The Noto Peninsula earthquake on Jan. 1, 2024, revealed flaws in specialized indoor shelters designed to protect evacuees from radiation leaks in nuclear power plant disasters.

These radiation-blocking facilities are equipped with systems to increase internal air pressure, ample storage space for food and water, and are supposed to comply with the latest earthquake-resistance standards.

But the magnitude-7.6 earthquake created cracks and caused other damage at 14 of the 20 emergency shelters in Ishikawa Prefecture.

At six shelters, defects and abnormalities that could result in malfunctions in the protection features were detected.

Although the quake, which registered a maximum intensity of 7 on the Japanese seismic scale, did not damage the Shika nuclear power plant in Ishikawa Prefecture, the cracks to the shelters raised concerns.

“It is difficult to completely prevent damage to facilities during a disaster,” a Cabinet Office official said. “We will be considering the introduction of additional facilities to support indoor evacuation.”

Susumu Kitano, 64, a victim of the quake who heads a group seeking legal procedures to decommission the Shika nuclear plant, questioned the effectiveness of the indoor evacuation centers.

He emphasized that even tiny openings in the walls can compromise the shelters’ ability to block radioactive materials, even with raised internal air pressure.

“Damages to indoor evacuation facilities have been reported in a spate of cases,” Kitano said. “This indicates that extra countermeasures are still indispensable to minimize the impact of radioactive substances.”

An earthquake with a seismic intensity of 7 or so inevitably results in home collapses and road closures.

The anti-radiation shelters are meant mainly for residents, such as elderly or disabled people, who cannot flee on their own in the event of a nuclear disaster.

According to the Cabinet Office, Japan has 300 radiation-protective shelters. About 10 are newly built while the remaining ones were converted from conventional facilities used for other purposes.

Under municipalities’ evacuation plans, residents living within 5 kilometers of nuclear plants are generally supposed to flee in their automobiles or buses arranged by local governments in a serious accident.

If roads become impassable due to damage and residents cannot evacuate by other means, they should remain indoors at home or in the designated shelters.

Hirotada Hirose, a professor emeritus of disaster risk studies at Tokyo Woman’s Christian University, pointed to another potential problem with the shelters: mental stress.

“Staying indoors for extended periods to guard against invisible radioactive substances can exacerbate feelings of anxiety and loneliness,” Hirose said.

He said the situation at the damaged nuclear plant could worsen while residents stay indoors, making it more difficult for them to flee safely.

Naoya Sekiya, a professor of disaster informatics and sociology at the University of Tokyo, called for stronger safety measures at the shelters.

“Buildings damaged by an earthquake are at risk of collapsing in aftershocks,” Sekiya said. “Having people remain indoors tentatively without assessing the danger of shelters’ collapses could directly contribute to fatal risks.”

He said it is “unrealistic” for residents to feel secure while indoors at the time of a tremor.

“Efforts should be made on a continual basis to minimize accident risks as long as threats persist,” he stressed.

SHELTER TOUR IN TOHOKU

Several indoor evacuation centers have been installed around Tohoku Electric Power Co.’s Onagawa nuclear power plant in Miyagi Prefecture.

Co-hosted by Onagawa town and Ishinomaki city, the plant resumed electricity generation at its No. 2 reactor on Nov. 15.

Nov. 16 marked 5,000 days since the 2011 Great East Japan Earthquake and tsunami devastated the northeastern Tohoku region. The disaster also affected the Onagawa power station.

Onagawa town recently organized a tour of the anti-radiation shelter completed in March in the Koyadori district north of the nuclear plant.

After opening heavy double-walled doors, a municipal official led tour participants into a reinforced concrete building with no windows. The indoor air had a scent reminiscent of a new home.

The first and second stories featured dedicated rooms for residents. The floors were color-coded to help evacuees identify their individual spaces, each measuring 2 meters by 2 meters.

A storage room there stockpiles enough food and water for 33 residents over seven days, according to the municipality’s emergency preparedness plan. An electric kettle is available to boil water.

The second floor contains a control panel to regulate the atmospheric pressure.

Once the guide turned the dial, the air pressure inside became 100 pascals higher than outside within a minute or so.

The increased indoor pressure can prevent outside air--and radioactive substances--from entering the building.

The shelter in Koyadori was installed in line with a municipal evacuation plan worked out by Onagawa town.

Ishinomaki city is similarly moving toward introducing indoor evacuation centers. Twelve shelters, eight in Ishinomaki and four in Onagawa, are now accessible.

Construction of the one in Koyadori required 400 million yen ($2.5 million) in taxpayers’ money in 2023. The other 11 shelters were remodeled from existing buildings.