On Saturday, Israel's Channel 2 aired footage of the facility, which is situated in the region of Galilee in the north of Israel.
The outlet's Roni Daniel said the reactor was geared to provide both civilian and military services.
He also said he was not at liberty to reveal details about its performance.
"This reactor's role is to monitor nuclear experiments and activities taking place underground in the world," said a female expert working at the facility.
Israel began building the Dimona plutonium and uranium processing facility in the Negev desert in 1958. Tel Aviv is widely believed to be the sole owner of nuclear weapons in the Middle East.
Former US President Jimmy Carter says Israel has a nuclear arsenal that includes between 200 and 300 warheads. Decades of recurrent reporting and aerial footage have also established the possession of atomic arms by Israel.
Tel Aviv neither confirms nor denies having the weapons, while refusing to join the Nuclear Non-Proliferation Treaty (NPT).
