Hi!

My microwave oven is almost 10 years old. I didn't notice a change in
the way it works, but I am still concerned whether there is a
"radiation leak" after so many years in operation. Any expert advice
will be appreciated.

There's nothing to be concerned about unless the oven has been physically
damaged (e.g. "dropped") in that time. Microwave ovens are very reliable and
age generally does not affect their safety. (Unless of course the oven has
been abused over time.)

William