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Wednesday, Oct. 26, 2011

Tepco manuals point to critical safety lapses

Instructions fail to address total loss of power to plant's reactors


Staff writer

Newly disclosed manuals for workers at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear plant highlight the utility's lack of preparedness for an emergency, a major factor leading to the meltdowns after the March 11 quake-tsunami, a review by The Japan Times showed Tuesday.

The Nuclear and Industrial Safety Agency disclosed the 170-page manuals for operators at the No. 1 reactor unit of the Fukushima plant, the first of the three reactors to melt down.

Instructions in the manuals were all based on the assumption that two backup direct current batteries at reactor 1 would keep working throughout any emergency. In fact, the batteries were knocked out by water when the monster tsunami struck and crippled the Fukushima plant.

The manuals also failed to instruct workers to open by hand critical valves normally powered by electricity to vent steam and thus reduce pressure in the containment vessel. The DC batteries were supposed to supply power to operate those valves.

The containment vessel is the last line of defense to prevent radioactive materials from escaping the reactors. Tepco tried to open the valves to keep the vessel from breaking apart on March 12. Pressure also needed to be reduced to allow coolant water to be injected to prevent a meltdown of the reactor core.

But it took hours for Tepco workers, who apparently had no training in how to open the valves manually, to vent the steam and relieve the pressure, and many experts say the delay may be a key factor that led to the meltdown at unit 1.

Asked at a news conference Monday if the conditions assumed in the manuals were unrealistic, Tepco spokesman Junichi Matsumoto responded, "It may be an open question.

"(But) we don't believe that we failed to do something that should have been done" to prevent the crisis from escalating, Matsumoto said.

The existence of the manuals has been the focus of media attention for weeks. Tepco initially disclosed copies to the Diet with entries blacked out to, the company said, protect sensitive information involving the intellectual property of Tepco and nuclear power plant makers.

Tepco also argued that disclosing all the information in the manuals would reveal critical information possibly useful to terrorists and raise serious concerns about the security of reactors.

But at the end of last month NISA ordered Tepco to submit unexpurgated manuals. A NISA official said Monday they found nothing in them that presented a serious security concern.

The March 11 tsunami disrupted the outside power supply to the plant, and knocked out the emergency diesel generators, shutting down the critical cooling system for the reactor cores at units 1, 2 and 3. The DC batteries at unit 1 that were supposed to supply electricity to valves and instrument gauges were knocked out.

Future accident cost?

Kyodo

A future nuclear accident may raise the cost of power generation by between ¥0.1 and ¥1 per kwh, a government research panel commissioned amid the Fukushima No. 1 power plant crisis said Tuesday, although members of the body said the figures were both unrealistic and way too low.

It is the first time the country has calculated some of the costs that could stem from a nuclear accident. The figure equates to a rise of between ¥120 and ¥1,200 in average household electricity bills annually.

But the panel head, Tatsujiro Suzuki, acknowledged there is "quite a lot of uncertainty" on the estimate depending on the projection of the amount of damage any future atomic accident might cause.

The figure was presented as a midpoint of government estimates ranging from ¥0.0046 per kwh and ¥1.2 per kwh, calculated on the assumption that a severe accident like the one in Fukushima occurs once between 500 years and 100,000 years.

Based on the Fukushima crisis, the panel's secretariat estimated the damage cost of a nuclear plant accident will reach almost ¥3.9 trillion, which includes compensation payments for the people and businesses affected and the decommissioning of reactors, but not decontamination.



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The Japan Times

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