I have some Portriga Rapid which dates back to the 70's & 80's which has been refrigerated most of it's life. Paper is still as good as new.

Portriga is Agfa's warm tone fiber paper while Brovira is a decidedly cold tone paper. Bromide emulsions don't tend to keep as well as chloride emulsions (warm tones) nevertheless the Brovira may still be capable of producing fine results.

If the paper does exhibit some fogging or greying in the highlights try mixing some Kodak #1 restrainer aka benzotriazole in increasing amounts to your developer as this could well retard the the highlight fogging.

Cheers