The listing, if approved by the securities regulator, could be the largest on the mainland since Agricultural Bank of China Ltd (>> Agricultural Bank of China Ltd) in July 2010 - though Guotai Junan Securities Co Ltd could take that accolade after applying for an IPO to raise 22 billion yuan, based on Reuters calculations.

State-owned China National Nuclear said in a preliminary prospectus on the regulator's website that it plans to sell 3.651 billion shares, or 25 percent of its enlarged capital base, to fund projects and replenish working capital.

The listing would be part of the government's drive towards cleaner energy, under which it aims for installed nuclear power capacity of 58 gigawatts (GW) by 2020 from 14.6 GW in 2013, rising to 200 GW by 2030 - a goal analysts labelled ambitious.

Expansion was suspended after the 2011 nuclear disaster at Fukushima, Japan, but plant construction is widely expected to resume in coming months.

China, the world's largest power producer, has emerged as the biggest market for nuclear plants, approving four to eight projects a year for the rest of the decade, many using U.S. or French technology, according to some estimates.

The country generates less than 2 percent of electricity from 17 nuclear reactors - nine owned by China National Nuclear and the rest by state-owned China General Nuclear Power Corporation (CGN). A further 31 more are under construction.

China National Nuclear, descended from the former nuclear ministry, is one of the country's biggest central-government controlled conglomerates and maintains strong military links.

The utility, alongside CGN, has been looking to internationalize its technologies and designs, many of which were developed with Toshiba Corp (>> Toshiba Corp) subsidiary Westinghouse and Areva SA (>> AREVA).

Last year, China National Nuclear won a contract to build two reactors for the Karachi Coastal Nuclear Power Project in Pakistan at a cost of $9.59 billion.

(Reporting by Samuel Shen, Kazunori Takada and Fayen Wong; Editing by Christopher Cushing)

Stocks treated in this article : Toshiba Corp, AREVA, Agricultural Bank of China Ltd