Japan Earthquake / No Irregularities at Nuclear Power Plants

Japan issued tsunami alerts and ordered evacuations following a series of earthquakes on Monday on Japan’s west coast. According to news media reports, the Japan Meteorological Agency (JMA) reported more than a dozen quakes off the coast of Ishikawa Prefecture   and nearby prefectures shortly after 4 PM Japan time on 01/01/24.  (Map and Data from USGS)

One of the quakes had a a preliminary magnitude of 7.6. Several aftershocks also rocked the region. The strongest tremor hit Ishikawa Prefecture. The area is 280 miles west of Tokyo on Japan’s west coast. (map)

The agency issued a major tsunami warning for Ishikawa (map left) and lower-level tsunami warnings or advisories for the rest of the western coast of the island of Honshu, as well as the northernmost of its main islands, Hokkaido.

The Japan Meteorological Agency (JMA) issued tsunami warnings for the coastal prefectures of Ishikawa, Niigata and Toyama.

A tsunami of about 3 meters (about 10 feet) high was expected to hit Niigata to the north of the epicenter of the quake, and other prefectures on the western coast of Japan. According to wire service reports, the waves were confirmed to have reached parts of the coastline.

No Impact Reported at Japanese Nuclear Reactors

(NucNet) No irregularities have been identified at nuclear power plants following a series of strong earthquakes in western Japan and warnings of possible tsunamis, the country’s Nuclear Regulatory Agency said in a statement to Japanese news media.

The NRA said in a media statement that reactors at Kansai Electric Power’s Ohi and Takahama nuclear stations in Fukui Prefecture, to the north of the main earthquake site in Ishikawa Prefecture, appear not to have been affected by the earthquakes.

It added. Ohi has two units in operation and Takahama has four. The stations are about 20 km (12 miles) from each other and both are in the affected area along Japan’s west coast.

Hokuriku Electric Power’s two-unit Shika nuclear station, about 250 km (155 miles) north of Ohi and closest to the strongest quake’s epicenter, has been offline since the 2011 Fukushima disaster and saw no impact from the quake, the NRA said.

It added there is “no risk of radioactivity leaking from nuclear power plants” in the areas affected by the earthquakes and tsunami.

The International Atomic Energy Agency said it is in contact with Japan’s Nuclear Regulatory Authority (NRA) and the NRA had confirmed no abnormalities in nuclear power plants within the affected area.

Status of Japan’s Nuclear Power Plants

Before Fukushima-Daiichi, Japan’s fleet of 54 nuclear plants generated about 30% of the country’s electricity. According to the International Atomic Energy Agency that figure was 7.2% in 2021.

Among the 33 operable nuclear reactors in Japan, 12 have now resumed operations after meeting post-Fukushima safety standards. It is expected that as many as 20 could be in revenue service by the end of 2024.

The NRA recently approved the delivery and installation of new nuclear fuel for the seven BWRs at TEPCO’s massive Kashiwazaki-Kariwa power station in Niigata prefecture which is north of the epicenter of the earthquake that occurred on 01/01/24. (map)

The restarted nuclear plants are: Sendai-1 and -2, Genkai-3 and -4, Ikata-3, Mihama-3, Ohi-3 and -4 and Takahama-1, -2, -3 and -4.

Prime minister Fumio Kishida’s government wants nuclear power generation to play a greater role in efforts to cut carbon emissions and ensure stable sources of energy.

Comparison to Fukushima Disaster of 2011

The earthquake and tsunami that hit Japan on March 11, 2011, was 8.9 on the Richter scale and the waves that hit the eastern coastline of Japan were as high as 15 meters (50 feet). The more destructive earthquakes typically have magnitudes between about 5.5 and 8.9. As the scale is logarithmic, a difference of one represents an approximate thirtyfold difference in magnitude.

Image Source: SMS Tsunami Warning Center

The March 11, 2011, tsunami, which resulted from the earthquake which had an epicenter just offshore of Japan’s east coast, disabled the power supply and cooling of three Fukushima Daiichi reactors, causing a major nuclear accident. All three cores largely melted in the first three days. All four reactors were scrapped and all of Japan’s nuclear reactors were shut down for safety checks.

If the reactors had been located at a higher elevation, and if the power supply and control lines had not been located on the seaward side of the site, its plausible that some of the damaged from the waves might have been avoided.

Warning stones along the slopes behind the reactors, some hundreds of years old, told of prior disasters from tsunami waves. TEPCO disregarded the warnings basing its decision on the costs of building the plants at the Fukushima coastal site at a higher location v. the probability of a similar event.

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