Employers warned earlier in March that the Naeci 'blue book' could be ripped up next year because they 'no longer believe it can provide a viable basis for employment relations beyond April 2007.'
But union chiefs are convinced the deal - which has kept the peace on steel, power and process sites for 25 years - has got a future.
Amicus national construction officer Tom Hardacre said: 'The Government seems committed to nuclear power and the investment will be so huge that they will need industrial relations stability on the labour side.
'The Naeci is the only way of guaranteeing that, and we have an ongoing dialogue with the Government and have met with the Nuclear Development Authority.'
Amicus chiefs are in talks with employers at The Electrical Construction Industry Association and are hoping to confirm the long-term future of the Naeci agreement later this year.
The union is holding its sector conference this week in Scarborough where it will be ramming home the importance of industrial relations agreements in engineering construction, electrical contracting, plumbing and heating and ventilation.
Assistant general secretary Les Bayliss said: 'These agreements are vital to best practice in the industry and that is the line we are pushing with the Government.
'This is a vital time for the construction sector with at least a decade of growth predicted and opportunities like the London Olympics.
'The Games can be a benchmark for the industry and we are discussing with the other unions and the Government how we can make sure they are a showcase for best practice.
'We have seen how proper industrial relations models can work on projects like T5 and we are keen for that to happen again.'
The conference will also discuss the proposed merger of Amicus, GMB and T&G to form a super union of 2.5 million members with a 120,000 strong construction sector.
Mr Bayliss said: 'The merger talks are well on track and we will be looking to ballot our members by the end of this year over the proposals then to progress things during the first quarter of next year.
'Construction is a key sector in the planned new organisation.'
Construction union Ucatt is not part of the planned merger but has been involved informally with the on-going discussions despite publicly vowing to remain independent.