Can triple bypass surgery be safe for an 82 year old man?

Depends: The answer depends on several factors mainly having to do with how healthy the heart muscle is and how healthy the other organs are such as kidneys, lungs and blood vessels to other organs. It could range from low risk (2 -3%) to high risk(>25%).

Probably: Depends more on physical status and other risk factors: smoking emphysema, obesity, diabetes etc.