Ministry of Defence (MoD) officials have tried to allay fears about plans to dismantle nuclear submarines at Devonport.
Space is running out for decommissioned nuclear subs
The MoD is in the second stage of public consultation on the proposals and held an exhibition and meeting at Plymouth Guildhall.
There are four firms bidding for the work to remove the reactors, and three of them are proposing dismantling the submarines at Devonport.
Eleven submarines have already been decommissioned but remain with their reactors intact floating in the docks at Rosyth in Fife and at Devonport, the UK's only nuclear-licensed dockyards.
But space is running out and there are 16 more submarines coming to the end of their working lives.
A number of proposals, including shipping the reactors to the Dounreay nuclear plant in Scotland, are also being considered as part of the consultation.
The dismantling work could create about 100 jobs, says the MoD.
But Ian Avent, of the Plymouth-based Campaign Against Nuclear Storage and Radiation (CANSAR), said many more jobs could be lost in tourism if the plans went ahead as people stayed away.
He said: "There is always a risk of an accident because you are using things like thermic lances and burning torches to cut the submarine up.
"If you had a fire in a reactor compartment, you could have the equivalent of a 'dirty bomb'."
The MoD say the reactors are defuelled before removal and the radioactivity involved is tiny.
Project manager Brian Hooper, of the Ministry of Defence, said: "There is more nuclear material in a nuclear refit than there is in cutting up one of these submarines.
"And the bids which we are considering for Devonport do not involve storing the reactors at Devonport.
"All of the bids at present are for taking the waste away from Devonport."
Dr Jane Hunt, from Lancaster University, is leading the public consultation team.
She said: "People are concerned about cancer rates and that the proposals are commercially driven and whether waste can be managed in the middle of a large city.
"People in Plymouth are saying take it somewhere remote like Scotland whereas people in Scotland are saying leave it in Plymouth."
She added: "One of the arguments that has been raised elsewhere is that Plymouth has had the benefit of the employment, so Plymouth should bear the burden of the waste.
"But clearly people in Plymouth do not feel like that."
Public consultation is continuing, with a decision expected in 2007.