Readying refrigeration lines to create a 30-meter-deep frozen barrier against groundwater
Japan’s TEPCO is about to flip the switch on the infamous ‘ice wall’ intended to divert flowing groundwater around its crippled reactors at Fukushima and thus help stem the contamination of fresh groundwater at the site. The widely mischaracterized and maligned installation—which is a barrier of frozen soil rather than a wall of ice—has every chance of delivering the hoped for results, say radiation cleanup experts at U.S. national laboratories and feedback from initial system tests.
“The frozen barrier is going to work,” predicts Brian Looney, senior advisory engineer at the U.S. Department of Energy’s Savannah River National Laboratory in South Carolina and co-author of an independent assessment of TEPCO’s frozen barrier. The report, produced in collaboration with researchers at Looney’s lab and at Pacific Northwest National Laboratory, was completed in February but only released late last month; it found the system’s design to be sound and within the bounds of prior practice. Continue reading →
Nuclear power plants’ reactor pressure vessels (RPVs)—the massive steel jars that hold a nuclear plant’s fissioning fuel—face incessant abuse from their radioactive contents. And they must be built with extra toughness to withstand pressure and temperature swings in the event of a loss-of-cooling accident like the one that occurred at Fukushima in 2011. As the triple meltdowns at Fukushima Daiichi showed, the next layer of defense against a nuclear release—the so-called containment vessels—can not be counted on to actually contain molten nuclear fuel that breaches the RPV.
Nuclear safety authorities have recently discovered weaknesses in several RPVs, and their contrasting responses suggest that the ultimate lessons from Fukushima are still sinking into international nuclear power culture—especially in the United States, where the Nuclear Regulatory Commission (NRC) is resisting calls to mandate tougher inspection of RPVs. Continue reading →
Amidst the stubbornly disappointing string of news emanating from Japan’s Fukushima Daiichi nuclear complex, there are signs that its melting nuclear fuel rods are inspiring some important and long-overdue developments in global power systems. And there’s good news for both nuclear supporters and critics.
Chancellor Angela Merkel’s decision last month to shut down Germany’s oldest nuclear reactors and temporarily scrub life extensions for the rest was widely seen as a sop to voters in the state of Baden-Württemberg. Well, Merkel’s Conservative Democrats lost the state to the Green Party, and she hasn’t looked back. Last week a document leaked from Germany’s Economy Ministry and reported by Bloomberg revealed plans to revamp the power grid–a precondition to replacing nuclear energy with solar, wind and other renewable power sources. Continue reading →
For those looking for hope amidst the nuclear threat afflicting post-Tsunami Japan, there are some glimmers of possibly positive developments to report from the Fukushima Daiichi nuclear power complex:
Japanese authorities say that water canons and aerial water drops from helicopters may have stabilized reactor 3 and its fuel pool (video below). Of Fukushima Daiichi’s six reactors this was viewed as the most dangerous Continue reading →
An explosion earlier today at Japan’s crippled Fukushima Daiichi nuclear power plant could indicate that the primary containment vessels protecting two of its reactors have now been breached. And yet, stunningly, that was not the day’s worst news. Instead concern increasingly focused on the plant’s highly radioactive spent fuel rods, stored in cooling pools above the reactors.
Damage sustained from last week’s massive earthquake and tsunami as well as subsequent fires and hydrogen explosions have critically limited plant operator Tokyo Electric Power’s ability to maintain cooling in several of the plants’ pools or even to replace water that is evaporating or boiling away. U.S. Nuclear Regulatory Commission chairman Gregory Jaczko told a Senate panel this afternoon that one of the pools was empty and that heating of the fuel bundles could thus melt them down—an outcome that could spread radioactive elements far beyond the site. Continue reading →