Power Restored at Fukushima I Nuke Plant, TEPCO Still Don’t Know What Went Wrong

Tuesday, March 19, 2013

EXSKF
http://ex-skf.blogspot.co.uk/2013/03/power-restored-at-fukushima-i-nuke.html

TEPCO still doesn’t know what caused the power failure and how, therefore does not have measures in place to prevent any future power failure. Pressure from the national government was clearly on the operator to just start cooling and not worry about minor details like what caused the failure.

Ad hoc has been the name of the game for the past two years. Why change now?

Asahi Shinbun (3/20/2013; part):

今回の停電は、東日本大震災での事故以降では最大規模。だが原因は特定できていない。東電によると、停電の発端と みられる不具合が起きた３、４号機につながる仮設の配電盤は、目で見て分かる異常は確認できなかったという。当初は原因を突き止め、対策を講じた上で復旧 させる予定だったが、復旧を優先させることにし、仮設配電盤を通さずに、別の配電盤に冷却装置を接続することで電源を確保した。

The power outage this time was the most severe since the start of the accident. However, the cause of the outage hasn’t been identified. According to TEPCO, there was no visible sign of abnormality in the temporary switchboard that is connected to Reactors 3 and 4, where a trouble that led to the power outage was thought to have started. The company had initially planned to identify the cause, install measures to prevent future problems, and then turn the power back on. However, restoring the power was given the priority, and the cooling systems were connected to a different switchboard, circumventing the temporary switchboard.

The particular temporary switchboard is “3/4 M/C (A)” (M/C stands for “metal clad”). The location (or connection) of the switchboard in the overall electrical system looks different in the two different diagrams below. Either way, I don’t quite understand why Reactor 1 should be affected by the failure of this switchboard, as the Reactor 1 cooling system does not appear to be connected to this switchboard.

As TEPCO’s spokesman Ono explained it (via Ryuichi Kino),

所内共通Ｍ／Ｃ」（２Ａ）と（２Ｂ）にも波及

[The trouble at “3/4/ M/C (A)”] had the ripple effect on Plant-wide common M/C (2A)(2B)

(I don’t have a clue as to how that could happen.)

3/4 M/C (A) (in blue circle that I added), in the diagram provided by TEPCO in the press conference on March 19, 2013, via Ryuichi Kino:

3/4 M/C (A), in the diagram from March 2012, from then-Nuclear and Industrial Safety Agency (NISA, also from Ryuichi Kino:

March 20, 2013 - Posted by arclight2011 | Uncategorized