On November 21, 2016 at 5:59 a.m., a 6.9-magnitude earthquake triggered a one- meter (39 inches) tsunami that hit the Fukushima Daiichi Nuclear Power Plant—the same nuclear power plant struck six years ago by a record-breaking earthquake and tsunami, which resulted in a meltdown of the cores of three reactors. The accident six years ago prompted renewed international focus on safety measures at nuclear facilities and led to some significant policy changes, but the most recent earthquake demonstrated that, even in the area most affected by the March 11, 2011 accident, vulnerabilities remain.
In 2011, most of the damage at the Fukushima Daiichi Nuclear Power Plant resulted from a failure of the cooling systems of reactors No. 1, 2, and 3. The cooling system for more than 1,000 spent fuel rods in the pool in the No. 4 reactor (which was not operating on March 11) shut down, but the dry storage facilities at Fukushima were just fine. After the 2016 earthquake, the cooling systems of the spent nuclear fuel pool at the Fukushima Daini Nuclear Power Plant shut down for 90 minutes. The earthquake shook the water cooling tank and its sensor detected abnormally low water levels, leading to the shutdown. Luckily, none of the reactors at the Daini sites had been operational for some time, but the earthquake itself was not an unusual event. Significant earthquakes of 6.0-6.9 magnitude occur on average 17 times per year in and around Japan – 1/10 the total number of earthquakes in the world. The 2016 demonstrates that the cooling systems for spent nuclear fuel pools remain vulnerable, particularly given the high level of seismic activity. So why are there still only two dry-cask storage facilities total in Japan?
Spent fuel storage is an urgent issue in Japan for many reasons, including safety. Even before the Fukushima accident in 2011, spent fuel with pools in Japan were rapidly filling up, creating pressure to increase storage capacity. In 2016, Japanese government revised the grants paid to municipalities to encourage them to accept the installation of dry-cask storage and the Nuclear Regulation Authority (NRA) eased earthquake-related and other regulations on storing spent fuel to provide incentives to increase the use of dry-cask facilities, but the public seems to oppose all things nuclear. A March 2017 poll conducted by the Mainichi Shimbun newspaper showed 55% of people opposed to restarting nuclear power.
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