This problem is so massive that it will likely take several decades and tens of billions of dollars to fix.Īhead of the anniversary of the earthquake and tsunami that triggered the disaster, CNET paid a visit to Fukushima to look at the different kinds of technology being employed at the facility, whether it's robots going into the reactors themselves, or drones and virtual reality offering views of the facility.
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It's also a place where technology plays a unique - and critical - role in the cleanup efforts.įixing Fukushima is a multipart series that explores the role technology plays in cleaning up the worst nuclear disaster in history. The meltdown at the Fukushima Daiichi Nuclear Power Plant in 2011 was the worst nuclear disaster in history.
To learn more about the ongoing cleanup efforts, read Japan's latest report, issued to the International Atomic Energy Agency earlier this month. "I hope that the pros and cons will be broadly discussed.Editor's note: This story originally ran on March 4, 2018, and we're reposting it for the 10th anniversary of the Fukushima Daiichi nuclear disaster to give readers a sense of the technology being employed to fix this enormous problem, which continues today. "There was already some controversy about pebble-bed HTGRs, but my impression was that many problems of them were not sufficiently published and thus not known to some of my colleagues," said Moormann. They also advise against the current plan of storing fuel waste in above-ground canisters. These should include continuous monitoring, the insulation of containment and cooling systems, and an extended start-up phase to allow the reactor to be observed and monitored as it comes up to operational temperature. To reduce risk, the paper’s authors advise that precautionary steps should be taken. Moormann also believes that such reactors produce a higher volume of radioactive waste than conventional reactors, although proponents of the design argue that the waste remains locked within the layers of ceramic and graphite that form the fuel pebbles. One issue that has arisen with prototype pebble bed reactors is that localised hotspots can form in the core and unexpectedly high levels of radioactive dust have formed. “The absence of core meltdown accidents does not mean that a dangerous event is not possible," said Moormann. Moormann, Kemp and Li’s main concern is that because pebble bed reactors are regarded as intrinsically safe, HTR-PM has been built without a high-pressure, leak-tight containment structure to serve asbackup in case of accidental release of radioactive material, and it also does not have a redundant active cooling system. A realistic understanding of those risks is essential, especially for operators, and so we urge caution and a spirit of scientific inquiry in the operation of HTR-PM.” Writing with Scott Kemp and Ju Li of MIT, Moorman said: “There is no reason for any kind of panic, but nuclear technology has risk in any case. In a paper in the journal Joule, German chemist and reactor safety expert Rainer Moormann, a critic of pebble bed reactors since the early 2000s, urges caution over the operation of HTR-PM. Image from Journal of Computational Multiphase Flows
The main nuclear island structures of the HTR-PM reactor at Shidao Bay. It is believed to be the first "Generation IV" reactor to enter service. Originally developed in Germany in the 1960s to breed uranium from thorium fuel, they operate at a much higher temperature than PWRs – over 900☌ at the reactor outlet compared with around 300☌ for a PWR – and are often believed to be fundamentally safer than PWRs because they are immune to meltdown even in the event of total coolant loss.Ī new commercial-scale pebble bed reactor called HTR-PM, with a thermal capacity of 200MW, is set to come online in China at the Shidao Bay Nuclear Power Plant (on the east coast of the body of water that separates China from the Korean peninsula) later this year. Instead of the fuel being packed into rods that are arranged in an array and surrounded by a liquid coolant, the fuel – which contains uranium enriched to lower degree than conventional nuclear fuel – is packed into spherical particles surrounded by layers of ceramic, and the coolant is helium under moderate pressure (around 30 atm).
Pebble-bed reactors use a very different reactor core configuration from conventional pressurised water reactors.