Mr Keenan, from Belfast, was captured by terror group Islamic Jihad in Lebanon on April 11, 1986.
The writer and broadcaster then spent four-and-a-half years in a concrete cell, often in solitary confinement, blind-folded, interrogated, chained half-naked and beaten by his captors.
Earlier this week he was guest speaker at the presentation of creative writing awards to prisoners in Magilligan.
Ronnie Armour, director general of the Northern Ireland Prison Service, said that Brian’s “philosophical outlook on life is truly inspiring and especially so after an inconceivable four-and-a-half year kidnapping ordeal”.
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“He has spoken about surviving the odds and finding peace of mind in surprising places, and his words will have given great hope and encouragement to the men in our care,” he added.
“This is all about building self-esteem in prisoners, supporting and challenging them to change which in turn will help reduce reoffending and ultimately make our community a safer place to live.”
Mr Keenan was released from captivity to Syrian military forces on August 24, 1990 and driven to Damascus.