Police officers stopped a car in the province of Bolu, near the Atatürk Forest Park.
"During the search, 18.1 grams of californium, which is used in nuclear warheads and nuclear power plants, were seized. This substance, valued at $72 million, requires special authorisation to import, transport and store research," the administration said in a statement.
It is noted that five people were detained in this case and an investigation is underway.