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Politics : View from the Center and Left -- Ignore unavailable to you. Want to Upgrade?

To: Wharf Rat who wrote (189970)	5/28/2012 10:20:18 AM
From: Wharf Rat	Respond to of 545080

Spent Fuel Rods Drive Growing Fear Over Plant in Japan Tomohiro Ohsumi/Bloomberg News Reporters and Tepco workers at Reactor No. 4 at Fukushima Daiichi, which the environment and nuclear minister visited Saturday. By HIROKO TABUCHI and MATTHEW L. WALD Published: May 26, 2012 TOKYO — What passes for normal at the Fukushima Daiichi plant today would have caused shudders among even the most sanguine of experts before an earthquake and tsunami set off the world’s second most serious nuclear crisis after Chernobyl. Fourteen months after the accident, a pool brimming with used fuel rods and filled with vast quantities of radioactive cesium still sits on the top floor of a heavily damaged reactor building, covered only with plastic. The public’s fears about the pool have grown in recent months as some scientists have warned that it has the most potential for setting off a new catastrophe, now that the three nuclear reactors that suffered meltdowns are in a more stable state, and as frequent quakes continue to rattle the region. The worries picked up new traction in recent days after the operator of the plant, Tokyo Electric Power Company, or Tepco, said it had found a slight bulge in one of the walls of the reactor building, stoking fears over the building’s safety. To try to quell such worries, the government sent the environment and nuclear minister to the plant on Saturday, where he climbed a makeshift staircase in protective garb to look at the structure supporting the pool, which he said appeared sound. The minister, Goshi Hosono, added that although the government accepted Tepco’s assurances that reinforcement work had shored up the building, it ordered the company to conduct further studies because of the bulge. Some outside experts have also worked to allay fears, saying that the fuel in the pool is now so old that it cannot generate enough heat to start the kind of accident that would allow radioactive material to escape. But many Japanese scoff at those assurances and point out that even if the building is strong enough, which they question, the jury-rigged cooling system for the pool has already malfunctioned several times, including a 24-hour failure in April. Had the outages continued, they would have left the rods at risk of dangerous overheating. Government critics are especially concerned, since Tepco has said the soonest it could begin emptying the pool is late 2013, dashing hopes for earlier action. “The No. 4 reactor is visibly damaged and in a fragile state, down to the floor that holds the spent fuel pool,” said Hiroaki Koide, an assistant professor at Kyoto University’s Research Reactor Institute and one of the experts raising concerns. “Any radioactive release could be huge and go directly into the environment.” Senator Ron Wyden, Democrat of Oregon, expressed similar concerns during a trip to Japan last month. The fears over the pool at Reactor No. 4 are helping to undermine assurances by Tepco and the Japanese government that the Fukushima plant has been stabilized, and are highlighting how complicated the cleanup of the site, expected to take decades, will be. The concerns are also raising questions about whether Japan’s all-out effort to convince its citizens that nuclear power is safe kept the authorities from exploring other — and some say safer — options for storing used fuel rods. “It was taboo to raise questions about the spent fuel that was piling up,” said Hideo Kimura, who worked as a nuclear fuel engineer at the Fukushima Daiichi plant in the 1990s. “But it was clear that there was nowhere for the spent fuel to go.” The worst-case situations for Reactor No. 4 would be for the pool to run dry if there is another problem with the cooling system and the rods catch fire, releasing enormous amounts of radioactive material, or for fission to restart if the metal panels that separate the rods are knocked over in a quake. That would be especially bad because the pool, unlike reactors, lacks containment vessels to hold in radioactive materials. (Even the roof that used to exist would be no match if the rods caught fire, for instance.) There is considerable disagreement among scientists over whether such catastrophes are possible. But some argue that whether the chances are small or large, changes should be made quickly because of the magnitude of the potential calamity. cont. nytimes.com