This photo taken from a Kyodo News airplane on April 30, 2025, shows the Tomari nuclear power plant’s No. 3 reactor in Hokkaido. (Kyodo)
TOKYO (Kyodo) — The Nuclear Regulation Authority effectively endorsed on Wednesday the restart of a reactor at the sole nuclear power plant on Japan’s northern main island of Hokkaido, approving a draft report that concluded the reactor had cleared its safety review.
With semiconductor and data center businesses projected to boost the prefecture’s electricity demand, Hokkaido Electric Power Co. plans to restart the Tomari plant’s No. 3 unit, Japan’s newest reactor, after completing the construction of a seawall by around March 2027, among other mandatory safety measures.
After the company applied for the review in July 2013, the authority checked whether the utility’s plan satisfies its new safety standards, enforced following the 2011 nuclear accident in Fukushima Prefecture triggered by a massive earthquake and tsunami.
The focus of the review included whether geologic faults on the premises of the power plant were active. The nuclear watchdog is still reviewing the safety of the No. 1 and No. 2 reactors.
Hokkaido Electric has upgraded its quake-resistant design for the facilities to cope with more intense acceleration of seismic waves — from up to 550 gals to 693 gals — and raised the height of potential tsunami it can withstand from 7.3 meters to 17.8 meters.
The utility had built a 16.5-meter-high seawall in 2014, but it will raise it to 19 meters based on the regulatory body’s advice on the possibility of liquefaction of soil.
The reactor will also be ready for an accumulation of volcanic ash to a depth of 40 centimeters.
The cost of construction related to safety measures for the No. 3 reactor, which started operation in December 2009, has ballooned to about 515 billion yen ($3.6 billion) from over 90 billion yen for all three reactors.
The Tomari power station began the operation of the No. 1 reactor in 1989 and the No. 2 unit in 1991, but all three reactors had halted by May 2012 under the stricter safety regulations implemented after the nuclear disaster.
The Sapporo District Court ordered the Tomari nuclear power plant to remain offline in May 2022 due to safety concerns. The case is currently being heard at the Sapporo High Court.
AloJapan.com