TEPCO's explanations of yesterday's power failure

October 8, 2013

Water injection for damaged Fukushima reactor accidentally halted

Kyodo

http://www.japantimes.co.jp/news/2013/10/08/national/water-injection-for-damaged-fukushima-reactor-accidentally-halted/#.UlPRyVM0_9k

A pump to inject water into one of the severely damaged reactors at the Fukushima No.1 nuclear complex halted Monday after a worker accidentally triggered a power failure, Tokyo Electric Power Co. said.

The halt occurred at around 9:47 a.m. but cooling of the No. 1 reactor immediately resumed through a backup pump, Tepco said.

The utility said the power failure occurred when one of two employees conducting routine checks of electricity equipment wrongly pushed a “stop” button on a switchboard, cutting power supply.

The utility does not have a procedure manual detailing how to manage the equipment and the worker had not previously conducted such checks, according to the utility. The other worker, who knew the proper procedure, was checking another switchboard and did not notice the mistake.

At the Fukushima plant in northeastern Japan, reactors 1 to 3 suffered meltdowns in March 2011 when tsunami hit the plant, flooding electrical equipment and triggering the failure of the reactor cooling system.

A power outage was also triggered last March when a rat touched a makeshift switchboard. The incident disabled the cooling system for the spent fuel pools of the reactors 1, 3 and 4 units and it took 29 hours to fully restore the system.

The reactors 1 to 3 are currently being kept cool by pouring around 400 tons of water into them every day. But the total amount of toxic water is increasing daily as groundwater is seeping into reactor buildings and mixing with water that passes through the reactors.

The government has decided to finance some measures to address the situation, such as the construction of a huge underground ice wall around reactor buildings to block the entry of groundwater.

Economy, Trade and Industry Minister Toshimitsu Motegi told a Diet committee Monday that the government may consider providing additional funds for a backup plan to be prepared in case the current planned measures fail to deal with the contaminated water.

“The government will play a proactive role on issues that involve technical difficulties,” he said.

The government has said it will spend ¥47 billion on construction of the ice wall, in which up to 1.4 kilometers of soil around the reactors 1 to 4 will be frozen.

An official at the Economy, Trade and Industry Ministry said that the annual operational cost of the system is expected to amount to several billion yen.