A United Nations tribunal is to rule next month on the Government's demand for information from the British authorities on the terrorist threat posed by Sellafield.
The demand is one of a series of measures sought by the Government in submissions this week to the Permanent Court of Arbitration in The Hague.
Ireland is also looking for full information on nuclear shipments in the Irish Sea, details of any accidents at the nuclear reprocessing plant in Cumbria and access to research studies into the effects of radioactive discharges from Sellafield.
In addition, the Government wants Britain to ensure that there are no liquid-waste discharges from the mixed oxide (Mox) plant at Sellafield, and that discharges from the Mox and THORP plants do not exceed 2002 levels.
The Irish demands, which would effectively result in the closure of Mox and severe restrictions on output from THORP, are certain to be rejected by British representatives making submissions before the tribunal today.
Britain has already refused to give Ireland access to information on discharges from Sellafield, citing security and commercial reasons.
However, it would have to comply if the tribunal were to decide in favour of any of the Republic's requests.
While the tribunal's sessions in The Hague have been generally open to the public, Irish demands for "reappraisals" on the terrorist threat posed by Sellafield since September 2001 were heard in private.
The Government's substantive case was abruptly adjourned last Friday when the tribunal said it had a "serious difficulty" in relation to its jurisdiction. Britain had argued that the dispute between two EU member-states should be heard by the European Court of Justice instead of the UN Convention on the Law of the Sea. The EU agrees with this position.
The shock announcement came four days into the presentation of Ireland's case by the Attorney General, Mr Rory Brady. To the embarrassment of the Government, the tribunal suspended further proceedings until December when, it is hoped, a clearer picture of the EU position will have emerged.
However, the tribunal did agree to allow Ireland to apply for provisional measures to protect the marine environment against serious pollution.
Last year, Ireland took a separate case against Sellafield under the Ospar Convention (for the protection of the marine environment in the North-East Atlantic). The result of this case, which also involved access to confidential information on the nuclear reprocessing plant, is expected shortly.
