Answer:
It is not possible.
Explanation:
How exact is exact? Since the circumference of a circle depends on pi, you have to discuss the nature of pi. C = pi * the diameter.
You are getting to a place where the air is pretty thin when you start dealing with pi. Pi has an infinite number of digits associated with it. Not only that, but if I were to tell you what the 100th digit was, you would have a random chance of figuring out what the 99th digit was or the 101 digit should be, that's only to the hundredth digit. The circumference would go beyond what we can measure with the thousandth digit.
In addition, pi is an irrational number. That means it cannot be represented by any kind of a fraction.