(Adds detail about business units)
By Geert De Clercq
PARIS, April 30 (Reuters) - French state-controlled nuclear group Areva said tough market conditions in the United States hit reactor servicing income as it posted a drop in first-quarter revenue.
The company said its revenue fell 18.1 percent to 1.78 billion euros ($2.47 billion) in comparison with an exceptionally strong first quarter last year. The drop was 17.3 percent on a like-for-like basis, it added.
U.S nuclear operators are struggling due to competition from cheap shale gas and several reactors have been closed in the past year.
Areva's reactors and services business saw revenue slide 14 percent to 684 million euros. The unit accounted for more than a third of the firm's revenue last year, according to Thomson Reuters data.
Areva has not sold a new reactor since 2007, when China Guangdong Nuclear Power Corp in Taishan bought two reactors, but hopes deals signed in Turkey and Britain last year will lead to confirmed reactor sales.
The unit gets a major part of its revenue from servicing its installed reactor base but the firm said revenue in that segment was down in the quarter due to weak demand in the United States, where it said market conditions were difficult.
Despite the first-quarter fall, Areva said it remained confident in its ability to generate revenue in line with its target for this year and that it expected greater activity in the second half of the year.
In February, the company said that for 2014 it expected positive operational cash flow, but it expected revenue would fall by 2 to 5 percent due to lower sales of highly enriched uranium. For 2015-2016, Areva expects sales growth of 4 to 5 percent per year.
Areva's nuclear fuel division saw revenue jump 59 percent to 561 million euros due to a sharp increase in uranium enrichment volumes sold in the United States, Asia and France and the ramp-up of production at Areva's new Georges Besse II enrichment plant in the south of France.
Sales in Areva's uranium mining unit plunged 63 percent to 145 million euros. Areva said order intake remained limited due to an uncertain market environment for uranium and weak uranium prices, which have hit multi-year lows in the past weeks. .
Areva said discussions with the Niger government about its mining operations there were continuing but gave no indication about their progress or when it expected to reach a deal.
The talks have been going on for more than two years, amid sharp criticism from Niger that Areva is not giving the country its fair share of the uranium revenue.
Areva's order book across all its businesses at the end of March fell 8.8 percent to 40.2 billion euros compared a year earlier.
In February Areva reported its 2013 net loss widened to 494 million euros from 99 million euros in 2012 due to provisions on its reactor project in Finland and losses in its renewable energy business.
$1 = 0.7212 Euros Editing by Elaine Hardcastle and Pravin Char