The Western Health and Social Services Board (WHSSB) was authorised to dump low level radioactive waste at the old Culmore landfill site from 1978, the Sentinel can reveal.
But this authorisation was cancelled in 1998.
The Northern Ireland Environment Agency (NIEA) says currently no radioactive waste is disposed of via the practice of controlled burial in Northern Ireland.
A spokesperson for the Department of the Environment (DoE) told the paper: “In 1978 the WHSSB was issued with an Authorisation under the Radioactive Substances Act 1960 to dispose of low level radioactive waste to a place provided by the Londonderry City Council for the disposal of refuse at Culmore Point, Londonderry for the purpose of disposal by a practice known as ‘controlled burial.’
“The WHSSB were required to give prior notice to the Council of any such disposals.
“A revised Authorisation was issued in 1998 which cancelled the option of disposal via controlled burial to Culmore Point.”
According to the Hansard record only one of four authorised sites - at Dargan Road, Belfast, was used between 1994 and 1998.
The Sentinel can reveal that small volumes (50 cubic metres per year) of Tritium, Carbon-14, Technetium and other isotopes with a half life of less than one year from hospitals and universities were dumped in the Belfast landfill site. A small amount of isotopes with a half life of more than a year were disposed of in Belfast in 1995.
Back in 1997, the newly-incumbent Environment junior in London, Angela Eagles, advised the “disposal of low radioactive waste [was] authorised under the Radioactive Substances Act 1993” at Derry City Council’s Culmore Point.
The dump - which lies on the Lough Foyle shore - was also revealed to have been one of just three unlined dumps in Northern Ireland where radioactive detritus could have been legally dumped. The risk of leachate flowing into underlying soils or groundwater would thus have been greater than at lined dumps, such as that at Dargan Road.
Ms Eagles said the radiological impact of disposals to these landfill sites were assessed by the Environment Agencies and the EHS - since succeeded by the NIEA - when determining applications for authorisation. Newly de-classified Government documents have shown two consignments of hospital waste were disposed of at the municipal dump in Culmore between 1977 and 1982.
Mark H. Durkan has asked the NIEA to report.