The operator of the wrecked Fukushima Daiichi nuclear power plant in Japan said Tuesday it has no new safety worries and envisions no changes to the plant's decommissioning plans even after a deadly earthquake on Jan. 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 outages 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.

"At the moment, we believe there won't be any change to our (Fukushima Daiichi decommissioning) plan because of the Noto quake," said Akira Ono, the head of the Tokyo Electric Power Company Holdings' decommissioning unit for Fukushima Daiichi.

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 unlivable.

Ono added that TEPCO's Kashiwazaki-Kariwa nuclear power plant, the world's largest, which holds seven reactors in its complex and is located 118 kilometers (73 miles) east of the epicenter, had no major problems and would not require additional safety measures. But he said the utility would 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's achieved. 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, Ono 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.

Ono said experts and workers at the Fukushima Daiichi plant hope to make progress in assessing more details of melted debris that still remain inside of the three reactors.

TEPCO plans to use a small drone to capture images from inside of the No. 1 reactor's primary containment vessel as early as February, while hoping to start collecting a tiny amount of melted debris from inside of the No. 2 reactor by using a robotic arm by the end of March.

TEPCO also plans to start releasing a fourth batch of 7,800 tons of treated radioactive wastewater from the plant into the ocean in mid-February, part of a decades-long process to get rid of massive radioactive wastewater held in tanks that have accumulated at the plant since the 2011 meltdown and make room for facilities needed for decommissioning.

The discharge, which began in late August, have been strongly opposed by fishing groups and neighboring countries including China, which banned all imports of Japanese seafood. Japan's government and TEPCO say the discharged wastewater is far safer than international standards and environmental impact is negligible.

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