Workers at the nuclear site in Sellafield are launching a campaign aimed at attracting fresh investment to help guarantee its future.
The Government will be urged to support a new nuclear power station in the area and to explore the potential of re-using existing plutonium stocks.
Ministers will also be pressed to work with those councils in Cumbria that backed a recent proposal to hold studies into a disposal facility for radioactive waste.
Kevin Coyne, national officer of the Unite union, said: "Sellafield is strategically important to the UK and it is crucial for the economic survival of Cumbria. Without Sellafield, Cumbria would become an economic wilderness while Britain would struggle to meet its low-carbon energy needs.
"That's why the Sellafield Workers Campaign is calling for a three-point plan for a sustained and coordinated investment strategy, including a commitment to a new nuclear power station at the site.
"However, it is also crucial that we begin a new search for a geological disposal facility and we examine ways of effectively re-using the stockpiles of plutonium currently being stored at Sellafield."
A Department for Energy and Climate Change spokesman said: "Sellafield has hosted nuclear waste facilities for decades, and Cumbria is essential to nuclear in the UK.
"Government will ensure that the conditions are right for investment in new nuclear power plants. However, ultimately it is a commercial decision for the developers as to where the new plants will be located.
"The Government remains firmly committed to geological disposal as the right policy for the long-term safe, responsible and cost-effective management of higher-activity radioactive waste from legacy and future nuclear power stations.
"We are reviewing the site selection aspects of the managing radioactive waste safely programme, and intend to launch a public consultation on proposals for a revised siting process in the autumn."