单选题
For an industry said to be on the verge of a renaissance, nuclear power has not been coping very well with an exceptionally hot European summer. On August 8th the firm that runs Finland"s grid announced that the country might run short of power in 2009, partly as a result of the delay in the construction of a new nuclear reactor, Europe"s first in over a decade. Earlier this month the Swedish government ordered the indefinite closure of four reactors while it investigated the failure of several safety systems during a power surge at one of them.
The most serious incident took place at Forsmark I, one of the three reactors 80 miles north of Stockholm. On July 25th a short circuit on the national grid cut the plant off from the mains. An accompanying power surge knocked out two of the four generators that provide the back-up power needed to shut down the reactor. Somehow, both a mechanism that protects against power surges and an auxiliary connection to the grid failed. Happily, other safety systems worked as advertised, and staff were able to shut the reactor down safely within 45 minutes.
Despite the claims of some alarmist commentators, says Vattenfall, the utility that owns the reactor, it was always several failsafes away from a meltdown. Spokesmen were quick to point out that most of Europe"s reactors follow different designs, and so could not suffer from the same flaw. But the episode has revived a political row over nuclear power ahead of elections next month. In theory, Sweden is weaning itself off nuclear power, as mandated by a referendum in 1980. In practice, the government has not set a date to decommission any of the ten remaining plants, for want of a more efficient alternative.
In fact, a prolonged drought has been sapping Sweden"s other main source of power, hydroelectric plants. Elsewhere in Europe, hot, dry weather has not only drained reservoirs and pushed up demand for power to run air conditioners; it has also warmed up the rivers used as a source of water to cool many nuclear reactors. In most countries, environmental rules prevent nuclear power stations from releasing water above a certain temperature back into rivers. Last month, a few nuclear plants in Spain and Germany had to scale back their operations to meet the rules.
In late July, as a result of all this, European wholesale electricity prices hit record levels. Such spikes will become more frequent if, as many project, global warming brings more stifling summers, and more power-hungry appliances to cope with them. If that happens, Europe will clearly need extra generating capacity—but the past few weeks have given many reasons to wonder whether nuclear is the right source.
单选题
We learn from the text that Europe"s nuclear plants ______