LAING O'Rourke is moving into the nuclear market with a bid to build a £40 million storage plant at Sellafield.
The firm is believed to be competing with more established rivals including Nuttall and Amec for the storage container scheme.
A source at O'Rourke said the British Nuclear Group is keen to get new firms involved in decommissioning work, which is estimated to be worth up to £70 billion.
He said: 'The client wants to see some new names on the list because there is the feeling it's a bit of a closed shop.
'This job is out for tender so we thought we'd have a go. The nuclear market is massive and Sellafield will account for a major chunk of it.' But rival firms warned that getting a foothold in the market will not be easy.
One company director said: 'The nuclear sector is a very different beast to normal civils work.
'There is a totally different culture with extreme attention to safety and a plethora of rules, regulations and security measures to comply with.
'Production rates are also much lower on nuclear jobs compared to normal sites but I'm sure O'Rourke will have a chance of winning this job if they put in their usual competitive tender.' A Sellafield spokeswoman said: 'It is fairly early in the process for this scheme so we don't want to comment on the firms involved.' News of O'Rourke's move into nuclear work came as it emerged the firm is also looking to expand in China.
O'Rourke is already involved in Chinese projects but is now believed to be looking to link up with a local partner company to expand in the country.
One local source said: 'They are looking at the water pipe relining market, bringing leaking pipes back up to standard. Also, much of China's sewer network is in a bad condition so there is a potentially huge market there. I think they are talking to several companies at the moment.'