Kenichi Ohmae's April 18 Focus page article, "Fukushima: Probability theory is unsafe," appears to criticize the government and Tokyo Electric Power Co., but actually it is an attempt to save the nuclear industry and the governments that support it.

Ohmae concludes that the culprit in the nuclear disaster was the March 11, 2011, tsunami that incapacitated the diesel generators, arguing that the disaster could have been avoided if multiple backup power sources had been prepared. Fact is that it is highly probable that some of the piping for coolant water was destroyed by the earthquake. What use is there for diesel generators, or whatever devices power the pumps, if the piping is broken?

Ohmae strangely evades the issue of how the nuclear facility was constructed. It is a devilishly complex structure, including a jungle of pipes, and it was extremely difficult to properly weld the pipes. It is also next to impossible to ensure the integrity of the piping in regular inspections. The pipes that carry the critically important coolant were connected by welders working under extremely difficult circumstances. It was very hard to check the workmanship after completion. Even if 99 percent of the welds were perfect, a small defective spot might fail under high pressure and a powerful quake. If a break grows, the coolant system can become disabled.

Ohmae writes, "We should not assume anything in the design of a nuclear reactor." But we can't design anything without assumptions: What load level must the structure withstand? How long must backups keep running? And so on.

He dismisses safety measures based on probability and tells us to be prepared for anything that can happen. Must we be prepared for the collision of a massive asteroid regardless of the probability?

The opinions expressed in this letter to the editor are the writer's own and do not necessarily reflect the policies of The Japan Times.

keisuke akita