The site is not expected to be totally cleared until 2096
A new storage centre that will house low level nuclear waste at the former Trawsfynydd nuclear power station has been officially opened.
Designed to stand until the end of the century it will store up to 333 crates of the waste mixed with concrete.
Meanwhile, local assembly member Dafydd Elis Thomas has publicly backed a new reactor for Wylfa B on Anglesey.
The Dwyfor Meirionnydd Plaid Cymru AM for said it would utilise technical skills at the area's two nuclear sites.
Lord Elis Thomas, who was opening the new waste storage facility at Trawsfynydd, said it was the first time he had come out in public in support of a new reactor.
BBC Wales environment correspondent Iolo ap Dafydd said it was in contrast to Plaid Cymru's stance on nuclear power.
In the party's 2005 general election manifesto, Plaid said it "does not support new nuclear power stations, particularly as civil nuclear power fuels nuclear weapons development; is heavily subsidised; and cannot safely dispose of the highly toxic waste".
Its 2007 assembly election manifesto said while Labour had confined itself to wind farms in a limited number of area, Plaid pledged to "bring clean secure energy to communities across Wales by supporting a range of alternatives including marine power, micro generation and fuel cell technology".
On the Trawsfynydd centre, site mangers said people living nearby should have no concerns as there were plenty of safeguards in place.
But campaigners opposed to new nuclear power stations said decommissioning costs were rising.
Work started to decommission the plant in 1993 with contractor Magnox North carrying out the clean-up for the Nuclear Decommissioning Authority (NDA).
Dr Phil Sprague, site director, said: "It's a major milestone for us, it's a major part of moving the waste to its final resting place.
"We are doing it in a slow methodical way.
"The waste itself is mixed with concrete and stored inside a steel box so it's what we call passively safe."
He said people living in the area need have "no concerns at all" about safety.
"It's not going to move anywhere, it's not going to go anywhere.
"There are plenty of barriers to safeguard people and the environment."
The storage facility is being officially opened by the Assembly's presiding officer Dafydd Elis Thomas.
The waste is the debris from vaults beneath the twin reactors and the old concrete towers which can still be seen from the A470 which runs pass the site.
If a national repository - or a new national centre to hold all the UK's nuclear waste has not been found, the waste could be retained at Trawsfynydd possibly until the site has been totally cleared by 2096.
Dylan Morgan, of the anti nuclear campaigning group People Against Wylfa B, said: "The legacy waste of the past 50 years is a massive headache.
"It's going to cost the NDU upwards of £80b to clean up the mess of all the nuclear power stations and of Sellafield.
"What we should emphasise about Trawsfynydd, while we welcome the setting up of a safe store for intermediate level waste the big problem remains the higher level waste within the reactor building."