a significant route for highly radioactive water and fuel to leak.

TEPCO also admits that part of unit 3’s suppression chamber is not sound. TEPCO explains it as “mostly sound” indicating it is not sound in some way but again refuses to tell how. TEPCO obviously has some information on the unit 3 suppression chamber but has opted to not tell the public. There was a partial exploration of the unit 3 suppression chamber room but TEPCO gave no conclusions and released limited information.

Robot inspection of unit 3 torus in 2012

Destroyed door found in the suppression chamber room during the 2012 robot inspection.

More images of the U3 robot inspection can be found here.

Rapid depressurization of unit 3: 

TEPCO makes this rather odd statement in the same past progress report:

Depressurization behavior of Fukushima Daiichi NPS Unit 3 (presented at meeting of the Atomic Energy Society of Japan on March 27, 2013) Based on operational logic of reactor depressurization function and plant parameters at the time of the accident, it was estimated what sort of mechanism caused the rapid depressurization of the reactor at Unit 3 at the time of the accident (March 13, 2011).

This information could not be found on the Atomic Energy Society of Japan’s website nor in their journal. So TEPCO says they have information about the cause of the rapid depressurization but won’t tell the public. Yet they apparently were willing to tell a bunch of nuclear industry insiders what they know.

Multiple somewhat significant admissions again buried away from public discourse and have not fully disclosed what they know.


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