Arwel Jones from the National Library of Wales told ITV News that he is hoping that the damage will be limited - "the most valuable stuff is housed in purpose-built cells at the very bottom of the library, and this fire is at the very top."
He admitted to concern that the damage from water pumped onto the building by firefighters would be as bad as the fire damage.
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Wales are hopeful all of their fresh injury concerns will be available ahead of the opening game of the autumn series against Australia.
Fitness instructor Phil Carleton is world powerlifting champion, despite only taking up the sport in the summer.
Cloudy for all with the odd spot of rain, particularly across central and southern parts of Wales.