Clare Crockett, 33, was tragically killed in an earthquake in Ecuador in April 2016.
The building where she had been teaching music collapsed.
Ms Crockett, from the Brandywell, was a larger-than-life character who had been an actor before choosing the religious life.
She turned down a chance to present on children’s TV channel Nickelodeon to become a nun.
She said friends were in disbelief when she declared she was going to be a nun while holding a “beer in one hand and a cigarette in the other”.
She ultimately took her Holy Orders with the Servant Sisters of the Home of the Mother order.
Her motto in life was “all or nothing” and she has previously been associated with fertility miracles.
The opening of the cause for the beatification of Sr Clare is scheduled to take place in the Cathedral of Alcala de Henares in Madrid at 5.30 pm local time (4.30 pm UK and Ireland time).
The ceremony is seen as a first step towards sainthood.
Friends and family have travelled for the event, which will be livestreamed online and at the Brunswick Moviebowl in Derry.
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