Is signing the university’s bond agreement involving Riba?

I am a university lecturer. I have applied to my university for study leave with pay. The university requires a bond that the person availing study leave will serve for the duration equal to the duration of study leave otherwise he/she will pay two times(double) of the salary that he will get during the period of study leave. This “two times condition” looks me as if involving Riba(sood). Please clear whether this is Riba. Can I sign this bond agreement with the university? If not then guide me what to do. Please reply me as early as possible because in three days I am to sign this bond.