Speaking of Al-Zarqan, I came across this letter hosted and translated by MEMRI about the reactor there. Al-Zarqan is in the Khuzestan province where the Arab minority lives. The Arabs in Iran hate the regime (simply because it is Shi'a) and are probably nervous about it going nuclear. The reactor is in the middle of a highly-populated area so the Iranian government can use civilian shields as a grievance if the reactor is bombed.
Here is the translation:
From the IRGC Commander in the city of Al-Ahwaz to the director in charge at the Mehab Qudus company for Construction and Supervision Mr. Mohammed Kayafir
Re: The nuclear reactor at Al-Zarqan
Greetings,
I thank you for the good services of the Mehab Qudus company, and at the same time I must remind you of the following items:
1. All construction materials must be transported from the warehouses to the construction site in top secrecy.
2. As part of the doctrine of caution, we reiterate yet again that during the transport of all required materials, you must ensure that this [transport] does not arouse the suspicions of any citizen in the region through which you are moving.
3. In general, it is absolutely forbidden to hire any Arabic speakers or any citizen from Khuzestan in the framework of the 'Al-Zarqan Nuclear Reactor' construction project. You must ensure that all manpower, including the driver, the accountant, the warehouse manager, the laborer, the technician, or the guard, comes from the northern provinces.
In conclusion, we say yet again that all the construction work in this project must be carried out under absolute secrecy.
From the aide to IRGC commander in the city of Al-Ahwaz, Hassan Jalaliyan.