The HAF601 is a regulation in the People's Republic of China dealing with the manufacture of safety class equipment for the Chinese nuclear power market.
[1] This regulation also applies to international (i.e. non-Chinese) firms producing equipment from a factory within China.
For equipment manufactured outside of China and imported into the country, a HAF 604 certificate is required instead.
HAF stands for "he anquan fagui" (核安全法) and means "nuclear safety laws" in Chinese.
This should not be confused with the United States' National Nuclear Security Administration, which shares the same acronym.