It is correct and usable in written English.
You can use it when you are speaking about the location of something. For example, "The primary site of the test was the university library."
This room was also the primary site of sexual violence.
Their principal function is to act as the primary site of photosynthesis in the plant.
The feature was a primary site of exploration for the Apollo 15 lunar-landing mission.
The lysosome is the primary site of lipid catabolism.
b Tumor cells from the primary site of the scalp (biopsy specimen).
The pattern of metastases depends upon the primary site of mucosal melanoma.
The liver is the primary site of distant hematogenous metastases for cancers of the gastrointestinal tract.
a The primary site of angiosarcoma of the scalp shows infiltrative spread.
The liver is the primary site of recurrence in 12 15% of breast cancer patients [1].
The lung is an important open organ and the primary site of respiration.
As skin muscle is the primary site of exposure, pollutants affected the epidermis abruptly.
