A senior official from British Nuclear Fuels has claimed that the 3.7 million iodine tablets, distributed by the Government two years ago, would have no beneficial effect in the event of radioactive material being released from Sellafield.
The claim was made during an address to a special meeting of Louth County Council.
Councillors were told that Sellafield is a very robust plant which could retain that capacity despite a terrorist attack.
John Clarke, BNFL's head of environment, said the worst thing possible would be to close Sellafield immediately as the nuclear legacy there needed to be dealt with.
Mr Clarke said Sellafield was undergoing a dramatic shift in operations in which cleaning up that legacy would be the prime objective from now on.
Sixteen councillors, TDs and candidate MEPs attended the meeting. There was a very small public attendance, with only seven people in the gallery.
Ahead of the meeting, the Radiological Protection Institute of Ireland said it has not received adequate information about BNFL's anti-terrorism plans. However, because the Government is in what it terms 'sensitive talks' with London, little detail is likely to emerge.
Apart from terrorism, the emission of radioactive material into the Irish Sea is another very sensitive issue.
Last night's RTÉ Prime Time programme revealed EU concerns over a radioactive lake at Sellafield, containing 1.3 tons of plutonium, because of gaps in its inventory and omissions in records.
