One loop partition function in plane waves R-R background

We compute the one loop partition function of type IIB string in plane wave R-R 5-form background F-5 using both path integral and operator formalisms and show that the two results agree perfectly. The result turns out to be equal to the partition function in the flat background. We also study the Tadpole cancellation for the unoriented closed and open string model in plane wave R-R 5-form background studied in [6] and find that the cancellation of the Tadpole requires the gauge group to be SO(8).