The body responsible for cleaning up ageing nuclear power stations wants a faster clean-up of sites in Wales.
The Nuclear Decommissioning Authority (NDA) wants Trawsfynydd turned back to a "green field" site within 25 years, instead of more than a century.
The NDA also wants to speed up site restoration at Wylfa on Anglesey, which is due to stop production in 2010.
The current timetable sees the site returned to "brown field" status in 2125.
But the NDA believes there is a strong case to release the site for development within 25 years - possibly as early as 2035.
The authority's intentions were laid out in its first report, published on Thursday.
In it, it said the cost of dealing with Britain's ageing power stations would cost £8bn more than first thought. It estimated that £56bn would have to be spent cleaning up 20 sites across the UK.
It has published consultation plans which will be open until 11 November, with a proposal finalised in December.
Trawsfyndd - which is licensed to Magnox Electric Limited - operated from 1965 to 1991. Decommissioning is already underway.
Wylfa will stop generating power in 2010
It was the only power station to be built inland, adjacent to a lake, which provided cooling water when the station was operation.
Under the existing plans it is assumed the site would be returned to green field status. Final site clearance and closure would be in 2096.
Wylfa - also a Magnox plant - was the last and largest power station of its type to be built. Although the end of production is planned for 2010, the closure date for the site is subject to change by the government.
The NDA will continue to run the plant until it closes, unless there are any technical problems or economic grounds to force early closure.
Under the current proposals, the site would be returned to brown field status in 2125.
NDA chairman Sir Anthony Cleaver said the £56bn estimate of the final clear-up was based on the costs over the whole lifetime of the sites, calculated by the UK Atomic Energy Authority and British Nuclear Fuels.
"It's important to recognise that we're talking about a programme that's running just over a century, so those changes in estimates don't seem very surprising," Sir Anthony said.
He said the consultation document was the first time anyone had had the opportunity to put together a coherent programme for all 20 sites.