Which country has launched Deep Underground and Ultra-low Radiation Background Facility (DUR

China's Deep Underground and Ultra-low Radiation Background Facility (DURF), the world's deepest underground laboratory, becomes operational.  Located 2,400 meters deep beneath Jinping Mountain in Liangshan Yi Autonomous Prefecture, Sichuan Province.  The DURF has a total room capacity of 330,000 cubic meters.  Scientists believe the lab enhances the global search for dark matter, a hypothetical form of matter that doesn't interact with light or the electromagnetic field.  It was launched after three years of upgrades and expansion, forming the second phase of China Jinping Underground Laboratory.  Constructed by Tsinghua University and Yalong River Hydropower Development Company, Ltd., the facility offers special testing conditions unavailable elsewhere.  The first phase of China Jinping Underground Laboratory, completed in 2010, contributed to scientific achievements in China's dark matter direct detection experiments.