LONDON, Sept 15 (Reuters) - The world nuclear industry aims to build about 1,000 gigawatts of new nuclear reactor capacity by 2050, World Nuclear Association Director-general Agneta Rising said on Thursday.

Past installations have often been below 5 gigawatt (GW) or less per year, but in 2014 the industry built 5 GW, which doubled to 10 GW in 2015. One gigawatt is the equivalent of about one medium-size nuclear reactor.

"We should be able to deliver 1,000 GW of new nuclear by 2050," Rising said at the opening of the annual WNA conference in London.

She said the target was for 10 GW per year from 2016 to 2020, rising to 25 GW per year from 2021 to 2025 and to 33 GW per year from 2026 to 2050.

Rising said the UK government's decision to go ahead with the 3.2 GW Hinkley Point project is an important boost for the industry.

"We congratulate the UK government on going ahead with the Hinkley Point decision. It is important to have reliable low-carbon energy sources."

(Reporting by Geert De Clercq and Susanna Twidale; editing by Jason Neely) ((geert.declercq@thomsonreuters.com; +33 14949 5343; Reuters Messaging: Twitter: @gvdeclercq))