(Updates throughout with details, comment)
By Susanna Twidale
LONDON, April 4 (Reuters) - Japanese conglomerate Hitachi Ltd's Horizon unit has applied to Britain's nuclear regulator for a site licence to build its Wylfa nuclear project in Wales, Horizon said on Tuesday.
The project is one of several new nuclear plants planned in the Britain, which is aiming to replace its ageing fleet of atomic reactors and coal plants in the next decade.
Horizon, a wholly owned subsidiary of Hitachi, plans to build and operate two nuclear reactors at Wylfa, capable of generating a total of 5.4 gigawatts of electricity, or enough to power around 10 million homes by the mid 2020s.
Britain's Office for Nuclear Regulation (ONR) said Horizon's application was the first for a new site since 2011 - for EDF's 18 billion pound ($22.40 billion) Hinkley Point C nuclear project in southwest England.
Horizon did not say how much the Wylfa project will cost, but has said it expects to make a final investment decision by the end of 2019.
In December, Japan's Nikkei newspaper reported an expected cost of 19 billion pounds ($23.7 billion) and that Hitachi would invest about 10 percent of that. A Hitachi official declined to comment on the report.
Horizon's licence application process will take around 19 months, and will include assessing safety requirements, the ONR said.
NuGen, a joint venture between Toshiba and French utility Engie also plans to build a nuclear plant in Britain in Moorside in northwest England.
But Toshiba said last month it planned to pull out of the construction work at the Moorside plant after posting a $6.3 billion writedown on its Westinghouse nuclear unit.
An ONR spokeswoman said NuGen had not yet applied for a site license for Moorside. ($1 = 0.8027 pounds) (Reporting by Susanna Twidale; editing by Jason Neely and Susan Thomas)