A planned explosion blasted apart a dam spanning the Yalu River, a border river between China and the Democratic People's Republic of Korea (DPRK), Tuesday as work crews from the two countries race to upgrade a dilapidated hydropower station.

The blast successfully tore down the 273-meter back-up dam to Shuifeng hydropower station and enabled engineers to finish the renovation project on time -- or by June next year, said officials in charge of the project.

Shuifeng hydropower station was built more than 70 years ago and remains till now the largest hydropower station on the Yalu River. The dam can hold up to 14.7 billion cubic meters of water.

It has generated more than 260 billion kw/h of electricity since China and the DPRK co-launched a power company to operate the hydropower station in 1955, official data shows. The generated electricity is shared by the two countries.

The renovation project started in August 2009.