New Grad Internship Bond

I will be graduating from Nursing school this December. A hospital has offered me an internship position with a reasonable starting salary. The Internship has 8 weeks of structured classroom instruction and also a mentorship program.
However they want me to sign a bond that I will work with them for 18 months or else have to pay back a $ 10k fine (prorated based on if and when I leave in 2 yrs). Is this ting common practice ? I just wanted to make sure im not signing something outside the norm.
Thanks