The Minister of State for Public Enterprise, Mr Joe Jacob, is seeking information from UK authorities about the closure of two reactors at the Wylfa nuclear plant in Anglesea, north Wales.
The two Magnox reactors at the plant at Wylfa have been shut down while an investigation is carried out into "unexpected marks" in the fuel channels which were discovered after a routine overhaul.
Mr Jacob has instructed officials in his Department and in the Radiological Protection Institute of Ireland to seek information from their British counterparts about reports surrounding the incident.
A spokeswoman for Mr Jacob confirmed that a preliminary report had been received from the British Nuclear Installations Inspectorate, stating that no radioactivity was released and that the significance of the incident was considered minor.
"I have consistently expressed my concerns to the UK authorities regarding the continued operation of these old Magnox reactors. I have consistently demanded their closure and will continue to do so," the Minister said.
"I am deeply concerned at the reports of this latest incident at Wylfa which serve to strengthen my determination to have these ageing Magnox reactors shut down," he added.
Celtic League, which campaigns on a broad range of issues, said the plant shutdown came just three months after the last incident, when the power station was closed because of problems with reactor fuel rods.
The group wrote to Mr Jacob asking him to seek information from the British government. In the letter, dated last Friday, Mr J. B. Moffatt, the secretary-general of the league, said that given recent developments within the nuclear industry in the UK, they were increasingly concerned about the operation of these plants.
Mr Moffatt said Wylfa was built in 1972, and in February of this year the British Department of the Environment had confirmed to the Celtic League that the station, as originally commissioned, had an anticipated operating life of 25 to 30 years.
However, British government safety regulators extended the operational life of the station, which was managed by British Nuclear Fuels, until 2004, when a further appraisal would be undertaken, he said.
A spokesman for the Health and Safety Policy Liaison Branch of the Department of the Environment in Britain confirmed that the reactors at the plant had been shut down.
He said there was a routine annual overhaul of the reactors on April 7th, and on April 20th Magnox began placing television cameras inside one of them.
The core of the reactors comprises vertical channels filled with fuel rods through which gas passes.
"I understand they found some unexpected marks on the side of one of the channels. There are two reactors at the station and they decided just in case there was any safety significance - and they don't think there is, and we don't think there is - that purely as a precautionary measure they would shut them down," he said.
The spokesman said that Magnox would have to investigate what these unexpected marks were and then make a report to the Health and Safety Policy Liaison Branch.