It followed a serious riot at Spike in 1985.
State papers from 1986 show Mr Dukes sought cabinet approval to reconstruct and develop Fort Mitchel to provide more than 300 prison places, despite the fact the prison had only been opened a year earlier on the basis it would be “for as short a term as possible”.
A riot by prisoners in August 1985 resulted in the destruction of the fort’s main prison block and parts of other buildings.
Mr Dukes defended his decision on the basis that 305 new spaces could be provided within four years, including 80 in just over a year at a cost of £30,000 per place compared to the estimated cost of £127,000 for each new place at the proposed prison at Dublin’s Wheatfield.
Mr Dukes said the Spike Island prison reconstruction was a more reasonable option than reactivating plans for new prisons at Wheatfield, Cork, and Portlaoise.
He cited how the country’s prison population had risen 50% over the previous four years to about 1,900 without new purpose-built accommodation — though the prisons’ capacity was just 1,526.
Mr Dukes said prisoners had been “doubling up” in cells and placed in dormitory-style accommodation. He expressed concern that such a shortfall caused difficulties for administration of prisons and had resulted in prisoners living in conditions that were undesirable for both themselves and the maintenance of good order.
In seeking the rebuilding of Spike Island prison, he said he accepted there was an urgent need to maximise the use of existing prison accommodation.
He warned that the only real alternative was to grant early releases to prisoners on a scale the government would not be able to defend and which would have serious implications for the operation of the criminal justice system.
Around 300 prisoners were already on “special leave” because of overcrowding. Mr Dukes admitted he was “uneasy” about such numbers being released. He claimed the only way of addressing the problems of an excessive prison population and “undesirably generous” early releases was the provision of extra prison spaces.
The planned new prison at Wheatfield, which would provide 320 spaces, was not scheduled to open until 1988.
Mr Dukes also expressed frustration and disappointment that the report of a committee of inquiry into Ireland’s penal system, which was chaired by senior civil servant TK Whitaker, didn’t make specific recommendations about the provision of further prison accommodation, apart from the need for more female prisoner spaces.
The prison on Spike, mainly used to hold young offenders and joyriders, was closed permanently in 2004.