Efforts have been made at nuclear power plants across the nation to ramp up safety measures in the wake of the series of serious accidents that occurred at Tokyo Electric Power Co.’s Fukushima No. 1 nuclear plant in the aftermath of the massive tsunami on March 11.
Plant operators reportedly aim to establish safety measures to prevent similar accidents from happening even if a plant is struck by a tsunami with a magnitude exceeding the scale assumed at the time of its design and construction. Compilation of such measures must be finished swiftly.
Such efforts have been made by electric power companies at the behest of the Ministry of Economy, Trade and Industry.
The nuclear reactors at the Fukushima plant stopped operating immediately after the temblor occurred. Up to that point, events corresponded to what had been assumed. But events beyond the scope of assumption followed due to the huge tsunami as it became impossible to use the emergency power sources needed to cool the nuclear fuel rods. Some of the rods melted due to overheating and this led to increased pressure inside the reactors, thereby bringing about an emergency involving the leakage of radioactive substances outside the reactors.
Based on this, METI called on the utilities to implement urgent measures by the end of this month, including moving the facilities for emergency power sources to higher ground to prevent them from being inundated and installing reserve power supply vehicles.
The ministry also made it mandatory for the power companies to work out operation manuals and hold disaster drills at plants to prepare for extreme emergency scenarios, thereby minimizing the damage should an emergency like one at the Fukushima plant happen.
These are measures to be taken for the time being, but METI should closely and strictly monitor whether such measures are being carried out at plants. If deficiencies are found, the ministry must take such stern measures as shutting down noncompliant plants.
There are a host of issues to be tackled from a medium- and long-term perspective.
One is that the scale of the maximum tsunami assumed at each nuclear plant has not been changed.
Precautionary measures against tsunami have been far from a major focus even in the government’s guidelines on anti-earthquake measures for nuclear power stations. The enormous tsunami that hit the Fukushima plant was as high as 15 meters―much higher than the 5.7-meter maximum assumed beforehand.
METI says it will reexamine the guidelines after inspecting the cause of accidents at the plant. But this is too late a response. Chubu Electric Power Co. has announced a plan to build a 15-meter-high anti-tsunami wall around its Hamaoka nuclear plant in Shizuoka Prefecture. The ministry needs to examine whether this is sufficient to ensure safety.
It is also essential to assume a greater scope of damage at each nuclear plant when a serious accident such as a leak of radioactive material happens. It is necessary to reexamine disaster response measures to be taken by the government and business operators in response to such damage assumptions. The measures include evacuating disaster victims and stemming the expansion of damage.
Conventional disaster response measures taken by the government so far have lacked realistic perspective. This is one reason behind the delay in measures taken this time.
Every one of these measures requires huge spending. Kansai Electric Power Co. intends to invest 70 billion yen in bolstering safety measures. The government, for its part, is urged to work out fiscal assistance steps.
Considering the size of damage to be incurred by the occurrence of a nuclear accident, investment in safety measures should not be spared.
(The Yomiuri Shimbun, April 25)