"As its chief designer, my feeling for the sub is like a father to his child. I not only love it, but also have full confidence in its quality," he told the crew. "Plus I can assist the captain in time should any problem occur."

The sub reached its depth limit and Huang became the first chief designer in the world to be onboard a sub for its test dive.

Huang also directed the upgrading of the first-generation of nuclear submarines, greatly improving the vessels' combat capability, organized advance research and provided constructive suggestions on new generations of subs. He still goes to the research institute to work and chat with young researchers.

"I'm positioning myself as a cheerleader now," Huang said. "I wave the flags, give cheers and support our younger scientists. When necessary, I can be their coach to offer some guidance."

Huang said he summarized his life in two words: obsession and joy.

"I have been madly obsessed with nuclear submarines in my life. It was my lifetime aspiration, with no regrets. And no matter how hard the life and work are, there is joy in pain," he said.

"Scientific research is boring, but it has infinite charm in the pursuit of truth and the unknown. There is endless joy once you can make a breakthrough."