Saturday, May 21, 2011

15/05 EDITORIAL: TEPCO desperately needs a 'plan B'


New discoveries about the condition of a crippled reactor at the Fukushima No.1 nuclear power plant have cast doubt on the plant operator's plan to bring the nuclear crisis under control.

Tokyo Electric Power Co. admitted on May 12 that the fuel rods in the No.1 reactor had probably melted and fallen to the bottom of the pressure vessel housing them.

Huge amounts of radioactive water may have been leaking from both the pressure vessel and the containment vessel enclosing it.

The leak is threatening to thwart TEPCO's efforts to flood the container vessel with water and cool the fuel rods.

In mid-April, the utility said the work to submerge the fuel in water would cool the reactors to a stable level in about three months.

That plan is now in jeopardy. TEPCO's estimate that the reactors can be brought to a stable state known as cold shutdown in six to nine months is also in doubt.

The new findings have delivered a blow to hopes that a successful stabilization of the No. 1 reactor could be replicated at the other troubled reactors.

The fact that fuel had melted became clear after workers entered the reactor building and adjusted a gauge measuring water levels in the pressure vessel.

One major issue complicating the effort at Fukushima No. 1 is unreliable data. Workers are having to guess what is happening within the reactor. Containing a stricken reactor involves a series of difficult challenges. It is like fighting an invisible enemy.

It is possible that remote-controlled cameras and robots might uncover a totally unexpected situation at the plant.

Under TEPCO's blueprint for bringing the crisis under control, the principal means to cool the reactors to a cold shutdown state is flooding the fuel with water.

Engineers involved in responding to the disaster considered other approaches but did not develop specific plans quickly enough. TEPCO has therefore gone ahead with the flooding plan.

New discoveries demanding a rethink of the plan have caused deep disappointment and distrust of the operator in foreign countries, in Japan and in the local communities most directly affected by the crisis.

The company should be offering more than one scenario in its new game plan. It should have a "plan B" to resort to immediately if "plan A" falls apart, and the firm should talk candidly about what it would do in a worst-case scenario.

Whatever approach is adopted, it is clear that efforts to cool the fuel at the bottom of the pressure vessel will continue for years.

It is worrisome that pouring on water to cool the fuel rods will increase the amount of contaminated water. TEPCO must expand its water storage capacity to prevent leaks off the compound.

It should start working immediately to establish a system to decontaminate and circulate water for cooling the fuel without increasing polluted water.

TEPCO must also now bear the crushing burden of figuring out a way to dispose of the melted fuel, a massive new headache for the beleaguered utility. After it accomplishes the urgent mission of bringing the reactors to a cold shutdown state, the company will have to tackle this colossal challenge.

--The Asahi Shimbun, May 14

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