[1] This shook the plant beyond design basis and initiated an extended shutdown for inspection, which indicated that greater earthquake-proofing was needed before the operation could be resumed.

In December 2023, the NRA finally approved the reloading of fuel at the plant, citing improvements in the safety management system.

[10] Reactors at the plant were shut down one by one following the 2002 discovery that TEPCO had deliberately falsified data surrounding safety inspections.

After the 2002 TEPCO data fabrication scandals, the president at the time, Nobuya Minami [jp], announced that plans to use the MOX fuel at the KK plant would be suspended indefinitely.

[14] These underground elements stabilize the reactor buildings, making them less likely to suffer sway due to resonance vibrations during an earthquake.

After the 2007 earthquake suspicions arose that another fault line may be closer to the plant than originally thought, possibly running straight through the site.

[21] TEPCO was ready to restart some of the units as of the next day, but the trade ministry ordered the plant to remain idle until additional safety checks could be completed.

On Sunday, 22 July 2007, the Nuclear and Industrial Safety Agency (NISA) announced that it would allow inspectors from the United Nations to review the damage.

[29] However, TEPCO determined that significant upgrades were required to cope with the improved understanding of the seismic environment and possible shaking effects at the plant site.

They concluded that much high-quality inspection work had been undertaken and noted the likely improvements to nuclear seismic design worldwide that may result from this process.

[30] An additional visit from an IAEA team of 10 experts occurred in December 2008, noting that the "unexpectedly large ground motions" were now well understood and could be protected against, and further confirming the safe performance of the plant during the quake.

[31][32] Initially, it was thought that some water (estimated to be about 1.5 L) from the spent fuel pool leaked into the Sea of Japan as a result of the quake.

About 400 drums containing low-level nuclear waste stored at the plant were knocked over by the aftershocks, 40 losing their lids.

[41] Company officials reported on 17 July that traces of the radioactive materials cobalt-60, iodine, and chromium-51 had been released into the atmosphere, presumably from the containers losing their lids.

While the reported amount of leaked radioactivity remained far below what poses a danger to the public, details changed multiple times in the few days after the quake and attracted significant media attention.

The company published an apology on that page, and data from the devices covering the off-line period was released later, showing no artificial abnormalities (note that the readings naturally fluctuate depending on whether it's raining or snowing and a host of other factors).

The IAEA's Mohamed ElBaradei encouraged full transparency throughout the investigation of the accident so that lessons learned could be applied to nuclear plants elsewhere.

[48] Reports of the leak caused thousands of cancellations at resorts and hotels along the Sea of Japan coast, even as far as Murakami, Niigata (140 km northeast) and Sado Island.

The height of a potential tsunami was assumed to be 3.3 m. Also, plans were made to rebuild the radioactive overflow storage pool to be completed by September 2012.

This survey, the first that TEPCO ever conducted on this subject, did start on 15 November 2011, and was planned to be completed in April 2012, and was done to examine the possibility of higher tsunamis than had been expected at the time the plant was designed and built.

These were based on a magnitude 7.85 quake caused by a 131 kilometer long fault near Sado Island in Niigata and a 3.3 meter-high tsunami.

Under the new regulations, the beta-fault could be classified as active because it moved a ground layer including volcanic ash around 240,000 years ago.

However, the Nuclear Regulation Authority released a report in April 2021 indicating that there were serious security infractions and enacted an order that postponed the restart indefinitely.

[60][66][67] Following the April 2021 NRA report, TEPCO admitted that its intruder detection system was left broken in order to reduce costs[68] and confirmed that an unauthorized personnel member used a colleague's ID card to access the plant's central control room in September 2020.

In response, TEPCO plans to implement anti-terrorism measures, install an intrusion detection system, and hire an additional 30 guards to protect nuclear material at the facility.

[66] According to a report from TEPCO, the NRA began Additional Inspection (Phase II) to monitor the new security measures at the plant.

[73] In October 2022, Japanese Prime Minister Kishida Fumio unveiled a new strategy for Japans nuclear power plants regarding new construction projects and license extensions.

Most of these issues relate to security discrepancies such as a worker who forgot his ID, borrowed his colleagues card to enter crucial areas.

[75] In late 2023, the national regulator lifted the operational ban on the plant, allowing it to begin applying for permits from local governments to reopen.

[3] On Monday, 8 April 2024, Japans Nuclear Regulation Authority approved plans submitted by TEPCO to fuel reactor No.