The operator of the wrecked Fukushima Daiichi nuclear power plant in Japan said on Tuesday that it has no new safety worries and envisions no changes to its decommissioning plans after a deadly earthquake on January 1 caused minor damage to another idled nuclear plant, rekindling concerns and prompting a regulatory body to order a close examination.

The magnitude 7.6 quake on New Year’s Day and dozens of strong aftershocks in Japan’s north-central region have left 222 people dead and 22 unaccounted for. The main quake also caused a small tsunami.

Two reactors at the Shika nuclear power plant on the western coast of the quake-struck Noto peninsula survived.

But its operator, Hokuriku Electric Power Co, later reported temporary power cuts due to damage to transformers, the spilling of radioactive water from spent fuel cooling pools, and cracks on the ground, but no radiation leaked outside.

Akira Ono, head of the Tokyo Electric Power Company (Tepco) Holdings’ decommissioning unit for Fukushima Daiichi, which was damaged by a massive earthquake and tsunami in 2011, said: “At the moment, we believe there won’t be any change to our (Fukushima Daiichi decommissioning) plan because of the Noto quake.”

He said Tepco’s assessment confirmed the integrity of all Fukushima Daiichi reactor buildings even in the potential case of a quake 1.5 times as powerful as the one that struck in March 2011.

The magnitude 9.0 earthquake and subsequent tsunami that year destroyed key cooling systems at the plant, triggering triple meltdowns, spewing radioactive materials to surrounding areas and leaving some areas still unsuitable for habitation.

Mr Ono added that Tepco’s Kashiwazaki-Kariwa nuclear power plant, the world’s largest, which holds seven reactors in its complex and is located 73 miles (118km) east of the epicentre, has no major problems and will not require additional safety measures.

But he said the utility will wait for nuclear safety regulators to review the impact of the Noto quakes.

He also acknowledged that the New Year’s Day earthquake caught many people “off guard” and was a wake-up call for Fukushima Daiichi, where multiple operations are carried out, so it will be better prepared to contain potential risks from the used equipment or facilities that remain at the complex when another major quake or a tsunami hits.

Tepco has since been working on the plant’s decommissioning, a daunting task expected to take decades to finish if it is achieved.

Mr Ono said facilities that have been built at the Fukushima Daiichi plant since the disaster have been designed under strict safety standards set by the Nuclear Regulation Authority.

“I believe there will be no major impact on them” from the Noto quake, he said.

The NRA at a meeting last week asked for further investigation even though initial assessments showed there was no immediate risk to the Shika plant.

NRA officials said Shika’s operator should consider the possibility of additional damage to transformers and other key equipment as aftershocks continue.

The NRA order reflects Japan’s greater vigilance over safety risks after the 2011 Fukushima meltdowns.

Tepco is eager to restart its only workable Kashiwazaki-Kariwa plant after more than 10 years of stoppage, following the NRA’s lifting of a more than two-year ban over its lax nuclear safeguard measures at the site.