The devastating earthquake that flattened many communities in the Noto Peninsula on Jan. 1 has highlighted many challenges for nuclear disaster prevention as well.

Electric utilities, the national government and local administrations need to examine these challenges from a broad perspective and contemplate what lessons can be gleaned from the disaster.

At Hokuriku Electric Power Co.’s Shika nuclear power plant, located in a town on the western coast of the peninsula, water spilled from the spent fuel pools at the two reactors of the plant and the cooling pumps stopped temporarily.

Transformers in both reactors were damaged and leaked oil, causing a temporary loss of power in one of the cooling pools.

Some of the radiation monitoring equipment set up around the plant by the local governments and the national government stopped transmitting data. It is vital to uncover the causes and assess the impacts of these incidents through detailed investigations.

Initially, Hokuriku Electric Power reported no fluctuations in the water level of the tank drawing seawater into the site due to the earthquake-generated tsunami.

However, it was later found that the water level had risen by about three meters. The quantity of oil that leaked from the transformer was more than five times the amount initially reported.

After these successive corrections to the utility’s announcements, the economy ministry instructed the company to provide accurate information.

While nuclear plant operators should avoid delays in announcing the impacts of a disaster due to excessive cautiousness, it is vital for them to understand that misinformation can cause anxiety among residents and underestimating the damage could lead to dire consequences.

This should be a lesson for other electric power companies operating nuclear plants as well.

The Shika nuclear plant is currently facing a prolonged safety review for the restart of its No. 2 reactor due to complicated issues concerning the assessments of multiple faults--fractures or zones of weakness in the Earth's crust--running beneath the plant.

In 2016, an expert panel assessed it as reasonable to consider these to be active faults--those that have shifted recently in geological terms and are likely to move again.

Hokuriku Electric Power challenged this assessment, and last year, the Nuclear Regulation Authority accepted the company's view.

On the other hand, the nuclear safety watchdog on Jan. 10 instructed its secretariat to gather knowledge and information about this earthquake and its impact on the plant.

The NRA member in charge of evaluating the risks posed by earthquakes said, "There is a possibility that several faults are moving in conjunction. It is necessary to follow the research of experts and utilize it in our assessments," calling for careful analysis and consideration of related issues.

The issues underscored by this earthquake, such as risks linked to active faults, earthquake interactions, the predicted intensity of shaking during large quakes and the impact of severe quakes on facilities, are common to nuclear power plants nationwide, not just Shika.

A plan to build a nuclear power plant in Suzu near the epicenter of this earthquake was once considered and later put on ice. Lessons must be gleaned from the latest giant quake and its consequences to improve nuclear regulations and disaster prevention efforts.

The earthquake also caused many parts of the Noto Peninsula to be isolated for a long time due to severed roads, bringing to the fore the vulnerabilities of peninsulas to major natural disasters.

Nuclear power plants such as the Shikoku Electric Power Co.’s Ikata and the Tohoku Electric Power Co.’s Onagawa are also located on peninsulas.

In the event of a severe nuclear accident at these plants, evacuation and rescue efforts could be seriously hindered.

The colossal damage caused by the Noto Peninsula quake to houses in broad areas suggests that indoor evacuations to avoid radiation may also be impossible during quake disasters.

The NRA says it will consider revising the guidelines for nuclear disaster response, but it should first focus on delving deeper into the key issues related to emergency response and evacuation measures.

The risks of nuclear power in a seismically active country such as Japan have once again been made alarmingly evident.

The government should rethink its overzealous approach to expanding nuclear power generation.

--The Asahi Shimbun, Jan. 18