Exact string match and replace in SQL??

Hi,

This column called Destinations has country names like Cananda,France or Iran/Syria.
I am trying to replace those with the trigraphs.
How do I match exact string??

I changed Iran to IRQ then I had a few IR. so when I replace IR with IRQ.
Previous IRQ became, IRQQ.

Is it possible to match exactly string not partial??

I used update table set location=replace(location, 'sss','dffdf')

Thannks