Kim Jong Il, top leader of the Democratic People's Republic of Korea (DPRK), has written to the builders of Huichon Power Station, expressing his gratitude for their hard work. In the letter, Kim said he was touched by the fact that the builders, including soldier-builders, created the 'Huichon Speed' at the construction sites, where temperatures fell to 30 degrees below zero, local newspaper Rodong Simun reported on Wednesday. Kim also spoke highly of their revolutionary spirit. 'It is a very difficult and Herculean task to finish the vast projects in a matter of two to three years but it is quite possible to do so as long as there are the inexhaustible strength of the army and the people and the foundation of the powerful self-supporting industry,' he said. Huichon Power Station is the biggest power station being built in the DPRK in the past 20 years, reports said. Kim visited the project twice in 2009 and once this year. 