【单选题】

Throughout Japan’s recent history of earthquakes, fires and tsunamis, none have matched the combined fury of those that battered the north of the country on March 11th, killing hundreds of people and leaving at least 1,000 unaccounted for.But on March 12th the Japanese faced another danger: a nuclear accident.

Two nuclear plants near the coast in Fukushima, a prefecture northeast of Tokyo, were being handled as emergency situations following the failure of systems to cool five nuclear reactors that have overheateD、If any were to release large quantities of radioactive material, it could create s whole new level of catastrophe.
At this point, it is hard to gauge the degree of risk. It is an unprecedented situation in Japan, which is one of the world’s most nuclear intensive countries. Overnight, the government extended the radius from which it evacuated people near the Fukushima FirstDaiichi) plant from 3 kilometers to 10km; according to news agency reports. This encompasses tens of thousands of people.
This morning, the plant, which is operated by TokyoElectric Power (Tepco) and is among the largest in the world, released some of the radioactive vapor that has built up in the first plant, in order to let off some of the pressure. It said radiation levels were not threatening—though in a central control room, they had risen to 1,000 times normal levels.
In its second plant, a few miles away, temperatures in three reactors have been reported to be three times the normal level; Tepco has decided to release pressure there, too. Many Japanese are worried that Tepco may downplay the risks: it has in the past. Whatever the immediate danger, this incident is bound to produce some soul-searching in quake-prone Japan about its nuclear-power industry, which the government has been keenly trying to promote around the world because as a green and safe industry.
Since last night, the government of Naoto Kan has so far appeared ready to share regular data on the status of the plants with the public, though it is obviously anxious not to sow paniC、It may not have helped that the initial reports were inconsistent: as the prime minister was telling reporters on Friday evening that the country’s nuclear power plants had automatically shut down as they should, the national news-agency, Kyodo, was reporting "abnormalities" at the Fukushima reactors.
The damage seems to have come from a variety of sources: the earthquake forced the plants to immediately halt operations, as they should have done.But the cooling systems, some of which use sea water to keep the reactor temperatures down, appear to have been affected by the tsunami.And backup power systems also appear to have failed, though some battery-powered replacements have been brought in.
There is not much talk as yet in Japan of what would happen in the worst case scenario that a reactor would overheat to the point that there was a meltdown or an explosion that released large amounts of radioactive material. There is more of that sort of discussion among pundits inAmerica, however, which the Japanese can hear on international news channels like theBBC、
Mr Kan, the prime minister, visited at least one of the plants by helicopter early Saturday, and returned saying there was no reason to expect adverse health affects. Whether he is right or not, he has a huge crisis on his hands. Latest reports from theDefense Ministry indicate the death toil could exceed 1,000; in Fukushima prefecture alone, 1,800 houses were destroyeD、Up to 300 bodies were washed ashore after the tsunami, and fires have raged along the NorthEastern coastline. Four trains are reportedly missing, as is a ship with 100 passengers.
There are regular aftershocks, too, which inevitably keeps the public on edge and must continue to be terrifying in devastated cities like Sendai, near the epicenter of the quake, and those in FukushimA、