Sinn Féin MEP Matt Carthy has called for the closure of the Sellafield nuclear plant in England.
Shocking revelations by the BBC's Panorama programme last night showed dangerous, radioactive material stored in degrading plastic bottles.
It also revealed that there is a lack of workers on the site on Britain’s Cumbria coast, and major risks of a major radioactive fire with devastating consequences right across western Europe.
Mr Carthy said: “Sellafield, which is a dirty word in Ireland, a nuclear free country, is now a threat to all of Europe. It must be closed and there should be a halt to the construction of any further nuclear power plants near the Irish Sea.
“The east coast of Ireland, particularly counties Louth and Meath, would be very directly threatened by any accident or fire at Sellafield.
“There has already been a long list of contamination incidents at Sellafield which is a grave threat to the health of citizens, not just in Britain itself but in Ireland and other European countries.
“Clearly the Irish Government must confront their British counterparts on this issue.
“Sellafield must be closed and we need to see concerted political action, especially by the Irish Government but also at a European level to this end.
“I intend to raise the Sellafield issue, and in particular the latest disturbing revelations, with EU Environment Commissione, Karmenu Vellaat the earliest opportunity.”
Sellafield nuclear site is not a danger to the public, the British Government has insisted after a whistleblower warned of a string of safety concerns.
The UK's Business minister Nick Hurd told MPs there the safety regulator is already aware of fears raised in a BBC Panorama programme and that "important progress has been made".
The BBC said its investigation was prompted by a former senior manager turned whistleblower who was worried about conditions at the site in Cumbria.
Answering an urgent question, Mr Hurd told the British House of Commons: "In relation to Sellafield, I can assure the House there is no safety risk to site staff or the public and it is wrong to suggest otherwise."
He added: "The Office for Nuclear Regulation (ONR) is satisfied, and has confirmed again this morning, that Sellafield is safe.
"The regulation of these facilities is the ONR's top priority, with a team of around 50 inspectors deployed. The ONR requires the site to continuously improve.
"The ONR has confirmed that none of the issues raised in the Panorama programme are new.
"The ONR operates transparently. The issues facing Sellafield have been reported to Parliament in the ONR's annual report and accounts where the ONR concluded that important progress has been made."
In Monday's Panorama show it was alleged that parts of the nuclear facility regularly have too few staff to operate safely and that radioactive plutonium and uranium have been stored in plastic bottles.
The whistleblower is reported to have told the programme his biggest fear was a fire breaking out in one of the nuclear waste silos or one of the processing plants.
The head of nuclear safety at Sellafield, Dr Rex Strong, told the BBC the site is safe and has been improved with significant investment in recent years.
Labour MP Jamie Reed, who described himself as a "third generation Sellafield worker", urged the regulator to respond to the allegations on a "point-by-point basis".
The Copeland MP said the site is a "national asset" and the British Government should commit to longer-term financing of it.
Raising the urgent question, Mr Reed said: "Viability and accountability for the work undertaken there should be welcomed, I would like to see more of it and I would like to see this done in a robust and responsible way."
Mr Hurd said Sellafield is "uniquely challenging" as the site of the UK's earliest nuclear programmes, when there was no plan for disposing of nuclear waste.
He insisted that the regulator is "doing their job and progress is being made".