No.404 Factory of China National Nuclear Corporation (中国核工业总公司第四零四厂), then the Ministry of Nuclear Industry, located in the Gobi desert in western part of Gansu province, is a closed town often called the nuclear town (核城). It is the biggest nuclear industry base in China and it was built in 1958. China built its first military nuclear reactor[27][28] there and 80% of the core parts for China's nuclear bombs were produced there.