For eight years, Ji Xingang worked relentlessly on his bomb defusing invention, modifying and improving the device. It was originally a hobby and he never thought it would be put to use. But the timing was perfect. He completed his project in March 2010 and in June 2010, someone from the public security bureau of Shijiazhuang, capital of Hebei province, found use for it.
"I was so excited but also nervous when I received the call," says the 38-year-old.
The caller needed Ji's device - a mobile water jet cutting machine - to detonate a 1.5-meter-long bomb covered with mud, which was discovered accidentally by an excavator driver while digging. He initially thought it was a rock.
After some investigations, the ammunition expert from Shijiazhuang public security bureau, Wu Yongjin, believed it belonged to the Flying Tigers, a famous American air force group which supported the Chinese army in its fight against the Japanese invaders during the War of Resistance against Japanese Aggression (1937-45).
It contained more than 100 kg of chemical explosive or trinitrotoluene.
"If it exploded, the blasting power could raze all the buildings within 600 square meters," Wu says. And that included residential buildings, a supermarket and a school.
The conventional way to defuse unexploded bombs was to transport them to remote localities and detonate them. But nobody could predict whether the bomb would explode during transportation.
Wu's unit transported the bomb to nearby open ground. More than 400 police personnel from the public security bureau were on guard everyday, to prevent anybody from approaching the bomb.
That was when Wu thought of Ji and his invention. Ji had obtained a national patent in 2009 for his invention, and had modified it further.