The first intake was delivered into One Wing at the jail, which had been criticised as being too old at the time of the downsizing.
"All the places which have been opened up for prisoners have been refurbished to bring them up to the adequate security requirements," the spokesperson said.
Former Grafton jail governor John Heffernan said the decision was pure spin.
"We all know One Wing, that was the main basis of the argument that both the department and the government presented to justify the partial closure of the centre a few years ago," Mr Heffernan said.
"It was described at the time as archaic in nature and therefore not up to the standard required for modern day incarceration. Well, how things change.
"I would like to think that the decision to bring the jail back online was the result of a pang of conscience by the government, that their moral compass had suddenly been recalibrated to distinguish right from wrong. But no, the decision is purely one of necessity. The inmate numbers are climbing through the roof and the corrections department has no where to put the influx of offenders."